Biosynthesis of Extracellular Polymeric Substances by the Marine BacteriumSaccharophagus degradansunder Different Nutritional Conditions

Yolanda González-García,Froylán M E Escalante,Jesús Córdova,Rosa María Camacho-Ruiz,Alejandra Heredia,Juan Carlos Meza-Contreras

doi:10.1155/2015/526819

Abstract

The effect of carbon source, carbon to nitrogen (C/N) ratio, and limitation in nutrients (N, P, K, Ca, Mg, and Fe) on extracellular polymeric substances (EPS) synthesis by the marine bacteriumSaccharophagus degradanswas studied. This strain was able to grow in mineral medium and produce EPS with different efficiency according to the C source used (g EPS/L): glucose or starch (1.5 ± 0.2); galactose, sucrose, or xylose (0.7 ± 0.2); and fructose (0.3 ± 0.1). The C/N ratio (glucose/ammonium) had a significant effect on EPS biosynthesis due to its production rise as the C/N ratio increased from 3 to 100 (0.7 to 2.1 g EPS/L). It was also observed that limitation in nutrients such as N, P, K, Ca, Mg, and Fe also favored EPS biosynthesis. When taking into account both factors (C/N ratio, 100; nutrients limitation, 50%) a positive synergistic effect was noted on EPS production since under these conditions the maximum concentration obtained was 4.12 ± 0.3 g/L after 72 h of culture. The polymer was found to be a polysaccharide of mainly glucose, mannose, and galactose. This is the first report on EPS production byS. degradanswhich is a new feature of this versatile marine bacterium.

Highlights

In recent years, the demand for natural polymers has triggered the interest in the production of exopolymeric substances (EPS) by microorganisms [1]
The effect of carbon source, carbon to nitrogen (C/N) ratio, and limitation in nutrients (N, P, K, Ca, Mg, and Fe) on extracellular polymeric substances (EPS) synthesis by the marine bacterium Saccharophagus degradans was studied. This strain was able to grow in mineral medium and produce EPS with different efficiency according to the C source used (g EPS/L): glucose or starch (1.5 ± 0.2); galactose, sucrose, or xylose (0.7 ± 0.2); and fructose (0.3 ± 0.1)
Three different experiments were performed in order to assess the production of EPS by S. degradans: (A) production from different C sources in a nutrient balanced medium denominated as basal medium (BM); (B) effect of C/N ratio and combined nutrients limitation using N, P, S, Mg, Fe, and Ca limited medium (NL), with glucose as C source; (C) bioreactor culture from glucose, using the best culture condition according to experiment B

Summary

Introduction

The demand for natural polymers has triggered the interest in the production of exopolymeric substances (EPS) by microorganisms [1]. EPS are environmentally friendly since they are renewable in nature, nontoxic, and biodegradable [4]. EPS exist in a wide variety of chemical structures: hexoses sugars, such as D-glucose, D-galactose, D- and L-mannose; pentoses such as D-ribose, D-arabinose, and D-xylose; few heptoses; and branched-chain sugars [5]. The production of exopolymers in marine bacteria, such as Alteromonas macleodii [6] and Halomonas ventosae [7], is a common phenomenon. EPS increase the ability of such bacteria to adhere to surfaces which is an important feature to survive successfully in aquatic environment. There is evidence they provide self-protection against desiccation, antimicrobial substances [8], and bacteriophages [3]

Methods

Results

Conclusion