Exploring the potential of novel thermophilic bacterial strain for the production of bioemulsifiers using the hydrolysate of sugarcane bagasse

Microbial bioemulsifiers are biodegradable and non-toxic compounds that stabilize oil-water emulsions. However, their widespread application necessitates their cost-effective production. The use of agro-wastes in the production medium can substantially reduce costs. This study reports the production of bioemulsifier by thermophilic bacteria using an enzymatic hydrolysate of sugarcane bagasse. Crude cellulase from the bacterial strain was used to saccharify sugarcane bagasse, and the hydrolysate was used as a medium for bioemulsifier production. The results showed that crude cellulase preparation from Brevibacillus borstelensis UE10, Neobacillus sedimentimangrovi UE25, and B. borstelensis UE27 yielded 1.2, 1.5, and 1.6 g L-1 of reducing sugars in the hydrolysate of sugarcane bagasse. Upon cultivation of these strains in the hydrolysates, 25-35% emulsification indices with bioemulsifier amounts that ranged between 107 and 113 mg mL(-1) were obtained. Based on the screening results and no prior reports on bioemulsifier production by any strain of Neobacillus, N. sedimentimangrovi UE25 was selected for statistical optimization of bioemulsifier production. Plackett-Burman design revealed significant effect of pH and incubation period which were optimized by central composite design. Under optimized conditions of temperature 60 degrees C, inoculum size 5%, NaCl and glucose concentration 0.5%, peptone concentration 1%, pH 7.6, and incubation period of 37.98 h, a 52% emulsification index was obtained. Moreover, structural analysis of the saccharified substrate by crude cellulase preparation using scanning electron microscopy and nuclear magnetic resonance revealed the removal of the cellulosic content. This bioemulsifier from a less-studied thermophilic bacterial strain makes it an interesting biotechnological product for various environmental and industrial applications.