Sunday Etim Bassey

Changes in the Treatment of Some Physico-Chemical Properties of Cassava Mill Effluents Using Saccharomyces cerevisiae

Cassava is majorly processed into gari by smallholders in Southern Nigeria. During processing, large volume of effluents are produced in the pressing stage of cassava tuber processing. The cassava mill effluents are discharged into the soil directly and it drain into nearby pits, surface water, and canals without treatment. Cassava mill effluents is known to alter the receiving soil and water characteristics and affects the biota in such environments, such as fishes (water), domestic animals, and vegetation (soil). This study investigated the potential of Saccharomyces cerevisiae to be used for the treatment of some physicochemical properties of cassava mill effluents. S. cerevisiae was isolated from palm wine and identified based on conventional microbiological techniques, viz. morphological, cultural, and physiological/biochemical characteristics. The S. cerevisiae was inoculated into sterile cassava mill effluents and incubated for 15 days. Triplicate samples were withdrawn from the setup after the fifth day of treatment. Portable equipment was used to analyze the in-situ parameters, viz. total dissolved solids (TDS), pH, dissolved oxygen (DO), conductivity, salinity, and turbidity. Anions (nitrate, sulphate, and phosphate) and chemical oxygen demand (COD) were analyzed using spectrophotometric and open reflux methods respectively. Results showed a decline of 37.62%, 22.96%, 29.63%, 20.49%, 21.44%, 1.70%, 53.48%, 68.00%, 100%, and 74.48% in pH, conductivity, DO, TDS, salinity, sulphate, nitrate, phosphate, and COD levels respectively, and elevation of 17.17% by turbidity. The study showed that S. cerevisiae could be used for the treatment of cassava mill effluents prior to being discharged into the environment so as to reduce the pollution or contamination and toxicity levels.

Ecological Risk Assessment of Heavy Metals in Cassava Mill Effluents Contaminated Soil in a Rural Community in the Niger Delta Region of Nigeria

M oil spill accidents give a variety of adverse influences on aquaculture organisms for a long time. Polycyclic aromatic hydrocarbons (PAHs), one of the major crude oil constituents, have been reported to induce developmental inhibition, morphological deformity, histopathological effects and genetic damage on fishes. In this study, we evaluated the impact of the PAHs on early life stages of three aquaculture fishes (red sea-bream, Pagrus major, rock bream, Oplegnathus fasciatus, and olive flounder, Paralichthys olivaceus) using pyrene, 2-methylnaphthalene, and phenanthrene. Embryonic development and larval morphology were investigated for each species. The median effect concentration (EC50) was not estimated for pyrene, and phenanthrene for all test species. The EC50s for 2-methylnaphthalene of Pagrus major, Oplegnathus fasciatus, and Paralichthys olivaceus were 12.8, 10.9 and 18.0 μmol/L, respectively. The no observed effect concentrations (NOECs) for pyrene of Pagrus major, Oplegnathus fasciatus and Paralichthys olivaceus were 99, 99, 0.013 μmol/L, respectively. The NOECs for 2-methylnaphthalene of Pagrus major, Oplegnathus fasciatus and Paralichthys olivaceus were 5.5, 5.5 and 3.5 μmol/L, respectively. The NOECs for phenanthrene of Pagrus major, Oplegnathus fasciatus and Paralichthys olivaceus were 7.0, 224, 0.96 μmol/L, respectively. There was no morphological deformity in the hatched larvae of Pagrus major exposed three PAHs. The spinal curvature and fin deformity were observed in Oplegnathus fasciatus at 11 μmol/L of 2-metylnaphthalene. Pericardial edema, ocular development inhibition, spinal curvature and fin deformity were observed in Paralichthys olivaceus exposed to 0.013 μmol/L of pyrene, 3.5 μmol/L of 2-metylnaphthalene, and 1.0 μmol/L of phenanthrene. It was considered that Paralichthys olivaceus to be more sensitive than Pagrus major and Oplegnathus fasciatus to PAHs. Some embryo of Paralichthys olivaceus successfully hatched in lower concentrations, while morphological deformity was observed in these concentrations. PAHs seem to have large effects on the early life stages of aquaculture fishes.B biofertilizers are those plant growths promoting rhizobacteria applied in the field to promote crop growth and to reduce the use of synthetic fertilizers. However, in conventional agriculture, the applying pesticides is a routine practice and is unavoidable to achieve reasonable profit. Thus, to develop effective bacterial biofertilizers, the effect of pesticides on plant growth promoting rhizobacteria (PGPR) should be considered before application. In this study, bacterial strains with both PGP traits and pesticide tolerant ability were isolated for selection as potential bacterial biofertilizers. Rice (Oryza sativa) seedlings were planted in the soils with high dose of fungicide etridiazole, metalaxyl, and tricyclazole applied. Endophytes were isolated from rice roots, and 16S rDNA sequence and related plant promoting characteristics including the potential nitrogen fixation, phosphorus solubilizing and indoleacetic acid (IAA) production ability for those endophytic bacteria were determined afterward. A total of seventeen different strains were isolated. Among them, five strains with both nitrogen fixation potentials and IAA production ability were identified. The species isolated included Rhizobium larrymoorei E2, Bacillus aryabhattai E7, Bacillus aryabhattai MN1, Pseudomonas granadensis T6, and Bacillus fortis T9. Except for T9, four strains out of five were even capable of tolerating two or more fungicides without retarding the growth rates. We inoculated the above four endophytic bacteria to the rice roots and confirmed that they were all equipped with rice growth promoting abilities. We applied recommendation rates of etridiazole and metalaxyl on the growth medium in Bacillus aryabhattai MN1 and found out that MN1 can produce high rates of IAA with fungicides applied. The bacteria strains isolated from this study presented PGP traits upon high rates of fungicides application and can be viewed as potential members in bacterial biofertilizers for sustainable agriculture application.