MOLECULAR IDENTIFICATION OF BACTERIA ASSOCIATED WITH THE DECOMPOSITION OF DOMESTIC FOOD WASTES

Abstract

This study was carried out to determine the molecular identities and genetic relatedness of the bacteria isolated during the decomposition of Domestic Food Wastes (DFW) from Akure metropolis, Nigeria. The ninety eight (98) bacteria used for the research were provided by the Department of Microbiology, Federal University of Technology, Akure. The genomic DNA of each bacterium was extracted by standard DNA isolation protocol and amplified in a Polymerase Chain Reaction using universal primer of bacterial 16S rRNA. The PCR products were sequenced by automated sequencing method. Phylogenetic trees were constructed for the sequences. Sixty four (64) different bacterial strains of seventy six (76) species identified consisted of thirty strains of Bacillus, eight strains of Pseudomonas, seven starins of Staphylococcus, three strains each of Lactobacillus, Proteus, Paenibacillus and Enterobacter, two strains each of Lynsinibacillus, Serratia and Streptomyces, as well as Klebsiella pneumoniae. The molecular identities compared with the previous probable bacterial identities revealed that Bacillus, Enterobacter, Staphylococcus, Paenibacillus, Pseudomonas, Streptomyces and Lactobacillus retained only their generic names while Bacillus subtilis AIMSTNMae5, B. pumilus NJ-V2, B. megaterium DZ011, B. licheniformis P33, Staphylococcus aureus OCB, B. thuringiensis LN and B. mycoides B1 retained both their generic and species names. Identified strain names of the bacteria revealed the detail names of the bacteria by the molecular technique. The constructed phylogenetic trees showed that some of the bacteria associated with 1-7 weeks of DFW decomposition are genetically related while some were not related or distant from each other. One, four and five weeks old decomposed DFW have more genetically related bacteria than other weeks. In one week old DFW Enterobacter cowanii AM and Serratia marcescens AAY2, Pseudomonas brenneri SKUAST-K36, P. poae 2FXS, Paenibacillus taichungensis SG3 and B. anthracis QS9 share recent genetic relationship but are distant from Klebsiella pneumoniae KP36, Bacillus licheniformis SCCKB is distantly related to P. fluorescens S16, P. poae 2FXS, Streptomyces griseus JE2 and Paenibacillus taichungiensis AW in four weeks old DFW. Similarly, phylogenetic tree of the bacteria in five weeks old revealed that the B. megaterium DZ011, B. circulans Q11, B. cereus E33L, B. licheniformis P33 and Staphylococcus aureus OCB are genetically related but distant to B. subtilis BCRC147.18. The identified strains of Bacillus subtilis has the highest level (50%) of occurrence in the weeks of the decomposition, while Pseudomonas brenneri, Enterobacter cloacae and Staphylococcus sciuri has the lowest (6%) occurrence. Serratia marcescens, Klebsiella pneumoniae, Enterobacter cowanni and pseudomonas putida occurred only at the early weeks (1-3 weeks) of the decomposing DFW, while different strains of Lactobacillus fermentum, Staphylococcus aureus, Pseudomonas fluorescens, Lysinibacillus sphearicus, and Paenibacillus taichungensis and Bacillus: B. cereus, B. circulans, B. licheniformis, B. subtilis, B. pumilus, B. megaterium dominate at the later weeks (4 - 7 weeks) to succeed the earlier bacteria of the DFW decomposition. The data obtained from this research have established the correct identities and genetic relationship that exist between the bacteria that were associated with the Domestic Food Wastes from Akure Metropolis. This information could be useful in the recycling of Domestic Food Wastes to control environmental pollution.