Evaluation of soil microbial communities as influenced by crude oil pollution

Impact of petroleum pollution in a vulnerable Niger Delta ecosystem was investigated to assess interactions in a first-generation phytoremediation site of a crude oil freshly-spilled agricultural soil. Community-level approach for assessing patterns of sole carbon-source utilization by mixed microbial samples was employed to differentiate spatial and temporal changes in the soil microbial communities. Genetic diversity and phenotypic expressions were measured for a more holistic perspective. The 5’-terminal restriction fragments generated after Csp digestion of 16S rRNA gene correlated with observed DNA concentrations in the community profile and revealed loss of diversity with pollution. Crude oil pollution significantly reduced phosphomonoesterases and respiratory activities and values were pH dependent. There were no expressed dehydrogenases activity in initial spill site but were enhanced with phytoremediation. Factor analysis of predictors and independent variables indicates that respiratory, alkaline phosphatase and â-glucosidase activities could be used to explain underlying factors. Positive soil – microbes - plant interactions were observed.Key words: Species diversity, impact of crude oil pollution, soil – biota interactions, ecosystem monitoring, genetic diversity

Performance and risk assessment of Bambara beans grown on petroleum contaminated soil and the biostimulation implications

The potential of Vigna subterranean commonly called Bambara beans for phytoextraction of copper in a crude oil contaminated soil was investigated. The contamination levels of crude oil in the soil for this pot experiment were 2, 4, 6, 8 and 10% (w/v). Amendments were added to increase the uptake and translocation of metal to aerial biomass. A range of amendments was tested for copper uptake enhancement with V. subterranean commonly called Bambara beans. Safe levels of exposure to contaminants were further investigated using albino Wistar rats for 28 feeding trial days to trace inherent biomagnifications. Bambara beans extracted up to 88.88 and 43.38 mg/kg into its shoot and root respectively at 10% contaminant dose while achieving 63.17% Cu removal unamended. Poultry manure was the most effective amendment for enhancing copper uptake and translocation into the shoots of Bambara beans with shoot tissue copper levels of 118.13 mg/kg compared to 98.25 and 93 mg/kg obtained for NPK and UREA amendments. 79.28, 70.07 and 70.99% Cu removal was achieved with poultry manure, NPK and UREA amendment respectively. An assay was carried out with animals on inherent biomagnifications. The results showed that the performance of rats fed diets formulated from contaminated soil differed significantly (P > 0.05) from those of the controls used. Hazard characterization revealed negative effects of potentially toxic copper on organ weight, optimum digestibility and animal growth rate. Weight of pancreas showed pancreatic hypertrophy in rats adapted to diets, which contain higher levels of contaminants compared to controls

Polycyclic Aromatic Hydrocarbons (PAHs) and some Trace metals in Yam, Cassava, Orange and Papaya from two Oil and Gas Flaring Impacted Communities in Southern Nigeria

The present investigation provides data on the levels of PAHs and trace nutrient elements in selected tubers (yam and cassava) and fruits (orange and papaya) harvested from oil impacted and gas flaring areas in Akalaolu and Ogale Niger Delta communities. PAHs and heavy metals concentrations were analysed by Gas Chromatography and Atomic Absorption Spectrometry. Akalaolu samples gave (mg kg-1 PAHs) 4.321, 2.934, 19.003 and 7.004 while Ogale samples gave 3.445, 3.200, 5.41, 0 and 5.021 for cassava, yam, papaya and orange respectively. All selected fruits and tubers collected from the two sites contained significantly decreased trace nutrient elements and signal deficiency conditions. These findings suggest that study food crops from exposed areas are markedly contaminated by carcinogenic PAHs and may pose public nutrition and health concerns. Also, determination of trace nutrient elements in papaya at contaminated sites showed that papaya markedly accumulates metals in response to contamination. Keywords: PAHs levels; Hydrocarbon contaminant exposure; Food safety; Fruits and tubers

Community level physiological profiling in a first generation phytoremediation experiment

590-597While biological methodologies have gained patronage in remediation of petroleum-impacted farmlands, only limited records are available on the functional ecosystem structure of such treated soils. Here, we conducted successfully a first generation soil heavy metal clean up in a 90d 4-factor phytoremediation pot experiment and studied the effect of such clean up on microbial communities. Influences with organic manure application were also evaluated. Microbial ecology of community was evaluated using BIOLOG. On analysis using multivariate factor, we observed correlation of consumption rates for polymer, carbohydrates, amines and amides correlates with metabolic patterns in the studied communities. Analysis of microbial diversity using Shannon H index, identified indigenous Hevea brasilensis cultivated soil populations with the highest diversity in polluted regimes and were more resistant, maintaining a steady growth after day 1 for the 9 days of incubation study. Lead removal was efficient using all four species studied with or without soil conditioner. Vigna subterranea may be a poor candidate for remediation of Cr contaminated soil following poor results obtained. Generally, legumes and indigenous plant species promoted distribution of communities more equitably among species. This study reveals the importance of plant-based bioremediation in microbial ecology and highlights the significance of soil conditioners and plants in microbial community behaviour

Conditioners and significance of t-RFLP profile of the assemblage of prokaryotic microorganisms in crude oil polluted soils

Following an increased interest in management practices designed to reduce posed phytotoxicity during phytoremediation experiments, crude oil polluted soil and variants from conditioners-aided phytoremediation experiment were subjected to terminal restriction fragment polymorphism (t-RFLP) to evalute the biodiversity of bacterial microflora of polluted soil and amendments conditions. Genetic fingerprinting showed that hydrocarbons stress led to depletion of the genetic resources of soil microflora and to a radical change in its qualitative composition. The amended stressed soils not only has a greater number of species present, but the individuals in the community are distributed more equitably among these species. Non-uniform marginal regain of community was clear with applied conditioner. Positive associations, however were observed with conditioner and phyto-assisted clean-up attempts.Keywords: Crude oil pollution, soil conditioners, microbial diversity, phytoremediation, environmentAfrican Journal of Biotechnology, Vol 13(44) 4220-422