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

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

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

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

NITRILE-METABOLIZING BACTERIAL STRAINS ASSOCIATED WITH MUNICIPAL WASTE TIPS IN THE LAGOS METROPOLIS, NIGERIA

Cyanide is one of the dominant pollutants in the environment. This study aimed at exploring the potential of microbes in the detoxification of cyanogenic substances. Bacillus sp. WOD8 KX774193 and Corynebacterium sp. WOIS2 KX774194 strains were isolated from solid waste leachates. The doubling times of strain WOD8 and strain WOIS2 when grown on glutaronitrile and benzonitrile (without supplementing glucose) were 12.2 and 7.86 d (specific growth rate, μ: 0.057 and 0.088 d-1) and 15.75 and 13.33 d (specific growth rate, μ: 0.044 and 0.052 d-1) respectively. Also, strains WOD8 and WOIS2 grew on glutaronitrile and benzonitrile (with supplementing glucose) with doubling times of 9.76 and 7.62 d (μ: 0.071 and 0.091 d-1) and 10.5 and 8.15 d (μ: 0.066 and 0.085 d-1) respectively. The results from the present study suggest that the nitrile-metabolizing capabilities of these bacterial isolates can potentially be explored for the degradation and bioremediation of nitrile contamination in the environment