Attenuation of petroleum hydrocarbon fractions using rhizobacterial isolates possessing alkB, C23O, and nahR genes for degradation of n-alkane and aromatics.

This work assessed the catabolic versatility of functional genes in hydrocarbon-utilizing bacteria obtained from the rhizosphere of plants harvested in aged polluted soil sites in Ogoni and their attenuation efficacy in a bioremediation study. Rhizosphere soil was enumerated for its hydrocarbon-utilizing bacteria. The bacteria were in-vitro screened and selected through the quantification of their total protein and specific intermediate pathway enzyme (catechol 2,3-dioxygenase) activity in the metabolism of hydrocarbon. Thereafter, agarose gel electrophoresis technique was deployed to profile the genome of the selected strains for catechol 2,3-dioxygenase (C23O), 1,2-alkane monooxygenase (alkB), and naphthalene dioxygenase (nahR). Four rhizobacterial isolates namely Pseudomonas fluorescens (A3), Achromobacter agilis (A4), Bacillus thuringiensis (D2), and Staphylococcus lentus (L1) were selected based on the presence of C23O, alkB, and nahR genes. The gel electrophoresis results showed an approximate molecular weight of 200 bp for alkB, 300 bp for C23O, and 400 bp for nahR. The gas chromatogram for residual total petroleum hydrocarbon (TPH) revealed mineralization of fractions C8-C17, phytane, C18-C30. TPH for in-vitro bioremediation of crude oil-polluted soil was observed to have an optimal reduction/loss of 97% within the 56th day of the investigation. This study has further revealed that the microbiome of plants pre-exposed to crude oil pollution could serve as a reservoir for mining group of bacterial with broad catabolic potentials for eco-recovery and waste treatment purposes.

Biostimulation of Petroleum-Contaminated Soil Using Organic and Inorganic Amendments.

The most common approaches for the in-situ bioremediation of contaminated sites worldwide are bioaugmentation and biostimulation. Biostimulation has often proved more effective for chronically contaminated sites. This study examined the effectiveness of optimized water hyacinth compost in comparison with other organic and inorganic amendments for the remediation of crude oil-polluted soils. Water hyacinth was found to be rich in nutrients necessary to stimulate microbial growth and activity. An organic geochemical analysis revealed that all amendments in this study increased total petroleum hydrocarbon (TPH) biodegradation by ≥75% within 56 days, with the greatest biodegradation (93%) occurring in sterilized soil inoculated with optimized water hyacinth compost. This was followed by polluted soil amended with a combination of spent mushroom and water hyacinth composts (SMC + WH), which recorded a TPH biodegradation of 89%. Soil amendment using the inorganic fertilizer NPK (20:10:10) resulted in 86% TPH biodegradation. On the other hand, control samples (natural attenuation) recorded only 4% degradation. A molecular analysis of residual polycyclic aromatic hydrocarbons (PAHs) showed that the 16 PAHs designated by the US EPA as priority pollutants were either completely or highly degraded in the combined treatment (SMC + WH), indicating the potential of this amendment for the environmental remediation of soils contaminated with recalcitrant organic pollutants.

Impact of composting factors on the biodegradation of lignin in Eichhornia crassipes (water hyacinth): A response surface methodological (RSM) investigation.

Water hyacinth (Eichhornia crassipes) is a hydrophyte weed that causes havoc in the aquatic ecosystem as an invasive plant that can obstruct waterways and bring about nutrient imbalance. This study aims to address how this invasive hydrophyte can be physically harvested and biochemically transformed into a bioproduct that can enhance the restoration of damaged soil. Biocomposting, a low-cost biotechnological technique, was designed to degrade the lignocellulosic Eichhornia crassipes biomass and transform it into a valuable bioproduct. The process used response surface methodology (RSM) to investigate the aggregate effect of moisture content, turning frequency, and microbial isolate (Chitinophaga terrae) inoculum size on the breakdown of lignin over 21 days. The moisture content (A), (45, 55, 65) % v/w, inoculum size (B), (5, 7.5, 10)% v/v, and turning frequency (C), (1, 3, 5) days were considered independent variables, while percentage lignin degradation was considered a response variable. The optimal conditions for lignin breakdown were 65.7 percent (v/w) moisture, 7.5 percent (v/v) inoculum concentration, and 5-day interval turning. The R2 score of 0.9733 demonstrates the model's integrity and reliability. Thus, the RSM approach resulted in a fine grain dark brown Nutri-compost that proved effective in enhancing soil fertility. This procedure is recommended for a scale-up process where large quantities of the hydrophyte could be treated for conversion into Nutri compost.

Optimization of bioremediation-cocktail for application in the eco-recovery of crude oil polluted soil.

Background: Environmental sustainability is the driver for finding the optimal bioremediation cocktail with the combination of highly potent hydrocarbonoclastic strains and the nutrient additives that significantly enhance mineralization of crude oil in polluted soil in order to mitigate its deleterious effects on the environment. In this study, four hydrocarbon-degrading bacterial strains were pre-selected from mined rhizobacterial isolates in aged crude oil-contaminated soil.  Method: Agrowaste residues of poultry-droppings, corn chaff, and plantain peel were selected among others for their ability to support high biomass of selected bacterial strains. Baseline proximate analysis was performed on the agrowaste residues. Simplified, one variable at a time (OVAT) was employed in the validation of the variables for optimization using the Multivariate analysis tool of Response Surface Methodology (RSM). To test the significant formulation variables, the Box-Behnken approach using 15 runs design was adopted. Results:  The rate of contaminant removal was observed to fit into a quadratic function. For optimal rate or contaminant removal, the fitted model predicted the optimal formulation cocktail condition to be within 0.54 mg/kg (Corn steep liquor), phosphate 137.49 mg/kg (poultry droppings) and 6.4% inocula for initial TPH of 9744 mg kg -1 and THC of 9641 mg kg -1 contaminant level. The model for the application of the bioremediation product and the variables evaluated had a significant p-value < 0.005 for the attainment of 85 to 96 % of TPH and THC removal after 56 days of treatment. Conclusions:  This study has shown the need to harness the abundant agrowaste nutrients in supporting high throughput rhizobacteria in the formulation of a bioremediation agent suitable for use in the reclamation of oil spill sites in the Niger Delta oil-producing region.

A study of natural attenuation processes involved in a microcosm model of a crude oil-impacted wetland sediment in the Niger Delta.

Sediment sample from a previously impacted Ochani stream was recreated in four glass chambers (A-D) as microcosms. The aim was to model and compare natural attenuation processes to forced aeration for remediation of a crude oil-impacted ecosystem. The initial hydrocarbon concentration was 90,212 mg/kg of sediment. After 60 days, the natural attenuation processes of photooxidation, evaporation, volatilization and biodegradation accounted for 31.9% of the total hydrocarbon removed while 13% was attributable to forced aeration, bringing the cumulative hydrocarbon removed to 44.9%. Photooxidation, evaporation and volatilization accounted for 15.6% of the total hydrocarbon removed. Biodegradation alone accounted for 24.7% removal. Gas chromatographic tracings showed appreciable reductions in peak heights and base. Hydrocarbon utilizing bacteria genera isolated included Pseudomonas, Micrococcus, Flavobacterium, Staphylococcus, Serratia, Bacillus, Chromobacterium, and Alkaligenes. Temperature was mesophilic (26-31 degrees C), while the pH tended towards acidity. The study revealed the applicability and the effectiveness of natural attenuation and forced aeration in the remediation of oil-impacted sediment in a typical Niger Delta setting.

Influence of temperature and pH on biomass production and protein biosynthesis in a putative Spirulina sp.

The influence of temperature and pH on biomass production and protein biosynthesis in a Spirulina sp. isolated from an oil-polluted brackish water environment in the Niger Delta was studied. The isolated organism was identified on the basis of its phenotypic characteristics such as nature and direction of helix, temperature, pH and salt tolerance ranges. Biomass concentration in the culture media was calculated as cell dry weight. The combination of 30 degrees C and pH 9.0 gave the highest values of 4.9 mg/ml and 48.2g/100 g for biomass and total crude protein, respectively. The effect of pH was modulated by temperature and vice versa during biomass production. This native isolate of Spirulina sp. offers a good source of natural protein that could be easily accepted by rural communities as single cell protein in the form of feed, food and health supplement when properly processed.