Quantification of Exopolysaccharide Produced by Bacillus subtilis and the Effect of Different Factors on its Production

Raghad R Al-Abbasi

doi:10.33899/rjs.2018.141189

Abstract

The present study included the extraction and characterization of EPS production by a local soil isolate Bacillus subtilis and examine the effect of different factors pH, inoculums size, incubation periods, and carbon, nitrogen and phosphate sources on EPS production. The exopolysaccharide was recovered from the culture supernatant by using a cold ethanol precipitation. The total carbohydrate content was determined by phenol sulfuric acid method at 488 nm, and major structural groups were detected by Fourier transform infrared (FTIR) spectroscopy at frequency range of 400 to 4000 cm-1. Basal salt solution (BSS) showed higher efficacy in supporting the bacteria to produce EPS (0.986 mg/ml) as dry weight. The study showed that glucose and fructose were gave maximum EPS production as a carbon source along with ammonium chloride as a nitrogen source. The optimal medium conditions were pH 7.0, inoculum size 5-6%, after four days of incubation to promote the maximum EPS production for the bacteria under study

Highlights

Microbial cells can persist in a free- living life style, while the majority of them establish a very complex and highly organized communities
The current study focuses on EPS produced by B. subtilis because it is ubiquitous, present in almost all ecosystems and the EPS produced by it has significant ecological relevance (Earl et al, 2008)
Other basal medium was tested for the efficacy of EPS production, nitrogen- free medium (NFM) and chemically defined medium (CDM), (Borgio et al, 2009)

Summary

Introduction

Microbial cells can persist in a free- living life style, while the majority of them establish a very complex and highly organized communities. Bacillus subtilis forms high structured colonies on semi-solid surfaces and in non- agitated liquid culture usually forms a floating biofilm called a pellicle at the air-liquid interface as a consequence of extracellular matrix production. EPS is a high molecular weight polymer consisting of monosaccharides and some non carbohydrate subunits such as protein; it may exists as tight capsules or loosely slimes or secreted to the surrounding environment (Rubinstein et al, 2012; Bragadeeswaran et al, 2011). The chemical composition of the EPS depends on the genetics of microbial cells and the physiochemical environment in which the biofilm matrix develops (Marvasi et al, 2010)

Methods

Results

Conclusion