Evaluating the Production Yield of an Exopolysaccharide Produced by Enterobacter cloacae subsp. Dissolvens in Seawater

Abstract

The aim of this study was to investigate the influence of different parameters on exopolysaccharide (EPS) production from Enterobacter cloacae subsp. dissolvens using seawater as a basal medium. For this purpose, the effect of carbon (sucrose, molasses, paraffin and sunflower oil) and nitrogen sources, NaCl concentration, incubation time, pH as well as seawater dilution or enrichment with distilled water or Aloe vera, respectively on EPS production was investigated. Incubation of bacteria at 30°C in the seawater for 24 hours resulted in 0.56% EPS production. Increasing the incubation time from 1 to 4 days led to a decrease in biopolymer production. EPS yield was not affected by the addition of sucrose, pH (6-8) or by bacteria inoculation in brine (1-4% NaCl). Dilution of seawater with different ratios of distilled water (1:2, 1:1 and 2:1) or seawater enrichment with various concentrations of Aloe vera leads to EPS yield reduction. Polymer production was drastically increased with sunflower (to 5%) or paraffin (to 3%) concentration. The interactions between different parameters on EPS production in the formulated mediums with distilled water were studied. The results showed that EPS production was reduced significantly in the formulated mediums containing different concentrations of water, NaCl, nutrient broth, glucose, ammonium sulfate and potassium phosphate. Among different formulations, the highest yield (0.27%) was achieved with the formulation of distilled water, 3.4% NaCl, 1% paraffin and 0.05% KH2PO4, indicating that simulation of seawater using formulated distilled water didn't provide comparable results. Therefore, paraffin and sunflower oil would be the matter of choice due to their higher productivity.