Cultural optimization of a new exopolysaccharide producer “Micrococcus roseus”

Abstract

The ability to produce polysaccharides is widely spread among bacteria. The usefulness of EPS molecules makes development of new strategies for improved synthesis of EPS is a necessity. A novel EPS Producer promisingly was obtained from a culture of Micrococcus roseus. In the present investigation, two screening steps for exopolysaccharide production were done using 9 strains and 7 isolates of different taxonomic bacterial groups isolated from different soil samples together with bacterial strains obtained from culture collections. The first screening for EPS-production was done on solid basal media based on the mucous aspect of colonies. The slimiest and mucous bacterial strains were again screened for EPS production in liquid cultures. Comparative data of the eleven bacterial strains showed that Micrococcus roseus proved to produce the maximum EPS in shacked culture and the maximum EPS production was amounting to 1.805 g EPS/l. An attempt was made to optimize and maximize the production of EPS by M. roseus. Maximum EPS production of 800 mg/100 ml observed after 96 h incubation at 25 °C using 4.5% and 0.02% of sucrose and ammonium sulphate concentration respectively at pH 7.0. A preliminary structural elucidation of the exopolysaccharide of M. roseus was done using spectroscopic technique FTIR and showed a characteristic band attributed to (1–3) β glucan linkage. The monomeric composition was glucose, galactose and rhamnose with two carbohydrate and protein portions 91.3% and 8.7% respectively.