Diversity and EPS Production Potential of Halotolerant Bacteria from Veraval and Dwarka

Abstract

The microbial EPS are used in several biotechnological applications viz., cosmetics, textiles, pharmaceuticals, agricultural, paints and petroleum industries. Due to their extensive range of applications and also their bioactive roles there is increased interest for unusual and novel EPS. Less exploited saline and hypersaline environment may harbor microorganisms capable of producing unusual EPS with biotechnological interest. There are no reports of EPS production by halophilic and halotolerant bacteria from Gujarat. Therefore, the main aim of the study was to isolate halophilic and halotolerant bacteria, study their diversity and test their potential for EPS production. Four saline soil samples were collected, three from Veraval and one from Dwarka. The halophilic bacteria were enriched in media supplemented with 5% glucose containing increasing salt concentration from 5% to 35% NaCl. After enrichment organisms were isolated on solidified media containing salt concentration mentioned. Increasing salt concentration adversely affected growth. A total of 73 morphologically distinct isolates were studied. Less diverse colonies were obtained at low as well as extremely high salt concentration. The incidence of gram negative isolates decreased with increasing salt concentration. Organisms capable of growing at 35% NaCl concentration have been isolated. Out of 73 isolates, 23 isolates showing mucoid appearance were tested for EPS production which ranged from 0.2 gl-l to 10.60gl-l.