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Crude oil degradation efficiency can be improved because of co-metabolism that exists when bacterial consortium is applied. However, because of possible vulnerability to environmental conditions and/or antagonistic interactions among members of the consortium, the degradation efficiency can be hampered. In this laboratory-based study, the biodegradation potentials of pure bacterial isolates namely Pseudomonas aeruginosa strain W15 (MW320658), Providencia vermicola strain W8 (MW320661) and Serratia marcescens strain W13 (MW320662) earlier isolated from crude oil-contaminated site and their consortium were evaluated using 3% crude oil-supplemented Bushnell Haas media. The efficiency was evaluated based on the viable cell count, biosurfactant analyses, percentage hydrocarbon degradation using gravimetric analysis and gas chromatography-mass spectrophotometry (GC-MS) analysis. There was decline in the population of W13 and predominance of W15 in the consortium as the incubation period progressed. Accelerated biodegradation of the crude oil hydrocarbons through co-metabolism was not achieved with the consortium; neither was there any improved resilience nor resistance to environmental changes of strain W13. The GC-MS analyses showed that the highest degradation was produced by W15 (48.23%) compared to W8 (46.04%), W13 (45.24%) and the Consortium (28.51%). The biodegradation of the crude oil hydrocarbons by W15, W8, W13 axenic cultures and their consortium treatments demonstrated that the bacterial constituent in a consortium can influence the synergistic effect that improves bioremediation. Future research that focuses on evaluating possible improvement in bioremediation through maintenance of diversity by continuous bioaugmentation using vulnerable but efficient degraders in a consortium is necessary to further understand the application of consortia for bioremediation improvement.

Potential petroleum degrading bacteria, Pseudomonas aerogenosa and Micrococcus sp. was isolated from petroleum contaminated soil in petroleum microbiology laboratory, Department of Microbiology University of Nigeria, Nsukka. Hydrocarbon utilization in liquid media was assessed through time – course optical density measurement. Concentrations of the heavy metals ranging from 50 to 200 mg/L were introduced into 100 ml of mineral salt medium containing 10 ml of kerosene inoculated with P. aeruginosa or Micrococcus sp. and incubated at room temperature (25-30°C) for 384 h. Control samples contained kerosene but no heavy metals. At low concentrations the heavy metals significantly (p Cadmium > Mercury. Key words: Heavy metals, kerosene, bioremediation, bacteria.

The optimization of key process parameters for the transformation of agro wastes into biofertilizer has been demonstrated using response surface methodology (RSM). Biofertilizer was produced by composting using 120 L capacity drum made of polyethylene as the composter. Composting time (X1), dosage ratio (X2) and moisture content (X3) were the independent factors while percentage nitrogen, phosphorus and potassium (N.P.K) were the response factors. The outcomes exhibited that composting time, dosage ratio and moisture content all significantly affects the mineralization of N.P.K at probability value of 0.0001. The coefficients of determination also called regression coefficients of 98.60%, 99.79% and 97.80% for nitrogen, phosphorus and potassium observed between the predicted and the real value are obvious that the developed regression models can fit the experimental data well. It was seen from the optimization studies that the pinnacle value of N.P.K from the ideal conditions are 9.62%, 8.97% and 5.62. Characterization of the composite uncovered that biofertilizer produced has a high potential for commercial application on agricultural land. It can be concluded that combination of sawdust, sewage sludge and vegetable waste is a good mixture for biofertilizer synthesis. Also, the nutrients release by the compost materials during the process of composting may be maximized when process conditions are circumspectly managed within the reported optimal value. Keywords: Optimization, Composting, Sawdust, Sewage sludge, Vegetable wastes, Response surface methodology

Highlights • Biofertilizer was produced by aerobic composting method. • Actinomycetes isolated was found to be good agents for biofertilizer synthesis. • Organic matter and Carbon content of the composts was found to be decreasing. • Nitrogen contents increased significantly with time. • Leaf area index revealed 10th week as the optimum growth period for Maize and Okra., In this work, biofertilizer was synthesized by mixing sawdust and other nitrogenous agricultural wastes into composites in the following ways: S1 (sawdust + chicken litter + vegetable waste), S2 (sawdust + sewage sludge + vegetable waste) and S3 (sawdust only as the control) respectively using actinomycetes as the microbial inoculums. In-vessel method of composting was employed with 120 L capacity polyethylene (PET) container as the bioreactor for the pilot scale study. Microorganisms were isolated from landfill extracts. Aeration was accomplished through turning of the compost twice weekly. Nitrogen, Carbon, Organic Matter and pH were determined at 5days intervals till the end of composting exercise. Flame Atomic Absorption Spectrometer (FAAS), was used for determination of the mineral composition of the raw materials and end products. American Society for Testing and Materials was used in the Analysis of Nitrogen, Carbon, and Organic Matter contents. Biofertilizer was analyzed more for activeness as organic fertilizer in the field studies using two crops (Maize and Okra). Biochemical test revealed that six genera of Actinomycetes were isolated. Inorganic salt starch agar medium was noticed to be effective isolation media for Actinomycetes. Actinomycetes were found to be good agents for biofertilizer synthesis due to their ability to mineralize nitrogen during composting. Preliminary investigation revealed that Rothia spp gave the highest percentage degradation of cellulose (21.6 %) as well as highest percentage mineralization of nitrogen (6.87 %) after 21days of incubation. Dosage ratio of 2:1:1 w: w, moisture content of 50–60 % and 25 days was found to be the optimum condition for nitrogen mineralization. Organic matter content of composts S1 and S2 decreased significantly with time while total kjeldahl nitrogen (TkN) content of the composts increased except compost S3 which on the contrary, reduced. The maximum temperature achieved at the end of 25 days compositing of substrate S2 was 64.6 ℃. Analysis of the leaf area index (LAI) revealed 10th week after transplant to be the period of optimum growth for both crops. In addition to, all the analysis conducted pointed to the fact that influence of biofertilizer on Okra and Maize growth performance is equivalent to the growth performance of chemical fertilizer on the same crops, affirming that organic fertilizer can comfortably replace chemical fertilizer in future.

Sustainable agriculture is a modern agro-practice that promotes safe environment and increases agricultural yield. It is a biotechnology approach designed to meet the present and future global food demands. Over the years, the upsurge in excessive chemical fertilizer application for crop production has caused imbalance in the soil quality and microbial community structure. This however has created the need for sustainable solutions. Of late, the use of biofertilizers as an alternative to chemical fertilizers has gained prominence. Fungal biofertilizers which involve the use of fungal agents (Mycorrhiza sp., Trichoderma sp., Chaetomium sp., and Gliocladium sp.) are formulated to provide nutrients to the host plant and safeguard crops against pathogens. As microbial consortium, they enhance plant growth, suppress abiotic stress conditions, and influence a number of biochemical developments and functions. In this chapter, we lay much emphasis on fungal biofertilizers, their interactions with associated soil microorganisms (bacteria) as well as their mechanisms of action and roles in soil nutrient enrichment. Besides exploring their application and influence in mineral acquisition and transportation, fungal biofertilizers composition and importance in sustainable agricultural production were also highlighted.

The aim of this research was to evaluate the impact of chromium (III) nitrate on soil microbial activities and growth performance and phytoremediation potentials of two staple leguminous crops, namely cowpea (Vigna unguiculata) and groundnut (Arachis hypogea). Pristine sandy loam soil samples were polluted with nitrate salts of chromium (III) at four different levels (50, 100, 200 and 400 mg/kg) in triplicates. There was a significant (P < 0.05) retarding effect of this metal on the study parameters. A consistent decrease in the total bacterial count in response to increase in dosage of the metal salt was observed. Chromium was also observed to significantly (P

Environmental pollution occasioned by artisanal activities and technical failures at exploration sites has affected mostly oil producing and other mineral resources mining regions in developed and developing nations. As conventional techniques of remediation seem to be progressively unreliable and inefficient, contaminated land management experts have adopted a plant-based technology described as 'phytoremediation' for effective detoxification and removal of contaminants in substrate environmental media (soil and sediment). This technique, has gained public acceptance because of its aesthetic, eco-friendly, solar energy driven and low cost attributes. With complexity of environmental pollution in Africa, identification of appropriate remediation approach that deliver net environmental benefit and economic profit to the society is vital, while also focusing on the exploitation of plants genetic tools for more clarity on phyto tolerance, uptake and translocation of pollutants. In this article, we reviewed the status, progress and challenges of phytoremediation in selected African countries (South Africa, Nigeria, Tanzania, Zambia, Egypt and Ghana), the ecological impact of the pollutants, phytoremediation strategies and the possible plants of choice. Besides highlighting the support roles played by soil fauna and flora, the fate of harvested biomass/dieback and its future prospects are also discussed. We further explored the factors challenging phytoremediation progress in Africa, amidst its promising potentials and applicability for sustainable ecosystem management paradigm.

This work was designed to assess the status of Salmonella and Shigella infections in Anyigba, Kogi State, Nigeria with a view to making informed statements that may guide policy makers and public health experts in the containment efforts against these infections. Salmonella and Shigella species isolated from human faecal samples were examined for resistance to some antibiotic agents using disc diffusion methods. Drug resistant isolates were analyzed for presence of plasmids by basic curing and transferability methods. Age distribution of sources of resistant isolates showed that Shigella isolates from Youths (18 - 30 years) were more resistant to Ampicilin (66.67%) and Augmentin (33.33%) than isolates from Infants (6 months - 4 years) (3% Ampicillin and 0% Augmentin). Salmonella species isolated from Adults (31 – above) were more resistant to Augmentin (45%) and Ampicillin (40%), than isolates from Youths (18- 31 years) (40% Ampicillin and 36.67% Augmentin). Salmonella isolated from Infants (6 months – 4 years) showed percentage resistance of 28.57% to Ampicillin and 14.29% to Augmentin while isolates from Children (5 - 17 years) showed percentage resistance of 25% to Ampicillin and 12.5% to Augmentin. Salmonella species showed higher percentage resistance to commonly used drugs than Shigella species. The result shows that 8% of Shigella species and 21.5% of Salmonella species were resistant to more than eight antibiotics with (MAR) index of between 0.2-0.9. Results of curing and agarose gel electrophoresis (AGE) presumptively showed that the resistance traits were plasmid borne. AGE showed plasmids of molecular weights 23.1 kb for both species of Salmonella and Shigella suggesting their possible exchange among them. This was substantiated by conjugative transfer of resistance determinants among few isolates. The results show convincing evidence of the presence of multidrug resistant Salmonella and Shigella spp. within the study population. Key words: Hospital patients, Salmonella spp., Shigella spp., drug resistance, plasmids, resistance index.

As human populations grow and transform landscapes, contact with wildlife concomitantly increases. Disease emergence has been an important consequence of these contacts, with many of emerging infectious diseases in humans arising from wildlife reservoirs. Drug resistance is a very important dimension of disease emergence and tracing the source is a veritable containment strategy. Escherichia coli and Proteus spp. have important roles in the increasing cases and dissemination of antibiotic resistance, potentially acquiring resistance determinants and acting as reservoirs for resistance genes. This study was conducted to determine the similarity or otherwise of the drug resistance pattern of Escherichia coli and Proteus spp. isolated from humans and those from wild animals (a source with only minimal, hypothetical or no antibiotic exposure). The human samples were obtained from two human groups: persons not on antibiotics and humans on antibiotics. Animal samples were taken from rats (Rattus spp.), grasscutters (Thryonomys swinderianus), squirrels (Xerus erythropus) antelopes (Tragelephus scriptus), rabbits (Oryctolagus cuniculus), and farm lizards (Agama spp.). Organisms were isolated and identified based on basic microbiological methods and subjected to antibiotic disc diffusion tests and electrophoretic plasmid analysis. Results show that E. coli strains isolated from persons on antibiotics were resistant to ampicillin (46.62%), augmentin (39.72%), clarithomycin (5.16%); while resistance to antibiotics by E. coli isolated from those that are not on antibiotics were ampicillin (27.27%), augmentin (20.00%), cetriaxone (18.18%) and nitrofurantoin (14.55%). Also, E. coli strains isolated from wild life were resistant to ampicillin (85.71%) and clarithomycin (14.29%). Proteus spp. isolated from human sources were susceptible to all test antibiotics except ampicillin; while those from wildlife were resistant to ampicillin (54.17%), chlorampenicol (16.67%), nitrofurantoin (8.33%), clarithomycin (8.33%), ofloxacin (4.17%), augmentin (4.17%) and pefloxacin (4.17%). The correlation matrices determined at p (≤ 0.05), revealed high resistance correlation among the different genera of bacteria isolated from one source to those from the other sources. Resistance plasmid analysis revealed the presence of 23 kb plasmid DNA in organisms obtained from the different sources. This suggests the possibility of bidirectional resistant gene transmission at the human–wildlife interface, indicating congruence between the drug resistance pattern of E. coli and Proteus spp. isolated from humans and wild animals. This calls for a holistic and forward-looking approach that will take the complex interconnections among species into full account, recognizing the important link between humans, animals and the environment in a bid to contain antibiotic resistance. Key words: Drug resistance, humans, wild animals, Escherichia coli, Proteus spp., resistance plasmids.

Beta-lactams are the most widely used antibiotics. Resistance to beta-lactam antibiotics is an increasing problem worldwide and beta-lactamase production is the most common mechanism of resistance to these drugs. Species of Salmonella and Shigella isolated from hospital patients in Anyigba, Kogi State, were analyzed for the presence of beta–lactamases using Nitrocefin, Iodometric, Acidimetric and Double Disc Synergy methods. Results showed that 9 (81.82%) of Shigella species and 22 (61.11%) of Salmonella species were beta-lactamase producers with 3 (27.27%) of Shigella species and 20 (55.56%) of Salmonella species producing extended spectrum beta-lactamases (ESBLs). Beta-lactamase production is an acknowledged threat to modern medicine especially antibiotic usage. Key words: Salmonella, Shigella, beta-lactams, beta-lactamase, extended spectrum beta- lactamases