Secretome profile of Cellulomonas sp. B6 growing on lignocellulosic substrates.

AIMS: Lignocellulosic biomass deconstruction is a bottleneck for obtaining biofuels and value-added products. Our main goal was to characterize the secretome of a novel isolate, Cellulomonas sp. B6, when grown on residual biomass for the formulation of cost-efficient enzymatic cocktails. METHODS AND RESULTS: We identified 205 potential CAZymes in the genome of Cellulomonas sp. B6, 91 of which were glycoside hydrolases (GH). By secretome analysis of supernatants from cultures in either extruded wheat straw (EWS), grinded sugar cane straw (SCR) or carboxymethylcellulose (CMC), we identified which proteins played a role in lignocellulose deconstruction. Growth on CMC resulted in the secretion of two exoglucanases (GH6 and GH48) and two GH10 xylanases, while growth on SCR or EWS resulted in the identification of a diversity of CAZymes. From the 32 GHs predicted to be secreted, 22 were identified in supernatants from EWS and/or SCR cultures, including endo- and exoglucanases, xylanases, a xyloglucanase, an arabinofuranosidase/ß-xylosidase, a ß-glucosidase and an AA10. Surprisingly, among the xylanases, seven were GH10. CONCLUSIONS: Growth of Cellulomonas sp. B6 on lignocellulosic biomass induced the secretion of a diverse repertoire of CAZymes. SIGNIFICANCE AND IMPACT OF THE STUDY: Cellulomonas sp. B6 could serve as a source of lignocellulose-degrading enzymes applicable to bioprocessing and biotechnological industries.

Optimization of simultaneous removal of Cr (VI) and phenol by a native bacterial consortium: its use for bioaugmentation of co-polluted effluents.

AIMS: This study was designed to isolate, identify and characterize micro-organisms or mixed cultures capable of simultaneously removing Cr (VI) and phenol in the surrounding area of a tannery localized in Elena, Córdoba, Argentina. In addition, nutritional and physical factors were optimized in order to improve the removal efficiency in a real effluent. METHODS AND RESULTS: The consortium SFC 500-1, composed of two bacterial strains belonging to Acinetobacter and Bacillus genus, was isolated from the heavily polluted wastewater discharge channel of a local tannery. SFC 500-1 was able to remove phenol at environmentally relevant concentrations (1000 mg l(-1) ) and reduce Cr (VI) to Cr (III), which was immobilized in the bacterial biomass. The consortium simultaneously removed these contaminants under a wide range of physicochemical conditions and different growth media, even in a tannery effluent. CONCLUSION: The ability of SFC 500-1 to simultaneously reduce Cr (VI) and degrade phenol in different synthetic growth media and even in the effluent from which it was isolated with high efficiency makes this consortium a potential candidate for the biotreatment of effluents. SIGNIFICANCE AND IMPACT OF THE STUDY: This finding is important, taking into account that industrial effluents present complex mixtures of toxic substances as well as native flora which often affect the bioremediation process. Considering the ecological advantages of using native bacteria for bioremediation, as well as the high efficiency of the consortium SFC 500-1 to simultaneously remove Cr (VI) and phenol, this could be a suitable biological system to improve the biotreatment of polluted effluents through a bioaugmentation strategy.