Skip to main content
Download PDF

Monomodular and multifunctional processive endocellulases: implications for swine nutrition and gut microbiome

Animal Microbiome volume 6, Article number: 4 (2024) Cite this article

Abstract

Poor efficiency of dietary fibre utilization not only limits global pork production profit margin but also adversely affects utilization of various dietary nutrients. Poor efficiency of dietary nutrient utilization further leads to excessive excretion of swine manure nutrients and results in environmental impacts of emission of major greenhouse gases (GHG), odor, nitrate leaching and surface-water eutrophication. Emission of the major GHG from intensive pork production contributes to global warming and deteriorates heat stress to pigs in tropical and sub-tropical swine production. Exogenous fibre enzymes of various microbial cellulases, hemicellulases and pectinases have been well studied and used in swine production as the non-nutritive gut modifier feed enzyme additives in the past over two decades. These research efforts have aimed to improve growth performance, nutrient utilization, intestinal fermentation as well as gut physiology, microbiome and health via complementing the porcine gut symbiotic microbial fibrolytic activities towards dietary fibre degradation. The widely reported exogenous fibre enzymes include the singular use of respective cellulases, hemicellulases and pectinases as well as their multienzyme cocktails. The currently applied exogenous fibre enzymes are largely limited by their inconsistent in vivo efficacy likely due to their less defined enzyme stability and limited biochemical property. More recently characterized monomodular, multifunctional and processive endoglucanases have the potential to be more efficaciously used as the next-generation designer fibre biocatalysts. These newly emerging multifunctional and processive endoglucanases have the potential to unleash dietary fibre sugar constituents as metabolic fuels and prebiotics, to optimize gut microbiome, to maintain gut permeability and to enhance performance in pigs under a challenged environment as well as to parallelly unlock biomass to manufacture biofuels and biomaterials.

Introduction

Biomass materials, including cellulose, hemicelluloses, lignin and pectin, constitute dietary fibre components of plant and alge origins in animal and human nutrition. Biomass is produced at about 1.5-trillion dry metric tons yearly in the globe [1, 2]. Thus, for the long haul, global biomass replenishing production via recycling of the air-borne carbon dioxide (CO2), carried out by photosynthesis and driven by the solar energy, can potentially provide inexhaustible metabolizable and prebiotic sugars for nutrition, health promotion, food security and other basic organic monomer compounds for sustainable biofuels and biomaterials for mankind in development of the sustainable global bioeconomy, as further illustrated in Fig. 1.

Fig. 1
figure 1

An illustration of the major processes and biological steps in utilization and conversion of plant biomass materials and dietary fibre in providing renewable functional ingredients to animal feed industry and human food industry as well as renewable lignocellulosic biofuels and biomaterials for a sustainable global bio-economy with an emphasis on the essential roles of the plant biomass and dietary fibre degradation microbial cellulases as novel industrial enzymes with adaption from Fan et al. [2]

Full size image

Emission of the major greenhouse gases (GHG) has become the existential threat to the global community, e.g., the global warming-caused rising sea level and extreme weather patterns [3, 4]. The world agricultural food animal production accounts for 15–16% of the total human-induced GHG emission while pork production contributes at about 9% within the entire animal production sector [3, 4]. Global pork sector now represents about 35% of the overall meat production [5, 6]. As reviewed by Cheng et al. and Fan et al. [6, 7], the core global pork production economic sustainability issue is primarily attributed to the poor efficiency of dietary fibre utilization, which limits global pork production profit margin. Dietary fibre is well known as the anti-nutritive factors [6], thus the poor efficiency of dietary fibre utilization also adversely affects utilization efficiency of other dietary nutrients such as crude protein (CP), amino acid (AA), crude fat and minerals in swine. Furthermore, poor utilization efficiency of nutrients, including CP, AA and minerals, leads to some negative environmental sustainability concerns because of swine manure excessive excretion of carbon and nitrogenous compounds and various minerals [6]. These negative environmental issues include anaerobic biogenesis and emission of the potent major GHG of methane (CH4) and nitrous oxide (N2O) and volatile odor compounds from swine manure slurry storages as well as nitrate leaching and phosphorus run-off associated with swine manure [6]. Therefore, it is imperative to improve efficiency of dietary fibre utilization for the development of sustainable global pork production.

Because of the economic constraint, a significant proportion of the world swine production is operated under the challenged environmental conditions such as unsanitary barns for housing pigs under chronic heat stress in the summer months in the tropical and sub-tropical regions including some of the large-economy and very large swine production countries [8,9,10]. Increases in emission of the major GHG from intensive pork production further contribute to the global warming effect and further deteriorate heat stress to pigs under the tropical and sub-tropical swine production setting [9]. As reviewed by Cheng et al. and Fan et al. [6, 7], one important strategy for mitigation is to further develop efficacious exogenous fibre enzymes for the swine industry.

Here in this paper, we aim to conduct a critical reviewing of the following aspects: firstly, the current understanding of limiting factors affect biomass processing and dietary fibre utilization; secondly, we review the recent discovery and characterization of the newly emerged monomodular, multifunctional and processive endoglucanases; we also critically review the up-to-dated literature of efficacy, nutrition and gut physiological responses of currently existing exogenous fibre enzymes of various microbial cellulases, hemicellulases and pectinases that are applied for improving growth performance, nutrient utilization, intestinal fermentation as well as gut physiology, microbiome and health in pigs; and lastly we assess the limitations of the currently reported exogenous fibre enzymes and the potential applications of a new group of monomodular, multifunctional and processive designer cellulases to modulate growth performance, nutrient utilization, intestinal physiology and gut microbiome as novel microbial gut enzyme modifier feed additives and to engage in industrial biomass processing as newly emerging biocatalysts.

Limiting factors in biomass and dietary fibre utilization

Biomass processing and dietary fibre utilization are commonly hindered by the plant cell wall recalcitrance that is collectively referring to the natural resistance of cell wall materials to microbial enzymatic deconstruction [2, 11]. The first layer of the biomass and fibre recalcitrance is reflected by its limited surface porosity diameter ranging 3.5–5.2 nm that is formed through cross-linking between the polyphenolic lignin and various hemicelluloses [2, 12]. Most microbial cellulases such as the bi-modular free cellulases and cellulosomes have an enzyme molecular size or dimension much larger than this upper porosity diameter size range (3.5–5.2 nm) that natural biomass and fibre materials possess, including various feedstuffs of the plant origin, thus limiting their accessibility to the hydrolytic cellulose surface area [2, 13]. The second layer of the natural plant cell wall recalcitrance is that natural cellulose polymers are further bundled up in a strong quasi-crystalline structure consisting of macrofibril, microfibril and elementary fibril units that are resistant to cellulosic enzyme degradation. As reviewed by Lynd et al. [13] and Fan et al. [2], most natural microbial cellulases such as free cellulases and cellulosomes have very limited and extremely low hydrolytic activities towards the natural crystalline cellulose in biomass materials and dietary fibre in comparison with hydrolytic activities towards other plant polymers such as starches and hemicelluloses.

As shown in Fig. 1, the first layer of the fibre biomass recalcitrance and protective sheath can be tackled via biological processing strategies, i.e., commercial application of various exogenous hemicellulases and pectinases under in vitro feed processing conditions and in vivo via dietary supplementation of exogenous fibre enzymes in swine nutrition, whereas use of lignin-degradation enzymes is very limited mainly due to the scarcity of lignin-degradation enzymes in commercial supplies and from the natural environment [2]. While plant feed material origins of the applicable prebiotics are the various hemicellulose-derived oligosaccharides, complete microbial hemicellulase enzymatic hydrolysis under in vivo and in vitro conditions would release their corresponding monosaccharides of xylose, mannose and arabinose as the typical monosaccharide prebiotic sugars for potentially promoting prebiotic bacterial proliferation (Fig. 1). The first layer of the fibre biomass recalcitrance can also be alternatively removed via chemical-physical processing, resulting in purified crystalline cellulose biomass without lignin. And lignin residuals can behave as a group of inhibitors to cellulases and hemicellulases in subsequent biomass processing steps and to endogenous digestive enzymes and exogenous enzymes in the digestive tracts of animals and humans [6]. Under this context, Solka-Floc is a typical commercially available pure crystalline cellulose product that is chemical-physical processed from economical biomass materials such as wheat straw and woodchips and this Solka-Floc cellulose has been widely used in nutrition research with applications for pigs and humans [14]. However, Solka-Floc is too expensive to be used at significant levels in commercial swine production. It is conceivable from the processed Solka-Floc cellulose example that in vitro chemical-physical processing of dietary fibre biomass materials for swine nutrition and production is likely limited in two major aspects, including 1) the high-processing cost and ii) the potential nutritive value loss of various hemicellulose-derived monosaccharide sugars as potential dietary prebiotic sugars that will be irreversibly lost and cannot be recovered from the pre-treatment alkaline and/or acidic solutions.

Furthermore, as shown in Fig. 1, the synergistical hydrolyses by the microbial cellulases of endocellulases and exo-cellulases and/or processive endocellulases would ensure the degradation of cellulose polymer into soluble cellodextrin including cellobiose without resulting in a significant amount of 1,4-ß-glucan as intermediate microbial hydrolytic products [2, 13]. And the final breakdown of cellodextrin into free glucose by microbial ß-glucosidases in the porcine gut lumen and in biomass processing is not considered to be a rate-limiting or bottleneck step [2, 13]. As illustrated in Fig. 1, ß-glucan, including 1,4-ß-glucan and branched-glucan, and pectin are regarded as the classic viscous soluble fibre components and are thus the well-recognized anti-nutritive factors in swine nutrition [6]. Thus, as reviewed by Lynd et al. [13] and Fan et al. [2], continued discovery and biological engineering of highly active and synergistical microbial cellulases of endocellulases and exo-cellulases, particularly very active processive endocellulases that hydrolyze natural crystalline cellulose, is the key to conquer recalcitrance in biomass material processing and efficient dietary fibre utilization. Without a doubt, the discovery and development of efficacious cellulases is a crucial and transformative area of research, considering its profound potential to resolve the global social, economic and environmental issues for sustainable development.

Discovery of the porcine gut symbiotic bacterial multi-functional processive endocellulase

The digestive utilization of dietary fibre in pigs is, in part, contributed by gut microbiota and is regulated at the level of gut microbiome [15, 16] with insoluble fibre digestibility being relatively low and variable at about 23–60% [6, 17, 18]. Commercial exogenous fibre enzymes presently used in swine nutrition are primarily tailored from the light industrial and biofuel enzymes that are characterized and engineered from Trichoderma, Humicola insolens and Aspergillus fungal species and the Bacillus sp. with limited intrinsic enzyme structure and functionality specificity in porcine dietary fibre degradation [2, 7, 19]. The endpoint responses of in vivo efficacy of the current exogenous fibre enzymes are frequently inconsistent and at variable levels of improvements particularly for cellulose degradation in pigs and this is also likely due to the poor or less defined fibre enzyme stability [17, 19]. Clearly, there is a need to further develop more efficacious cellulases to improve efficiency of dietary fiber utilization in commercial swine production.

When we broadly examined microbial systems that had active fibre biomass degradation activities to search for novel microbial cellulase genes, we were somehow surprised to appreciate the relatively high crystalline cellulose digestibility of 62 and 82%, respectively, measured at the distal ileal and the fecal level in growing pigs when fed a high-fat and animal protein-based diet with 10% Solka-Floc as the sole dietary fibre in our previous study [14]. We were able to further show that the fractional Solka-Floc cellulose degradation rates at the distal ileal (39%/h) and at the fecal (1.9%/h) levels in the growing pigs were much higher than the fractional Solka-Floc cellulose degradation rate (1.2%/h) in the cow rumen; and these comparisons suggested that the porcine gut microbiome would be a much faster turnover microbial eco-system and possess novel genes encoding highly active cellulases [20]. We also knew that majority of the porcine gut symbiotic bacteria were not culturable to mine novel and efficacious target bacterial cellulases, thus we had chosen the metagenomic approaches. The metagenomic sequencing and cataloguing-based approach, as reported by Hess et al. [21], was also not financially feasible for our research program [22]. We had chosen the metagenomic functional expression screening library as a feasible approach, as further illustrated in Fig. 2. We established a metagenomic functional cellulase expression screening library through using the porcine gut metagenomic DNA purified from the distal ileo-cecal digesta of growing pigs fed the Solka-Floc cellulose-based diet for 4 wk [22]. A positive clone harboring the glycosyl hydrolase family-5 (GH5) endocellulase gene, referred to as GH5-p4818Cel5_2A, showed a superb cellulase activity and was effectively screened out of the established porcine hindgut microbial metagenomic expression library [20]. The porcine gut microbial GH5-p4818Cel5_2A endocellulase activity was 307– to 1079–fold higher than the activities of the endocellulases that were characterized from the ruminal Fibrobacter succinogenes as reviewed by Fan et al. [2]. And these comparisons are consistent with the above-compared patterns of the fractional Solka-Floc cellulose degradation rates between the pig and the cow.

Fig. 2
figure 2

An illustrated road-map of using a metagenomic expression screening library approach in the discovery and characterization of the novel biomass and fibre degradation cellulases from the porcine gut microbiome

Full size image

This porcine gut symbiotic microbial GH5-p4818Cel5_2A processive endocellulase has matched well in several aspects with another unique GH5 processive endoglucanase, referred to as GH5-tCel5A1, that was originated and then truncated from the extremely thermophilic Thermotoga maritima [2, 23]. Both GH5-p4818Cel5_2A and GH5-tCel5A1 are characterized as monomodular endocellulases without requiring a carbohydrate-binding domain for the hydrolysis of crystalline substrates and have relatively small molecular weights with an estimated spherical diameter at about or < 4.6 nm [2, 23]. Both GH5-p4818Cel5_2A and GH5-tCel5A1 endocellulases have an optimal pH at the slightly acidic pH and act as processive β-1,4-endoglucanases [2, 23]. The porcine GH5-p4818Cel5_2A is a mesophilic cellulase enzyme, whereas the GH5-tCel5A1 is a thermophilic cellulase enzyme [2, 23]. Both endocellulases are active in hydrolyzing natural crystalline and pre-treated cellulosic substrates and have multifunctionality towards several hemicelluloses including β-glucans, xylan, xylogulcans, mannans, galactomannans and glucomannans [2, 23]. Cheng et al. [7] further showed that both GH5-p4818Cel5_2A and GH5-tCel5A1 endocellulases had similar enzyme activities (0.0090 vs. 0.0080 µmol/min•mg protein) towards the assay crystalline cellulose substrate Avicel at the porcine gut physiological temperature and pH of 6.0. However, both GH5-p4818Cel5_2A and GH5-tCel5A1 endocellulases were susceptible to auto-oxidation by the airborne O2 and were unstable under the gastric acidic-pH and proteases conditions [7]. Thus, post-fermentation enzyme processing such as coating and/or site-specific mutagenesis enzyme protein engineering may be further needed in order to further optimize both the GH5-p4818Cel5_2A and GH5-tCel5A1 processive endocellulases for their future commercial applications.

Current fibre enzymes and emerging endocellulases in swine nutrition and gut microbiome

It has been well documented that pigs housed under unsanitary conditions and chronic a heat stress environment experience changes in systemic immunity and have decreased growth performance and productivity [8,9,10, 24]. Pigs and other species of animals and humans under unsanitary housing and chronic heat stress environments typically display changes in intestinal contents of microbial metabolites, gut microbiome and increased gut permeability [10, 24, 25,26,27,28,29]. As shown in Fig. 3, dietary supplementation of trophic AA as well as various probiotics, prebiotics and synbiotics have been proposed and reviewed to improve gut mucosal morphology, optimize gut micro-environment and to maintain gut permeability [10, 30, 31]. Nevertheless, holistic thinking and systemic approaches need to be further taken to curb the human-induced GHG emission and the global warming-effect trend through focusing on developing concrete novel cellulase biotechnologies to improve efficiency of dietary fibre utilization by the porcine gut in swine production and biomass processing for the entire overall bioeconomy sectors.

Fig. 3
figure 3

Proposed mechanistic contributions of exogenous fibre degradation microbial enzymes along with prebiotics and trophic amino acids as essential gut modifiers and/or therapeutics in modulation of the porcine gut microbiome, gut permeability and growth performances in adaptation to chronic heat stress with adaption from Fan et al. [6]

Full size image

Through the past decade of multi-disciplinary research efforts, both GH5-p4818Cel5_2A and GH5-tCel5A1 have been discovered, developed and characterized as multifunctional endocellulases and are known to act uniquely as monomodular and processive endocellulases in hydrolyzing dietary fibre and other biomass origins of natural cellulose materials into soluble cello-dextrin and D-glucose as well as degrading various hemicelluloses into hemicellulose-derived oligosaccharides and sugars that have prebiotic effects [2, 7, 20, 22, 23]. According to Gibson and Roberfroid [32], fructooligosaccharides were the only defined original prebiotics back then. The prebiotic list has been further expanded to also include inulin, resistant starch as well as various hemicellulose-derived oligosaccharides and their constituent monosaccharide prebiotic sugars that exert the prebiotic effects via enhancing gut beneficial bacterial proliferation, host immunity and other physiological and health parameters [33, 34]. Although ß-glucans and pectin are the common viscous soluble fibre components in swine feeds, these two viscous soluble fibre components are not regarded as prebiotics in swine nutrition [33]. Hayhoe et al. [10] and Ringseis and Eder [31] reviewed that prebiotics are the effective strategies to prevent gut dysbiosis, optimize gut microbiome and maintain gut permeability in pigs under unsanitary housing and chronic heat stress.

The current technologies to provide the hemicellulose-derived oligosaccharide prebiotics and their constituent monosaccharide prebiotic sugars to swine diets include dietary supplementation of various exogenous microbial cellulases and hemicellulases and through biological processing of biomass materials [33, 35]. We have thoroughly reviewed a total of 49 original efficacy research papers published during 2004–2022 in the area of dietary supplementation of various exogenous microbial cellulases, hemicellulases and pectinases, including 15 papers in the post-weaned pigs [36, 37] and 34 papers in the growing-finishing pigs [38, 39]. One study reported the use of exogenous xylanase originating from the thermophilic Thermopolyspora flexuos [40]. Almost all of our other reviewed studies reported the use of their exogenous fibre enzymes with the genes originating from the mesophilic fungal species of Aspergillus aculeatus, Aspergillus niger, Aspergillus sulphurous, Fusarium verticilloide, Trichoderma longibrachiatumi, Trichoderma reesei and Talaromyces versatilis [38, 41,42,43,44] as well as the mesophilic bacterial species of Bacillus subtilis WL-1 and Penicillium funiculosum [45, 46]. Thus, their study test enzymes were supplemented in the mash form but not pelleted diets. Most of our reviewed these papers reported the use of singular or combined hemicellulases of ß-glucanases, ß-mannanase and xylanases [39, 40, 42, 43, 47,48,49,50]. Whereas some studies used the combined multienzyme cocktails of cellulases, various hemicellulases and pectinases [38, 51,52,53,54] with showing inconsistent response endpoints in vivo efficacy in growth performance, fibre and other nutrient digestibility, intestinal physiological as well as microbial metabolite and population abundances in the post-weaned, growing-finishing pigs and sows [38, 51,52,53,54]. The literature reported total tract pectin digestibility was relatively high ranging from 77 to 79%, as indicated by changes in uronic acid digestibility in growing pigs and gestation sows [54]. Dietary supplementation of pectinases along with other multienzymes could improve the total tract pectin digestibility by 4–5% in growing pigs and gestation sows as indicated by changes in the digestibility of uronic acids including the pectin constituent galacturonic acid [54]. Thus, the lack of consistent efficacy endpoint responses in the currently reported exogenous fibre enzymes are likely due to their less defined in vitro and in vivo enzyme stability and limited fibre enzyme biochemical property specific to the common swine diets.

Under this context, the afore-discussed recently emerged monomodular and multifunctional processive endocellulases of GH5-p4818Cel5_2A and GH5-tCel5A1 have three potential advantages to become the potent next-generation designer exogenous fibre biocatalysts. First, they are globular and are much smaller in molecular size, thus highly penetrating into biomass pores for their hydrolytic action; second, these two cellulases are multifunctional and each enzyme molecule can catalyze multiple cellulose and hemicellulose substrates without the need to use multiple enzymes to be economical; and third, these two cellulases are well characterized for their limited in vitro and in vivo enzyme stability and functional properties for potential further in vivo efficacy application optimization through use of commercially available enzyme coating polymer compounds. Therefore, further research efforts will be needed to enable these cellulase enzymes to emerge as novel biocatalysts for biomass processing to produce the hemicellulose-derived oligosaccharide and/or their constituent monosaccharide sugar prebiotics and as new porcine gut exogenous microbial feed enzyme modifier additives to optimize gut microbiome, maintain gut functionality and enhance growth performance and productivity for pigs through exerting prebiotic effects in adaptation to unsanitary housing conditions and a chronic heat stress environment under the tropical and sub-tropical swine production setting.

Conclusion

Poor efficiency of dietary fibre utilization is the recognized core issue of the pork production sustainability. Poor dietary fibre utilization not only limits global pork production profit margin but also collectively contributes to significant anaerobic biogenesis and emission of the potent GHG and the global warming effect. Optimization and development of more efficacious next-generation designer multifunctional monomodular processive cellulases will enable these newly emerging biocatalysts to unlock biomass for bio-processing and as exogenous feed enzyme gut modifier additives. We anticipate that these newly developed gut modifier feed enzyme additives can unleash dietary fibre sugar constituents as metabolic fuels and prebiotics to optimize gut microbiome and maintain gut functionality, nutrition, growth performance and productivity in pigs for adaptation to challenged global swine production environmental conditions such as unsanitary housing and chronic heat stress.

Data availability

Not applicable.

Abbreviations

AA:

Amino acid

CH4 :

Methane

CO2,:

Carbon dioxide

CP:

Crude protein

GH5:

Glycosyl hydrolase family-5

GHG:

Greenhouse gases

N2O:

Nitrous oxide

References

  1. Vanholme B, Desmet T, Ronsse F, Rabaey K, Van Breusegem F, De Mey M, Soetaert W, Boerjan W. Towards a carbon-negative sustainable bio-based economy. Front Plant Sci. 2013;4:174.

    Article  PubMed  PubMed Central  Google Scholar 

  2. Fan MZ, Wang W, Cheng L, Chen J, Fan W, Wang M. Metagenomic discovery and characterization of multi-functional and monomodular processive endoglucanases as biocatalysts. Appl Sci. 2021;11:5150.

    Article  CAS  Google Scholar 

  3. Gerber PJ, Steinfeld H, Henderson B, Mottet A, Opio C, Dijkman J, Falcucci A, Tempio G. Tackling climate change through livestock– a global assessment of emissions and mitigation opportunities. Rome: Food and Agriculture Organization (FAO) of the United Nations; 2013.

    Google Scholar 

  4. Grossi GP, Goglio AV, Williams AG. Livestock and climate change: impact of livestock on climate and mitigation strategies. Anim Front. 2019;9:69–76.

    Article  PubMed  Google Scholar 

  5. VanderWaal K, Deen J. Global trends in infectious diseases of swine. Proc Natl Acad Sci USA. 2018;115:11495–500.

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  6. Fan MZ, Kerr B, Trabue S, Yin X, Yang Z, Wang W. Chapter 20. Swine nutrition and environment. In: Sustainable Swine Nutrition, 2nd edition, Chiba, L. I. Hoboken, NJ: John Wiley & Sons, Inc. 2023;365–412.

  7. Cheng L, Wang W, Fan MZ. Characterization of in vitro stability for two processive endoglucanases as exogenous fibre biocatalysts in pig nutrition. Sci Rep. 2022;12:9135.

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  8. Pearce SC, Mani V, Boddicker RL, Johnson JS, Weber TE, Ross JW, Rhoads RP, Baumgard LH, Gabler NK. Heat stress reduces intestinal barrier integrity and favors intestinal glucose transport in growing pigs. PLoS ONE. 2013;8(8):e70215.

    Article  ADS  CAS  PubMed  PubMed Central  Google Scholar 

  9. Mayorga EJ, Renaudeau D, Ramirez BC, Ross JW, Baumgard LH. Heat stress adaptations in pigs. Anim Front. 2018;9:54–61.

    Article  PubMed  PubMed Central  Google Scholar 

  10. Hayhoe MAN, Archbold T, Wang Q, Yang X, Fan MZ. Prebiotics and β-Glucan as gut modifier feed additives in modulation of growth performance, protein utilization status and dry matter and lactose digestibility in weanling pigs. Front Anim Sci. 2022;3:855846.

    Article  Google Scholar 

  11. Himmel ME, Ding SY, Johnson DK, Adney WS, Nimlos MR, Brady JW, Foust TD. Biomass recalcitrance: engineering plants and enzymes for biofuels production. Sci. 2007;315:804–7.

    Article  ADS  CAS  Google Scholar 

  12. Carpita N, Sabularse D, Montezinos D, Delmer DP. Determination of the pore size of cell walls of living plant cells. Sci. 1979;205:1144–7.

    Article  ADS  CAS  Google Scholar 

  13. Lynd LR, Weimer PJ, Van Zyl WH, Pretorius IS. Microbial cellulose utilization: fundamentals and biotechnology. Microbiol Mol Biol Rev. 2002;66:506–77.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  14. Rideout TC, Liu Q, Wood P, Fan MZ. Nutrient utilization and intestinal fermentation are differentially affected by the consumption of resistant starch varieties and conventional fibers in pigs. Br J Nutr. 2008;99:984–92.

    Article  CAS  PubMed  Google Scholar 

  15. Varrel VH, Yen JT. Microbial perspective on Fiber utilization by Swine. J Anim Sci. 1997;75:2715–22.

    Article  Google Scholar 

  16. Flint HJ, Bayer EA, Rincan MT, Lamed R, White BA. Polysaccharide utilization by gut bacteria: potential for new insights from genomic analysis. Nat Rev Microbiol. 2008;6:121–31.

    Article  CAS  PubMed  Google Scholar 

  17. Kerr BJ, Shurson GC. Strategies to improve fiber utilization in swine. J Anim Sci Biotechnol. 2013;4:112–23.

    Article  Google Scholar 

  18. Woyengo TA, Beltranena E, Ziglstra RT. Controlling feed cost by including alternative ingredients into pig diets: a review. J Anim Sci. 2014;92:1293–305.

    Article  CAS  PubMed  Google Scholar 

  19. Adeola O, Cowieson AJ. BOARD-INVITED REVIEW: opportunities and challenges in using exogenous enzymes to improve nonruminant animal production. J Anim Sci. 2011;89:3189–218.

    Article  CAS  PubMed  Google Scholar 

  20. Wang W, Archbold T, Lam JS, Kimber MS, Fan MZ. A processive endoglucanase with multi-substrate specificity is characterized from porcine gut microbiota. Sci Rep. 2019;9:13630.

    Article  ADS  PubMed  PubMed Central  Google Scholar 

  21. Hess MA, Sczyrba R, Egan TW, Kim H, Chokhawala G, Schroth S, Luo DS, Clark F, Chen T, Zhang RI, Mackie LA, Pennacchio SG, Tringe A, Visel T, Woyke Z, Rubin EM. Rumen Sci. 2011;331:463–7. Metagenomic discovery of biomass-degrading genes and genomes from cow.

    Article  CAS  Google Scholar 

  22. Wang W, Archbold T, Kimber MS, Li J, Lam JS, Fan MZ. The porcine gut microbial metagenomic library for mining novel cellulases established from growing pigs fed cellulose-supplemented high-fat diets. J Anim Sci. 2012;90:400–2.

    Article  PubMed  Google Scholar 

  23. Basit A, Akhtar MW. Truncation of the processive Cel5A of Thermotoga maritima results in soluble expression and several Fold increase in activity. Biotechnol Bioeng. 2018:1675–84.

  24. Xiong Y, Cao S, Xiao H, Wu Q, Yi H, Jiang Z, Wang L. Alterations in intestinal microbiota composition coincide with impaired intestinal morphology and dysfunctional ileal immune response in growing-finishing pigs under constant chronic heat stress. J Anim Sci Biotechnol. 2022;13(1):1.

    Article  PubMed  PubMed Central  Google Scholar 

  25. Koch F, Thom U, Albrecht E, Weikard R, Nolte W, Kuhla B, Kuehn C. Heat stress directly impairs gut integrity and recruits distinct immune cell populations into the bovine intestine. Proc. Natl. Acad. Sci. USA. 2013;116 (21):10333–10338.

  26. Hylander BL, Repasky EA. 2019. Temperature as a modulator of the gut microbiome: what are the implications and opportunities for thermal medicine? Int. J. Hyperthermia. 2019;36:83–89.

  27. Lian P, Braber S, Garssen J, Wichers HJ, Folkerts G, Fink-Gremmels J, Varasteh S. Beyond heat stress: intestinal integrity disruption and mechanism-based intervention strategies. Nutrients. 2020;12(3):734.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  28. Wen C, Wei S, Zong X, Wang Y, Jin M. Microbiota-gut-brain axis and nutritional strategy under heat stress. Anim Nutr. 2021;7(4):1329–36.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  29. Xia B, Wu W, Fang W, Wen X, Xie J, Zhang H. Heat stress-induced mucosal barrier dysfunction is potentially associated with gut microbiota dysbiosis in pigs. Anim Nutr. 2022;8(1):289–99.

    Article  CAS  PubMed  Google Scholar 

  30. Morales A, González F, Bernal H, Camacho RL, Arce N, Vásquez N, González-Vega JC, Htoo JK, Viana MT, Cervantes M. Effect of arginine supplementation on the morphology and function of intestinal epithelia and serum concentrations of amino acids in pigs exposed to heat stress. J Anim Sci. 2021;99(9):kab179.

    Article  Google Scholar 

  31. Ringseis R, Eder K. Heat stress in pigs and broilers: role of gut dysbiosis in the impairment of the gut-liver axis and restoration of these effects by probiotics, prebiotics and synbiotics. J Anim Sci Biotechnol. 2022;13(1):126.

    Article  PubMed  PubMed Central  Google Scholar 

  32. Gibson GR, Roberfroid MB. Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics. J Nutr. 1995;125:1401–12.

    Article  CAS  PubMed  Google Scholar 

  33. Fan MZ. Chapter 16. Swine Nutrition and Environment. Sustainable Swine Nutrition, Chiba, LI. Hoboken, NJ: John Wiley & Sons, Inc; 2013. pp. 365–411.

    Chapter  Google Scholar 

  34. Jana UK, Kango N, Pletschke B. Hemicellulose-derived oligosaccharides: emerging prebiotics in disease alleviation. Front Nutr. 2021;27(8):670817.

    Article  Google Scholar 

  35. Rajan K, D’Souza DH, Kim K, Choi JM, Elder T, Carrier DJ, Labbé N. Production and characterization of high value prebiotics from biorefinery-relevant feedstocks. Front Microbiol. 2021;12:675314.

    Article  PubMed  PubMed Central  Google Scholar 

  36. Diebold G, Mosenthin R, Piepho HP, Sauer WC. Effect of supplementation of xylanase and phospholipase to a wheat-based diet for weanling pigs on nutrient digestibility and concentrations of microbial metabolites in ileal digesta and feces. J Anim Sci. 2004;82(9):2647–56.

    Article  CAS  PubMed  Google Scholar 

  37. Das TK, Debnath J, Chakraborty S, Debnath BS. The effects of enzyme complex on performance and nutrient digestibility of weaned pigs in North Eastern Region of Tripura. J Anim Res. 2022;12(03):337–42.

    Article  Google Scholar 

  38. Fang ZF, Peng J, Liu ZL, Liu YG. Responses of non-starch polysaccharide-degrading enzymes on digestibility and performance of growing pigs fed a diet based on corn, soya bean meal and Chinese double-low rapeseed meal. J Anim Physiol Anim Nutr (Berl). 2007;91(7–8):361–8.

    Article  CAS  PubMed  Google Scholar 

  39. Oliveira MSF, Espinosa CD, Blavi L, Mortada M, Almeida FN, Stein HH. Effects of a mixture of xylanase and glucanase on digestibility of energy and dietary fiber in corn- or sorghum based diets fed to growing pigs. Anim Feed Sci Technol. 2022;294:15485.

    Article  Google Scholar 

  40. Boontiam W, Phaenghairee P, Van Hoeck V, Vasanthakumari BL, Somers I, Wealleans A. Xylanase impact beyond performance: effects on gut structure, faecal volatile fatty acid content and ammonia emissions in weaned piglets fed diets containing fibrous ingredients. Anim (Basel). 2022;12(21):3043.

    Google Scholar 

  41. Ngoc TTB, Len NT, Ogle B, Lindberg JE. Influence of particle size and multi-enzyme supplementation of fibrous diets on total tract digestibility and performance of weaning (8–20kg) and growing (20–40kg) pigs. Anim Feed Sci Technol. 2011;169(1–2):86–95.

    Article  CAS  Google Scholar 

  42. Lv JN, Chen YQ, Guo XJ, Piao XS, Cao YH, Dong B. Effects of supplementation of β-mannanase in corn-soybean meal diets on performance and nutrient digestibility in growing pigs. Asian-Australas J Anim Sci. 2013;26(4):579–87.

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  43. Ndou SP, Kiarie E, Agyekum AK, Heo JM, Romero LF, Arent S, Lorentsen R, Nyachoti CM. Comparative efficacy of xylanases on growth performance and digestibility in growing pigs fed wheat and wheat bran- or corn and corn DDGS-based diets supplemented with phytase. Anim Feed Sci Technol. 2015;209:230–9.

    Article  CAS  Google Scholar 

  44. Sun H, Cozannet P, Ma R, Zhang L, Huang YK, Preynat A, Sun L. Effect of concentration of arabinoxylans and a carbohydrase mixture on energy, amino acids and nutrients total tract and ileal digestibility in wheat and wheat by-product-based diet for pigs. Anim Feed Sci Technol. 2020;262:114380.

    Article  CAS  Google Scholar 

  45. Reilly P, Sweeney T, O’Shea C, Pierce KM, Figat S, Smith AG, Gahan DA, O’Doherty JV. The effect of cereal-derived beta-glucans and exogenous enzyme supplementation on intestinal microflora, nutrient digestibility, mineral metabolism and volatile fatty acid concentrations in finisher pigs. Anim Feed Sci Technol. 2010;158(3–4):165–76.

    Article  CAS  Google Scholar 

  46. Mok CH, Kong C, Kim BG. Combination of phytase and β-mannanase supplementation on energy and nutrient digestibility in pig diets containing palm kernel expellers. Anim Feed Sci Technol. 2015;205:116–21.

    Article  CAS  Google Scholar 

  47. Smith AG, Reilly P, Sweeney T, Pierce KM, Gahan DA, Callan JJ, O’Doherty JV. The effect of cereal type and exogenous enzyme supplementation on intestinal microbiota and nutrient digestibility in finisher pigs. Livest Sci. 2010;133(1–3):148–50.

    Article  Google Scholar 

  48. Agyekum AK, Regassa A, Kiarie E, Nyachoti CM. Nutrient digestibility, digesta volatile fatty acids, and intestinal bacterial profile in growing pigs fed a distillers dried grains with solubles containing diet supplemented with a multi-enzyme cocktail. Anim Feed Sci Technol. 2016;212:70–80.

    Article  CAS  Google Scholar 

  49. Rho Y, Wey D, Zhu C, Kiarie E, Moran K, van Heugten E, de Lange CFM. Growth performance, gastrointestinal and digestibility responses in growing pigs when fed corn-soybean meal-based diets with corn DDGS treated with fiber degrading enzymes with or without liquid fermentation. J Anim Sci. 2018;96(12):5188–97.

    PubMed  PubMed Central  Google Scholar 

  50. Kiarie EG, Parenteau IA, Zhu C, Ward NE, Cowieson AJ. Digestibility of amino acids, energy, and minerals in roasted full-fat soybean and expelled-extruded soybean meal fed to growing pigs without or with multienzyme supplement containing fiber-degrading enzymes, protease, and phytase. J Anim Sci. 2020;98(6):kaa174.

    Article  Google Scholar 

  51. Omogbenigun FO, Nyachoti CM, Slominski BA. Dietary supplementation with multienzyme preparations improves nutrient utilization and growth performance in weaned pigs. J Anim Sci. 2004;82(4):1053–61.

    Article  CAS  PubMed  Google Scholar 

  52. Carneiro MSC, Lordelo MM, Cunha LF, Freire JPB. Effects of dietary fibre source and enzyme supplementation on faecal apparent digestibility, short chain fatty acid production and activity of bacterial enzymes in the gut of piglets. Anim Feed Sci Technol. 2008;146:124–36.

    Article  CAS  Google Scholar 

  53. Li Q, Gabler NK, Loving CL, Gould SA, Patience JF. A dietary carbohydrase blend improved intestinal barrier function and growth rate in weaned pigs fed higher fiber diets. J Anim Sci. 2018;96(12):5233–43.

    PubMed  PubMed Central  Google Scholar 

  54. Shipman GL, Perez-Palencia JY, Rogiewicz A, Patterson R, Levesque CL. Evaluation of multienzyme supplementation and fiber levels on nutrient and energy digestibility of diets fed to gestating sows and growing pigs. J Anim Sci. 2023;101:1–11.

    Article  Google Scholar 

Download references

Acknowledgements

JC and WF received the International Ph.D. student Tuition Waiver scholarships from the University of Guelph Graduate Studies. JC also received a major scholarship from the China Scholarship Council.

Funding

Related research was supported by projects from the Natural Science and Engineering Research Council (NSERC) of Canada; Agriculture, Agri-Food Canada (AAFC) Swine Innovation Porc (SIP) Swine Cluster Program; and the Metagen Enzyme Corporation (to MZF).

Author information

Authors and Affiliations

  1. Department of Animal Biosciences, University of Guelph, N1G 2W1, Guelph, ON, Canada

    Ming Z. Fan, Laurence Cheng, Min Wang, Jiali Chen, Wenyi Fan, Fatmira Jashari & Weijun Wang

  2. One Health Institute, University of Guelph, N1G 2W1, Guelph, ON, Canada

    Ming Z. Fan

  3. Transpharmation LTD, N1M 2W3, Fergus, ON, Canada

    Wenyi Fan

  4. Department of Human Health and Nutritional Sciences, University of Guelph, N1G 2W1, Guelph, ON, Canada

    Fatmira Jashari

  5. The Canadian Food Inspection Agency Ontario Operation, N1G 4S9, Guelph, ON, Canada

    Weijun Wang

Authors
  1. Ming Z. Fan
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Laurence Cheng
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Min Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Jiali Chen
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Wenyi Fan
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Fatmira Jashari
    View author publications

    You can also search for this author in PubMed Google Scholar

  7. Weijun Wang
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

MZF wrote the manuscript; MZF and WW made the graphical figures. All authors, revised read/or approved the final manuscript.

Corresponding author

Correspondence to Ming Z. Fan.

Ethics declarations

Ethics approval and consent to participate

Not applicable.

Consent for publication

Not applicable.

Competing interests

MZF is the co-founder and board chairman of the Metagen Enzyme Corporation, a company which is working to commercialize novel enzymes for use in food animal agriculture, companion animals, human nutraceuticals & foods and in medical indications. And he had an active grant-in-aid research funding at the University of Guelph from the Metagen Enzyme Corporation from which both MW and WW were supported for the duration of their collaborating research. WW is also a board member of the Metagen Enzyme Corporation. The other authors declare that no competing interests exist.

Additional information

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Fan, M.Z., Cheng, L., Wang, M. et al. Monomodular and multifunctional processive endocellulases: implications for swine nutrition and gut microbiome. anim microbiome 6, 4 (2024). https://doi.org/10.1186/s42523-024-00292-w

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1186/s42523-024-00292-w

Keywords

Animal Microbiome

ISSN: 2524-4671