Isolation of cellulolytic bacteria from the intestine of Diatraea saccharalis larvae and evaluation of their capacity to degrade sugarcane biomass

KARINA I DANTUR, ; RAMÓN ENRIQUE, ; BJÖRN WELIN; ATILIO P CASTAGNARO

AMB Express

Springer

Año: 2015

2191-0855

As a strategy to find efficient lignocellulose degrading enzymes/microorganisms for sugarcane biomass pretreatmentpurposes, 118 culturable bacterial strains were isolated from intestines of sugarcane-fed larvae of the moth Diatraeasaccharalis. All strains were tested for cellulolytic activity using soluble carboxymethyl cellulose (CMC) degrading assaysor by growing bacteria on sugarcane biomass as sole carbon sources. Out of the 118 strains isolated thirty eight werefound to possess cellulose degrading activity and phylogenetic studies of the 16S rDNA sequence revealed that allcellulolytic strains belonged to the phyla γ-Proteobacteria, Actinobacteria and Firmicutes. Within the three phyla,species belonging to five different genera were identified (Klebsiella, Stenotrophomonas, Microbacterium, Bacillusand Enterococcus). Bacterial growth on sugarcane biomass as well as extracellular endo-glucanase activity inducedon soluble cellulose was found to be highest in species belonging to genera Bacillus and Klebsiella. Good cellulolyticactivity correlated with high extracellular protein concentrations. In addition, scanning microscopy studies revealedattachment of cellulolytic strains to different sugarcane substrates. The results of this study indicate the possibility tofind efficient cellulose degrading enzymes and microorganisms from intestines of insect larvae feeding on sugarcaneand their possible application in industrial processing of sugarcane biomass such as second generation biofuel production