Optimization of factors influencing exopolysaccharide production by <em>Halomonas xianhensis</em> SUR308 under batch culture

Abstract

A moderately halophilic bacterium, Halomonas xianhensis SUR308 (GenBank Accession No. KJ933394) was isolated from multi-pond solar salterns of Odisha, India. Exopolysaccharide (EPS) production by this strain in malt extract yeast extract (MY) medium has been optimized under batch culture system. Among the different media tested, MY medium showed an EPS production of 2.55 g/L, which increased to 2.85 g/L under optimized aeration. An initial pH of 7.5 and incubation temperature of 32 °C were found to be most suitable for EPS production by the isolate under aerobic condition. An EPS production of 3.85 g/L was achieved when the growth medium was supplemented with 2.5% NaCl. Glucose was the most favourable carbon source for EPS production and maximum production (5.70 g/L) was recorded with 3% glucose. However, growth as well as production of EPS was remarkably affected when the growth medium was supplemented with hydrocarbons as sole source of carbon. Among different nitrogen sources, casein hydrolysate at 0.5% level was proved to be the best for EPS production and an initial inoculum dose of 7% (v/v) enhanced the EPS production to 7.78 g/L, while the divalent metal ions were in general toxic to growth and EPS production, EPS synthesis by SUR308 was enhanced with Cr (VI) supplementation.

High bioreactor production and emulsifying activity of an unusual exopolymer by Chromohalobacter canadensis 28

“…Investigations performed in the current study revealed a high effect of the agitation and aeration on EP production and twofold higher production (up to 2.34 mg/mL) in comparison with the EP yield of 1.2 mg/mL in shaking flasks [10] was observed reaching a degree of increase not reported before by other authors. This ratio is significantly higher than EPS production by H. xianhensis SUR308 for which an increase after optimized aeration was from 2.55 mg/mL to 2.85 mg/mL [23]. The reached EP yield of 3.085 mg/mL was three times more than the observed average production yield for marine EPS of around 1 mg/mL [24].…”

Genome analysis of a halophilic bacterium Halomonas malpeensis YU-PRIM-29T reveals its exopolysaccharide and pigment producing capabilities

“…Among the reported EPS producing Halomonas spp., H. stenophila HK30 produces haloglycan type of EPS and in aqueous medium it shows moderate to high viscosity and pseudoplastic behaviour 44 . H. xianhensis SUR308 EPS exhibit high viscosity and pseudoplasticity and stable over a wide pH range 45 . The EPS produced from Halomonas spp.…”

Halophiles as Chassis for Bioproduction

“…AAD6 (JCM 15723) yielded 1.073 and 1.844 g L −1 EPS under flasks and bioreactor condition, respectively . When the growth medium was supplemented with 2.5% NaCl and 0.5% casein hydrolysate at pH 7.5, Halomonas xianhensis generated to 7.78 g L −1 EPS . Other significant halophilic EPS producers Haloterrigena turkmenica and Halolactibacillus miurensis were reported.…”