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- ItemOpen AccessAerobic Degradation of Di- and Trichlorobenzenes by Two Bacteria isolated from Polluted Tropical Soils.(2007) Adebusoye, S.A; Picardal, F.W; Ilori, M.O; Amund, O.O; Fuqua, C; Grindle, NTwo polychlorinated biphenyl (PCBs)-degrading bacteria were isolated by traditional enrichment technique from electrical transformer fluid (Askarel)-contaminated soils in Lagos, Nigeria. They were classified and identified as Enterobacter sp. SA-2 and Pseudomonas sp. SA-6 on the basis of 16S rRNA gene analysis, in addition to standard cultural and biochemical techniques. The strains were able to grow extensively on dichloro- and trichlorobenzenes. Although they failed to grow on tetrachlorobenzenes, monochloro- and dichlorobenzoic acids, they were able to utilize all monochlorobiphenyls, and some dichlorobiphenyls as sole sources of carbon and energy. The effect of incubation with axenic cultures on the degradation of 0.9 mM 1,4-dichlorobenzene, 0.44 mM 1,2,3- and 0.43 mM 1,3,5-trichlorobenzene in mineral salts medium was studied. Approximately, 80–90% of these xenobiotics were degraded in 200 h, concomitant with cell increase of up to three orders of magnitude, while generation times ranged significantly (P < 0.05) from 17–32 h. Catechol 1,2-dioxygenase and catechol 2,3-dioxygenase activities were detected in crude cell-free extracts of cultures pre-grown with benzoate, with the latter enzyme exhibiting a slightly higher activity (0.15–0.17 lmol min1 mg of protein1) with catechol, suggesting that the meta-cleavage pathway is the most readily available catabolic route in the SA strains. The wider substrate specificity of these tropical isolates may help in assessing natural detoxification processes and in designing bioremediation and bioaugmentation methods.
- ItemOpen AccessBacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian Contaminated Systems.(Oyetibo, et al (2010). Bacteria with dual resistance to elevated concentrations of heavy metals and antibiotics in Nigerian Contaminated Systems. Environ Monit Assess 168:305–314, 2009) Oyetibo, G.O; Ilori, M.O; Adebusoye, S.A; Obayori, O.S; Amund, O.OSamples of soil, water, and sediments from industrial estates in Lagos were collected and analyzed for heavy metals and physicochemical composition. Bacteria that are resistant to elevated concentrations of metals (Cd2+, Co2+, Ni2+, Cr6+, and Hg2+) were isolated from the samples, and they were further screened for antibiotic sensitivity. The minimum tolerance concentrations (MTCs) of the isolates with dual resistance to the metals were determined. The physicochemistry of all the samples indicated were heavily polluted. Twenty-two of the 270 bacterial strains isolated showed dual resistances to antibiotics and heavy metals. The MTCs of isolates to the metals were 14 mM for Cd2+, 15 mM for Co2+ and Ni2+, 17 mM for Cr6+, and 10 mM for Hg2+. Five strains (Pseudomonas aeruginosa, Actinomyces turicensis, Acinetobacter junni, Nocardia sp., and Micrococcus sp.) resisted all the 18 antibiotics tested. Whereas Rhodococcus sp. and Micrococcus sp. resisted 15 mM Ni2+, P. aeruginosa resisted 10 mM Co2+. To our knowledge, there has not been any report of bacterial strains resisting such high doses of metals coupled with wide range of antibiotics. Therefore, dual expressions of antibiotics and heavy-metal resistance make the isolates, potential seeds for decommissioning of sites polluted with industrial effluents rich in heavy metals, since the bacteria will be able to withstand in situ antibiosis that may prevail in such ecosystems.
- ItemOpen AccessBiodegradation of Polycyclic Aromatic Hydrocarbon Mixtures by Rhodococcus Pyridinivorans FF2 and Pseudomonas Aeruginosa F4b Isolated from Sediments of Lagos Lagoon, Nigeria(Biogeneric science and Research, 2020) Obi, C.C; Adebusoye, S.A; Amund, O.O; Ugoji, E.E; Hickey, W.JPolycyclic 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 ring-hydroxylating 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.
- ItemOpen AccessBiodegradation of crude oil and phenanthrene by heavy metal resistant Bacillus subtilis isolated from a multi-polluted industrial wastewater creek(International Biodeterioration & Biodegradation (ELSEVIER), 2017-02) Oyetibo, G.O; Chien, M.F; keda-Ohtsubo, W; Suzuk, H; Obayori, O.S; Adebusoye, S.A; Ilori, M.O; Amund, O.O; Endo, OA critical bottleneck associated with bioremediation technology in multi-polluted environments is microbiostasis due to metal toxicity. Autochthonous Bacillus species that would harness a repertory of traits to catabolize hydrocarbons and simultaneously sequester heavy metals (HMs) is invaluable in the environment contaminated with divergent pollutants. Fourteen HM-resistant bacilli from polluted creek were characterized using phenotypic and molecular criteria, and studied for hydrocarbon degradation in chemically defined media amended with Co2þ and Ni2þ (5.0 mmol l 1 each). Phylogenetic analyses revealed distribution of the bacilli into three clades. Two dissimilar strains of Bacillus subtilis (M16K, and M19F) with 19.1% sequence divergence, exhibited excellent degradation of crude oil (>94.0%) with evidence of early degradation of isoprenoid hydrocarbons and concurrent metal removal 18 d postinoculation. Similarly, phenanthrene degradation (>85.0%), and corresponding metal detoxification occurred in 28 d axenic culture of the strains. Strain M16K and M19F were metabolically active in matrices containing HMs, degraded hydrocarbons and simultaneously removed HMs from the medium. To the best of our knowledge, this is the first report of metal-resistant Bacillus subtilis strains showing simultaneous degradation of hydrocarbons and detoxification of metals, particularly in the Sub-Saharan Africa. The bacilli could be useful as potential biological agents in effective bioremediation campaign for multi-polluted environments.
- ItemOpen AccessBiodegradation of Crude Oil and Phenanthrene by Heavy Metal Resistant Bacillus Subtilis Isolated from a Multi-Polluted Industrial Wastewater Creek(Elservier Limited, 2017) Oyetibo, G.O; Chien, M; Ikeda-Ohtsubo, W; Suzuki, H; Obayori, O.S; Adebusoye, S.A; Ilori, M.O; Amund, O.O; Endo, GA critical bottleneck associated with bioremediation technology in multi-polluted environments is microbiostasis due to metal toxicity. Autochthonous Bacillus species that would harness a repertory of traits to catabolize hydrocarbons and simultaneously sequester heavy metals (HMs) is invaluable in the environment contaminated with divergent pollutants. Fourteen HM-resistant bacilli from polluted creek were characterized using phenotypic and molecular criteria, and studied for hydrocarbon degradation in chemically defined media amended with Co2þ and Ni2þ (5.0 mmol l 1 each). Phylogenetic analyses revealed distribution of the bacilli into three clades. Two dissimilar strains of Bacillus subtilis (M16K, and M19F) with 19.1% sequence divergence, exhibited excellent degradation of crude oil (>94.0%) with evidence of early degradation of isoprenoid hydrocarbons and concurrent metal removal 18 d postinoculation. Similarly, phenanthrene degradation (>85.0%), and corresponding metal detoxification occurred in 28 d axenic culture of the strains. Strain M16K and M19F were metabolically active in matrices containing HMs, degraded hydrocarbons and simultaneously removed HMs from the medium. To the best of our knowledge, this is the first report of metal-resistant Bacillus subtilis strains showing simultaneous degradation of hydrocarbons and detoxification of metals, particularly in the Sub-Saharan Africa. The bacilli could be useful as potential biological agents in effective bioremediation campaign for multi-polluted environments.
- ItemOpen AccessBiodegradation of p-Chloroaniline by Bacteria Isolated from Contaminated Sites(2010) Fashola, M.O; Obayori, O.S; Omotayo, A.E; Adebusoye, S.A; Amund, O.OEnrichment of water from a contaminated site in a textile industry in Ikeja resulted in the isolation of two bacteria belonging to the genera Alcaligenes and Cellulomonas. These bacteria were able to mineralize para-chloroaniline (p-chloroaniline). Time course degradation of p-chloroaniline using pure cultures of these organisms showed that p-chloroaniline supported the growth of these isolates. An initial increase in cell densities of 7.50-9.46 cfu/mL was recorded from day 0-9th day for Cellulomonas sp. while for Alcaligenes denitrificans it was 7.20-9.40 cfu/mL. After day 9, a decrease in population occurred, indicating non-availability of nutrients or toxicity of the medium. Simultaneously, a decrease in the pH, indicative of increased acidity of the medium, was also observed from the first day. The result of the GC analysis of the pure isolates on p-chloroaniline shows that 86.5% of the p-chloroaniline was degraded by the Cellulomonas sp. while 81.2% was degraded by the A. denitrificans in 30 days. These bacterial isolates utilized other hydrocarbons such as pyrene, anthracene, crude oil and chlorobenzoates as sole source of carbon and energy but not phenanthrene, naphthalene and biphenyl. The two isolates tolerated NaCl concentration of up to 5%.
- ItemOpen AccessBiodegradation of p-Chloroaniline by Bacteria Isolated from Contaminated Sites(2013-01) Fashola, M.O; Obayori, O.S; Amund, O.O; Omotayo, A.E; Adebusoye, S.AEnrichment of water from a contaminated site in a textile industry in Ikeja resulted in the isolation of two bacteria belonging to the genera Alcaligenes and Cellulomonas. These bacteria were able to mineralize para-chloroaniline (p-chloroaniline). Time course degradation of p-chloroaniline using pure cultures of these organisms showed that p-chloroaniline supported the growth of these isolates. An initial increase in cell densities of 7.50-9.46 cfu/mL was recorded from day 0-9th day for Cellulomonas sp. While for Alcaligenes denitrificans it was 7.20-9.40 cfu/ml. After day 9, a decrease in population occurred, indicating non-availability of nutrients or toxicity of the medium. Simultaneously, a decrease in the pH, indicative of increased acidity of the medium, was also observed from the first day. The result of the GC analysis of the pure isolates on p-chloroaniline shows that 86.5% of the p-chloroaniline was degraded by the Cellulomonas sp. While 81.2% was degraded by the A. denitrificans in 30 days. These bacterial isolates utilized other hydrocarbons such as pyrene, anthracene, crude oil and chlorobenzoates as sole source of carbon and energy but not phenanthrene, naphthalene and biphenyl. The two isolates tolerated NaCl concentration of up to 5%.
- ItemOpen AccessCharacterization of Multiple novel aerobic Polychlorinated Bipenyl (PCB)-Utilizing Bacterial Strains Indigenous to Contaminated Tropical African Soils(2008) Adebusoye, S.A; Picardal, F.W; Ilori, M.O; Amund, O.O; Fuqua, CContaminated sites in Lagos, Nigeria were screened for the presence of chlorobiphenyl-degrading bacteria. The technique of continual enrichment on Askarel fluid yielded bacterial isolates able to utilize dichlorobiphenyls (diCBs) as growth substrates and six were selected for further studies. Phenotypic typing and 16S rDNA analysis classified these organisms as species of Enterobacter, Ralstonia and Pseudomonas. All the strains readily utilized a broad spectrum of xenobiotics as sole sources of carbon and energy. Growth was observed on all monochlorobiphenyls (CBs), 2,2'-, 2,3-, 2,4'-, 3,3'- and 3,5-diCB as well as di- and trichlorobenzenes Growth was also sustainable on Askarel electrical transformer fluid and Aroclor 1221. Time-course studies using 100 ppm of 2-, 3- or 4-CB resulted in rapid exponential increases in cell numbers and CB transformation to respective chlorobenzoates (CBAs) within 70 h. Significant amounts of chloride were recovered in culture media of cells incubated with 2-CB and 3-CB, suggesting susceptibilities of both 2- and 3-chlorophenyl rings to attack, while the 4-CB was stoichiometrically transformed to 4-CBA. Extensive degradation of most of the congeners in Aroclor 1221 was observed when isolates were cultivated with the mixture as a sole carbon source. Aroclor 1221 was depleted by a minimum of 51% and maximum of 71%. Substantial amounts of chloride eliminated from the mixture ranged between 15 and 43%. These results suggest that some contaminated soils in the tropics may contain exotic micro-organisms whose abilities and potentials are previously unknown. An understanding of these novel strains therefore, may help answer questions about the microbial degradation of polychlorinated biphenyls (PCBs) in natural systems and enhance the potential use of bioremediation as an effective tool for cleanup of PCB-contaminated soils.
- ItemOpen AccessCharacterization of multiple novel aerobic polychlorinated biphenyl (PCB)-utilizing bacterial strains indigenous to contaminated tropical African soils(2008) Adebusoye, S.A; Picardal, F.W; Ilori, M.O; Amund, O.O; Fuqua, CContaminated sites in Lagos, Nigeria were screened for the presence of chlorobiphenyl-degrading bacteria. The technique of continual enrichment on Askarel fluid yielded bacterial isolates able to utilize dichlorobiphenyls (diCBs) as growth substrates and six were selected for further studies. Phenotypic typing and 16S rDNA analysis classified these organisms as species of Enterobacter, Ralstonia and Pseudomonas. All the strains readily utilized a broad spectrum of xenobiotics as sole sources of carbon and energy. Growth was observed on all monochlorobiphenyls (CBs), 2,2'-, 2,3-, 2,4'-, 3,3'- and 3,5-diCB as well as di- and trichlorobenzenes Growth was also sustainable on Askarel electrical transformer fluid and Aroclor 1221. Time-course studies using 100 ppm of 2-, 3- or 4-CB resulted in rapid exponential increases in cell numbers and CB transformation to respective chlorobenzoates (CBAs) within 70 h. Significant amounts of chloride were recovered in culture media of cells incubated with 2-CB and 3-CB, suggesting susceptibilities of both 2- and 3-chlorophenyl rings to attack, while the 4-CB was stoichiometrically transformed to 4-CBA. Extensive degradation of most of the congeners in Aroclor 1221 was observed when isolates were cultivated with the mixture as a sole carbon source. Aroclor 1221 was depleted by a minimum of 51% and maximum of 71%. Substantial amounts of chloride eliminated from the mixture ranged between 15 and 43%. These results suggest that some contaminated soils in the tropics may contain exotic micro-organisms whose abilities and potentials are previously unknown. An understanding of these novel strains therefore, may help answer questions about the microbial degradation of polychlorinated biphenyls (PCBs) in natural systems and enhance the potential use of bioremediation as an effective tool for cleanup of PCB-contaminated soils.
- ItemOpen AccessCo-metabolic Degradation of Polychlorinated Biphenyls (PCBs) by Axenic Cultures of Ralstonia sp. Strain SA-5 and Pseudomonas sp. Strain SA-6 obtained from Nigerian Contaminated Soils(Springer Science+Business Media B.V. 2007, 2008) Adebusoye, S.A; Ilori, M.O; Picardal, F. W; Amund, O.OSubstantial metabolism of 2,3,4,5-tetrachlorobiphenyl (2,3,4,5-tetraCB) and 2,3′,4′,5-tetraCB by axenic cultures of Ralstonia sp. SA-5 and Pseudomonas sp. SA-6 was observed in the presence of biphenyl supplementation, although, the strains were unable to utilize tetrachlorobiphenyls as growth substrate. The former was more amenable to aerobic degradation (∼70% degradation) than the latter (22–45% degradation). Recovery of 2,5-chlorobenzoic acid and chloride from 2,3′,4′,5-tetraCB assay is an indication of initial dioxygenase attack on the 3,4-dichlorophenyl ring. The PCB-degradative ability of both strains was also investigated by GC analysis of individual congeners in Aroclor 1242 (100 ppm) following 12-day incubation with washed benzoate-grown cells. Results revealed two different catabolic properties. Whereas strain SA-6 required biphenyl as inducer of the degradation activity, such induction was not required by strain SA-5. Nearly all the detectable congeners in the mixture were extensively degraded (% reduction in ECD area counts for individual congeners ranged from 50.0 to 100% and 14.2 to 100%, respectively, for SA-5 and SA-6). The two strains exhibited no noticeable specificity for congeners with varying numbers of chlorine substitution and positions. The degradative competence of these isolates most especially SA-5 makes them among the most versatile PCB-metabolizing organisms yet reported.
- ItemOpen AccessDegradation of hydrocarbons and biosurfactant production by Pseudomonas sp. strain LP1(Springer Science+Business Media B.V. 2007, 2009) Obayori, O.S; Ilori, M.O; Adebusoye, S.A; Oyetibo, G.O; Omotayo, A.E; Ahmed, O.OPseudomonas sp. strain LP1, an organism isolated on the basis of its ability to grow on pyrene, was assayed for its degradative and biosurfactant production potentials when growing on crude, diesel and engine oils. The isolate exhibited specific growth rate and doubling time of 0.304 days⁻¹ and 2.28 days, respectively on crude oil (Escravos Light). The corresponding values on diesel were 0.233 days⁻¹ and 2.97 days, while on engine oil, were 0.122 days⁻¹ and 5.71 days. The organism did not show significant biosurfactant production towards crude oil and diesel, but readily produced biosurfactant on engine oil. The highest Emulsification index (E₂₄) value for the biosurfactant produced by LP1 on engine oil was 80.33 ± 1.20, on day 8 of incubation. Biosurfactant production was growth-associated. The surface-active compound which exhibited zero saline tolerance had its optimal activity at 50°C and pH 2.0.
- ItemOpen AccessEffect of Corn Steep liquor on growth rate and Pyrene Degradation by Pseudomonas strain(Springer Links, 2010) Obayori, O.S; Ilori, M.O; Adebusoye, S.A; Oyetibo, G.O; Omotayo, A.E; Amund, O.OThe growth rates and pyrene degradation rates of Pseudomonas sp. LPl and Pseudomonas aeruginosa LP5 were increased in corn steep liquor (CSL) supplemented. On pyrene alone the higher specific growth rate of LPl was 0.818 h-1, while on CSL-supplemented pyrene MSM, the value was 0.026 h-1. For LP5 the highest growth rate on CSL-supplemented pyrene-MSM was 0.034 h-1. Conversely, on pyrene alone the highest rate was 0.024 h-1. CSL led to marked reduction in residual pyrene. In the case of Pseudomonas sp. LPl values of residual pyrene were 58.54 and 45.47 %, respectively, for the unsupplemented and supplanted both cultures, showing a difference of 13.09 %. For LP5 the corresponding values were 64.01 and 26.96 %, respectively, showing a difference of 37.05 %. The rate of pyrene utilization by LPl were 0.08 and 0.11 mg l-1 h-1 on unsupplemented and supplemented media, respectively. The corresponding values for LP5 were 0.07 and 0.015 mg l-1 h-1, respectively. These results suggest that CSL, a cheap and readily available waste product, could be very useful in the bioremediation of environments contaminated with pyrene.
- ItemOpen AccessEfficiency of Cassava Steep Liquor for Bioremediation of Diesel-oil Contaminated Tropical Agricultural Soil(Springer Links, 2010) Adebusoye, S.A; Ilori, M.O; Obayori, O.S; Oyetibo, G.O; Akindele, K.A; Amund, O.OSoil artificially contaminated with diesel oil, treated with cassava steep liquor (CSL) and designated EXPS. Similar polluted soil without CSL amendment (CSSl) and uncontaminated soil (CSS2) served as controls. There were dramatic changes in the physic-chemistry of systems EXPS and CSSl with utilization of the inorganic nutrients to near-depletion in the former than the latter. In contrast, the properties of CSS2 remained relatively stable throughout the investigated period. Similarly, the population densities of microflora in the polluted soils showed an initial decrease between days 0 and 5 before assuming an increasing trend with percent hydrocarbon-utilizers ranging significantly (P < 0.05) from 0.56 to 6.6, 0.1 to 2.46 and 0.56 to 0.26, respectively for EXPS, CSSl, and CSS2. In EXPS, the residual oil decreased from 98,045 to 1,102.3 mg/kg soil at day 35 representing about 98.88% degradation. The corresponding value for CSSl was 98,106.1 to 52,110 mg/kg soil, amounting to 46.88% oil disappearance. The GC finger prints of alkane fractions of the recovered oil reduced significantly by day 15 for EXPS with near-similar results of CSSl. However, by day 35, there was complete disappearance of all peaks including the pristane and phytane molecules in the former whereas in CSS1, there were no observable changes. The germination and growth profiles of maize seed plants as evidence of recovery of oil-impacted soils were poor in CSS1 (10%) with pronounced abnormal morphology when compared with the data obtained for EXPS (74%) and CSS2 (80%). These results suggest that CSL could be an indispensable tool in bioremediation of environments contaminated with hydrocarbons. The technology of application is simple, rapid and cost-effective and may be appropriate for use in developing countries to ameliorate the problems of petroleum pollution
- ItemOpen AccessEvidence of Aerobic Utilization of di-Ortho-Substituted Trichlorobiphenyls as Growth Substrates by Pseudomonas sp SA-6 and Ralstonia sp SA-4(2008) Adebusoye, S.A; Ilori, M.O; Picardal, F. W; Amund, O.ORobust and effective bioremediation strategies have not yet been developed for polychlorinated biphenyl (PCB)-contaminated soils. This is in part a result of the fact that otho- or ortho- and para-substituted congeners, frequent dead-end products of reductive dechlorination of PCB mixtures, have greatly reduced aerobic biodegradability. In this study, we report substantial evidence of utilization of diortho-substituted trichlorobiphenyls (triCBs) as growth substrates by Ralstonia sp. SA-4 and Pseudomonas sp. SA-6 in which ortho-substitution resulted in no obvious paterns of recalcitrance. These stains exhibited unusual preferences for growth on congeners chlorinated on both rings. Substrate uptake studies with benzoate grown cells revealed that the isolates attacked the 2-chlorophenyl rings of 2,2’,4- and 2,2’,5-triCB. Between 71% and 93% of the initial 0.23-0.34 mM dose of congeners were transformed in less than 261 h concomitant with non-stoichiometric production of respective dichlorobenzoates and chloride ion. In enzyme assays, activity of 2,3-dihydroxybiphenyl 1,2-dioxygenase was constitutive. Additionally, these strains harboured no detectable plasmids which, coupled with exponential growth on the two triCB congeners, suggested chromosomal location of PCB degradative genes. In addition to the fact that there is a paucity of information on degradation of PCBs by tropical isolates, growth on triCBs as a sole carbon and energy source has never been demonstrated for any natural or engineered microorganisms. Such isolates may help prevent accumulation of ortho-substituted congeners in natural systems and offer the hope for development of effective bioaugmentation or sequential anaerobic-aerobic bioremediation strategies.
- ItemOpen AccessExtensive Biodegradation of polychlorinated Biphenyls in Aroclor 1242 and electrical Transformer Fluid (Askarel) by natural Strains of Microorganisms indigenous to contaminated African Systems(2008) Adebusoye, S.A; Ilori, M.O; Picardal, F. W; Amund, O.OEvidence for substantial aerobic degradation of Aroclor 1242 and Askarel fluid by newly characterized bacterial strains belonging to the Enterobacter, Ralstonia and Pseudomonas genera is presented. The organisms exhibited degradative activity in terms of total PCB/Askarel degradation, degradation of individual congeners and diversity of congeners attacked. Maximal degradation by the various isolates of Askarel ranged from 69% to 86% whereas, Aroclor 1242, with the exception of Ralstonia sp. SA-4 (9.7%), was degraded by 37% to 91%. PCB analysis showed that at least 45 of the representative congeners in Aroclor 1242 were extensively transformed by benzoate-grown cells without the need for biphenyl as an inducer of the upper degradation pathway. In incubations with Aroclor 1242, no clear correlation was observed between percentage of congener transformed and the degree of chlorination, regardless of the presence or absence of biphenyl. Recovery of significant but nonstoichiometric amounts of chloride from the culture media showed partial dechlorination of congeners and suggested production of partial degradation products. Addition of biphenyl evidently enhanced dechlorination of the mixture by some isolates. With the exception of Ralstonia sp. SA-5, chloride released ranged from 24% to 60% in the presence of biphenyl versus 0.35% to 15% without biphenyl.
- ItemOpen AccessGrowth and Biosurfactant Synthesis by Nigerian Hydrocarbon-Degrading Estuarine Bacteria(2008) Adebusoye, S.A; Amund, O.O; Ilori, M.O; Domeih, D.O; Okpuzor, JThe ability of microorganisms to degrade petroleum hydrocarbons is important for finding an environmentally-friendly method to restoring contaminated environmental matrices. Screening of hydrocarbon utilizing and biosurfactant-producing abilities of organisms from an estuarine ecosystem in Nigeria, Africa, resulted in the isolation of five microbial strains identified as Corynebacterium sp. DDVl, Flavobacterium sp. DDV2, Micrococcus roseus DDV3,Pseudomonas aeruginosa DDV4 and Saccharomyces cerevisae DDV5. These isolates grew readily on several hydrocarbons including hexadecane, dodecane, crude oil and petroleum fractions. Axenic cultures of the organisms utilized diesel oil (1.0%v/v) with generation times that ranged significantly (t-test, P < 0.05) between 3.25 and 3.88 day, with concomitant production of biosurfactants. Kinetics of growth indicates that biosurfactant synthesis occurred predominantly during exponential growth phase, suggesting that the bioactive molecules are primary metabolites. Strains DDV1 and DDV4 were evidently the most metabolically active in terms of substrate utilization and biosurfactant synthesis compared to other strains with respective emulsification index of 63 and 78%. Preliminary biochemical characterization indicates that the biosurfactants are heteropolymers consisting of lipid, protein and carbohydrate moieties. The hydrocarbon catabolic properties coupled with biosurfactant-producing capacibilities is an asset that could be exploited for cleanup of oil-contaminated matrices and also in food and cosmetic industries.
- ItemOpen AccessGrowth and Biosurfactant Synthesis by Nigerian Hydrocarbon-Degrading Estuarine Bacteria.(Revista de Biologia Tropical, 2008) Adebusoye, S.A; Amund, O.O; Ilori, M.O; Domeih, D.O; Okpuzor, JThe ability of microorganisms to degrade petroleum hydrocarbons is important for finding an environmentally-friendly method to restoring contaminated environmental matrices. Screening of hydrocarbon utilizing and biosurfactant-producing abilities of organisms from an estuarine ecosystem in Nigeria, Africa, resulted in the isolation of five microbial strains identified as Corynebacterium sp. DDVl, Flavobacterium sp. DDV2, Micrococcus roseus DDV3,Pseudomonas aeruginosa DDV4 and Saccharomyces cerevisae DDV5. These isolates grew readily on several hydrocarbons including hexadecane, dodecane, crude oil and petroleum fractions. Axenic cultures of the organisms utilized diesel oil (1.0%v/v) with generation times that ranged significantly (t-test, P < 0.05) between 3.25 and 3.88 day, with concomitant production of biosurfactants. Kinetics of growth indicates that biosurfactant synthesis occurred predominantly during exponential growth phase, suggesting that the bioactive molecules are primary metabolites. Strains DDV1 and DDV4 were evidently the most metabolically active in terms of substrate utilization and biosurfactant synthesis compared to other strains with respective emulsification index of 63 and 78%. Preliminary biochemical characterization indicates that the biosurfactants are heteropolymers consisting of lipid, protein and carbohydrate moieties. The hydrocarbon catabolic properties coupled with biosurfactant-producing capacibilities is an asset that could be exploited for cleanup of oil-contaminated matrices and also in food and cosmetic industries.
- ItemOpen AccessGrowth on Dichlorobiphenyls with Chlorine Substitution on Each Ring by Bacteria Isolated from Contaminated African Soils.(2007) Adebusoye, S.A; Picardal, F.W; Ilori, M.O; Amund, O.O; Fuqua, C; Grindle, NUntil recently, it was generally believed that the presence of more than one chlorine substituent prevented chlorinated biphenyls from serving as a sole source of carbon and energy for aerobic bacteria. In this study, we report the isolation of three aerobic strains, identified as Enterobacter sp. SA-2, Ralstonia sp. SA-4, and Pseudomonas sp. SA-6 from Nigeria polluted soils, that were able to grow on a wide range of dichlorobiphenyls (diCBs). In addition to growing on all monochlorobiphenyls (monoCBs), the strains were all able to utilize 2,2’-, 2,4’-, and 2,3-diCB as a sole source of carbon and energy. With the exception of strain SA-2, growth was also sustainable on 3,3’-, and 3,5-diCB. Washed benzoate-grown cells were typically able to degrade 68 to 100% of the diCB (100 ppm) within 188 h, concomitant with a cell number increase of up to three orders-of-magnitude and elimination of varying amounts of chloride. In many cases, stoichiometric production of a chlorobenzoate (CBA) as a product was observed. During growth on 2,2’, and 2,4’-diCB, organisms exclusively attacked an o-chlorinated ring resulting in the production of 2-CBA and 4-CBA, respectively. A gradual decline in the concentration of the latter was observed, which suggested that the product was being degraded further. In the case of 2,3-diCB, the unsubstituted ring was preferentially metabolized. Initial diCB degradation rates were greatest for 2,4’-diCB (11.2+0.91 to 30.3+7.8 nmol/min per 109 cells) and lowest for 2,2’-diCB (0.37+0.12 to 2.7+1.2 nmol/min per 109 cells).
- ItemOpen AccessInfluence of Chlorobenzoic acids on the Growth and Degradation Potentials of PCB-Degrading Microorganisms.(2008) Adebusoye, S.A; Picardal, F.W; Ilori, M.O; Amund, O.OThe biodegradation of polychlorinated biphenyls (PCBs) by diverse bacteria including those utilized in this study is often incomplete, a concomitant accumulation of chlorobenzoic acids (CBAs) are released as dead-end products. The build-up of these metabolites in the growth medium may result in feed-back inhibition and impede PCB biotransformation. In this investigation using GC-ECD and HPLC analyses, we confirmed that CBAs inhibit growth and PCB biodegradation potentials of five tropical bacteria namely, Pseudomonas aeruginosa SA-1, Enterobacter sp. SA-2, Ralstonia sp. SA-3, Ralstonia sp. SA-5 and Pseudomonas sp. SA-6. Among the four CBAs (2-CBA, 3-CBA, 4-CBA acids and 2,3-diCBA), 3-CBA was the strongest inhibitor followed by 4-CBA. Furthermore, we found that 3-CBA heavily inhibited growth of SA-3 and SA-6 on monochlorobiphenyls by 82-90% while elimination rate was inhibited by 71-88%. In the case of 2,3-diCBA, inhibition was generally less than 60%. However, effects of both acids were stronger in SA-3 than SA-6. We also found that 3-CBA and 2,3-diCBA completely inhibited carbon-chloride cleavage of 2-CB and 3-CB since cultivation in the absence of the acids resulted in recovery of 23-50% chloride in the culture fluids of organisms. These findings may therefore, have practical and ecological significance and are useful for improving the efficiency and the stability of some biological treatment processes.
- ItemOpen AccessMetabolism of Chlorinated Biphenyls: Use of 3,3/-and 3,5-Dichlorobiphenyl as Sole Sources of Carbon by Natural Species of Ralstonia and Pseudomona(2008) Adebusoye, S.A; Ilori, M.O; Picardal, F. W; Amund, O.ORalstonia sp. SA-3, Ralstonia sp. SA-4 and Pseudomonas sp. SA-6 are natural strains with a novel capacity to utilize meta-substituted dichlorobiphenyls (diCBs) hitherto not known to serve as a sole source of carbon and energy for polychlorobiphenyl-degraders. In growth experiments, axenic cultures of isolates grew logarithmically on 3,3’-diCB with generation times that ranged insignificantly (t-test, P>0.05) from 30.4 to 33.8 h. Both 3-chlorobenzoate (3-CBA) and chloride produced as metabolites were recovered in non-stoichiometric quantities. The release of chloride by the cultures lagged substantially, indicating that the initial dioxygenase attack preceded cleavage of carbon-chloride bonds and that chloride must have been released from the chlorinated hydroxypentadienoate. In the case of 3,5-diCB, SA-3 and SA-6 metabolised this substrate primarily to 3,5-CBA. The lack of chloride in the culture media coupled with stoichiometric recovery of 3,5-CBA suggests that growth by these strains occurred predominantly at the expense of the unsubstituted phenyl ring. The unique metabolic properties of these three aerobic isolates point to their potential usefulness as seeds for bioremediation of PCBs polluted environments without the need for repeated inoculation or supplementation by a primary growth substrate such as biphenyl.