Isolation of Cellulolytic Organisms from the Gut Contents of Termites Native to Nepal and Their Utility in Saccharification and Fermentation of Lignocellulosic Biomass

Abstract

Lignocellulose is one of the most abundant renewable materials that could serve as a source for fermentable sugars. However, its commercial deployment is limited by the fact that lignocellulose is recalcitrant and requires heroic efforts to release sugars. Although very few, there are cellulose degrading organisms in nature that can efficiently degrade the cellulosic biomass and one among them is termite. Termites are responsible for mass turnover of the cellulosic biomass and they accomplish this task by harbouring a consortium of cellulolytic and lignolytic microorganisms. In the present study, we have isolated eight bacterial and five fungal cellulose degrading organisms from the gut of a termite native to Nepal via basal culture medium enrichment with filter paper as substrate. The isolated organisms were identified as Bacillus sp., Cellulomonas sp., Enterobacter sp., and Aspergillus sp. The Congo red screening assay for cellulase production showed the largest zone of hydrolysis (38 mm) for Aspergillus sp. The carboxymethyl cellulose assay revealed that the Bacillus sp (S3B8; 0.12± 0.01 IU/ml obtained within96 hours) and Aspergillus sp. (S3F3; 0.07 ±0.01 IU/ml obtained within 168 hours) were most efficient cellulase producers. The saccharification and fermentation of lignocellulosic biomass to ethanol was successfully achieved via culturing of selected bacterial [Bacillus (S3B8)] and fungal isolates [Aspergillus (S3F3)] and then fermentation with Saccharomyces cerevisiae (S2Y1). Further characterization of these organisms and optimization of fermentation of lignocellulosic biomass is ongoing.

Symbiotic cellulolytic bacteria from the gut of the subterranean termite Psammotermes hypostoma Desneux and their role in cellulose digestion

“…The pure colonies from each isolates were grown in 50 mL medium containing (g/L) 0.2 K 2 HPO 4 , 0.01 MgSO 4 , 1 NaCl, 0.5 NaNO 3 , 0.05% yeast extract and 10 g CMC according to Sharma et al (2015). Cultures were incubated at 37 °C for 72 h. At the end of incubation 1 mL of each culture suspension was centrifuged at 5000 rpm for 10 min and the pellets were re-suspended in fresh medium.…”

“…The Congo red screening assay for cellulase production showed the widest zone of hydrolysis (38 mm) for Aspergillus sp. (Sharma et al 2015).…”

Isolation, Screening and the Influence of Cultivation Factors on Cellulase of Bacteria Isolated From Termites Gut

“…According to Sharma, Bacillus. sp S3B8 isolated from termites gut was also produced maximum CMCase at pH 7 [10].…”

“…It is believed that the temperature influences the secretion of extracellular enzyme by possibly changing/or altering the physical properties of the cell membrane. Bacillus grew best at 37 °C in numerous reports [5,6,10].…”

Molecular Characterization of Cellulolytic Bacteria Derived From Termite Gut and Optimization of Cellulase Production

“…The results obtained are similar with the previous studies. Sharma et al, 2015 found optimum pH at 7 for endoglucanase activity by Bacillus sp. isolated from termite.…”