Isolation and Enzymatic Activity of Thermo-tolerant Bacteria from Waste Dumpsites in Umudikeand Environs

Abstract

The research studied the isolation of thermo-tolerant bacteria with enzymatic activity from waste dumpsites. 30 soil samples were collected using sterile spatular into sterile universal bottles, labelled and taken to the laboratory analyses. The soil samples were serially diluted and inoculated by spread plate method on different media and incubated at 30oC for 48 hrs. The isolates were observed for colonial morphologies and later sub-cultured to get pure isolates which were stored in agar slants and kept in the refrigerator for further use. The isolates were Gram stained and also subjected to biochemical and sugar fermentation tests. The isolates were then cultured at thermophilic temperature and those with positive results were screened for the production of amylase, protease and lipase activity. The effect of temperature, pH and nitrogen sources on enzyme activity of the thermophilic bacterial isolates was also assessed. Results show that Bacillus subtilis (70.0%), Bacillus licheniformis (43.3%), Bacillus cereus (56.7%), Pseudomonas aeruginosa (56.7%), Streptomyces species (36.7%), Bacillus brevis (43.3%)and Norcadia species (30%) were recovered from the soil samples. All the bacterial isolates tolerated 55oC of temperature while only Bacillus cereus, Bacillus brevis and Norcadia species were isolated at 60oC. All the isolates except Pseudomonas aeruginosa gave amylase activity while all the isolates gave protease activity. All the isolates except Bacillus licheniformis and Nocardia species had lipase activity. Temperature and pH had varied effects on the enzyme activity of the isolates. The potentials of these bacterial isolates as good sources of enzymes at elevated temperatures, varied pH and nitrogenous sources for commercial uses was recognized.