Isolation and characterization of bacteria from the gut of Bombyx mori that degrade cellulose, xylan, pectin and starch and their impact on digestion

A. Alwin Prem Anand1,4a, S. John Vennison2b, S. Gowri Sankar1,2, D. Immanual Gilwax Prabhu1,2, P. Thirumalai Vasan1,2, T. Raghuraman1, C. Jerome Geoffrey1, S. Ezhil Vendan1,3

1Research Centre for Biological Sciences, Naesam Trust, Ellis Nagar, Madurai, 625016, India
2Dept. of Biotechnology, Anna University, Tiruchirappalli, 620 024, India
3Present address: Entomology Research Institute, Loyola College, Chennai, 600034, India
4Present address: University of Tübingen, Institute of Anatomy, Österbergstrasse 3, 72074 Tübingen

Abstract

Bombyx mori L. (Lepidoptera: Bombycidae) have been domesticated and widely used for silk production. It feeds on mulberry leaves. Mulberry leaves are mainly composed of pectin, xylan, cellulose and starch. Some of the digestive enzymes that degrade these carbohydrates might be produced by gut bacteria. Eleven isolates were obtained from the digestive tract of B. mori, including the Gram positive Bacillus circulans and Gram negative Proteus vulgaris, Klebsiella pneumoniae, Escherichia coli, Citrobacter freundii, Serratia liquefaciens, Enterobacter sp., Pseudomonas fluorescens, P. aeruginosa, Aeromonas sp., and Erwinia sp.. Three of these isolates, P. vulgaris, K. pneumoniae, C. freundii, were cellulolytic and xylanolytic, P. fluorescens and Erwinia sp., were pectinolytic and K. pneumoniae degraded starch. Aeromonas sp. was able to utilize the CMcellulose and xylan. S. liquefaciens was able to utilize three polysaccharides including CMcellulose, xylan and pectin. B. circulans was able to utilize all four polysaccharides with different efficacy. The gut of B. mori has an alkaline pH and all of the isolated bacterial strains were found to grow and degrade polysaccharides at alkaline pH. The number of cellulolytic bacteria increases with each instar.

Keywords: Aeromonas sp., Bacillus circulans; Citrobacter freundii; Enterobacter sp., Erwinia sp., Klebsiella pneumoniae; Proteus vulgaris; Pseudomonas aeruginosa; Pseudomonas fluorescens; Serratia liquefaciens
Abbreviations: CFU, colony formaing units; CMC, carboxy methyl cellulose

Correspondence: aalwinprem@gmail.com, bjohnvennison36@gmail.com
Associate Editor: Allen Cohen was editor of this paper.

Received: 29 July 2008 | Accepted: 30 April 2009 | Published: 13 July 2010

ISSN: 1536-2442 | Volume 10, Number 107

Anand AAP, Vennison SJ, Sankar SG, Prabhu DIG, Vasan PT, Raghuraman T, Geoffrey CJ, Vendan SE. 2010. Isolation and characterization of bacteria from the gut of Bombyx mori that degrade cellulose, xylan, pectin and starch and their impact on digestion. Journal of Insect Science 10:107, available online: insectscience.org/10.107


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