Production of a Peptidoglycolipid Bioemulsifier by Pseudomonas aeruginosa Grown on Hydrocarbon

A strain of Pseudomonas aeruginosa isolated from a polluted soil was found to produce an extracellular bioemulsifier when cultivated on hexadecane as sole carbon source. The emulsifier was precipitated with acetone and redissolved in sterile water. Dodecane, crude oil and kerosene were found to be good substrates for emulsification by the bioemulsifier. Growth and bioemulsifier production reached the optimal levels on the fourth and fifth day, respectively. Emulsifying activity was observed over a pH range of 3.5 to 10.0 with a maximum at pH 7.0. The activity of the bioemulsifier was heat stable up to 70 °C while about 50 percent of its activity was retained at 100 °C. The components of the bioemulsifier were determined, it was found to contain carbohydrate, protein and lipid. The protein complex was precipitated with ammonium sulphate and fractionated on a Sephadex G-100. Gel electrophoresis of the bioemulsifier showed a single band whose molecular weight was estimated as 14,322 Da. The bioemulsifier was classified as a peptidoglycolipid. Certain strains of P. aeruginosa produce peptidoglycolipid in place of rhamnolipid

Kraft lignin degradation by autochtonous streptomyces strains isolated from a tropical lagoon ecosystem

Kraft lignin contributes to the toxicity of the pulping plant effluent and is known to resist microbial treatment.The lignin component must be removed from lignocellulose biomass to enhance the release of fermentable sugars for the production of biofuel and other value-added end products. Lignin-degrading bacteria provide an advantage due to their ease of isolation,wider tolerance of environmental conditions and genetic manipulations compared with their fungal counterparts. There is no documented evidence on the degradation of kraft lignin by bacteria in the tropical estuarine ecological niche in Nigeria. Bacterial growth and assessment of kraft-lignin degradation in submerged fermentation was carried out for a period of 10 days using Streptomyces spp isolated from a tropical lagoon as the inocula. The organisms utilized 23 to 99 % kraft-lignin at the rate of 2.3×10-5 to 9.9×10-5 g.d-1cm-3 with specific growth rates of 0.020 - 0.084 h-1and doubling times of 8.3 - 35.1 h. Maximum values obtained for laccase and peroxidase activities were 9.5x10-2 and 400 μ mol mg -1min -1 respectively. The aim of this study was to obtain evidences for Kraft lignin degradation by indigenous tropical estuarine Streptomyces species from Lagos, Nigeria. The Autochthonous bacterial species of the Lagos lagoon utilize kraft lignin as a sole carbon source and may be good candidates for biotechnological purposes. The outcome of this study has bridged an information gap in the tropical environment and will complement existing global data because the information on the degradation of kraft lignin by marine Streptomyces is not common

Pyrene Biodegradation Potential of an Actinomycete, Microbacterium Esteraromaticum Isolated from Tropical Hydrocarbon-Contaminated Soi

A novel pyrene-degrading actinomycete, phylogenetically identified as Microbacterium esteraromaticum strain SL9 was isolated from a polluted hydrocarbon-contaminated soil in Lagos, Nigeria. Growth of the isolate on pyrene was assayed using total viable counts, pyrene degradation was monitored using gas chromatography (GC-FID) while UV-Vis spectrophotometry was used to detect metabolites of pyrene degradation. The isolate tolerated salt concentration of up to 6%, grew luxuriantly on crude oil and exhibited weak utilization of fluorene, acenaphthene and engine oil. It resisted cefotaxime, ciprofloxacin and amoxicilin, but was susceptible to meropenem, linezolid and vancomycin. It also resisted elevated concentrations of heavy metals such as 1-5 mM lead and nickel. On pyrene, the isolate exhibited growth rate and doubling time of 0.023 h-1 and 1.25 h, respectively. It degraded 55.16 (27.58 mg L-1) and 89.28% (44.64 mg L-1) of pyrene (50 mg L-1) within 12 and 21 days respectively, while the rate of pyrene utilization was 0.09 mg L-1h-1. Catechol dioxygenase assay using UV-Vis spectrophotometry revealed the detection of meta cleavage compound, 2-hydroxymuconic semialdehyde in the crude cell lysate. The results of this study showed the catabolic versatility of Microbacterium species on hydrocarbon substrates and their potential as seeds for bioremediation of environments co-contaminated with polycyclic aromatic hydrocarbons and heavy metals

Characterization of lignocellulolytic bacterial strains associated with decomposing wood residues in the Lagos lagoon, Nigeria

Aims: The presence of lignocelluloses, especially sawdust in the Lagos lagoon and the attendant ecological problems warranted studies on their degradation. This study aimed to isolate and identify the indigenous bacterial strains capable of utilizing lignocellulosic wastes under the prevalent tropical estuarine conditions. Methodology and results: Nine bacterial species were obtained by elective culture from decomposing wood residues in the lagoon. They were identified on the basis of morphology, biochemical characteristics and analysis of their 16S rRNA gene sequences as Streptomyces, Bacillus and Paenibacillus species. They were cultured on various ligninrelated lignocellulosic substrates over a period of 7 to 12 days. All the isolates showed moderate to very good growth on sugarcane baggase. Streptomyces albogriseolus strain AOB and Paenibacillus sp. ROB showed good growth on grass while on sawdust, only Streptomyces AOB, and Bacillus megaterium strain NOB showed good growth. High performance liquid chromatographic analysis showed that the Streptomyces species completely utilized coniferyl alcohol, B. megaterium strain NOB utilized 90-100% of all the lignin- related aromatic compounds. All the bacterial species utilized less than 40% of sinapyl alcohol, Bacillus sp. OOB and Paenibacillus sp. strain ROB failed to utilize vanillic acid. Conclusion, significance and impact of study: The isolates degraded lignocellulosic wastes and lignin-related compounds. The role of fungi in the breakdown of lignocellulose in the Lagos lagoon had been the subject of previous research considerations whilst the role of bacteria spp was unreported. Autochthonous bacterial species may equally play a role in the bio-rehabilitation of the sawdust-polluted water of the Lagos lagoon

Growth of Pseudomonas aeruginosa LP5 on 2, 5-dicchlorobenzoate: Detection of aromatic ring hydroxylating dioxygenase (ARHDO) gene

Pseudomonas aeruginosa LP5 grew on 2, 5-dichlorobenzoate with doubling time (D) 6.64 d and mean growth rate (k) 0.104 d-1. The organism showed a prolonged lag period lasting 9 days followed by a sudden rise within 3 days (D= 1.1 d; k= 0.628 d-1) and death in less than 72 hours on 2, 6-dichlorobenzoate. Polymerase chain reaction (PCR) amplification of DNA of LP5 showed aromatic dihydroxylating (ARHDO) gene band with molecular weight corresponding to the targeted fragment (0.73 kb). The capability of LP5 on dichlorobenzoates and detection of dioxygenase genes is a validation of its versatility and potential for bioremediation

A Comparative Study of Biosurfactant Synthesis by Pseudomonas aeruginosa Isolated from Clinical and Environmental Samples

Evaluation of emulsifying activities indicates that biosurfactants were produced by an environmental (strain EP1) and a clinical (strain CP1) species of Pseudomonas aeruginosa. During growth on hydrocarbons, the organisms produced biosurfactants. Both strains grew luxuriantly on motor oil and readily synthesized abundant surfactants at the expense of easily metabolizable substrates. During a 12-day cultivation on motor oil, the organisms produced growth-associated extracellular surfactants with emulsification activities of 71 and 38% for EP1 and CP1, respectively. The generation times obtained for EP1 and CP1 were 1.74 and 2.66 days. The biosurfactants that could not be secreted on glucose were partially purified and putatively identified as rhamnolipids. The surface-active compounds present high emulsification activity and stability in the pH range of 3.0–10.0, temperature range of 4°C–100°C, and salinity range of 16–44% and are capable of stabilizing oil-in-water emulsions with several hydrocarbons. Typical emulsions produced were stable for several weeks. The results also showed that the biosurfactants were able to remove a significant amount of crude oil from contaminated soil; for instance, strain EP1 surfactant removed 54%, CP1 41%, detergent 42%, and water 30%. The rhamnolipids from these strains represent a new class of biosurfactants that have potential for use in a variety of biotechnological and industrial applications where extremes of pH, thermal, and saline conditions would have little or no effect on activity

Metal biouptake by actively growing cells of metal-tolerant bacterial strains

Metal uptake potentials of Pseudomonas aeruginosa CA207Ni, Burkholderia cepacia CA96Co, Rhodococcus sp. AL03Ni, and Corynebacterium kutscheri FL108Hg were studied to determine their competence in detoxification of toxic metals during growth. Metabolism-dependent metal biouptake of the bacteria revealed appreciable uptake of the metals (57–61, 10–30, 23–60, and 10–16 mg g dw−1 of Ni2+, Cr6+, Co2+, and Cd2+, respectively) from medium, after initial drop in pH, without lag phase. The bacteria exhibited 95–100 % removal efficiency for the metals from aqueous medium as 21 (±0.8)–84 (±2.0) concentration factors of the metals were transported into the bacterial systems. Passive adsorption onto the cell surfaces occurred within 2-h contact, and afterwards, there was continuous accumulation for 12 days. Biosorption data of the bacteria were only fitted into Langmuir isotherm model when strains AL96Co, CA207Ni, and AL03Ni interacted with Ni2+, achieving maximum uptake of 9.87, 2.72, and 2.69 mg g dw−1, respectively. This study established that the actively growing bacterial strains displayed, at least, 97.0 % (±1.5) continuous active removals of metals upon adsorption. The bacteria would be good candidates for designing bioreactor useful in the detoxification campaign of heavy metal-polluted systems

Microbial Activity in Industrial Cutting Emulsions in the Tropical Environment

Bacterial strains were isolated from in-use metal cutting fluids from 5 locations in Nigeria. They were identified as species of Bacillus, Proteus, Enterobacter, Lactobacillus, Corynebacterium, Chromobacterium and Pseudomonas. Chromobacterium spp had the highest potential of utilizing the cutting fluid while Pseudomonas spp had the highest growth potential with n-dodecane. These isolates appeared to be the bacteria that pioneer the deterioration of metal cutting fluids in this environment

Influence of pH, temperature and nutrient addition on the degradation of atrazine by Nocardioides spp. isolated from agricultural soil in Nigeria.

Aims: To effectively exploit the atrazine degrading capabilities of Nocardioides spp. isolated from agricultural soil samples in Nigeria and ascertain the effect of pH, temperature and nutrient addition on the degradation process. Methodology and results: Isolates were cultivated on atrazine mineral salts medium at a temperature range of 4 °C - 45 °C and a pH range of 3-10. An optimum atrazine degrading activity was observed in the isolates between temperatures of 25 °C and 37 °C and between pH 5 and 8. Different carbon sources (glycerine, glucose, chitin, cellulose and sodium citrate) and nitrogen sources (urea, biuret, cyanuric acid, potassium nitrate and ammonium chloride) were also added to the medium. The addition of carbon and nitrogen sources did not increase degradation rates although urea and glycerine repressed the degradation ability of the isolates. Statistical analyses of variance at P < 0.05 showed no significant differences in the growth and degradation rates by both bacterial isolates under these conditions. Conclusion, significance and impact study: Atrazine degradation by Nocardioides spp. is pH and temperature dependent, and requires no additional sources of carbon and nitrogen. Hence, its use in bioremediation of atrazine contaminated agricultural soil should be explored