Isolation, characterization and cultural optimization of cellulolytic bacteria from municipal solid waste landfill site

The municipal solid waste is composed of 40–50% of cellulosic material that is the most abundant biomass and carbon source on earth. In the present study waste samples were used for the isolation of cellulolytic bacteria on Carboxy Methyl Cellulose agar media (CMC) at pH of 7.0, temperature of 30°C after 48 hours by using serial dilution and pour plate method. A total of 35 bacteria were isolated out of which a total of only 15 isolates showed cellulolytic activity by forming zone of hydrolysis on CMC agar media. All the isolates were screened for cellulase activities by Congo Red Dilution Assay (qualitative enzyme activity) and dinitrosalicylic acid (DNS) method was used for quantitative cellulase activity. Results of congo red dilution assay revealed that all the isolates were significant cellulase producers and the isolate I7 was significantly most efficient by forming hydrolysis zone diameter and zone-colony ratio of 33mm and 3.3respectively after 72 hours of incubation period. Further results of quantitative screening of the isolates were in accordance with the qualitative screening and the isolate I7 again showed significantly maximum cellulase activity of 3.0U/ml. Based on morphological and biochemical characteristics, the efficient bacterial isolate I7 was identified as Bacillus sp. Further the optimization of process parameters was done for the isolate and the optimum parameters were: pH of 7.0, temperature 30°C, Incubation time 72 hours, Glucose as carbon source and 1% CMC concentration as substrate. It was concluded that the landfill site houses a diverse group of cellulose degrading bacteria with significant cellulase production potential and the isolates could be used for enhanced composting of cellulose rich municipal solid waste or could have industrial applications.