Community dynamics of cellulose-adapted thermophilic bacterial consortia
Summary Enzymatic hydrolysis of cellulose is a key process in the global carbon cycle and the industrial conversion of biomass to biofuels. In natural environments, cellulose hydrolysis is predominately performed by microbial communities. However, detailed understanding of bacterial cellulose hydrol...
Saved in:
| Published in: | Environmental microbiology Vol. 15; no. 9; pp. 2573 - 2587 |
|---|---|
| Main Authors: | , , , , , , , |
| Format: | Journal Article |
| Language: | English |
| Published: |
Oxford
Blackwell Publishing Ltd
01-09-2013
Blackwell Wiley Subscription Services, Inc |
| Subjects: | |
| Online Access: | Get full text |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Summary: | Summary
Enzymatic hydrolysis of cellulose is a key process in the global carbon cycle and the industrial conversion of biomass to biofuels. In natural environments, cellulose hydrolysis is predominately performed by microbial communities. However, detailed understanding of bacterial cellulose hydrolysis is primarily confined to a few model isolates. Developing models for cellulose hydrolysis by mixed microbial consortia will complement these isolate studies and may reveal new mechanisms for cellulose deconstruction. Microbial communities were adapted to microcrystalline cellulose under aerobic, thermophilic conditions using green waste compost as the inoculum to study cellulose hydrolysis in a microbial consortium. This adaptation selected for three dominant taxa – the Firmicutes, Bacteroidetes and Thermus. A high‐resolution profile of community development during the enrichment demonstrated a community transition from Firmicutes to a novel Bacteroidetes population that clusters in the Chitinophagaceae family. A representative strain of this population, strain NYFB, was successfully isolated, and sequencing of a nearly full‐length 16S rRNA gene demonstrated that it was only 86% identical compared with other validated strains in the phylum Bacteroidetes. Strain NYFB grew well on soluble polysaccharide substrates, but grew poorly on insoluble polysaccharide substrates. Similar communities were observed in companion thermophilic enrichments on insoluble wheat arabinoxylan, a hemicellulosic substrate, suggesting a common model for deconstruction of plant polysaccharides. Combining observations of community dynamics and the physiology of strain NYFB, a cooperative successional model for polysaccharide hydrolysis by the Firmicutes and Bacteroidetes in the thermophilic cellulolytic consortia is proposed. |
|---|---|
| Bibliography: | ark:/67375/WNG-HF8FZ72S-4 ArticleID:EMI12159 Figure S1. Maximum likelihood tree of representative sequences from dominant OTUs in the NIC enrichments MCC and wheat arabinoxylan as uncovered in (1) Sanger-based passage 4 DNA and cDNA clone libraries at passage 4, (2) SSU amplicon sequencing of passage 4 (described as 454_OTU97_#) and (3) high-resolution of MCC-adapted thermophilic passage (described as TC_OTU97_#). The tree is based on the 16S rRNA gene using sequences (ca. 800 bp) obtained from and environmental clones. Small SSU amplicon sequences (454_OTU97_#) were quick added to the tree with parsimony.Figure S2. Differential endoglucanase activity for thermophilic consortia adapted to microcrystalline cellulose (mcc) and wheat arabinoxylan (xylan) on filter sterilized (0.2 μm filter) supernatant (fs), unfiltered whole cells (wc) and sonicated cells (son).Figure S3. Glycosyl hydrolase activities during the establishment of the thermophilic, microcrystalline cellulose Picture depicts the colorometric changes noted during the development of this consortia.Figure S4. Relationship between the relative abundance of Bacteroidetes (A), Firmicutes (B) and Thermus (C) based on SSU amplicon libraries and CrI using X-ray diffraction. Starting crystallinity of the cellulose prior to microbial transformation is depicted with an arrow in each panel.Figure S5. Experimental design of the establishment for the thermophilic consortia (A) and high-resolution analysis of the MCC-adapted thermophilic consortia within a passage (B).Table S1. Average DNA (μg) per 50 ml of culture ± standard deviation (n = 3 biological replicates).Table S2. Relative proportion clusters (OTU97, > 1%) for passage 4 microcrystalline cellulose (MCC) and wheat arabinoxylan (xylan). Phylum description was assigned by the Ribosomal Database Project Classifier, Release 10. The OTU identification was assigned by GenBank.Table S3. Average endoglucanase and endoxylanase activities (U ml-1 min-1) ± standard deviation (n = 3 biological replicates) measured in whole cell fractions across the five passages for the various substrates at 65°C, pH = 6.5. ND = not detected.Table S4. Physical and chemical properties the Newby Island compost inoculum used in the thermophilic enrichments. ΔSoil testing was performed at New Mexico State University Soil, Water, and Agricultural Testing Lab (Las Cruces, NM). U.S. Department of Energy, Office of Science, Office of Biological and Environmental Research - No. DE-AC02-05CH11231 Office of Science of the U.S. Department of Energy - No. DE-AC02-05CH11231 istex:731EA72ABC4B0643C1B9E9692B6627BD240E78B0 ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23 USDOE Office of Science (SC), Biological and Environmental Research (BER) |
| ISSN: | 1462-2912 1462-2920 |
| DOI: | 10.1111/1462-2920.12159 |