Optimization of Dairy Sludge for Growth ofRhizobiumCells

Abstract

In this study dairy sludge was evaluated as an alternative cultivation medium forRhizobium. Growth of bacterial strains at different concentrations of Dairy sludge was monitored. Maximum growth of all strains was observed at 60% Dairy sludge concentration. At 60% optical density (OD) values are 0.804 forRhizobium trifolii(MTCC905), 0.825 forRhizobium trifolii(MTCC906), and 0.793 forRhizobium meliloti(MTCC100). Growth pattern of strains was observed at 60% Dairy sludge along with different synthetic media (tryptone yeast,Rhizobiumminimal medium and yeast extract mannitol). Growth in 60% Dairy sludge was found to be superior to standard media used forRhizobium. Media were optimized using 60% dairy sludge along with different concentrations of yeast extract (1–7 g/L) and mannitol (7–13 g/L) in terms of optical density at different time intervals, that is, 24, 48 and 72 hours. Maximum growth was observed in 6 g/L of yeast extract and 12 g/L of mannitol at 48-hour incubation period in all strains. The important environmental parameters such as pH were optimized using 60% dairy sludge, 60% dairy sludge +6 g/L yeast extract, and 60% dairy sludge +12 g/L mannitol. The maximum growth of all strains was found at pH 7.0. The present study recommends the use of 60% dairy sludge as a suitable growth medum for inoculant production.