1
|
Ravn JL, Ristinmaa AS, Coleman T, Larsbrink J, Geijer C. Yeasts Have Evolved Divergent Enzyme Strategies To Deconstruct and Metabolize Xylan. Microbiol Spectr 2023; 11:e0024523. [PMID: 37098941 PMCID: PMC10269524 DOI: 10.1128/spectrum.00245-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 04/08/2023] [Indexed: 04/27/2023] Open
Abstract
Together with bacteria and filamentous fungi, yeasts actively take part in the global carbon cycle. Over 100 yeast species have been shown to grow on the major plant polysaccharide xylan, which requires an arsenal of carbohydrate active enzymes. However, which enzymatic strategies yeasts use to deconstruct xylan and what specific biological roles they play in its conversion remain unclear. In fact, genome analyses reveal that many xylan-metabolizing yeasts lack expected xylanolytic enzymes. Guided by bioinformatics, we have here selected three xylan-metabolizing ascomycetous yeasts for in-depth characterization of growth behavior and xylanolytic enzymes. The savanna soil yeast Blastobotrys mokoenaii displays superior growth on xylan thanks to an efficient secreted glycoside hydrolase family 11 (GH11) xylanase; solving its crystal structure revealed a high similarity to xylanases from filamentous fungi. The termite gut-associated Scheffersomyces lignosus, in contrast grows more slowly, and its xylanase activity was found to be mainly cell surface-associated. The wood-isolated Wickerhamomyces canadensis, surprisingly, could not utilize xylan as the sole carbon source without the addition of xylooligosaccharides or exogenous xylanases or even co-culturing with B. mokoenaii, suggesting that W. canadensis relies on initial xylan hydrolysis by neighboring cells. Furthermore, our characterization of a novel W. canadensis GH5 subfamily 49 (GH5_49) xylanase represents the first demonstrated activity in this subfamily. Our collective results provide new information on the variable xylanolytic systems evolved by yeasts and their potential roles in natural carbohydrate conversion. IMPORTANCE Microbes that take part in the degradation of the polysaccharide xylan, the major hemicellulose component in plant biomass, are equipped with specialized enzyme machineries to hydrolyze the polymer into monosaccharides for further metabolism. However, despite being found in virtually every habitat, little is known of how yeasts break down and metabolize xylan and what biological role they may play in its turnover in nature. Here, we have explored the enzymatic xylan deconstruction strategies of three underexplored yeasts from diverse environments, Blastobotrys mokoenaii from soil, Scheffersomyces lignosus from insect guts, and Wickerhamomyces canadensis from trees, and we show that each species has a distinct behavior regarding xylan conversion. These findings may be of high relevance for future design and development of microbial cell factories and biorefineries utilizing renewable plant biomass.
Collapse
Affiliation(s)
- Jonas L. Ravn
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | | | - Tom Coleman
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| | - Johan Larsbrink
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
- Wallenberg Wood Science Center, Chalmers University of Technology, Gothenburg, Sweden
| | - Cecilia Geijer
- Department of Life Sciences, Chalmers University of Technology, Gothenburg, Sweden
| |
Collapse
|
2
|
Watanabe Y, Saito Y, Hara T, Tsukuda N, Aiyama-Suzuki Y, Tanigawa-Yahagi K, Kurakawa T, Moriyama-Ohara K, Matsumoto S, Matsuki T. Xylan utilisation promotes adaptation of Bifidobacterium pseudocatenulatum to the human gastrointestinal tract. ISME COMMUNICATIONS 2021; 1:62. [PMID: 37938239 PMCID: PMC9723692 DOI: 10.1038/s43705-021-00066-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 10/10/2021] [Accepted: 10/12/2021] [Indexed: 05/27/2023]
Abstract
Dietary carbohydrates impact the composition of the human gut microbiota. However, the relationship between carbohydrate availability for individual bacteria and their growth in the intestinal environment remains unclear. Here, we show that the availability of long-chain xylans (LCX), one of the most abundant dietary fibres in the human diet, promotes the growth of Bifidobacterium pseudocatenulatum in the adult human gut. Genomic and phenotypic analyses revealed that the availability of LCX-derived oligosaccharides is a fundamental feature of B. pseudocatenulatum, and that some but not all strains possessing the endo-1,4-β-xylanase (BpXyn10A) gene grow on LCX by cleaving the xylose backbone. The BpXyn10A gene, likely acquired by horizontal transfer, was incorporated into the gene cluster for LCX-derived oligosaccharide utilisation. Co-culturing with xylanolytic Bacteroides spp. demonstrated that LCX-utilising strains are more competitive than LCX non-utilising strains even when LCX-derived oligosaccharides were supplied. In LCX-rich dietary interventions in adult humans, levels of endogenous B. pseudocatenulatum increased only when BpXyn10A was detected, indicating that LCX availability is a fitness determinant in the human gut. Our findings highlight the enhanced intestinal adaptability of bifidobacteria via polysaccharide utilisation, and provide a cornerstone for systematic manipulation of the intestinal microbiota through dietary intervention using key enzymes that degrade polysaccharide as biomarkers.
Collapse
Affiliation(s)
| | - Yuki Saito
- Yakult Central Institute, Kunitachi, Tokyo, Japan
| | - Taeko Hara
- Yakult Central Institute, Kunitachi, Tokyo, Japan
| | | | | | | | | | | | | | | |
Collapse
|
3
|
Non-oral Prevotella stepping into the spotlight. Anaerobe 2021; 68:102321. [PMID: 33482304 DOI: 10.1016/j.anaerobe.2021.102321] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 01/12/2021] [Accepted: 01/14/2021] [Indexed: 02/07/2023]
Abstract
Species now affiliated to genus Prevotella have been known for decades as an integral part of human oral cavity microbiota. They were frequently isolated from patients with periodontitis or from dental root canals but also from healthy subjects. With the exception of Prevotella intermedia, they were considered opportunistic pathogens, as they were isolated also from various bacterial abscesses from the head, neck, breast, skin and various other body sites. Consequently, Prevotella were not in the focus of research activities. On the other hand, the four species found in the rumen never caused any disease and seemed early on to be numerous and important part of the rumen ecosystem indicating this genus harbored bacteria with enormously diverse habitats and lifestyles. The purpose of this review is to illustrate the main research themes performed in Prevotella on a path from less noted oral bacteria and from hard to cultivate and study rumen organisms to important mutualistic bacteria in guts of various mammals warranting major research efforts.
Collapse
|
4
|
Multimodularity of a GH10 Xylanase Found in the Termite Gut Metagenome. Appl Environ Microbiol 2021; 87:AEM.01714-20. [PMID: 33187992 PMCID: PMC7848910 DOI: 10.1128/aem.01714-20] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 11/03/2020] [Indexed: 01/01/2023] Open
Abstract
Xylan is the major hemicellulosic polysaccharide in cereals and contributes to the recalcitrance of the plant cell wall toward degradation. Bacteroidetes, one of the main phyla in rumen and human gut microbiota, have been shown to encode polysaccharide utilization loci dedicated to the degradation of xylan. Here, we present the biochemical characterization of a xylanase encoded by a bacteroidetes strain isolated from the termite gut metagenome. The functional screening of a Pseudacanthotermes militaris termite gut metagenomic library revealed an array of xylan-degrading enzymes, including P. militaris 25 (Pm25), a multimodular glycoside hydrolase family 10 (GH10). Sequence analysis showed details of the unusual domain organization of this enzyme. It consists of one catalytic domain, which is intercalated by two carbohydrate binding modules (CBMs) from family 4. The genes upstream of the genes encoding Pm25 are susC-susD-unk, suggesting Pm25 is a Xyn10C-like enzyme belonging to a polysaccharide utilization locus. The majority of Xyn10C-like enzymes shared the same interrupted domain architecture and were vastly distributed in different xylan utilization loci found in gut Bacteroidetes, indicating the importance of this enzyme in glycan acquisition for gut microbiota. To understand its unusual multimodularity and the possible role of the CBMs, a detailed characterization of the full-length Pm25 and truncated variants was performed. Results revealed that the GH10 catalytic module is specific toward the hydrolysis of xylan. Ligand binding results indicate that the GH10 module and the CBMs act independently, whereas the tandem CBM4s act synergistically with each other and improve enzymatic activity when assayed on insoluble polysaccharides. In addition, we show that the UNK protein upstream of Pm25 is able to bind arabinoxylan. Altogether, these findings contribute to a better understanding of the potential role of Xyn10C-like proteins in xylan utilization systems of gut bacteria. IMPORTANCE Xylan is the major hemicellulosic polysaccharide in cereals and contributes to the recalcitrance of the plant cell wall toward degradation. Members of the Bacteroidetes, one of the main phyla in rumen and human gut microbiota, have been shown to encode polysaccharide utilization loci dedicated to the degradation of xylan. Here, we present the biochemical characterization of a xylanase encoded by a Bacteroidetes strain isolated from the termite gut metagenome. This xylanase is a multimodular enzyme, the sequence of which is interrupted by the insertion of two CBMs from family 4. Our results show that this enzyme resembles homologues that were shown to be important for xylan degradation in rumen or human diet and show that the CBM insertion in the middle of the sequence seems to be a common feature in xylan utilization systems. This study shed light on our understanding of xylan degradation and plant cell wall deconstruction, which can be applied to several applications in food, feed, and bioeconomy.
Collapse
|
5
|
Deciphering the Bifidobacterial Populations within the Canine and Feline Gut Microbiota. Appl Environ Microbiol 2020; 86:AEM.02875-19. [PMID: 32005736 DOI: 10.1128/aem.02875-19] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/27/2020] [Indexed: 01/14/2023] Open
Abstract
During the course of evolution, dogs and cats have been subjected to extensive domestication, becoming the principal companion animals for humans. For this reason, their health care, including their intestinal microbiota, is considered of considerable importance. However, the canine and feline gut microbiota still represent a largely unexplored research area. In the present work, we profiled the microbiota of 23 feline fecal samples by 16S rRNA gene and bifidobacterial internally transcribed spacer (ITS) approaches and compared this information with previously reported data from 138 canine fecal samples. The obtained data allowed the reconstruction of the core gut microbiota of the above-mentioned samples coupled with their classification into distinct community state types at both genus and species levels, identifying Bacteroides, Fusobacterium, and Prevotella 9 as the main bacterial components of the canine and feline gut microbiota. At the species level, the intestinal bifidobacterial gut communities of dogs and cats differed in terms of both species number and composition, as emphasized by a covariance analysis. Together, our findings show that the intestinal populations of cats and dogs are similar in terms of genus-level taxonomical composition, while at the bifidobacterial species level, clear differences were observed, indicative of host-specific colonization behavior by particular bifidobacterial taxa.IMPORTANCE Currently, domesticated dogs and cats are the most cherished companion animals for humans, and concerns about their health and well-being are therefore important. In this context, the gut microbiota plays a crucial role in maintaining and promoting host health. However, despite the social relevance of domesticated dogs and cats, their intestinal microbial communities are still far from being completely understood. In this study, the taxonomical composition of canine and feline gut microbiota was explored at genus and bifidobacterial species levels, allowing classification of these microbial populations into distinct gut community state types at either of the two investigated taxonomic levels. Furthermore, the reconstruction of core gut microbiota coupled with covariance network analysis based on bifidobacterial internally transcribed spacer (ITS) profiling revealed differences in the bifidobacterial compositions of canine and feline gut microbiota, suggesting that particular bifidobacterial species have developed a selective ability to colonize a specific host.
Collapse
|
6
|
Terry SA, Badhan A, Wang Y, Chaves AV, McAllister TA. Fibre digestion by rumen microbiota — a review of recent metagenomic and metatranscriptomic studies. CANADIAN JOURNAL OF ANIMAL SCIENCE 2019. [DOI: 10.1139/cjas-2019-0024] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Plant biomass is the most abundant renewable resource on the planet, and the biopolymers of lignocellulose are the foundation of ruminant production systems. Optimizing the saccharification of lignocellulosic feeds is a crucial step in their bioconversion to ruminant protein. Plant cell walls are chemically heterogeneous structures that have evolved to provide structural support and protection to the plant. Ruminants are the most efficient digesters of lignocellulose due to a rich array of bacteria, archaea, fungi, and protozoa within the rumen and lower digestive tract. Metagenomic and metatranscriptomic studies have enhanced the current understanding of the composition, diversity, and function of the rumen microbiome. There is particular interest in identifying the carbohydrate-active enzymes responsible for the ruminal degradation of plant biomass. Understanding the roles of cellulosomes- and polysaccharide-utilising loci in ruminal fibre degradation could provide insight into strategies to enhance forage utilisation by ruminants. Despite advancements in “omics” technology, the majority of rumen microorganisms are still uncharacterised, and their ability to act synergistically is still not understood. By advancing our current knowledge of rumen fibre digestion, there may be opportunity to further improve the productive performance of ruminants fed forage diets.
Collapse
Affiliation(s)
- Stephanie A. Terry
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, NSW, Australia
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Ave South, Lethbridge, AB T1J 4B1, Canada
| | - Ajay Badhan
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Ave South, Lethbridge, AB T1J 4B1, Canada
| | - Yuxi Wang
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Ave South, Lethbridge, AB T1J 4B1, Canada
| | - Alexandre V. Chaves
- School of Life and Environmental Sciences, Faculty of Science, University of Sydney, Sydney, NSW, Australia
| | - Tim A. McAllister
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, 5403 1st Ave South, Lethbridge, AB T1J 4B1, Canada
| |
Collapse
|
7
|
Surface Exposure and Packing of Lipoproteins into Outer Membrane Vesicles Are Coupled Processes in Bacteroides. mSphere 2018; 3:3/6/e00559-18. [PMID: 30404931 PMCID: PMC6222051 DOI: 10.1128/msphere.00559-18] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Species from the Bacteroides genus are predominant members of the human gut microbiota. OMVs in Bacteroides have been shown to be important for the homeostasis of complex host-commensal relationships, mainly involving immune tolerance and protection from disease. OMVs carry many enzymatic activities involved in the cleavage of complex polysaccharides and have been proposed as public goods that can provide growth to other bacterial species by release of polysaccharide breakdown products into the gut lumen. This work shows that the presence of a negatively charged rich amino acid motif (LES) is required for efficient packing of the surface-exposed alpha-amylase SusG into OMVs. Our findings strongly suggest that surface exposure is coupled to packing of Bacteroides lipoproteins into OMVs. This is the first step in the generation of tailor-made probiotic interventions that can exploit LES-related sequences to generate Bacteroides strains displaying proteins of interest in OMVs. Outer membrane vesicles (OMVs) are spherical structures derived from the outer membranes (OMs) of Gram-negative bacteria. Bacteroides spp. are prominent components of the human gut microbiota, and OMVs produced by these species are proposed to play key roles in gut homeostasis. OMV biogenesis in Bacteroides is a poorly understood process. Here, we revisited the protein composition of Bacteroides thetaiotaomicron OMVs by mass spectrometry. We confirmed that OMVs produced by this organism contain large quantities of glycosidases and proteases, with most of them being lipoproteins. We found that most of these OMV-enriched lipoproteins are encoded by polysaccharide utilization loci (PULs), such as the sus operon. We examined the subcellular locations of the components of the Sus system and found a split localization; the alpha-amylase SusG is highly enriched in OMVs, while the oligosaccharide importer SusC remains mostly in the OM. We found that all OMV-enriched lipoproteins possess a lipoprotein export sequence (LES), and we show that this signal mediates translocation of SusG from the periplasmic face of the OM toward the extracellular milieu. Mutations in the LES motif caused defects in surface exposure and recruitment of SusG into OMVs. These experiments link, for the first time, surface exposure to recruitment of proteins into OMVs. We also show that surface-exposed SusG in OMVs is active and rescues the growth of bacterial cells incapable of growing on starch as the only carbon source. Our results support the role of OMVs as “public goods” that can be utilized by other organisms with different metabolic capabilities. IMPORTANCE Species from the Bacteroides genus are predominant members of the human gut microbiota. OMVs in Bacteroides have been shown to be important for the homeostasis of complex host-commensal relationships, mainly involving immune tolerance and protection from disease. OMVs carry many enzymatic activities involved in the cleavage of complex polysaccharides and have been proposed as public goods that can provide growth to other bacterial species by release of polysaccharide breakdown products into the gut lumen. This work shows that the presence of a negatively charged rich amino acid motif (LES) is required for efficient packing of the surface-exposed alpha-amylase SusG into OMVs. Our findings strongly suggest that surface exposure is coupled to packing of Bacteroides lipoproteins into OMVs. This is the first step in the generation of tailor-made probiotic interventions that can exploit LES-related sequences to generate Bacteroides strains displaying proteins of interest in OMVs.
Collapse
|
8
|
Integrated Functional-Omics Analysis of Thermomyces lanuginosus Reveals its Potential for Simultaneous Production of Xylanase and Substituted Xylooligosaccharides. Appl Biochem Biotechnol 2018; 187:1515-1538. [PMID: 30267287 DOI: 10.1007/s12010-018-2873-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Accepted: 08/24/2018] [Indexed: 11/27/2022]
Abstract
Thermophiles have several beneficial properties for the conversion of biomass at high temperatures. Thermomyces lanuginosus is a thermophilic filamentous fungus that was shown to secrete 40 glycoside hydrolases and 25 proteases when grown on different carbon sources. Among the 13 identified glycoside hydrolases with high expression levels, 9 were reduced sugar glycosidases (RSGs) belonging to seven GH families, and 7 of the 10 identified proteases were exopeptidases belonging to six different protease families. High expression of RSGs and exopeptidases may allow the fungus to efficiently degrade oligosaccharides and oligopeptides in saprophytic habitats. There were no xylan side chain-degrading enzymes predicted in the genome of T. lanuginosus, and only one thermophilic GH11 xylanase (g4601.t1) and one GH43 xylosidase (g3706.t1) were detected by liquid chromatography-mass spectrometry/mass spectrometry when T. lanuginosus grown on xylan, which led to the accumulation of substituted xylooligosaccharides (SXOS) during corncob xylan degradation where SXOS output made up more than 8% of the total xylan. The SXOS are beneficial prebiotics and important inducers for enzymes secretion of microorganisms. Thus, T. lanuginosus exhibits distinct advantages in utilizing cheap raw materials producing one thermostable xylanase and the high value-added SXOS as well as microbial inoculants to compost by batch fermentation.
Collapse
|
9
|
Jonnadula R, Imran M, Poduval PB, Ghadi SC. Effect of polysaccharide admixtures on expression of multiple polysaccharide-degrading enzymes in Microbulbifer strain CMC-5. ACTA ACUST UNITED AC 2018. [PMID: 29541601 PMCID: PMC5849783 DOI: 10.1016/j.btre.2017.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Microbulbifer strain CMC-5 produces agarase, alginate lyase, xylanase, carboxymethyl cellulase and carrageenase. The extracellular production of the above carbohydrases was investigated by growing Microbulbifer strain CMC-5 in a sea water based medium containing homologous/heterologous polysaccharides as a single substrate or as a combination of mixed assorted substrate. Presence of singular homologous polysaccharides in the growth medium induces respective carbohydrase at high levels. Any two polysaccharides in various combinations produced high level of homologous carbohydrase and low level of other heterologous carbohydrase. All five carbohydrases were consistently produced by strain CMC-5, when carboxymethyl cellulose was included as one of the substrate in dual substrate combination, or in presence of mix blends of all five polysaccharides. Interestingly, thalli of Gracilaria sp. that contain agar and cellulose predominantly in their cell wall induces only agarase expression in strain CMC-5.
Collapse
Affiliation(s)
- RaviChand Jonnadula
- Department of Biotechnology, Goa University, Taleigao Plateau, Goa 403206, India
| | - Md Imran
- Department of Biotechnology, Goa University, Taleigao Plateau, Goa 403206, India
| | - Preethi B Poduval
- Department of Biotechnology, Goa University, Taleigao Plateau, Goa 403206, India
| | - Sanjeev C Ghadi
- Department of Biotechnology, Goa University, Taleigao Plateau, Goa 403206, India
| |
Collapse
|
10
|
Udatha DBRKG, Topakas E, Salazar M, Olsson L, Andersen MR, Panagiotou G. Deciphering the signaling mechanisms of the plant cell wall degradation machinery in Aspergillus oryzae. BMC SYSTEMS BIOLOGY 2015; 9:77. [PMID: 26573537 PMCID: PMC4647334 DOI: 10.1186/s12918-015-0224-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 10/28/2015] [Indexed: 12/30/2022]
Abstract
Background The gene expression and secretion of fungal lignocellulolytic enzymes are tightly controlled at the transcription level using independent mechanisms to respond to distinct inducers from plant biomass. An advanced systems-level understanding of transcriptional regulatory networks is required to rationally engineer filamentous fungi for more efficient bioconversion of different types of biomass. Results In this study we focused on ten chemically defined inducers to drive expression of cellulases, hemicellulases and accessory enzymes in the model filamentous fungus Aspergillus oryzae and shed light on the complex network of transcriptional activators required. The chemical diversity analysis of the inducers, based on 186 chemical descriptors calculated from the structure, resulted into three clusters, however, the global, metabolic and extracellular protein transcription of the A. oryzae genome were only partially explained by the chemical similarity of the enzyme inducers. Genes encoding enzymes that have attracted considerable interest such as cellobiose dehydrogenases and copper-dependent polysaccharide mono-oxygenases presented a substrate-specific induction. Several homology-model structures were derived using ab-initio multiple threading alignment in our effort to elucidate the interplay of transcription factors involved in regulating plant-deconstructing enzymes and metabolites. Systematic investigation of metabolite-protein interactions, using the 814 unique reactants involved in 2360 reactions in the genome scale metabolic network of A. oryzae, was performed through a two-step molecular docking against the binding pockets of the transcription factors AoXlnR and AoAmyR. A total of six metabolites viz., sulfite (H2SO3), sulfate (SLF), uroporphyrinogen III (UPGIII), ethanolamine phosphate (PETHM), D-glyceraldehyde 3-phosphate (T3P1) and taurine (TAUR) were found as strong binders, whereas the genes involved in the metabolic reactions that these metabolites appear were found to be significantly differentially expressed when comparing the inducers with glucose. Conclusions Based on our observations, we believe that specific binding of sulfite to the regulator of the cellulase gene expression, AoXlnR, may be the molecular basis for the connection of sulfur metabolism and cellulase gene expression in filamentous fungi. Further characterization and manipulation of the regulatory network components identified in this study, will enable rational engineering of industrial strains for improved production of the sophisticated set of enzymes necessary to break-down chemically divergent plant biomass. Electronic supplementary material The online version of this article (doi:10.1186/s12918-015-0224-5) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- D B R K Gupta Udatha
- The Norwegian Structural Biology Centre, Department of Chemistry, Faculty of Science and Technology, University of Tromsø, N-9037, Tromsø, Norway. .,Section for Genetics and Evolutionary Biology, Department of Biosciences, University of Oslo, Oslo, Norway.
| | - Evangelos Topakas
- Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, Athens, 15780, Greece.
| | - Margarita Salazar
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden. .,Wallenberg Wood Science Center, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
| | - Lisbeth Olsson
- Department of Chemical and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden. .,Wallenberg Wood Science Center, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
| | - Mikael R Andersen
- Department of Systems Biology, Technical University of Denmark, Søltofts plads 223, DK-2800, Lyngby, Denmark.
| | - Gianni Panagiotou
- School of Biological Sciences, The University of Hong Kong, Kadoorie Biological Sciences Building, Hong Kong, China.
| |
Collapse
|
11
|
Fukuma N, Koike S, Kobayashi Y. Involvement of recently cultured group U2 bacterium in ruminal fiber digestion revealed by coculture with Fibrobacter succinogenes S85. FEMS Microbiol Lett 2012; 336:17-25. [PMID: 22849722 DOI: 10.1111/j.1574-6968.2012.02649.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 07/26/2012] [Accepted: 07/26/2012] [Indexed: 11/28/2022] Open
Abstract
In a previous study, we reported the ecological significance of uncultured bacterial group U2 in the rumen. In this study, the involvement of a recently cultured group U2 bacterium, strain R-25, in fiber digestion was tested in coculture with the fibrolytic bacterium Fibrobacter succinogenes S85. Dry matter (DM) digestion, growth and metabolites were examined in culture using rice straw as the carbon source. Although strain R-25 did not digest rice straw in monoculture, coculture of strain R-25 and F. succinogenes S85 showed enhanced DM digestion compared with that for F. succinogenes S85 monoculture (36.9 ± 0.6% vs. 32.8 ± 1.3%, P < 0.05). Growth of strain R-25 and production of the main metabolites, d-lactate (strain R-25) and succinate (F. succinogenes S85), were enhanced in the coculture. Enzyme assay showed increased activities of carboxymethylcellulase and xylanase in coculture of strain R-25 and F. succinogenes S85. Triculture including strain R-25, F. succinogenes S85 and Selenomonas ruminantium S137 showed a further increase in DM digestion (41.8 ± 0.8%, P < 0.05) with a concomitant increase in propionate, produced from the conversion of d-lactate and succinate. These results suggest that the positive interaction between strains R-25 and F. succinogenes S85 causes increased rice straw digestion.
Collapse
Affiliation(s)
- Naoki Fukuma
- Graduate School of Agriculture, Hokkaido University, Sapporo, Japan
| | | | | |
Collapse
|
12
|
Koropatkin NM, Cameron EA, Martens EC. How glycan metabolism shapes the human gut microbiota. Nat Rev Microbiol 2012; 10:323-35. [PMID: 22491358 DOI: 10.1038/nrmicro2746] [Citation(s) in RCA: 948] [Impact Index Per Article: 79.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Symbiotic microorganisms that reside in the human intestine are adept at foraging glycans and polysaccharides, including those in dietary plants (starch, hemicellulose and pectin), animal-derived cartilage and tissue (glycosaminoglycans and N-linked glycans), and host mucus (O-linked glycans). Fluctuations in the abundance of dietary and endogenous glycans, combined with the immense chemical variation among these molecules, create a dynamic and heterogeneous environment in which gut microorganisms proliferate. In this Review, we describe how glycans shape the composition of the gut microbiota over various periods of time, the mechanisms by which individual microorganisms degrade these glycans, and potential opportunities to intentionally influence this ecosystem for better health and nutrition.
Collapse
Affiliation(s)
- Nicole M Koropatkin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, USA
| | | | | |
Collapse
|
13
|
Mandal A, Kar S, Das Mohapatra PK, Maity C, Pati BR, Mondal KC. Regulation of xylanase biosynthesis in Bacillus cereus BSA1. Appl Biochem Biotechnol 2012; 167:1052-60. [PMID: 22222433 DOI: 10.1007/s12010-011-9523-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
Abstract
Microbial xylanases have a promising biotechnological potential to be used in industries. In this study, regulation of xylanase production was examined in Bacillus cereus BSA1. Xylanase production was induced by xylan. The enzyme production further increased in the presence of xylose and arabinose in very low concentration with addition of xylan (0.5% up to 6.02 U/ml). Addition of glucose (about 0.1%) to the media supplemented with xylan repressed xylanase production. Even higher concentration (>0.1%) of xylose and arabinose repressed xylanase biosynthesis. Glucose-mediated repression was partially relived by addition of cyclic adenosine monophosphate. Chemical like 2-4-dinitrophenol, which can inhibit adenosine triphosphate synthesis in cell, repressed xylanase synthesis and it suggested xylanase synthesis to be an energy dependent process.
Collapse
Affiliation(s)
- Asish Mandal
- Post Graduate Department of Botany, Ramananda College, Bishnupur, Bankura 722122, West Bengal, India
| | | | | | | | | | | |
Collapse
|
14
|
Martens EC, Lowe EC, Chiang H, Pudlo NA, Wu M, McNulty NP, Abbott DW, Henrissat B, Gilbert HJ, Bolam DN, Gordon JI. Recognition and degradation of plant cell wall polysaccharides by two human gut symbionts. PLoS Biol 2011; 9:e1001221. [PMID: 22205877 PMCID: PMC3243724 DOI: 10.1371/journal.pbio.1001221] [Citation(s) in RCA: 586] [Impact Index Per Article: 45.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2011] [Accepted: 11/07/2011] [Indexed: 12/16/2022] Open
Abstract
Competition for nutrients contained in diverse types of plant cell wall-associated polysaccharides may explain the evolution of substrate-specific catabolic gene modules in common bacterial members of the human gut microbiota. Symbiotic bacteria inhabiting the human gut have evolved under intense pressure to utilize complex carbohydrates, primarily plant cell wall glycans in our diets. These polysaccharides are not digested by human enzymes, but are processed to absorbable short chain fatty acids by gut bacteria. The Bacteroidetes, one of two dominant bacterial phyla in the adult gut, possess broad glycan-degrading abilities. These species use a series of membrane protein complexes, termed Sus-like systems, for catabolism of many complex carbohydrates. However, the role of these systems in degrading the chemically diverse repertoire of plant cell wall glycans remains unknown. Here we show that two closely related human gut Bacteroides, B. thetaiotaomicron and B. ovatus, are capable of utilizing nearly all of the major plant and host glycans, including rhamnogalacturonan II, a highly complex polymer thought to be recalcitrant to microbial degradation. Transcriptional profiling and gene inactivation experiments revealed the identity and specificity of the polysaccharide utilization loci (PULs) that encode individual Sus-like systems that target various plant polysaccharides. Comparative genomic analysis indicated that B. ovatus possesses several unique PULs that enable degradation of hemicellulosic polysaccharides, a phenotype absent from B. thetaiotaomicron. In contrast, the B. thetaiotaomicron genome has been shaped by increased numbers of PULs involved in metabolism of host mucin O-glycans, a phenotype that is undetectable in B. ovatus. Binding studies of the purified sensor domains of PUL-associated hybrid two-component systems in conjunction with transcriptional analyses demonstrate that complex oligosaccharides provide the regulatory cues that induce PUL activation and that each PUL is highly specific for a defined cell wall polymer. These results provide a view of how these species have diverged into different carbohydrate niches by evolving genes that target unique suites of available polysaccharides, a theme that likely applies to disparate bacteria from the gut and other habitats. Bacteria inhabiting the human gut are critical for digestion of the plant-derived glycans that compose dietary fiber. Enzymes produced by the human body cannot degrade these abundant dietary components, and without bacterial assistance they would go unused. We investigated the molecular strategies employed by two species belonging to one of the most abundant bacterial groups in the human colon (the Bacteroidetes). Our results show that each species has evolved to degrade a unique subset of glycans; this specialization is reflected in their respective genomes, each of which contains numerous separate gene clusters involved in metabolizing plant fiber polysaccharides or glycans present in secreted mucus. Each glycan-specific gene cluster produces a related series of membrane-associated proteins which together serve to bind and degrade a specific glycan. Expression of each glycan-specific gene cluster is controlled by an environmental sensor that responds to the presence of a unique molecular signature contained in the substrate that it targets. These results provide a view of how related bacterial species have diverged into different carbohydrate niches by evolving genes that sense and degrade unique suites of available polysaccharides, a process that likely applies to disparate bacteria from the gut and other habitats.
Collapse
Affiliation(s)
- Eric C. Martens
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
- * E-mail: (ECM); (DNB)
| | - Elisabeth C. Lowe
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
| | - Herbert Chiang
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Nicholas A. Pudlo
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America
| | - Meng Wu
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Nathan P. McNulty
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - D. Wade Abbott
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, CNRS and Universities of Aix-Marseille I & II, Marseille, France
| | - Harry J. Gilbert
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - David N. Bolam
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle University, Newcastle upon Tyne, United Kingdom
- * E-mail: (ECM); (DNB)
| | - Jeffrey I. Gordon
- Center for Genome Sciences and Systems Biology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| |
Collapse
|
15
|
Nepi M, Bini L, Bianchi L, Puglia M, Abate M, Cai G. Xylan-degrading enzymes in male and female flower nectar of Cucurbita pepo. ANNALS OF BOTANY 2011; 108:521-7. [PMID: 21813563 PMCID: PMC3158684 DOI: 10.1093/aob/mcr165] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND AND AIMS Nectar is a very complex mixture of substances. Some components (sugars and amino acids) are considered primary alimentary rewards for animals and have been investigated and characterized in numerous species for many years. In contrast, nectar proteins have been the subject of few studies and little is known of their function. Only very recently have detailed studies and characterization of nectar proteins been undertaken, and then for only a very few species. This current work represents a first step in the identification of a protein profile for the floral nectar of Cucurbita pepo. In this regard, the species studied is of particular interest in that it is monoecious with unisexual flowers and, consequently, it is possible that nectar proteins derived from male and female flowers may differ. METHODS Manually excised spots from two-dimensional (2-D) electrophoresis were subjected to in-gel protein digestion. The resulting peptides were sequenced using nanoscale LC-ESI/MS-MS (liquid chromatography-electrospray ionization/tandem mass spectrometry). An MS/MS ions search was carried out in Swiss-Prot and NCBInr databases using MASCOT software. KEY RESULTS Two-dimensional electrophoresis revealed a total of 24 spots and a different protein profile for male and female flower nectar. Four main proteins recognized by 2-D electrophoresis most closely resemble β-d-xylosidases from Arabidopsis thaliana and have some homology to a β-d-xylosidase from Medicago varia. They were present in similar quantities in male and female flowers and had the same molecular weight, but with slightly different isoelectric points. CONCLUSIONS A putative function for xylosidases in floral nectar of C. pepo is proposed, namely that they may be involved in degrading the oligosaccharides released by the nectary cell walls in response to hydrolytic enzymes produced by invading micro-organisms. Several types of oligosaccharides have been reported to increase the pathogenic potential of micro-organisms. Thus, it is possible that such a mechanism may reduce the virulence of pathogens present in nectar.
Collapse
Affiliation(s)
- M Nepi
- BIOCONNET, Biodiversity and Conservation Network, Department of Environmental Sciences G. Sarfatti, University of Siena, Via Mattioli 4, 53100 Siena, Italy.
| | | | | | | | | | | |
Collapse
|
16
|
Abstract
It is becoming increasingly clear that diet is one of the major factors that drives the function and composition of the intestinal microbiota. The diet of humans is highly diverse when considering different populations or even a single individual over a relatively short period of time. However, we are just beginning to understand the mechanisms that connect dietary change to intestinal microbiota dynamics. The community of microbes within our distal digestive tract influences numerous aspects of our biology, and aberrant shifts in its composition appear to be associated with several diseases. It is, therefore, necessary to understand how our behaviour and environmental factors, such as changes in diet, impact our intestinal residents. Here we look to recent work to highlight some of the major questions on the horizon for understanding the key role that the Bacteroidetes play in the commerce of dietary polysaccharides within the intestine.
Collapse
Affiliation(s)
- David N Bolam
- Institute for Cell and Molecular Biosciences; Newcastle University; Medical School; Newcastle-Upon-Tyne, UK
| | - Justin L Sonnenburg
- Department of Microbiology and Immunology; Stanford University School of Medicine; Stanford, CA USA
| |
Collapse
|
17
|
Dodd D, Mackie RI, Cann IKO. Xylan degradation, a metabolic property shared by rumen and human colonic Bacteroidetes. Mol Microbiol 2010; 79:292-304. [PMID: 21219452 DOI: 10.1111/j.1365-2958.2010.07473.x] [Citation(s) in RCA: 165] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Microbial inhabitants of the bovine rumen fulfil the majority of the normal caloric requirements of the animal by fermenting lignocellulosic plant polysaccharides and releasing short chain fatty acids that are then metabolized by the host. This process also occurs within the human colon, although the fermentation products contribute less to the overall energy requirements of the host. Mounting evidence, however, indicates that the community structure of the distal gut microbiota is a critical factor that influences the inflammatory potential of the immune system thereby impacting the progression of inflammatory bowel diseases. Non-digestible dietary fibre derived from plant material is highly enriched in the lignocellulosic polysaccharides, cellulose and xylan. Members of the Bacteroidetes constitute a dominant phylum in both the human colonic microbiome and the rumen microbial ecosystem. In the current article, we review recent insights into the molecular mechanisms for xylan degradation by rumen and human commensal members of the Bacteroidetes phylum, and place this information in the context of the physiological and metabolic processes that occur within these complex microbial environments.
Collapse
Affiliation(s)
- Dylan Dodd
- Department of Microbiology, University of Illinois, Urbana, IL 61801, USA.
| | | | | |
Collapse
|
18
|
Dodd D, Moon YH, Swaminathan K, Mackie RI, Cann IKO. Transcriptomic analyses of xylan degradation by Prevotella bryantii and insights into energy acquisition by xylanolytic bacteroidetes. J Biol Chem 2010; 285:30261-73. [PMID: 20622018 DOI: 10.1074/jbc.m110.141788] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enzymatic depolymerization of lignocellulose by microbes in the bovine rumen and the human colon is critical to gut health and function within the host. Prevotella bryantii B(1)4 is a rumen bacterium that efficiently degrades soluble xylan. To identify the genes harnessed by this bacterium to degrade xylan, the transcriptomes of P. bryantii cultured on either wheat arabinoxylan or a mixture of its monosaccharide components were compared by DNA microarray and RNA sequencing approaches. The most highly induced genes formed a cluster that contained putative outer membrane proteins analogous to the starch utilization system identified in the prominent human gut symbiont Bacteroides thetaiotaomicron. The arrangement of genes in the cluster was highly conserved in other xylanolytic Bacteroidetes, suggesting that the mechanism employed by xylan utilizers in this phylum is conserved. A number of genes encoding proteins with unassigned function were also induced on wheat arabinoxylan. Among these proteins, a hypothetical protein with low similarity to glycoside hydrolases was shown to possess endoxylanase activity and subsequently assigned to glycoside hydrolase family 5. The enzyme was designated PbXyn5A. Two of the most similar proteins to PbXyn5A were hypothetical proteins from human colonic Bacteroides spp., and when expressed each protein exhibited endoxylanase activity. By using site-directed mutagenesis, we identified two amino acid residues that likely serve as the catalytic acid/base and nucleophile as in other GH5 proteins. This study therefore provides insights into capture of energy by xylanolytic Bacteroidetes and the application of their enzymes as a resource in the biofuel industry.
Collapse
Affiliation(s)
- Dylan Dodd
- Department of Microbiology, University of Illinois, Urbana, Illinois 61801, USA
| | | | | | | | | |
Collapse
|
19
|
Fukuda M, Watanabe S, Yoshida S, Itoh H, Itoh Y, Kamio Y, Kaneko J. Cell surface xylanases of the glycoside hydrolase family 10 are essential for xylan utilization by Paenibacillus sp. W-61 as generators of xylo-oligosaccharide inducers for the xylanase genes. J Bacteriol 2010; 192:2210-9. [PMID: 20154127 PMCID: PMC2849441 DOI: 10.1128/jb.01406-09] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2009] [Accepted: 02/08/2010] [Indexed: 11/20/2022] Open
Abstract
Paenibacillus sp. W-61 is capable of utilizing water-insoluble xylan for carbon and energy sources and has three xylanase genes, xyn1, xyn3, and xyn5. Xyn1, Xyn3, and Xyn5 are extracellular enzymes of the glycoside hydrolase (GH) families 11, 30, and 10, respectively. Xyn5 contains several domains including those of carbohydrate-binding modules (CBMs) similar to a surface-layer homologous (SLH) protein. This study focused on the role of Xyn5, localized on the cell surface, in water-insoluble xylan utilization. Electron microscopy using immunogold staining revealed Xyn5 clusters over the entire cell surface. Xyn5 was bound to cell wall fractions through its SLH domain. A Deltaxyn5 mutant grew poorly and produced minimal amounts of Xyn1 and Xyn3 on water-insoluble xylan. A Xyn5 mutant lacking the SLH domain (Xyn5DeltaSLH) grew poorly, secreting Xyn5DeltaSLH into the medium and producing minimal Xyn1 and Xyn3 on water-insoluble xylan. A mutant with an intact xyn5 produced Xyn5 on the cell surface, grew normally, and actively synthesized Xyn1 and Xyn3 on water-insoluble xylan. Quantitative reverse transcription-PCR showed that xylobiose, generated from water-insoluble xylan decomposition by Xyn5, is the most active inducer for xyn1 and xyn3. Luciferase assays using a Xyn5-luciferase fusion protein suggested that xylotriose is the best inducer for xyn5. The cell surface Xyn5 appears to play two essential roles in water-insoluble xylan utilization: (i) generation of the xylo-oligosaccharide inducers of all the xyn genes from water-insoluble xylan and (ii) attachment of the cells to the substrate so that the generated inducers can be immediately taken up by cells to activate expression of the xyn system.
Collapse
Affiliation(s)
- Mutsumi Fukuda
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| | - Seiji Watanabe
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| | - Shigeki Yoshida
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| | - Hiroya Itoh
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| | - Yoshifumi Itoh
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| | - Yoshiyuki Kamio
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| | - Jun Kaneko
- Department of Microbial Biotechnology, Graduate School of Agricultural Science, Tohoku University, Tsutsumidori 1-1 Amamiyamachi, Sendai 981-8555, Japan, Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan, Department of Human Health and Nutrition, Graduate School of Comprehensive Human Sciences, Shokei Gakuin University, 4-10-1 Yurigaoka, Natori 981-1295, Japan
| |
Collapse
|
20
|
Flint HJ, Bayer EA. Plant cell wall breakdown by anaerobic microorganisms from the Mammalian digestive tract. Ann N Y Acad Sci 2008; 1125:280-8. [PMID: 18378598 DOI: 10.1196/annals.1419.022] [Citation(s) in RCA: 153] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Degradation of lignocellulosic plant material in the mammalian digestive tract is accomplished by communities of anaerobic microorganisms that exist in symbiotic association with the host. Catalytic domains and substrate-binding modules concerned with plant polysaccharide degradation are found in a variety of anaerobic bacteria, fungi, and protozoa from the mammalian gut. The organization of plant cell wall-degrading enzymes, however, varies widely. The cellulolytic gram-positive bacterium Ruminococcus flavefaciens produces an elaborate cellulosomal enzyme complex that is anchored to the bacterial cell wall; assembly of the complex involves at least five different dockerin:cohesin specificities, and the R. flavefaciens genome encodes at least 180 dockerin-containing proteins that encompass a wide array of catalytic and binding activities. On the other hand, in the cellulolytic protozoan, Polyplastron multivesiculatum, individual plant cell wall-degrading enzymes appear to be secreted into food vacuoles, while the gram-negative bacterium Prevotella bryantii appears to possess a sequestration-type system for the utilization of soluble xylans. The system that is employed for polysaccharide utilization must play a major role in defining the ecological niche that each organism occupies within a complex gut community. 16S rRNA analyses are also revealing uncultured bacterial species closely adherent to fibrous substrates in the rumen and in the large intestine of animals and humans. The true complexity, both at a single organism and community level, of the microbial enzyme systems that allow animals to digest plant material is beginning to become apparent.
Collapse
Affiliation(s)
- Harry J Flint
- Microbial Ecology Group, Rowett Research Institute, Greenburn Road, Bucksburn, Aberdeen AB21 9SB, UK.
| | | |
Collapse
|
21
|
Polysaccharide utilization by gut bacteria: potential for new insights from genomic analysis. Nat Rev Microbiol 2008; 6:121-31. [PMID: 18180751 DOI: 10.1038/nrmicro1817] [Citation(s) in RCA: 1081] [Impact Index Per Article: 67.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The microbiota of the mammalian intestine depend largely on dietary polysaccharides as energy sources. Most of these polymers are not degradable by the host, but herbivores can derive 70% of their energy intake from microbial breakdown--a classic example of mutualism. Moreover, dietary polysaccharides that reach the human large intestine have a major impact on gut microbial ecology and health. Insight into the molecular mechanisms by which different gut bacteria use polysaccharides is, therefore, of fundamental importance. Genomic analyses of the gut microbiota could revolutionize our understanding of these mechanisms and provide new biotechnological tools for the conversion of polysaccharides, including lignocellulosic biomass, into monosaccharides.
Collapse
|
22
|
Rizzatti ACS, Freitas FZ, Bertolini MC, Peixoto-Nogueira SC, Terenzi HF, Jorge JA, Polizeli MDLTDM. Regulation of xylanase in Aspergillus phoenicis: a physiological and molecular approach. J Ind Microbiol Biotechnol 2008; 35:237-44. [PMID: 18228069 DOI: 10.1007/s10295-007-0290-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Accepted: 12/10/2007] [Indexed: 10/22/2022]
Abstract
Microbial xylanolytic enzymes have a promising biotechnological potential, and are extensively applied in industries. In this study, induction of xylanolytic activity was examined in Aspergillus phoenicis. Xylanase activity induced by xylan, xylose or beta-methylxyloside was predominantly extracellular (93-97%). Addition of 1% glucose to media supplemented with xylan or xylose repressed xylanase production. Glucose repression was alleviated by addition of cAMP or dibutyryl-cAMP. These physiological observations were supported by a Northern analysis using part of the xylanase gene ApXLN as a probe. Gene transcription was shown to be induced by xylan, xylose, and beta-methylxyloside, and was repressed by the addition of 1% glucose. Glucose repression was partially relieved by addition of cAMP or dibutyryl cAMP.
Collapse
Affiliation(s)
- Ana Carolina Segato Rizzatti
- Departamento de Biologia da Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Av. Bandeirantes, 3900, Ribeirão Preto, SP 14040-901, Brazil
| | | | | | | | | | | | | |
Collapse
|
23
|
Grootaert C, Delcour JA, Courtin CM, Broekaert WF, Verstraete W, Van de Wiele T. Microbial metabolism and prebiotic potency of arabinoxylan oligosaccharides in the human intestine. Trends Food Sci Technol 2007. [DOI: 10.1016/j.tifs.2006.08.004] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|