Novel multispecies microbial consortia involved in lignocellulose and 5-hydroxymethylfurfural bioconversion

Abstract

To develop a targeted metagenomics approach for the analysis of novel multispecies microbial consortia involved in the bioconversion of lignocellulose and furanic compounds, we applied replicated sequential batch aerobic enrichment cultures with either pretreated or untreated wheat straw as the sources of carbon and energy. After each transfer, exponential growth of bacteria was detected using microscopic cell counts, indicating that the substrate was being utilized. In batch, the final bacterial abundances increased from an estimated 5 to 8.7-9.5 log 16S rRNA gene copy numbers/ml. The abundances of fungal propagules showed greater variation, i.e., between 5.4 and 8.0 log ITS1 copies/ml. Denaturing gradient gel electrophoresis analyses showed that the bacterial consortia in both treatments reached approximate structural stability after six transfers. Moreover, the structures of the fungal communities were strongly influenced by substrate treatment. A total of 124 bacterial strains were isolated from the two types of enrichment cultures. The most abundant strains were affiliated with the genera Raoultella/Klebsiella, Kluyvera, Citrobacter, Enterobacter, Pseudomonas, Acinetobacter, Flavobacterium and Arthrobacter. Totals of 43 and 11 strains obtained from the untreated and pretreated substrates, respectively, showed (hemi)cellulolytic activity (CMC-ase and xylanase), whereas 96 strains were capable of growth in 7.5 mM 5-hydroxymethylfurfural. About 50 % of the latter showed extracellular oxidoreductase activity as detected by a novel iodide oxidation method. Also, (hemi)cellulolytic fungal strains related to Coniochaeta, Plectosphaerella and Penicillium were isolated. One Trichosporon strain was isolated from pretreated wheat straw. The two novel bacterial-fungal consortia are starting points for lignocellulose degradation applications.

Metabolic Engineering of Raoultella ornithinolytica BF60 for Production of 2,5-Furandicarboxylic Acid from 5-Hydroxymethylfurfural

“…First, we isolated and identified a new strain, R. ornithinolytica BF 60, that can efficiently produce FDCA from 5-HMF, which is a basic furanic compound, from biorenewable sources. It was recently reported that Raoultella species are members of lignocellulose-degrading communities and play an active role in the response to furanic compounds (21). For the production of fine chemicals and pharmaceutical compounds, whole-cell-based biotransformation processes have been developed through process optimization and engineering of cellular metabolic pathways (22,23).…”

Characterization of the Microbial Communities in Rumen Fluid Inoculated Reactors for the Biogas Digestion of Wheat Straw

“…In addition, members of other phyla were also important for the anaerobic digestion process, e.g., the presence of Citrobacter and Escherichia in the reactors may be responsible for lignin degradation [60,61], and Spirochaeta is involved in cellulose degradation [54].…”

Heterologous expression of cellulase genes in natural Saccharomyces cerevisiae strains

“…The use of microbial consortia for industrial production of bio-products has not yet been studied to any great extent (82). The main advantage of using a consortia co-culture system is the flexibility that is absent in mono-cultures systems of individual strains for the rational design of secretome compositions (54).…”

“…The main advantage of using a consortia co-culture system is the flexibility that is absent in mono-cultures systems of individual strains for the rational design of secretome compositions (54). Microbial consortia, also known as co-fermentation systems, have been studied due to their usefulness in bio-processing (83), moreover consortia can consist of multiple species or a single species with different engineered lines (82).…”