Medium optimization for the production of exopolysaccharide by Bacillus subtilis using synthetic sources and agro wastes

Authors : Sirajunnisa Abdul RAZACK, Vijayagopal VELAYUTHAM, Viruthagiri THANGAVELU

Pages : 280-288

Doi:10.3906/biy-1206-50

View : 17 | Download : 7

Publication Date : 2013-12-01

Article Type : Research Paper

Abstract :Exopolysaccharides insert ignore into journalissuearticles values(EPSs); play an extensive role as biopolymers in the environment by replacing synthetic polymers as they are degradable, nontoxic, and produced by microorganisms. An attempt was made to optimize a medium, by the one-factor-at-a-time method, for an enhanced production of EPS from a soil isolate, Bacillus subtilis. The study was carried out by experimenting on various nutrients at different concentrations. EPS was precipitated using ethanol, the total carbohydrate content was determined by phenol sulfuric acid method, and functional groups were detected by Fourier transform infrared insert ignore into journalissuearticles values(FTIR); spectrophotometry. The finalized medium contained sucrose insert ignore into journalissuearticles values(20 g/L);, yeast extract insert ignore into journalissuearticles values(5 g/L);, NaCl insert ignore into journalissuearticles values(7 g/L);, CaCl2 insert ignore into journalissuearticles values(0.5 g/L);, L-asparagine insert ignore into journalissuearticles values(0.05 g/L);, and ascorbic acid insert ignore into journalissuearticles values(0.05 g/L);. The carbon source was replaced with certain agro substrates, cane molasses, and rice bran. Cane molasses at a concentration of 2% gave the highest yield of 4.86 g EPS/L as compared to a medium with sucrose insert ignore into journalissuearticles values(2.98 g EPS/L);. The effect of UV radiations on growth and synthesis was negative, decreasing the growth rate and quantity of EPS produced. Different solvents were checked for their efficiency on precipitating EPS; those other than ethanol, diethyl ether, and methanol were not able to sediment the polymer. FTIR analysis of the extracted product revealed that the polymer was made up of units of sucrose. Thus, the present study showed that the agro wastes could be an alternative for synthetic substrates, providing a way for an economical production of EPS.
Keywords : Key words Bacillus subtilis, exopolysaccharide, cane molasses, rice bran, FTIR spectrophotometry