Browsing by Author "Buraimoh, Olanike Maria"
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Item Nitrilase gene detection and nitrile metabolism in two bacterial strains associated with waste streams in Lagos, Nigeria(Bulletin of the National Research Centre, 2022-05) Ogunyemi, Adewale Kayode; Buraimoh, Olanike Maria; Ogunyemi, Bukola Caroline; Samuel, Titilola Aderonke; Ilori, Matthew Olusoji; Amund, Olukayode OladipoBackground: The use of nitrile compounds is usually high, particularly in chemical industries, which calls for serious concern because of their relevance to the environment. The essential role of nitrilases in the bioremediation of harmful nitriles from environmental wastes cannot be overemphasized. The study aimed to unveil the biodegradative potentials of bacterial strains associated with the degradation of nitrile pollutants. Methods: Bacterial strains capable of utilizing glutaronitrile as the sole source of carbon and nitrogen were isolated from solid waste leachates by a selective enrichment culture technique. The test organisms were grown in mineral salts medium (MSM), and the metabolic products were determined using gas chromatography-fame ionization detection (GC-FID). The nitrilase gene was amplifed by polymerase chain reaction (PCR) and by using appropriate primers. Results: The growth studies showed that the test organisms grew on the two nitriles. The doubling times of 12.16 d and 9.46 d (specifc growth rate, µ=0.082 d−1 , 0.106 d−1 ) were obtained for each pure culture of Bacillus sp. srain WOD8 and Corynebacterium sp. srain WOIS2 on glutaronitrile (as single substrate), respectively. While the same strains had doubling times of 11.11 d and 10.00 d (µ=0.090 d−1 , 0.100 d−1 ) on benzonitrile (as single substrate). However, the mixed culture (comprising the two strains) had doubling times of 7.40 d and 7.75 d (µ=0.135 d−1 , 0.129 d−1 ) on glutaronitrile (as single and mixed substrates), respectively. While doubling times of 8.09 d and 8.71 d (µ=0.124 d−1 , 0.115 d−1 ) were obtained for the same mixed culture on benzonitrile (as single and mixed substrates). Based on gas chromatographic analysis, the residual glutaronitrile concentrations at day 16 for strains WOD8 and WOIS2 were 35.77 g L−1 (72.2%) and 9.30 g L−1 (92.5%), respectively, whereas the residual benzonitrile concentrations for the same strains were 27.39 g L−1 (78.8%) and 13.79 g L−1 (89.2%), respectively. For the mixed culture, residual glutaronitrile and benzonitrile concentrations at day 16 were 13.40 g L−1 (88.5%) and 10.42 g L−1 (91.5%), respectively, whereas for the mixed substrates (glutaronitrile and benzonitrile), 7.21 g L−1 (91.7%) and 4.80 g L−1 (94.2%) of residual glutaronitrile and benzonitrile concentrations were obtained by the same consortium. The gene for nitrilase involved in nitrile degradation was detected in the genome of the bacterial strains. The amplifed nitrilase gene gave PCR products of sizes 1400 bp and 1000 bp, as expected for strains WOD8 and WOIS2, respectively. 4-Cyanobutyric acid (4CBA), glutaric acid (GA), and benzoic acid (BA) were obtained as metabolites following nitrile degradation in vitro.Conclusion: These results revealed that strains WOD8, WOIS2 and the mixed culture (consisting of the two strains) have proven to have the capacity to metabolize nitriles (glutaronitrile and benzonitrile) as the carbon and nitrogen sources. However, the mixed culture had higher nitrile degradation rate as compared to each pure culture of the two test organisms. These results also provide insight into the evolutionary genetic origin of a nitrilase gene that encodes an enzyme that catalyzes nitrile degradation in these strains. Hence, the bacterial strains that harbor this kind of gene may be used as promising biological agents for the remediation of sites polluted with nitriles, thereby opening new perspectives for encouraging data for a bioremediation bioprocessItem Potentials of Hydrocarbon Utilization by Wood-Digesting Bacteria Isolated from the Lagos Lagoon, Nigeria(JOURNAL OF TROPICAL LIFE SCIENCE, 2020-02-01) Buraimoh, Olanike Maria; Ogunyemi, Adewale Kayode; Oyegbite, Isaac Edward; Amund, Olukayode Oladipo; Ilori, Matthew OlusojiThere is a continuous search for environmental–friendly methods to address oil-polluted environments, hence this study aimed to establish the potential of using tropical estuarine bacterial strains for degradation of crude oil in polluted environ-ment. Microbial degradation of hydrocarbons has been considered a promising, natural, less toxic and cost-effective technology. Lignocellulose-utilizing bacterial strains (Bacillus megaterium strain NOB, Streptomyces pseudogriseolus strain EOB and Paenibacillus sp. strains ROB) were isolated from decomposing wood residues in a tropical lagoon. They were identified on the basis of morphological and biochemical characteristics, observation under scanning electron microscope and 16S rRNA gene sequencing. Microbial growth assessment coupled with bio-surfactant production were performed in triplicates under aerobic batch conditions in Erlenmeyer flasks containing mineral salts medium fortified with trace elements and crude oil as the sole carbon source. The generation times of strains NOB, EOB and ROB were 28.3, 44.9 and 46.8 h respectively; with specific growth rates of 14.2, 8.9 and 8.6 h-1, respectively on crude oil. Gas chromatographic analysis of residual hydrocarbons from the growth cultures of isolates revealed that the three strains had degraded the oil by 89.34, 86.33 and 79.37%, respectively at the end of 21 days. The cell hydrophobicity of the bacterial strains also reached 83.6, 79.4 and 69.4%, respectively. The results from this study suggest that wood-digesting bacterial strains from a tropical lagoon possess hydrocarbon utilization capabili-ties. They could therefore have potentials for deployment in the bioremediation of petrochemical spills in polluted environments.