DEGRADATIVE ABILITY AND PRODUCTION OF CELLULASE BY MICROBIAL ISOLATES FROM WASTES DUMPED AT DIFFERENT SITES IN AKURE

Abstract

This investigation was conducted to study the degradative ability and cellulase production of microorganisms from waste dump sites soil, cellophane and cellulosic materials of three different dump sites in Akure metropolis. These sites include; Ondo State Waste Management Board dump site; Federal University of Technology, Akure, Main dump site and Government dump Site. Soil samples, cellophane, wood shaves, maize cob and leachate were collected from different dumping sites and transfered to the laboratory for physicochemical analyses and microbiological studies. Microorganisms associated with the above samples were isolated and identified by microbiological techniques. Qualitative and quantitative screening for cellulolytic activity of above isolates were done by subculturing on the mineral salt medium supplemented with carboxylmethylcellulose as carbon source to check for cellulose utilisation. Purification of crude cellulase using ammonium sulphate precipitation, dialysis, ion exchange chromatography and gel filtration chromatography were carried out to obtain purified cellulase. The effect of innoculums, broth cultures, crude and purified enzymes of the best cellulolytic microorganisms on waste degradation was evaluated against wood shave, waste, tissue, carton and cellophane papers. The bacteria isolated from the samples from dump sites include; Bacillus acidovorans, B. cereus, B. subtilis, Clostridium botulinum, Escherichia coli, Klebsiella pneumoniae, Micrococcus luteus, Proteus vulgaris, Pseudomonas aeruginosa, Pseudomonas fluorescens, Serratia marcescens, Staphylococccus aureus and Streptococcus faecalis. The fungi isolated from the above samples were Aspergillus niger, A. nidulans, A. flavus, A. fumigatus, A. ripens, A. terrus, Trichoderma viride, Mucor mucedo, Fusarium oxysporum, Saccharomyces cerevisiae, Penicillium notatum, P. chrysogenum, Rhizopus stolonifer. Eleven out of thirteen bacteria and ten out of thirteen fungal isolates produced cellulase, but the enzyme produced was found to be higher in B. subtilis among the identified bacteria and A. flavus among the identified fungi respectively when subjected to qualitative and quantitative screening. Following ammonium sulphate precipitation, the crude cellulase produced by B. subtilis was purified 1.08 fold with a recovery of 17.57% and a specific activity of 2.58 U/mg of protein. The concentrated active fractions were finally purified by a gel filtration chromatography with a recovery of 7.88% and specific activity of 12.84 U/mg of protein, while cellulase produced by A. flavus was purified with a recovery of 16.45% and specific activity of 2.47 U/mg of protein and finally purified with a recovery of 9.13% and specific activity of 15.50 U/mg of protein. In the degradation of the solid wastes, there was a decrease in the weights of woodshave, waste, tissue, carton and cellophane papers by inoculums, broth culture, crude cellulase and purified cellulase of B. subtilis and A. flavus. The highest decrease in weight of the degraded wastes was found in tissue paper (from 5.0 to 0.8g) caused by purified cellulase of A. flavus after 56 days. Purified cellulase of A. flavus is hereby recommended for degradation of tissue, waste and carton papers.