Microbial Diversity of Nigerian Sludge and Its Potential for Use as Biofertilizer

Abstract

Sludge samples were collected from a wastewater treatment plant in Nigeria for characterization and evaluation for agricultural applications. Conventional and Molecular techniques were adopted for the isolation and identification of indigenous microorganisms and resulting isolates were characterized and identified by consulting Bergey’s manual of determinative bacteriology and subjected to further screenings to assess their biofertilizer potential using standard microbiological techniques. The viable cells obtained were enumerated and were found to be in the range of 1.03 ± 0.09 x103 cfu/g to 7.45 ± 0.78 x103 cfu/g for heterotrophic Bacteria and 1.63 ± 0.74 x103 cfu/g for fungal community. The Molecular analysis carried out revealed a rich assemblage of diverse species of microorganisms with Bacteria (99.40%) being the most dominant group, followed by Fungi (0.39%) and others (0.21%). Thirty (30) isolates belonging to four (4) Phyla was recovered culturally and identified with Firmicutes 9(30%) being the most dominant group, followed by Proteobacteria 8(26.7%) and Zygomycota 1(3.33%) was the least dominant. The phosphate solubilization index range from 0.86 to 6.3 for bacterial and 2.5 to 3.8 for fungal isolates respectively. The molecular analysis also revealed microbes adept at improving soil fertility to include those in the order Rhizobiales and Actinomycetales. Although pathogens are of a concern in the land application of sludge, our findings have revealed rich microbial consortia of heterotrophic microorganisms whose beneficial attributes can be harnessed to produce nutrient rich biofertilizer and soil amendment.