Biosynthesis of Extracellular Polymeric Substances by the Marine Bacterium Saccharophagus degradans under Different Nutritional Conditions

الملخص EN

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).

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 by S.

degradans which is a new feature of this versatile marine bacterium.