INCIDENCE OF MICROORGANISMS, THEIR ENZYMES, SENSITIVITY PATTERN AND PHYSICOCHMICAL CHARACTERISTICS OF SOME WASTE DUMPSITES IN ADO-EKITI, NIGERIA

Abstract

The research was carried out to investigate the incidence of microorganisms, their enzymes, sensitivity pattern and physico-chemical characteristics of some waste dumpsites in Ado-Ekiti, Nigeria. The physicochemical parameters and heavy metals assessment of the waste dump site were determined using standard methods. The microbiological analysis was carried out by first cultivating and enumerating bacteria and fungi using conventional methods. The bacteria isolates were identified by morphological and standard biochemical tests while that of the fungi was by macroscopic and microscopic method. Antibiotic susceptibility of isolates was done by disc diffusion method. Plasmid DNA in multiple antibiotic resistant isolates was extracted by alkali lysis (TENS) method. Amylase production was detected using starch agar while carboxyl methyl cellulose agar was used for cellulose screening. The pH of the soil samples ranged from 5.7 to 9.0. The temperature values of all the soil samples ranged from 24.7 to 28.9oC while the moisture contents of the soil samples ranged from 4.20 to 15.1%. The highest mean bacteria load (5.38 x 106 cfu/g) was obtained from Oke-Ori Omi dumpsite soil sample while the least value (2.32 x 106) was recorded for Bawa dumpsite soil sample. The highest fungi count (1.16 x 106 cfu/g) was obtained from Similoluwa dumpsite’s soil samples while Bawa dumpsite soil samples had the least value of 2.21 x 103 cfu/g. The bacteria isolates include Bacillus sp. Clostridium sp. Corynebacterium sp. Escherichia coli, Staphylococcus sp., Proteus sp., Enterobacter sp., Micrococcus sp., Klebsiella sp., Pseudomonas sp. and Serratia sp. while that of fungi include Penicillium sp., Fusarium sp., Aspergillus niger, Aspergillus fumigatus, Mucor sp. and Candida sp. The frequency of isolation of the bacteria isolates ranged from 2 (3.30%) to 23 (37.1%) while that of fungi ranged from 1 (5.88%) to 5 (29.41%). Among the bacteria isolates, Bacillus sp., Escherichia coli and Staphylococcus sp. were recovered from all the study areas while none of the fungi isolates were evenly distributed in all the study sites. Bacillus sp. and Aspergillus niger were the most isolated bacteria and fungi respectively. Except Aspergillus funmigatus, all the fungi isolates produce amylase. Also, Mucor, Fusarium and Candida species isolated did not produce cellulase while others were cellulase producers. Overall resistance among Gram positive bacteria isolated ranged from 39.5 to 84.2% while that of the Gram negative bacteria ranged from 33.3 to 83.3%. In general, 31 (86.84%) of the Gram positive bacteria recovered from all the soil samples were MDRs with 31 different resistant patterns while 18 (75.0%) of the Gram negative bacteria were MDRs with 15 different resistotypes. Some of the bacteria harbored plasmids ranging from 1-3 and molecular weights of the plasmids ranged from 1162 to 33043 kb. Heavy metal concentrations varied among the soil samples. Heavy metals concentrations in all the soil samples analysed were below the recommended safe limits of heavy metals by WHO, FAO, EU standards. Refuse dumpsites could serve as a sources of novel organisms that can be employed in environmental, bioremediation and biotechnology but the health hazard associated with the indiscriminate dumping of refuse around residential areas and other ecological sensitive areas such as rivers and streams and arable lands should not be underestimated.