1. Academic Validation
  2. Halotolerant microbial consortia able to degrade highly recalcitrant plant biomass substrate

Halotolerant microbial consortia able to degrade highly recalcitrant plant biomass substrate

  • Appl Microbiol Biotechnol. 2018 Mar;102(6):2913-2927. doi: 10.1007/s00253-017-8714-6.
Larisa Cortes-Tolalpa 1 Justin Norder 2 Jan Dirk van Elsas 2 Joana Falcao Salles 2
Affiliations

Affiliations

  • 1 Department of Microbial Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands. l.cortes.tolalpa@gmail.com.
  • 2 Department of Microbial Ecology, Groningen Institute for Evolutionary Life Sciences, University of Groningen, Nijenborgh 7, 9747 AG, Groningen, The Netherlands.
Abstract

The microbial degradation of plant-derived compounds under salinity stress remains largely underexplored. The pretreatment of lignocellulose material, which is often needed to improve the production of lignocellulose monomers, leads to high salt levels, generating a saline environment that raises technical considerations that influence subsequent downstream processes. Here, we constructed halotolerant lignocellulose degrading microbial consortia by enriching a salt marsh soil microbiome on a recalcitrant carbon and energy source, i.e., wheat straw. The consortia were obtained after six cycles of growth on fresh substrate (adaptation phase), which was followed by four cycles on pre-digested (highly-recalcitrant) substrate (stabilization phase). The data indicated that typical salt-tolerant bacteria made up a large part of the selected consortia. These were "trained" to progressively perform better on fresh substrate, but a shift was observed when highly recalcitrant substrate was used. The most dominant bacteria in the consortia were Joostella marina, Flavobacterium beibuense, Algoriphagus ratkowskyi, Pseudomonas putida, and Halomonas meridiana. Interestingly, fungi were sparsely present and negatively affected by the change in the substrate composition. Sarocladium strictum was the single Fungal strain recovered at the end of the adaptation phase, whereas it was deselected by the presence of recalcitrant substrate. Consortia selected in the latter substrate presented higher cellulose and lignin degradation than consortia selected on fresh substrate, indicating a specialization in transforming the recalcitrant regions of the substrate. Moreover, our results indicate that bacteria have a prime role in the degradation of recalcitrant lignocellulose under saline conditions, as compared to fungi. The final consortia constitute an interesting source of lignocellulolytic haloenzymes that can be used to increase the efficiency of the degradation process, while decreasing the associated costs.

Keywords

Bacterial-fungal consortia; Biomass degradation; Halotolerant degrader consortia.

Figures
Products