Production of Cocktail of Lignolytic, Cellulolytic and Hemicellulolytic Enzymes by the Novel Bacterium Burkholderia sp SMB1 Utilizing Rice Bran and Straw: Application in the Saccharification of Untreated Agro-wastes for Bioethanol Production
2022
Beladhadi, R. V. | Caṅkar Kumār, | Jayalakshmi, S. K. | Sreeramulu, Kuruba
PURPOSE: This study focuses to assess the potentiality of the locally isolated Burkholderia sp SMB1. It was aimed for the cocktail of lignocellulolytic enzymes production involved in the depolymerization of the agro-wastes to release sugars for bioethanol production. METHODS: The optimization of enzymes cocktail (lignolytic, cellulolytic, hemicellulolytic) production by isolated bacterium utilizing inexpensive substrates like bran and straw of rice was done using response surface methodology. Further this cocktail secreted by the bacterium at optimized conditions was employed for saccharifying untreated agro-wastes for sugars production which were fermented to bioethanol by S. cerevisiae. RESULTS: This strain produced high titer of cellulase (10.8 U/mL), xylanase (76 U/mL), mannanase (14.23 U/mL), pectinase (62.18 U/mL) and laccase (24.25 U/mL) using rice bran at 7 pH and 40 °C using 10% (w/v) of rice bran. The production of cocktail of enzymes was slightly increased by adding CaCO₃ (2mM) in the growth medium. This cocktail was able to hydrolyze untreated agro-wastes to release highest reducing sugars 28.5 g/L using untreated corn husk after 24 h of saccharification process. These sugars of corn husk were fermented by S. cerevisiae to produce highest 9.04 g/L bioethanol. CONCLUSIONS: This paper represents the exploitation of the locally isolated strain for the production of lignocellulolytic enzymes using rice bran and straw for the first time promising the significance of the study. This study helps in waste disposal process by valorizing the waste biomass to produce value added products like sugars, bioethanol and hence increases agricultural economy.
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