MICROBIAL COMPOSITION OF DECOMPOSING DOMESTIC FOOD WASTES FROM AKURE METROPOLIS, ONDO STATE,NIGERIA

Abstract

This study was carried out to explore the loads and identities of microorganisms associated with the decomposition of domestic food wastes from Akure Metropolis, Nigeria. Also, the occurrence of the microbes at the different stages of the decomposition was studied. Fifteen domestic food wastes which were cooked rice, yam peel, cassava peel, cocoyam peel, pineapple peel, pawpaw peel, banana peel, ripe and unripe plantain peel, orange pulp and peel, spoilt tomato fruits and vegetables (Amaranthus hybridus, Spinacia oleracea, Senecio biafrae) were collected from different locations in Akure. These wastes were mixed with poultry droppings in ratio 3:1 after which they were left to decompose naturally for seven weeks during which sampling was done at an interval of one week. Microorganisms were isolated from all the samples using pour plate and streak methods after serial dilution. Cultural, microscopic and biochemical features of the microbes were studied using standard microbiological methods and biochemical tests. The bacterial load (3.19 x 107cfu/g) and fungal population (2.25 x 107sfu/g) of the freshly mixed wastes were high. These loads decreased at the end (seven weeks) of the degradation process to 2.04 x 107 cfu/g and 0.29 x 107 sfu/g respectively. A total of thirty-three bacteria were identified which include Escherichia coli, Pseudomonas aeruginosa, Alkaligene faecalis, Enterobacter aerogenes, Klebsiella species, Acenitobacter iwoffi, Bacillus subtilis, Micrococcus luteus, Corynebacterium humiferum, Clostridium difficile, and Paenibacillus macerans. The fungi isolated were nineteen different types and they include Articulospora inflata, Aspergillus niger, Bdellospora helicoides, Candida albicans, Fusarium oxysporum, Geotrichum spp., Merismella concinna, Penicillium spp., Saccharomyces spp., Trichoderma spp. and Varicosporium elodea. Bacteria were the dominant microbial group observed during the decomposition with the genus Bacillus emerging as the most occurring bacteria while yeast cells were isolated from the beginning to the end of decomposition process. Moulds became prominent after two weeks of the decomposition with Aspergillus niger being the most occurring. Pseudomonas fluorescence, Bacillus badius, and R. stolonifer, Staphylococcus aureus, Bacillus polymyxa and Fusarium solani, Pseudomonas asplenii, Bacillus sphearicus, Streptothrix atra, Penicillium spp., Aspergillus fumigatus and A. niger, Paenibacillus macerans, Bdellospora helicoides and Varicosporium elodeae, Bacillus brevis, Zoopage nitrospora, Merismella concinna and Articulospora inflata, and Bacillus mycoides, Aspergillus flavus, and Trichoderma spp. emerged at 1, 2, 3, 4, 5 and 6 weeks respectively. There were no new bacteria isolated at week 7. This study has revealed the population, identities and occurrence of microbial flora associated with the various stages of decomposing domestic food wastes from Akure, Nigeria.