Agrowastes as Feedstock for the Production of Endo-β-Xylanase from <b><i>Cohnella</i></b> sp. Strain AR92

Abstract

Members of Cohnella sp. isolated from a variety of environments have been shown to be glycoside hydrolase producers. Nevertheless, most evaluations of members of this genus are limited to their taxonomic description. The strain AR92, previously identified as belonging to the genus Cohnella, formed a well-supported cluster with C. thailandensis and C. formosensis (>80% bootstrap confidence). Its growth and xylanase production were approached by using a mineral-based medium containing alkali-pretreated sugarcane bagasse as the main carbon source, which was assayed as a convenient source to produce biocatalysts potentially fitting its degradation. By means of a two-step statistical approach, the production of endoxylanase was moderately improved (20%). However, a far more significant improvement was observed (145%), by increasing the inoculum size and lowering the fermentation temperature to 25°C, which is below the optimal growth temperature of the strain AR92 (37°C). The xylanolytic preparation produced by Cohnella sp. AR92 contained mild temperature-active endoxylanase (identified as redundant GH10 family) for the main activity which resulted in xylobiose and xylo-oligosaccharides as the main products from birchwood xylan.

A genome–proteome‐based approach for xylan degradation by Cohnella sp. AR92

“…AR92 genome data identified 209 pegs containing one or more carbohydrate active enzyme domains, including 115 GHs, 72 GTs, 28 CEs, 1 PL, 2 AA and 54 CBMs (Figure 1A), placing AR92 strain as a highly CAZyme containing genomes within the Panibacillaceae family. The predicted CAZymes were found to be targeted to various substrates (Supporting Material S2), which is well correlated with the capability of AR92 strain to grow and metabolize plant biomass polysaccharides, particularly xylan (Manfredi et al, 2015; Pisa et al, 2017).…”

“…A hypothetical model for xylan utilization by AR92 strain is proposed based on the genomic and proteomic assessment performed (Figure 4). Accordingly, at least six endo‐β‐xylanases belonging GH10 and GH11 families were identified as probable tools to reduce the polymerization degree of xylan backbone, releasing varied xylooligomer sizes by this microorganism (Hero et al, 2021; Pisa et al, 2017). The redundancy of such enzymes was observed in other bacterial strains able to degrade complex polysaccharides from vegetal biomass.…”