Evaluating \u3ci\u3ePseudomonas aeruginosa\u3c/i\u3e as Plant Growth–Promoting Rhizobacteria in West Africa

Some parameters of growth were examined in three test crops as indices of plant growth–promoting rhizobacteria (PGPR) ability of Pseudomonas aeruginosa. Crops include Abelmoschus esculentus L. (okra), Lycopersicon esculentum L. (tomato), and Amaranthus sp. (African spinach). This study aimed to examine the effectiveness of PGPR in West Africa and determine whether the inoculation method has an impact on PGPR’s effectiveness. Bacterium was isolated from topsoil in the Botanical Garden, University of Lagos, Nigeria. Inoculation with bacteria was done by soaking seeds in 106 cfu/ml of bacterial suspension, and coating was done using 10% starch (w/v) as seed adhesive with 106 cfu/ml of bacterial suspension. The third treatment involved soaking seeds in distilled water and later applying NPK 15:15:15 fertilizer. Control seeds were soaked in distilled water. Two methods of bacterial inoculation (soaking and coating) produced statistically similar results to plants grown with fertilizer but performed better than the control, suggesting a high potential of P. aeruginosa as PGPR

Biodegradation of Polycyclic Aromatic Hydrocarbon Mixtures by Rhodococcus Pyridinivorans FF2 and Pseudomonas Aeruginosa F4b Isolated from Sediments of Lagos Lagoon, Nigeria

Polycyclic aromatic hydrocarbons (PAH) are widespread environmental pollutants that need urgent attention because of their toxicity. Development of microbial inoculants for PAH bioremediation is a potential avenue by which the environmental hazards posed by PAH can be addressed. The goal of the study was to determine if using PAH mixtures, rather than single PAH, as enrichment substrates would yield isolates that have superior PAH degradation abilities and/or are retrieve novel taxa from the PAH-contaminated sediments of Lagos Lagoon, Nigeria. The use of a quaternary mixture of PAH (pyrene, fluoranthene, fluorene, benz[a ]anthracene) was successful in yielding two isolates, Pseudomanas aeruginosa strain F4b and Rhodococcus pyridinivorans strain FF2 with capabilities to grow on multiple PAH, and thus potentially useful in bioremediation. In addition to the PAH degraded both isolates could grow on a wide range of other hydrocarbon substrates. The isolates of P. aeruginosa and R. pyridinivorans were identified as possessing PAH ringhydroxylating dioxygenases of the nahAC and narAa genotypes, respectively. The present study extends our knowledge of PAH biodegradation by P. aeruginosa and is the first report of PAH biodegradation by R. pyridinivorans. The capability of the R. pyridinivorans isolate to effectively degrade a highly toxic PAH, benz[a]anthracene, has particular importance for use in bioremediation

Evaluating \u3ci\u3ePseudomonas aeruginosa\u3c/i\u3e as Plant Growth–Promoting Rhizobacteria in West Africa

Some parameters of growth were examined in three test crops as indices of plant growth–promoting rhizobacteria (PGPR) ability of Pseudomonas aeruginosa. Crops include Abelmoschus esculentus L. (okra), Lycopersicon esculentum L. (tomato), and Amaranthus sp. (African spinach). This study aimed to examine the effectiveness of PGPR in West Africa and determine whether the inoculation method has an impact on PGPR’s effectiveness. Bacterium was isolated from topsoil in the Botanical Garden, University of Lagos, Nigeria. Inoculation with bacteria was done by soaking seeds in 106 cfu/ml of bacterial suspension, and coating was done using 10% starch (w/v) as seed adhesive with 106 cfu/ml of bacterial suspension. The third treatment involved soaking seeds in distilled water and later applying NPK 15:15:15 fertilizer. Control seeds were soaked in distilled water. Two methods of bacterial inoculation (soaking and coating) produced statistically similar results to plants grown with fertilizer but performed better than the control, suggesting a high potential of P. aeruginosa as PGPR

Microbial communities in sediments of Lagos lagoon, Nigeria: elucidation of community structure and potential impacts of contamination by municipal and industrial wastes

Estuarine sediments are significant repositories of anthropogenic contaminants, and thus knowledge of the impacts of pollution upon microbial communities in these environments is important to understand potential effects on estuaries as a whole. The Lagos lagoon (Nigeria) is one of Africa’s largest estuarine ecosystems, and is impacted by hydrocarbon pollutants and other industrial and municipal wastes. The goal of this study was to elucidate microbial community structure in Lagos lagoon sediments to identify groups that may be adversely affected by pollution, and those that may serve as degraders of environmental contaminants, especially polycyclic aromatic hydrocarbons (PAHs). Sediment samples were collected from sites that ranged in types and levels of anthropogenic impacts. The sediments were characterized for a range of physicochemical properties, and microbial community structure was determined by Illumina sequencing of the 16S rRNA genes. Microbial diversity (species richness and evenness) in the Apapa and Eledu sediments was reduced compared to that of the Ofin site, and communities of both of the former two were dominated by a single operational taxonomic unit (OTU) assigned to the family Helicobacteraceae (Epsilonproteobacteria). In the Ofin community, Epsilonproteobacteria were minor constituents, while the major groups were Cyanobacteria, Bacteroidetes, and Firmicutes, which were all minor in the Apapa and Eledu sediments. Sediment oxygen demand (SOD), a broad indicator of contamination, was identified by multivariate analyses as strongly correlated with variation in alpha diversity. Environmental variables that explained beta diversity patterns included SOD, as well as levels of naphthalene, acenaphthylene, cobalt, cadmium, total organic matter, or nitrate. Of 582 OTU identified, abundance of 167 was significantly correlated (false discovery rate q≤ 0.05) to environmental variables. The largest group of OTU correlated with PAH levels were PAH/hydrocarbon-degrading genera of the Oceanospirillales order (Gammaproteobacteria), which were most abundant in the hydrocarbon-contaminated Apapa sediment. Similar Oceanospirillales taxa are responsive to marine oil spills and thus may present a unifying theme in marine microbiology as bacteria adapted for degradation of high hydrocarbon loads, and may represent a potential means for intrinsic remediation in the case of the Lagos lagoon sediments