Assessment of the effects of cassava mill effluent on the soil and its microbiota in Biase local government area of Cross river state, Nigeria

The effects of cassava mill effluent (CME) on the soil and soil micro-biota was investigated. Soil samples were collected from sites polluted with CME and also from an adjacent site not polluted with CME. Standard microbiological methods were used in the isolation, antibiotic susceptibility and enumerating the population of the microorganisms while the physico-chemical parameters of the soil were determined using standard chemical processes. The bacteria isolates were Bacillus sp., Pseudomonas sp., Enterobacter sp., Escherichia coli, Corynebacterium sp. and Proteus sp. and the fungal isolates were Aspergillus sp., Candida sp., Mucor sp., Penicillium sp., Saccharomyces sp. and Rhizopus sp. The mean aerobic bacterial count for the soil samples ranged from 7.1±0.11x105 cfu/g for the control soil to 8.0±0.19x105 cfu/g for the CME impacted soil. The mean heterotrophic fungal counts varied from 4.7±0.41x105 cfu/g for CME impacted soil to 4.2±0.57x105 cfu/g for the control soil. Susceptibility profile showed that Bacillus sp. from the CME impacted site had reduced susceptibility to levoflacin, amoxil, chloramphenicol, and Ciprofloxacin. Pseudomonas sp. from the same site had reduced susceptibility to streptomycin, ampicilin, tarivid, peflacin, augmentin and ciprofloxacin. Escherichia coli had reduced susceptibility to streptomycin, ampicilin, ciprorex and nalidixic acid. The heavy metals Cu, Zn, Ni, Co, and Fe content of the CME impacted soil increased greatly. Excessive application of CME had negative effects on the soil, hence the high concentration of heavy metals in CME dumpsites and high microbial presence. The study also showed that CME can induce the resistance potential of some soil microbes to antibiotics and seriously affect the physicochemical parameters of soil.