Sources for isolation of extracellular polymeric substances (EPSs) producing bacterial strains which are capable of using wastewater sludge as solo substrate.

Isolation of extracellular polymeric substances (EPSs) producing bacterial strains capable of using sludge as low-cost growth substrate was carried out in this study. A total of 110 EPS-producing strains were isolated from different sources, which include sludge of beer and winery wastewater treatment plant (WWTP); young, 2-month-old and 10-year-old leachate. Thirty-seven isolated strains showed good growth in sludge medium with cell count varying from 10(6) to 10(10) most probable number (MPN)/mL and total EPS concentration from 2737 to 6639 mg/L. Twenty-one strains produced EPS with high flocculation activity (FAmax varied from 72.0% to 80.2%). The highest FAmax (80.2%) was observed with EPS produced by strain BES 19, which was isolated from sludge of beer WWTP. Sludge of beer WWTP, young leachate and 10-year-old leachate were good sources for isolation of EPS-producing bacteria.