C and 40 C were used to determine the temperature effect on the growth of H. fulvum. Maximum growth of H. fulvum was obtained at 25 C and 30 C temperatures. The fungus was also cultured on 100, 92.5, 85, 74 and 32.5% relative humidity regimes. The fungus showed maximum growth at 92.5 and 100% relative humidity. The growth of the fungus was observed to increase with increase in relative humidity and vice versa. There were significant differences (P 0.05) in the growth of the fungus at different temperature and relative humidity regimes. The implication of these findings were discussed.

Changes in microbial community content as well as physico-chemical properties of soil contaminated with tannery effluents in Sokoto metropolis were determined using standard procedures. The results showed that the soil sample contained a variety of microorganisms which include Bacillus cereus, Bacillus subtilis, Pseudomonas aeroginosa, Proteus mirabilis, Serratia marcensces, Escherichia coli, Streptococcus pyogenes, Klebsiella pneumoniae, Aspergillus niger, Aspergillus flavus, Aspergillus fumigatus, Penicillium notatum, Mucor pusillus as well as Fusarium sporotrichioides. It also revealed high counts of bacteria and fungi in all the sampling sites. The viable count of bacteria was in the range of 8.60±1.80 -8.70±0.52 ×10 5 cfu/g while that of fungi was 1.70±0.30 -2.0±0.10 × 10 4 cfu/g. Similarly, it revealed high levels of sulphide (0.35-0.44mg/g), ammonia (0.40-0.60mg/g), and chromium (0.20-0.26mg/g) in all the sampling sites. These levels exceeded the tolerable levels set by the Federal Ministry of Environment. The presence of these microorganisms and chemical substances pose a potential threat to the local inhabitants of these areas.

Abstract-In the study rice husks and groundnut shells were hydrolysed with 3, 4 and 5% concentrations of dilute hydrochloric acid and the reducing sugar concentration was determined using the dinitrosalicylic acid (DNS) colorimetric method. The concentration of the bioethanol produced was determined using the potassium dichromate method. The results revealed that there is no significance difference (p<0.05) in the yields of the reducing sugar obtained from the substrates at different treatment conditions (0.46mg/l from rice husks at 3%, 40oC for 30 minutes, 0.45mg/l from groundnut shells at 4%, 30oC for 25 minutes and 0.46mg/l from rice husks and groundnut shells at 5%, 30oC for 30 minutes). Similarly, the result revealed that both S. cerevisiae and Z. mobilis produced their highest bioethanol concentrations of 0.58% and 0.54% respectively from rice husks after 24 hours of fermentation while their combination produced its highest concentration (0.524%) after 72 hours. It is evidently clear that there despite the fact that there was no significance difference (p<0.05) in the yields of bioethanol produced by S. cerevisiae and Z. mobilis, S. cerevisiae proved to be a better choice in bioethanol production using these substrates that either Z. mobilis or their combination.

Ten grams (10 g) of soil sample was obtained from a rice husk dumpsite in Sokoto metropolis and analyzed. The species isolated were Bacillus licheniformis, Bacillus lentus and Bacillus megaterium. The Bacillus species isolated were screened for amylolytic activities. The isolate with the widest zone of clearance (A 1 ) was selected for further analysis. The highest activity was observed in B. licheniformis (2.00±0.01 mm) followed by B. lentus (1.96±0.40 mm) and B. megaterium (1.70±0.18 mm) had the least activity. Amylase activity was determined using DNS method. The optimum temperature for the activity of the amylase produced was obtained at 90 °C with a concentration of 0.373 mg/ml. Optimum pH activity was obtained at 4.0 with a concentration of 0.376 mg/ml. Bacillus licheniformis has the greatest potential for producing amylase than the other isolates and rice husk can be exploited for amylase production. The B. licheniformis strain produced thermostable alpha-amylase with characteristics suitable for application in starch processing and other food industries.

A screen house experiment was conducted to test the efficacy of leaf extract of mahogany (Khaya senegalensis L) for the control of root-knot nematodes of tomato. The completely randomized design was used to test the materials. Results obtained showed that the leaf extracts of the mahogany plant significantly (P˂0.05) reduced the population of the nematodes compared to the untreated seedlings. It also indicated that there is significant difference (P˂0.05) on the effect of the extract on the test organism between the varying concentrations of the extract used. The study revealed that the higher the concentration of the extract the more its effect on the test organism. The result also showed a significant variation (P˂0.05) in the extent of galling, plant height and root lenght in tomato treated with different levels of concentrations of the leaves extracts. The implications of these findings were discussed.

A yeast biofilter consisting of Candida krusei, Candida morbosa, Torulopsis dattila, Torulopsis glabrata, and Saccharomyces chevalieri was constructed to bioremediate abattoir wastewater. Potato peels were used as filter bed for the growth of the yeasts. Wastewater samples were collected from three different points in Sokoto (Nigeria) abattoir and the physiochemical as well as the microbiological qualities of the wastewater were determined before and after biofiltration. The results revealed that after the biofiltration process, the pH, biochemical oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD), and the nitrate content of the wastewater were drastically reduced. Similarly, there was a decrease in the variety of microorganisms isolated as well as in microbial counts after the biofiltration process. Salmonella typhi, Neisseria lactamica, Serratia marcescens, Branhamella catarrhalis, Shigella sp, Penicillium sp, Curvularia sp, and Trichophyton rubrum were completely eliminated after the biofiltration process. The reduction in the pH, BOD, DO, COD, nitrate as well as in the variety and total counts of bacteria and fungi for the wastewater after the biofiltration process indicated that the biofilter was effective in bioremediation of the wastewater. The percentage efficiency of the biofilter was found to be 42.5%.

Petroleum hydrocarbon contamination remains a major challenge confronting soil health, environmental sustainability, and food security in oil exploration areas. In this study, the effect of Bonny Light crude oil on cowpea (Vigna unguiculata L. Walp.) was investigated with a view to assessing its toxicity to plant growth and performance. Pristine soil samples were collected in different pots and contaminated with crude oil to achieve 0.0%, 2.5%, 5.0%, 7.5% and 10.0% v/w contamination levels. Viable seeds of cowpea were planted and monitored for the emergence and subsequent growth for a period of 12 weeks. Results showed that the crude oil extended the period of seed germination and delayed the emergence of sprouts by 2 days at a rate of 96.7%, 80.0%, 50.0%, 96.7%, and 73.3% emergence respectively. The plants’ shoots, roots, and leaves lengths were longer in control than in the contaminated soil. Phytotoxicity study showed that shoots, roots and leaves lengths of the plants were significantly reduced by ≥ 50% of the control. The relative plants' weights, chlorophyll, and the number of leaves were worst affected especially in plants grown in higher crude oil concentrations where fewer or absence of leaves was observed at the end of the experiments. No yield parameter was observed in all plants grown in contaminated soil as opposed to the control where flowers, fruits, and seeds were produced. The findings illustrated that the growth rate of V. unguiculata was severely affected due to hydrocarbon contamination in a concentration-dependent manner. It further demonstrated the imminent danger to food security especially in frontier basins with impending oil exploration activities. Therefore, there is a need to identify and integrate effective measures that minimize or prevent oil spillage in the course of oil exploration activities with a view to avoiding the repeat of persistent pollution problems disturbing host communities.

To understand the in uence of cowpea on its rhizosphere physicochemical and biological conditions. MethodsPristine soil samples were contaminated with Bonny-Light crude oil and viable seeds of cowpea were planted to establish rhizosphere soil. Cowpea root exudates were collected and characterized while soil metabolic activities, physicochemical properties and rhizosphere effect were monitored following plant emergence. ResultsCowpea root exudates were composed of organic acids, phenolics, carbohydrates and hydrocarbons. High rate of soil respiration and microbial biomass carbon were observed in the contaminated rhizosphere reaching its peak on 12th week (70.56 mgCO 2 g −1 day −1 ) and 10th week (23.18mg/Kg) respectively. Lower rates of soil respirations and microbial biomass carbon were observed in contaminated (10.28 mgCO 2 g −1 day −1 ; 1.24 mg/Kg) and uncontaminated (0.23 mgCO 2 g −1 day −1 ; 0.37 mg/Kg) non-rhizosphere control soils respectively. The metabolic properties were positively correlated with soil organic matter contents and microbial size (r = 0.98; p < 0.05). There was considerable improvement in soil physicochemical properties in the cowpea rhizosphere as compared to non-rhizosphere soil Microbial populations were generally improved with positive rhizosphere effect values (>1) presumably due to the presence of compounds in exudates that promote microbial growth. ConclusionThe results highlighted the in uence of cowpea on its rhizosphere conditions which is a good indication for its ability to promote plant growth and environmental cleanup. Therefore, there is the need to further understand the microbial community dynamics in cowpea rhizosphere using culture-independent techniques.