Isolation, molecular characterisation and screening of mesophilic and thermophilic bacteria from compost for enzymatic activity

Abstract Some bacteria have been found to produce enzymes and other metabolites that are of industrial and commercial importance. Accurate identification and characterization of these bacteria is therefore essential. This work focused on the isolation and molecular characterization of mesophillic and thermophillic aerobic bacteria from compost. The composting was done for 90 days with initial temperature of the heap after mixing being 30°C which was higher than the environmental temperature (25oC). Bacteria were isolated from the compost using the spread plate method. During the first 15 days, the pile temperature reached 35°C and then increased to 50°C on 45th day and further dropped to 28°C by the 90th day. Bacillus cereus, Bacillus subtilis and Bacillus licheniformis occurred the most, with 23.33% each, followed by Serratia marcescens (10%). Pseudomonas aeruginosa, Staphylococcus aureus and Pseudomonas flourescens represented 6.67% each being the least available isolates. The quantities of the cellulase enzyme produced showed that Bacillus subtilis had the highest cellulase and xylanase, giving 26.18 ± 0.10 and 24.10 ± 0.12 enzyme unit (EU) respectively. This was followed by Bacillus licheniformis which produced 25.10 ± 0.20EU and 22.50 ± 0.20EU for cellulase and xylanase respectively, Bacillus cereus with 22.14 ± 0.11EU and 20.02 ± 0.02EU for cellulase and xylanase respectively, Serratia marcescens with 20.09 ± 0.14EU and 18.20 ± 0.18EU for cellulase and xylanase respectively, Staphylococcus aureus with 19.22 ± 0.21EU and 17.40 ± 0.17EU for cellulase and xylanase respectively, Pseudomonas flourescens 18.50 ± 0.50 EU and 16.33 ± 0.25EUfor cellulase and xylanase respectively and Pseudomonas aeruginosa 16.20 ± 0.21 EU and 14.11 ± 0.08 EU for cellulase and xylanase respectively being the least value. Although substantial amount of enzymes were produced but, there was no significant difference (P > 0.05) between the cellulase and xylanase activities produced by isolated thermophillic and mesophillic bacteria from compost.