Impact of cassava mill effluent on the microbial population and distribution in polluted soils in Abakaliki, Ebonyi State, Nigeria

Abstract

Cassava mill effluent generated from cassava processing when discharged to the soil, alters
the nature of soil properties and also becomes a major cause of environmental degradation.
This research characterized bacteria and fungi distributed in cassava effluent polluted soils in
Abakaliki, Ebonyi State, Nigeria. Soil samples were collected over a period of three months
using a sterile soil auger into a sterile sample zip bag for analysis. The bacterial count from the
different sites varied significantly (p<0.01). The total colony count of bacteria from the effluent obtained from rice mill cassava processing sites ranged from 4.0±0.2x10⁶ CFU/g to 8.6±0.8x10⁶ CFU/g. During August, the bacterial loads also differed very significantly (p<0.01) ranging from 3.3±0.3x10⁶ CFU/g to 6.5±0.6x10⁶ CFU/g across the locations. Similarly, the fungal count varied significantly (p<0.01) ranging from 1.7±0.1x10⁶ CFU/g to 3.4±0.3x10⁶ CFU/g across the locations in June. The bacteria species isolated from the polluted soil sample include E.coli, Staphylococcus spp, Klebsiella pneumoniae, Shigella spp, Pseudomonas aeruginosa and Proteus spp, while the fungal species identified include Articulospora inflata, Trichoderma spp, Aspergillus spp and Penicillium spp. These organisms were also present in the unpolluted soil samples except for Articulospora inflata which was solely isolated from polluted soil sample in some of the sampled sites. This study has shown that bacterial population was higher in cassava mill polluted soil compared to the unpolluted sites. Whereas, the fungal population indicated only a mild increase in the polluted compared to the unpolluted sites.