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Front. Microbiol. | doi: 10.3389/fmicb.2018.00299

Temporal expression dynamics of plant biomass-degrading enzymes by a synthetic bacterial consortium growing on sugarcane bagasse.

  • 1Microbial Ecology, University of Groningen, Netherlands

Plant biomass (PB) is an important source of sugars useful for biofuel production, whose degradation efficiency depends on synergistic and dynamic interactions of different enzymes. Here, using a metatranscriptomics-based approach, we explored the expression of PB-degrading enzymes in a five-species synthetic bacterial consortium during cultivation on sugarcane bagasse as a unique carbon source. By analyzing the temporal expression dynamics of a selection of enzymes we revealed the functional role of each consortium member and disentangled the potential interactions between them. Based on normalized expression values and the taxonomic affiliation of all the transcripts within thirty carbohydrate-active enzyme (CAZy) families, we observed a successional profile. For instance, endo-glucanases/-xylanases (e.g. GH8, GH10 and GH16) were significantly expressed at 12 hours, whereas exo-glucanases (e.g. GH6 and GH48) and alpha-arabinosidases/beta-xylosidases (e.g. GH43) were highly expressed at 48 hours. Indeed, a significant peak of extracellular β-xylosidase activity was observed at this stage. Moreover, we observed a higher expression of several CAZy families at 12-48 hours, suggesting easy access to the main plant polysaccharides. Based on this evidence, we predicted that the highest level of collaboration between strains take place at the initial stages of growth. Here, Paenibacillus, Brevundimonas and Chryseobacterium were the most important contributors, whereas Stenotrophomonas was highly active at the end of the culture (96-192 hours) without contributing to a large extent to the expression of lignocellulolytic enzymes. Our results contribute to the understanding of enzymatic and ecological mechanisms within PB-degrading microbial consortia, yielding new perspectives to improve PB saccharification processes.

Keywords: Bacterial consortium, expression dynamics, lignocellulolytic enzymes, metatranscriptomics, Synergism, sugarcane bagasse

Received: 21 Sep 2017; Accepted: 08 Feb 2018.

Edited by:

Suhelen Egan, University of New South Wales, Australia

Reviewed by:

François Thomas, UMR8227 Laboratoire de Biologie intégrative des modèles marins, France
Johan Larsbrink, Chalmers University of Technology, Sweden
Guillermina Hernandez-Raquet, Institut National de la Recherche Agronomique (INRA), France
Fabio M. Squina, Universidade de Sorocaba, Brazil  

Copyright: © 2018 Jiménez, Chaib De Mares and Falcão Salles. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Diego J. Jiménez, University of Groningen, Microbial Ecology, Nijenborgh 7, Groningen, 9747AG, Netherlands, djimenez1909@gmail.com