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

Abstract

As a strategy to find efficient lignocellulose degrading enzymes/microorganisms for sugarcane biomass pretreatment purposes, 118 culturable bacterial strains were isolated from intestines of sugarcane-fed larvae of the moth Diatraea saccharalis. All strains were tested for cellulolytic activity using soluble carboxymethyl cellulose (CMC) degrading assays or by growing bacteria on sugarcane biomass as sole carbon sources. Out of the 118 strains isolated thirty eight were found to possess cellulose degrading activity and phylogenetic studies of the 16S rDNA sequence revealed that all cellulolytic 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, Bacillus and Enterococcus). Bacterial growth on sugarcane biomass as well as extracellular endo-glucanase activity induced on soluble cellulose was found to be highest in species belonging to genera Bacillus and Klebsiella. Good cellulolytic activity correlated with high extracellular protein concentrations. In addition, scanning microscopy studies revealed attachment of cellulolytic strains to different sugarcane substrates. The results of this study indicate the possibility to find efficient cellulose degrading enzymes and microorganisms from intestines of insect larvae feeding on sugarcane and their possible application in industrial processing of sugarcane biomass such as second generation biofuel production.

Influence of Diatraea saccharalis (Lepidoptera: Crambidae) infestation on sweet sorghum productivity and juice quality

“…This corroborates observations by Milano (2012) who isolated bacteria that degraded cellulose in the digestive tract of the species. Although, Saldarriaga (2009) and Dantur et al (2015) reported that bacteria isolated from the intestinal tract of D. saccharalis showed a positive response in in vitro degradation tests for cellulose, hemicellulose and lignin in sugarcane bagasse, they showed a greater efficiency in cellulose degradation.…”

Characterization and Strain Improvement of a Hypercellulytic Variant, Trichoderma reesei SN1, by Genetic Engineering for Optimized Cellulase Production in Biomass Conversion Improvement

“…Diverse cellulolytic microorganisms, including fungi and bacteria, have been isolated from various environments (Jyotsna et al, 2010; Raddadi et al, 2013; Dantur et al, 2015; Premalatha et al, 2015). However, the ability to produce cellulose-degrading enzymes by using wild strains is not always fit for industrial requirements (Weiss et al, 2013).…”

Comparative analysis of stirred catalytic basket bio-reactor for the production of bio-ethanol using free and immobilized Saccharomyces cerevisiae cells

“…The concentration of ethanol produced in a fermentation broth as well as calibration curve was measured with the same method as in previous paper (Hussain et al 2015a). The fermentation broth samples (each having volume 600 μl) were collected, transferred to an Eppendorf tube and centrifuged at 9000 rpm for 5 min to pellet the cells.…”

“…The traditional setups used in the ethanol production like membrane bioreactor, airlift bioreactor, fixed bed bioreactors and stirred tank reactors have some drawbacks of less product yield due to low mass and heat transfer, inefficient conversion of substrate, uneven mixing and shear stress on biocatalysts (Hussain et al 2015a). To overcome these problems and to improve the efficiency of a bioreactor, four most important factors need to be put in consideration i.e.…”