Giuliano Degrassi, Rodrigo Hoshino, Milan Koijc, Mariela Catone, Vibha Bhardwaj and Mario A Rosato
A Bacillus subtilis endoglucanase gene was amplified and cloned in Escherichia coli, the enzyme was expressed and purified to homogeneity by affinity chromatography and conditions for its optimal activity and stability were determined. The E. coli M15 (pREP4) heterologous expression system was grown and induced under controlled fermentation conditions and the purified enzyme was used for enzymatic pre-treatment of corn silage and digestate from a corn silage-fed anaerobic digestor. The biochemical methane potential of enzyme pre-treated and non-pre-treated corn silage and digestate was estimated, showing that in both cases there is a statistically significant increase of BMP of more than 30% due to the enzymatic pre-treatment. This result suggests that enzymatic pre-treatment of feedstocks could be a technology to befurther explored as a tool for increasing the efficiency of biogas production process, also from the economic sustainability point of view.
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