Differential utilization of pyrene as the sole source of carbon by Bacillus subtilis and Pseudomonas aeruginosa strains: role of biosurfactants in enhancing bioavailability

AIMS: Our goal is to compare the efficiency of utilization of pyrene as the sole source of carbon for growth and energy by two nonactinomycetous groups of bacteria viz., Bacillus subtilis DM-04 and Pseudomonas aeruginosa mucoid (M) and nonmucoid (NM) strains, isolated from a petroleum-contaminated soil sample of north-east India. METHODS AND RESULTS: Bacillus subtilis DM-04 and P. aeruginosa M and NM bacterial strains were capable of secreting biosurfactant in the culture medium while growing on pyrene and their pyrene utilizing efficiency was demonstrated by correlating the bacterial growth in the presence of pyrene as the sole source of carbon along with a concomitant decrease in pyrene content from the culture medium with respect to time. The biosurfactant secreted by the respective bacterial strains enhanced the apparent solubility of pyrene by factors of 5-7 and influenced the bacterial cell surface hydrophobicity resulting in higher uptake and utilization of pyrene by bacteria. The growth of B. subtilis DM-04 and P. aeruginosa M and NM strains at the expense of pyrene after 96 h showed an assimilation of about 48.0 +/- 1.1% (mean +/- SD) and 32.0 +/- 0.6% (mean +/- SD) of pyrene carbon, respectively, showing differences in metabolism of pyrene by these bacterial strains. CONCLUSIONS: Bacillus subtilis DM-04 strain exhibited higher utilization and cellular assimilation of pyrene compared with P. aeruginosa M and NM strains. Further, the biosurfactants produced by the bacteria under study are capable of enhancing the solubility of pyrene in aqueous media and can influence the cell surface hydrophobicity of the biosurfactant-producing strains that results in a higher uptake of pyrene. SIGNIFICANCE AND IMPACT OF THE STUDY: It may be suggested that the bacteria used in this study are suitable candidates for practical field application for effective in situ bioremediation of pyrene-contaminated sites.     

Correlation between diverse cyclic lipopeptides production and regulation of growth and substrate utilization by Bacillus subtilis strains in a particular habitat

The two Bacillus subtilis strains (DM-03 and DM-04) were isolated from two extremely different habitats; one from the traditional fermented food and another one from a petroleum contaminated soil sample. These strains produced quantitatively and qualitatively different cyclic lipopeptides isoforms under laboratory culture conditions. MALDI-TOF mass spectral analysis revealed that lipopeptide profile varied according to the producing B. subtilis strains; iturins and surfactins isoforms were pre-dominant cyclic lipopeptides produced by B. subtilis DM-03 and DM-04 strains, respectively. A comparative study showed that these strains possessed distinct preferences for the carbon and nitrogen substrates, temperature and pH for optimal growth and biosurfactant production. Our study documented that the cyclic lipopeptide isoforms produced by the respective strains played an important role in the utilization of available hydrophobic substrate(s) from their natural habitats and conferred some kind of competitive advantage to the producing B. subtilis strains in their parent ecological niche.     

Degradation of anthracene by bacteria isolated from oil polluted tropical soils

Four bacteria, identified as Pseudomonas aeruginosa, Alcaligenes eutrophus, Bacillus subtilis and Micrococcus luteus were isolated from crude oil polluted soils using anthracene as the sole carbon and energy source. All the organisms utilized n-hexadecane, n-tetradecane, diesel oil, engine oil and naphthalene as sole carbon sources. None could utilize hexane, cycloheptane, xylene, benzene, toluene, phenol, fluoranthene,and kerosene as carbon sources. Highest cell density obtained with 0.1% (w/v) anthracene were 4.5 x 10(7) (cfu/ml), 8.6 x 10(6) (cfu/ml), 5.4 x 10(6) and 2.4 x 10(6) (cfu/ml) respectively, for P. aeruginosa, A. eutrophus, B. subtilis and M. luteus after 30 days incubation. Growth of the organisms on a Nigerian crude oil resulted in a residual oil concentration of 22.2%, 33.3%, 39.3%, 44% and 91.7% respectively, for P. aeruginosa, A. eutrophus, B. subtilis, M. luteus and the noninoculated control on the 14 th day. Ring fission enzymes of the meta pathway were detected in induced cells of P. aeruginosa and A. eutrophus while ortho pathway enzymes were detected in B. subtilis and M. luteus. P. aeruginosa and A. eutrophus had specific catechol-2,3-dioxygenase activities of 3.8 +/- 0.183 and 0.64 +/- 0.032 micromol/min x mg protein respectively while catechol-1,2-dioxygenase activities of 1.95 +/- 0.029 and 1.89 +/- 0.026 micromol/min x mg protein were detected in B. subtilis and M. luteus respectively. This work, highlights the capability of these unreported tropical strains of A. eutrophus, B. subtilis and M. luteus as anthracene degraders.     

Evaluation of genetic diversity among Pseudomonas citronellolis strains isolated from oily sludge-contaminated sites

The diversity among a set of bacterial strains that have the capacity to degrade total petroleum hydrocarbons (TPH) in soil contaminated with oily sludge (hazardous hydrocarbon waste from oil refineries) was determined. TPH is composed of alkane, aromatics, nitrogen-, sulfur-, and oxygen-containing compound, and asphaltene fractions of crude oil. The 150 bacterial isolates which could degrade TPH were isolated from soil samples obtained from diverse geoclimatic regions of India. All the isolates were biochemically characterized and identified with a Biolog microbial identification system and by 16S rDNA sequencing. Pseudomonas citronellolis predominated among the 150 isolates obtained from six different geographically diverse samplings. Of the isolates, 29 strains of P. citronellolis were selected for evaluating their genetic diversity. This was performed by molecular typing with repetitive sequence (Rep)-based PCR with primer sets ERIC (enterobacterial repetitive intergenic consensus), REP (repetitive extragenic palindromes), and BOXAIR and PCR-based ribotyping. Strain-specific and unique genotypic fingerprints were distinguished by these molecular typing strategies. The 29 strains of P. citronellolis were separated into 12 distinguishable genotypic groups by Rep-PCR and into seven genomic patterns by PCR-based ribotyping. The genetic diversity of the strains was related to the different geoclimatic isolation sites, type of oily sludge, and age of contamination of the sites. These results indicate that a combination of Rep-PCR fingerprinting and PCR-based ribotyping can be used as a high-resolution genomic fingerprinting method for elucidating intraspecies diversity among strains of P. citronellolis.     

Evaluation of Genetic Diversity among Pseudomonas citronellolis Strains Isolated from Oily Sludge-Contaminated Sites

The diversity among a set of bacterial strains that have the capacity to degrade total petroleum hydrocarbons (TPH) in soil contaminated with oily sludge (hazardous hydrocarbon waste from oil refineries) was determined. TPH is composed of alkane, aromatics, nitrogen-, sulfur-, and oxygen-containing compound, and asphaltene fractions of crude oil. The 150 bacterial isolates which could degrade TPH were isolated from soil samples obtained from diverse geoclimatic regions of India. All the isolates were biochemically characterized and identified with a Biolog microbial identification system and by 16S rDNA sequencing. Pseudomonas citronellolis predominated among the 150 isolates obtained from six different geographically diverse samplings. Of the isolates, 29 strains of P. citronellolis were selected for evaluating their genetic diversity. This was performed by molecular typing with repetitive sequence (Rep)-based PCR with primer sets ERIC (enterobacterial repetitive intergenic consensus), REP (repetitive extragenic palindromes), and BOXAIR and PCR-based ribotyping. Strain-specific and unique genotypic fingerprints were distinguished by these molecular typing strategies. The 29 strains of P. citronellolis were separated into 12 distinguishable genotypic groups by Rep-PCR and into seven genomic patterns by PCR-based ribotyping. The genetic diversity of the strains was related to the different geoclimatic isolation sites, type of oily sludge, and age of contamination of the sites. These results indicate that a combination of Rep-PCR fingerprinting and PCR-based ribotyping can be used as a high-resolution genomic fingerprinting method for elucidating intraspecies diversity among strains of P. citronellolis.     

石油污染土壤堆制微生物降解研究

采用异位生物修复技术堆式堆制处理方法 ,对辽河油田原油污染土壤进行了生物修复处理研究 .处理工程设 4个处理料堆单元 ,每个处理单元长 118.5cm ,宽 6 5 .5cm ,高 12 .5cm .研究结果表明 ,当进行处理的石油污染土壤中石油烃总量为 5 .2 2 g·10 0 g-1土时 ,利用黄孢原毛平革菌 (Phanerochaetechrysospori um) ,经过 5 5d的运行 ,石油烃总量去除率达 5 4.2 % .堆制处理中影响污染土壤石油烃总量生物降解的主要变化因子为污染土壤的O2 和CO2 含量、降解石油烃微生物的数量、污染土壤pH的变化 .通过监测这些数据的变化 ,可直接反映该工程的处理石油污染土壤的效果 .本处理工程采用定期通风措施 ,操作简单、运行费用低廉 ,为石油污染土壤生物修复实用化提供了一种简单易行的污染土壤清洁技术 .     

Potential application of cyclic lipopeptide biosurfactants produced by Bacillus subtilis strains in laundry detergent formulations

AIMS: Crude cyclic lipopeptide (CLP) biosurfactants from two Bacillus subtilis strains (DM-03 and DM-04) were studied for their compatibility and stability with some locally available commercial laundry detergents. METHODS AND RESULTS: CLP biosurfactants from both B. subtilis strains were stable over the pH range of 7.0-12.0, and heating them at 80 degrees C for 60 min did not result in any loss of their surface-active property. Crude CLP biosurfactants showed good emulsion formation capability with vegetable oils, and demonstrated excellent compatibility and stability with all the tested laundry detergents. CONCLUSION: CLP biosurfactants from B. subtilis strains act additively with other components of the detergents to further improve the wash quality of detergents. The thermal resistance and extreme alkaline pH stability of B. subtilis CLP biosurfactants favour their inclusion in laundry detergent formulations. SIGNIFICANCE AND IMPACT OF THE STUDY: This study has great significance because it is already known that microbial biosurfactants are considered safer alternative to chemical or synthetic surfactants owing to lower toxicity, ease of biodegradability and low ecological impact. The present study provides further evidence that CLP biosurfactants from B. subtilis strains can be employed in laundry detergents.     

Petroleum Degradation,Biosurfactant and Laccase Production by Fusarium neocosmosporiellum RH-10: A Microcosm Study

The aim of this study was to evaluate the potential of crude oil removal by fungal strains isolated from Arak refinery. The results showed that the RH10 strain is a potent strain as a surfactant producer and degrader of petrochemical hydrocarbons. The strain was identified as a Fusarium neocosmosporiellum and could degrade 58% of hydrocarbons in the minimal medium and reduce the surface tension from 45 to 26.5 mN m^?1. Moreover, residual crude oil analysis with Fourier transform infrared spectrophotometry showed that this strain was able to degrade 50% of aliphatic compounds. To investigate the mechanism of degradation, oxidase enzymes were assayed and it was found that F. neocosmosporiellum can produce 1.94 U L^?1 of laccase in 10 g L^?1 crude oil. Carbon, nitrogen, phosphorus and soil pattern optimization in a microcosm study showed that this strain removed 44% and 27% of the crude oil from contaminated soil in 1% and 5% crude oil concentrations, respectively. Under optimum condition, 9.66 g kg^?1 crude oil was removed by F. neocosmosporiellum when the initial oil concentration was 50 g kg^?1, at the end of 150 days microcosm experiment. The results demonstrated the promising potential of fungi strain for cleaning of contaminated soil.     

Crude oil degradation efficiency of a recombinant Acinetobacter baumannii strain and its survival in crude oil-contaminated soil microcosm

A hydrocarbon degrading Acinetobacter baumannii S30 strain, isolated from crude oil-contaminated soil, was inserted with the lux gene from the luciferase gene cassette luxCDABE. Soil microcosms were designed to study the degradation efficacy for total petroleum hydrocarbon (TPH) of crude oil by lux-tagged A. baumannii S30 pJES. Bioaugmentation of a TPH-contaminated microcosm with A baumannii S30 pJES showed that TPH levels were reduced from 89.3 to 53.9 g/kg soil in 90 days. Biodegradation of TPH by A baumannii S30 pJES was also monitored in shake flask conditions, which showed a reduction of initial TPH levels by over 50% at the end of 120 h. A lux-PCR-based approach along with the standard dilution plating with selective antibiotics was successfully utilized to monitor the survivability of the lux-tagged strain A. baumannii S30 pJES in soil microcosms and stability of the lux insert in the host strain A. baumannii S30. The selective plating technique indicated the population of A. baumannii S30 pJES to be 6.5+/-0.13 x 10(8) CFU/g at day zero (just after bioaugmentation) and 2.09+/-0.08 x 10(8) CFU/g of soil after 90 days of incubation. lux-PCR confirmed the stability of the insert in all the randomly selected colonies of A. baumannii strains from the antibiotic plates. The lux insert was stable after 50 generations in Luria Bertini broth and storage at -70 degrees C as glycerol stocks for over a year. These results revealed that the lux insert was stable and lux-tagged A. baumannii S30 strain could survive in a TPH-contaminated soil microcosm and could degrade TPH in the soil microcosm conditions. It can be used as an effective marker to monitor the survival of augmented strains at a bioremediation site.     

Characterization of bacterial strains able to grow on high molecular mass residues from crude oil processing

Oil residues containing high molecular mass hydrocarbons, rich in polyaromatic compounds, are frequent end-products of crude oil processing and are poorly biodegradable. Their disposal poses an environmental problem. Through batch-enrichments from contaminated soils we have isolated and characterized seven bacterial strains that can use a residue from crude oil processing as a source of carbon and energy. The residue was a complex mixture of high molecular mass compounds, including saturated, aromatic and polycyclic aromatic hydrocarbons (PAHs). Analysis of the metabolic profiles of the strains isolated showed that they could all metabolize long-chain-length alkanes efficiently, but not PAHs. Strains degrading naphthalene, a simple PAH, did exist in the soil inocula used, but could be isolated only when enrichments were performed using pure naphthalene as the sole carbon source. All strains tested emulsified the oil residue and their ability to produce surfactants was studied.     

In vitro antibacterial activity of a 7-O-beta-D-glucopyranosyl-nutanocoumarin from Chaptalia nutans (Asteraceae)

Ethanolic crude extracts from the roots of Chaptalia nutans, traditionally used in Brazilian folk medicine, were screened against Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa by using the disk diffusion test technique. S. aureus with 14 mm inhibition zone was considered susceptible. E. coli and P. aeruginosa without such a zone were considered resistant. As a result of this finding, the ethanolic crude extract was fractionated on silica gel column chromatography into five fractions. The ethyl acetate fraction was active against S. aureus and Bacillus subtilis. Further column chromatography separation of the ethyl acetate fraction afforded 30 fractions, which were assayed against S. aureus. Fractions 16 and 17 showed inhibition zones with S. aureus, indicating the presence of active compounds, and were subjected to purification by repeated preparative thin layer chromatography. The pure compound 7-O-beta-D-glucopyranosyl-nutanocoumarin inhibited B. subtilis and S. aureus at concentrations of 62.5 g/ml and 125 g/ml, respectively. The antibacterial property of C. nutans appears to have justified its use for the treatment of wounds, which are contaminated through bacterial infections.     

Intergeneric Complementation of Anthranilate Synthase Subunits

Partially purified subunits of anthranilate synthase were prepared from Bacillus subtilis and Pseudomonas aeruginosa. The large component from B. subtilis (I(B)) complements well with the small component from P. aeruginosa (II(P)) to reconstitute a glutamine-reactive anthranilate synthase. This interaction can be demonstrated with crude extracts from a B. subtilis trpX mutant and a P. aeruginosa trpA mutant. Complementation was also observed with the large component from P. aeruginosa (I(P)) and the small subunit from B. subtilis (II(B)). At saturation the heterologous complex I(B)II(P) has 93% of the activity of the homologous complex I(B)II(B), whereas the hybrid I(P)II(B) is only 22% as active as the homologous complex I(P)II(P).     

Enhancing Degradation of Total Petroleum Hydrocarbons and Uptake of Heavy Metals in a Wetland Microcosm Planted with Phragmites Communis by Humic Acids Addition

The effects of humic acid (HA) on heavy-metal uptake by plants and degradation of total petroleum hydrocarbons (TPHs) in a wetland microcosm planted with Phragmites communis were evaluated by comparing waterlogged soils and water-drained upland soils. Experiments were conducted on soils artificially contaminated with heavy metals (Pb, Cu, Cd, Ni) and diesel fuel. HA showed a positive influence on biomass increase for all conditions, but more for belowground than aboveground biomass, and lower in contaminated than uncontaminated soil. The bioavailability and leachability factor (BLF) for all heavy metals except Ni increased with HA addition in both the control and the P. communis planted microcosms, suggesting that more heavy metals could be potentially phytoavailable for plant uptake. Microbial activities were not affected by both heavy metals and TPH contamination, and HA effects on stimulating microbial activities were much greater in the contaminated soil than under uncontaminated conditions. HA addition enhanced the degradation of TPH and n-alkane in waterlogged conditions. The results show that HA can increase the remedial performance in P. communis dominated wetlands simultaneously contaminated with heavy metals and petroleum hydrocarbons and thus prevent contamination of groundwater or other adjacent ecosystems.     

Bioremediation of Crude Oil–Contaminated Soil By Immobilized Bacteria on an Agroindustrial Waste—Sunflower Seed Husks

This study reports the immobilization and performance of a hydrocarbon-degrading Rhodococcus sp. strain (designated as QBTo) on sunflower seed husks (SH) for the bioremediation of soils polluted with crude oil. The SH performance as inoculants carrier was compared with peat, which is a vegetal material traditionally used in carrier-based inoculants production. The stability of the immobilized culture under storage conditions was assessed by viability at different times when stored at 25°C and 10°C. The catabolic activity of immobilized and free QTBo cells introduced into sandy loam soil, freshly contaminated with crude oil, was studied in microcosms. A higher number of viable QTBo cells were recovered from the inoculants formulated with SH (QTBo-SH) after prolonged storage at 10°C and 25°C. The microcosms amended with QTBo-SH inoculants showed a removal of about 66% of total petroleum hydrocarbons (TPH), whereas in those inoculated with QTBo-peat inoculants, the decrease was of about 47%. In the control microcosms (noninoculated) and liquid culture–amended soils, the TPH removal was about 28%. SH is a waste of edible oil industry, nontoxic, and biodegradable and has demonstrated to confer to the immobilized cultures greater potential to survive not only during storage but also in the soil environment, improving bioremediation process.     

The Pseudomonas aeruginosa membranes: a target for a new amphiphilic aminoglycoside derivative?

Aminoglycosides are among the most potent antimicrobials to eradicate Pseudomonas aeruginosa. However, the emergence of resistance has clearly led to a shortage of treatment options, especially for critically ill patients. In the search for new antibiotics, we have synthesized derivatives of the small aminoglycoside, neamine. The amphiphilic aminoglycoside 3',4',6-tri-2-naphtylmethylene neamine (3',4',6-tri-2NM neamine) has appeared to be active against sensitive and resistant P. aeruginosa strains as well as Staphylococcus aureus strains (Baussanne et al., 2010). To understand the molecular mechanism involved, we determined the ability of 3',4',6-tri-2NM neamine to alter the protein synthesis and to interact with the bacterial membranes of P. aeruginosa or models mimicking these membranes. Using atomic force microscopy, we observed a decrease of P. aeruginosa cell thickness. In models of bacterial lipid membranes, we showed a lipid membrane permeabilization in agreement with the deep insertion of 3',4',6-tri-2NM neamine within lipid bilayer as predicted by modeling. This new amphiphilic aminoglycoside bound to lipopolysaccharides and induced P. aeruginosa membrane depolarization. All these effects were compared to those obtained with neamine, the disubstituted neamine derivative (3',6-di-2NM neamine), conventional aminoglycosides (neomycin B and gentamicin) as well as to compounds acting on lipid bilayers like colistin and chlorhexidine. All together, the data showed that naphthylmethyl neamine derivatives target the membrane of P. aeruginosa. This should offer promising prospects in the search for new antibacterials against drug- or biocide-resistant strains.     

Characterization of hydrocarbon-degrading microbial populations in contaminated and pristine Alpine soils

Biodegradation of petroleum hydrocarbons in cold environments, including Alpine soils, is a result of indigenous cold-adapted microorganisms able to degrade these contaminants. In the present study, the prevalence of seven genotypes involved in the degradation of n-alkanes (Pseudomonas putida GPo1 alkB; Acinetobacter spp. alkM; Rhodococcus spp. alkB1, and Rhodococcus spp. alkB2), aromatic hydrocarbons (P. putida xylE), and polycyclic aromatic hydrocarbons (P. putida ndoB and Mycobacterium sp. strain PYR-1 nidA) was determined in 12 oil-contaminated (428 to 30,644 mg of total petroleum hydrocarbons [TPH]/kg of soil) and 8 pristine Alpine soils from Tyrol (Austria) by PCR hybridization analyses of total soil community DNA, using oligonucleotide primers and DNA probes specific for each genotype. The soils investigated were also analyzed for various physical, chemical, and microbiological parameters, and statistical correlations between all parameters were determined. Genotypes containing genes from gram-negative bacteria (P. putida alkB, xylE, and ndoB and Acinetobacter alkM) were detected to a significantly higher percentage in the contaminated (50 to 75%) than in the pristine (0 to 12.5%) soils, indicating that these organisms had been enriched in soils following contamination. There was a highly significant positive correlation (P < 0.001) between the level of contamination and the number of genotypes containing genes from P. putida and Acinetobacter sp. but no significant correlation between the TPH content and the number of genotypes containing genes from gram-positive bacteria (Rhodococcus alkB1 and alkB2 and Mycobacterium nidA). These genotypes were detected at a high frequency in both contaminated (41.7 to 75%) and pristine (37.5 to 50%) soils, indicating that they are already present in substantial numbers before a contamination event. No correlation was found between the prevalence of hydrocarbon-degradative genotypes and biological activities (respiration, fluorescein diacetate hydrolysis, lipase activity) or numbers of culturable hydrocarbon-degrading soil microorganisms; there also was no correlation between the numbers of hydrocarbon degraders and the contamination level. The measured biological activities showed significant positive correlation with each other, with the organic matter content, and partially with the TPH content and a significant negative correlation with the soil dry-mass content (P < 0.05 to 0.001).     

生物反应器法处理油泥污染土壤的研究

采油过程产生的油泥是整个石油烃污染源的重点。在陆地生态环境中 ,烃类的大量存在往往对植物的生物学质量产生不利影响 ,更重要的是石油中的一些多环芳烃是致癌和致突变物质 ,这些致癌和致突变的有机污染物进入农田生态系统后 ,在动植物体内逐渐富集 ,进而威胁人类的生存和健康[1 ,1 1 ] 。大量的废弃油泥 ,不仅污染农田 ,同时也给石油行业带来巨大的经济损失。污染土壤的治理主要有物理、化学和生物 (生物修复 )方法 ,生物修复方法被认为最有生命力。污染土壤生物修复技术主要有 3种 ,即原位处理、挖掘堆置处理和反应器处理。反应器处理是…     

Screening Plant Species for Growth on Weathered,Petroleum Hydrocarbon-Contaminated Sediments

Rapid and cost-effective techniques are needed to select plant species and genotypes for use in phytoremediation, vegetative capping, or revegetation at hazardous waste sites. A greenhouse screening procedure to aid the selection of plant materials would help increase success and decrease the cost. Twenty-nine vascular plant species were compared for growth in weathered sediments contaminated with petroleum hydrocarbons. An uncontaminated reference soil was used to estimate relative seedling growth in stressed and unstressed conditions. Plants were grown in a greenhouse and harvested at 60 and 180 days after planting to estimate variation in seedling growth and full-season growth. Plant growth characteristics measured included height, aboveground biomass, root biomass, root diameter, root-length density, and root surface area density. Concentration of total petroleum hydrocarbons (TPH) was estimated at the final harvest. Considerable variation existed among species for all characteristics except TPH concentration. Under the conditions and length of this trial, no variations in rates of TPH degradation were detected. In general, plant growth was stunted in the contaminated soil compared with the uncontaminated soil; however, differences among plant species for relative seedling growth indicated that they varied in their tolerance to the petroleum hydrocarbon-contaminated soil. For example, tall fescue, Festuca arundinacea, seemed tolerant to the contaminated soil, whereas barley, Hordeum vulgare, seemed sensitive. Comparison of results from the 60- and 180-day harvests suggested that a short-season greenhouse screening could aid selection of species for planting in contaminated soil, if plant growth results are interpreted along with information on the life history characteristics of the species under consideration.     

Selection and identification of bacteria isolated from waste crude oil with polycyclic aromatic hydrocarbons removal capacities

Fifteen bacterial strains isolated from solid waste oil samples were selected due to their capacity of growing in the presence of hydrocarbons. The isolates were identified by PCR of the 16S rDNA gene using fD1 and rD1 primers. The majority of the strains belonged to genera Bacillus, Bacillus pumilus (eight strains) and Bacillus subtilis (two strains). Besides, three strains were identified as Micrococcus luteus, one as Alcaligenes faecalis and one strain as Enterobacter sp. Growth of the above-mentioned strains in mineral liquid media amended with naphthalene, phenanthrene, fluoranthene or pyrene as sole carbon source was studied and our results showed that these strains can tolerate and remove different polycyclic aromatic hydrocarbons that may be toxic in the environment polluted with hydrocarbons. Finally, the capacity of certain strains to emulsify octane, xilene, toluene, mineral oil and crude oil, and its ability to remove hydrocarbons, look promising for its application in bioremediation technologies.     

Profiling of plants at petroleum contaminated site for phytoremediation

The paucity of information in the literature on the characteristics of plants that could be used for phytoremediation of petroleum hydrocarbons (PHC)-contaminated sites was the principal reason for this study. The aim of the study was to identify indigenous plants growing in PHC-impacted soil in Umuahia in eastern-Nigeria that have the ability to phytoremediate soils contaminated with hydrocarbons under tropical monsoon climate conditions. A total of 28 native plant species from different families growing in and around hydrocarbon-impacted soil in the vicinity of vandalized pipelines carrying petroleum products were collected and studied for their ability to grow in a hydrocarbon-impacted soil and remove the PHC from the impacted soil. Some of the plants demonstrated the ability to grow in soil with high levels of the total petroleum hydrocarbons (TPH), which shows that they may be tolerant to hydrocarbons in soil and could potentially phytoremediate a hydrocarbon-contaminated soil. Chromolaena odorata, Aspilia africana, Chloris barbata, Pasparlum vaginatum, Bryophyllum pinnatum, Paspalum scrobiculatum, Cosmos bipinnatus, Eragrostis atrovirens, Cyperus rotundus, and Uvaria chamae showed tendencies to phytoremediate contaminated soil. By using bioaccumulation coefficient (BAC) as a measure of phytoremediation, results showed that C. odorata, A. africana, and U. chamae demonstrated the highest potentials to phytodegrade hydrocarbons in soil.