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

Abstract

Purpose: This study focuses to assess the potentiality of the locally isolated Burkholderia sp SMB1. It was aimed for the cocktail of lignocellulolytic enzyme production involved in the depolymerization of the agro-wastes to release sugars for bioethanol production.Methods: The optimization of enzyme 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 o C using 10% (w/v) of rice bran. The production of cocktail of enzymes was slightly increased by adding CaCO 3 (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 sacchari cation process. These sugars of corn husk were fermented by S. cerevisiae to produce highest 9.04 gL -1 bioethanol.Conclusion: This paper represents the exploitation of the locally isolated strain for the production of lignocellulolytic enzymes using rice bran and straw for the rst time promising the novelty 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. Statement Of NoveltyThe production of the cocktail of lignolytic, cellulolytic and hemicellulolytic enzymes by the microorganisms has being the interesting topic because of its potentiality of utilizing the lignocellulosic agrowastes for the production of fermentable sugars. These sugars can be directly fermented to bioethanol without any detoxi cation as there may be less or no production of yeast inhibitors during the sacchari cation process through microbial or enzymatic process. Hence, the process becomes economically feasible as the steps required during fermentation (detoxi cation) may be reduced.Moreover, the isolated Burkholderia sp SMB1 becomes novel as it secretes high titer of enzymes after 24 h. This work represents to be the rst study on production of several lignocellulolytic enzymes by Burkholderia sp SMB1 strain utilizing several lignocellulosic agro-wastes. Thus, Burkholderia sp SMB1 strain shows the potentiality for its industrially application in biofuel industries as the cocktail of enzymes were utilized for the sacchari cation of agro-wastes to release fermentable sugars which are fermented to bioethanol by yeast strain.

Lignocellulolytic Biocatalysts: The Main Players Involved in Multiple Biotechnological Processes for Biomass Valorization

“…In addition, it promotes a circular economy and more sustainable production, helping to reduce the impact on the environment of waste that would previously be largely disposed of incorrectly [ 239 ]. Some examples of agro-industrial waste used are: straw and rice bran, corn straw, coffee husks, sawdust, sugarcane bagasse, and waste from the paper industry, among others [ 240 , 241 , 242 , 243 , 244 , 245 ] ( Figure 1 ).…”

Integrating 1G with 2G Bioethanol Production by Using Distillers’ Dried Grains with Solubles (DDGS) as the Feedstock for Lignocellulolytic Enzyme Production

“…thermoidea [46] Bacteria Bacillus pseudomycoides [47] Bacillus velezensis [48] Bacillus amyloliquefaciens FW2 [49] Lactobacillus plantarum RI 11 [50] Burkholderia sp. [51] In the literature, many research articles have been published, which identify and emphasize many fungal species as best producers of cellulases and hemicellulases. Most studies focus on solid-state fermentation methods, which are ideal for fungal strains.…”