Carbazole angular dioxygenation and mineralization by bacteria isolated from hydrocarbon-contaminated tropical African soil.

Four bacterial strains isolated from hydrocarbon-contaminated soils in Lagos, Nigeria, displayed extensive degradation abilities on carbazole, an N-heterocyclic aromatic hydrocarbon. Physicochemical analyses of the sampling sites (ACPP, MWO, NESU) indicate gross pollution of the soils with a high hydrocarbon content (157,067.9 mg/kg) and presence of heavy metals. Phylogenetic analysis of the four strains indicated that they were identified as Achromobacter sp. strain SL1, Pseudomonas sp. strain SL4, Microbacterium esteraromaticum strain SL6, and Stenotrophomonas maltophilia strain BA. The rates of degradation of carbazole by the four isolates during 30 days of incubation were 0.057, 0.062, 0.036, and 0.050 mg L(-1) h(-1) for strains SL1, SL4, SL6, and BA. Gas chromatographic (GC) analyses of residual carbazole after 30 days of incubation revealed that 81.3, 85, 64.4, and 76 % of 50 mg l(-1) carbazole were degraded by strains SL1, SL4, SL6, and BA, respectively. GC-mass spectrometry and high-performance liquid chromatographic analyses of the extracts from the growing and resting cells of strains SL1, SL4, and SL6 cultured on carbazole showed detection of anthranilic acid and catechol while these metabolites were not detected in strain BA under the same conditions. This study has established for the first time carbazole angular dioxygenation and mineralization by isolates from African environment.

Factors affecting biosurfactant production by oil degrading Aeromonas spp. isolated from a tropical environment.

An Aeromonas spp. was isolated from tropical estuarine water. The organism grew on crude oil and produced biosurfactant that could emulsify hydrocarbons. The peak growth and biosurfactant production was on the 8th day. The organism grew on a range of hydrocarbons that include crude oil and hexadecane while no growth was recorded on some hydrocarbons that include benzene. The biosurfactant produced by the organism emulsified a range of hydrocarbons with diesel (E24=65) as the best substrate and hexane (E24=22) as the poorest. After purification, the biosurfactant was found to contain about 38% carbohydrate and an unidentified lipid. No protein was present in the purified biosurfactant. Production of biosurfactant was highest in medium with glucose and lowest in the medium with diesel+acetate. Soybean was the best nitrogen source for biosurfactant production. The activity of the biosurfactant was enhanced optimally at NaCl concentration of 5%, pH of 8.0 and temperature of 40 degrees C. The biosurfactant retained 77% of its original activity after 120 min of exposure to heat at a temperature of 100 degrees C. Biosurfactant may be produced with this organism using non-hydrocarbon substrates such as glucose and soybean that are readily available and would not require extensive purification for use in food and pharmaceutical industries.

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 degrees C while about 50 percent of its activity was retained at 100 degrees 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.

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.

Ultrastructure of two oil-degrading bacteria isolated from the tropical soil environment.

Two oil-degrading bacteria identified as Pseudomonas aeruginosa and Micrococcus luteus were isolated from crude-oil-polluted soils in Nigeria. The organisms were grown on n-hexadecane and sodium succinate and then examined for the presence of hydrocarbon inclusions. Inclusion bodies were found in n-hexadecane-grown cells and were absent in succinate-grown cells. Formation of hydrocarbon inclusion bodies appears to be a general phenomenon among hydrocarbon utilizers.

Utilization of cyclohexanol by bacteria in a tropical estuarine water.

The Lagos lagoon is a wide expanse of estuarine water. The range of temperature, pH and conductivity of samples collected from 3 sources were 27-30 degrees C, 7.8-8.3 and 2.34-2.85 mS respectively. Consistent increase and decrease in the population of indigenous bacteria occurred in the test and control experiments respectively. Organisms in samples from Apapa and Iddo utilized cyclohexanol better than those in the sample from the University of Lagos. The cyclohexanol degrading bacteria were identified as species of Pseudomonas. Acinetobacter, Vibrio, Micrococcus and Flavobacterium. Pseudomonas sp. had the highest growth potential on cyclohexanol. These organisms play important roles in reducing the pollutant loads of the Lagos lagoon.

Isolation and characterization of heavy metals resistant bacteria from Lagos Lagoon.

A total of 228 bacteria with an ability to resist toxic heavy metals were isolated from 8 selected sites of the Lagos Lagoon. The bacteria isolated were Staphylococcus sp., Bacillus sp., Pseudomonas sp., Streptococcus sp., Moraxella sp., Escherichia coli, Proteus sp., Klebsiella sp. and Salmonella sp. The heavy metals to which resistance was recorded were mercury, lead, zinc, cobalt, copper and chromium. The lagoon sites from which the highest number of resistant bacteria were isolated were Marina and Ebute-Ero. The heavy metal to which most bacteria were resistant was cobalt, while the least was chromium. The significance of the result is discussed in relation to the Nigerian environment and human health.

Purification and properties of an alpha-amylase produced by a cassava-fermenting strain of Micrococcus luteus.

An extracellular alpha-amylase produced by a cassava-fermenting strain of Micrococcus luteus was purified 26-fold by gel filtration and ion-exchange chromatography. The molar mass was estimated to be approximately 56 kDa. The optimum temperature of the enzyme was 30 degrees C, optimum pH 6.0 and optimum substrate concentration was 0.6% (W/V). Treatment of the enzyme at 70 degrees C for 10 min resulted in 70% loss of activity. The activation energy was determined to be 34.8 kJ/mol. The activity of the enzyme was enhanced by Mg2+, Ca2+, K+, Na+ and inhibited by EDTA, KCN and citric acid. The enzyme may find some application in local food processing.

Degradation of commercial detergent products by microbial populations of the Lagos lagoon.

The biodegradability potentials of three detergent products with the trade names Omo, Teepol and sodium dodecyl sulfate (SDS) by the native bacteria of the Lagos lagoon was carried out using the lagoon die-away method. Physicochemical parameters of the water samples showed that the lagoon in Apapa was more polluted than at the University of Lagos. In 12 days, approximately 30, 60 and 97% of Omo, Teepol and SDS respectively were degraded. SDS with an alkyl sulfate moiety as surfactant supported the highest growth of the detergent-utilizing organisms, indicating that the components of Omo and Teepol are more resistant to microbial attack. The detergent-utilizing bacteria identified were mainly Gram-negative and of the following genera: Vibrio, Klebsiella, Flavobacterium, Pseudomonas, Escherichia, Enterobacter, Proteus, Shigella and Citrobacter. Vibrio was the most frequently encountered organism while Proteus was the rarest. Results of this investigation had shown that detergents made in Nigeria may still contain components that are recalcitrant to biodegradation.

Antidiarrhoeal activities of Ocimum gratissimum (Lamiaceae).

The antidiarrhoeal activities of leaf extracts of Ocimum gratissimum were investigated by disc diffusion and tube dilution methods. The extracts were active against Aeromonas sobria, Escherichia coli, Plesiomonas shigelloides, Salmonella typhi, and Shigella dysenteriae. The leaf extracts were most active against S. dysenteriae and least active against S. typhi. The sensitivity of the organisms measured in terms of zone of inhibition ranged from 8.00 to 19.50 mm. The minimum inhibitory concentrations were from 4.00 to 50.00 mg ml-1, while the minimum bactericidal concentration ranged from 8.00 to 62 mg ml-1. The potentials of the leaf extract for the treatment of diarrhoeal diseases is discussed.

Estrogen induces the expression of c-fos and c-jun genes in fibroblasts derived from human uterine endometrium.

The ratio of membrane/cytosolic protein kinase C (PKC) activity and the levels of c-fos and c-jun expressions in uterine endometrial fibroblasts were increased and reached peak levels with the administration of estradiol, but were partially diminished by the addition of progesterone. The response of c-fos was earlier than that of c-jun. Twelve-0-tetradecanoylphorbol-13-acetate (TPA) increased c-fos and c-jun expressions in endometrial fibroblasts as estradiol did, and pretreatment with 1-(5-isoquinolinesulfonyl)-2-methylpiperazine dihydrochloride (H-7) reduced the estrogen-inducible c-fos and c-jun expressions. Therefore, it is suggested that oncogenes c-fos and c-jun in uterine stromal cells might be induced by estrogen partly via PKC, involving the interplay of the anti-estrogenic effect of progesterone, and there might be a cross talk between estrogen and PKC stimulants for c-fos and c-jun expressions.

Short communication: Purification and properties of a glucose-forming amylase of Lactobacillus brevis.

An extracellular glucose-forming amylase was produced by Lactobacillus brevis isolated from 'Kagasok tea'. The enzyme was purified 70-fold and had optimal activity at 55°C and pH 6.5. Its K m value for starch was 0.27 mg ml(-1) and its M r was approx. 75,900 Da. The activity of the enzyme was enhanced by Ca(2+), Mg(2+), Na(+) or K(+) and inhibited by EDTA, KCN, citric acid and L-cysteine.

Nutritional evaluation of spent grains from sorghum malts and maize grit.

Potential use of the high protein by-product of beer production from 77% sorghum malt and 23% maize grit was investigated. Red sorghum spent grains (RSSG) and white sorghum spent grains (WSSG) contained 23.4 and 19.3% crude protein (CP), 54 and 43% dietary fiber (NDF), 1.44 and 0.78% ash, 4.5 and 3.2% hexane extract and tannin content of 7.5 and 1.0 mg/g catechin equivalent respectively. Magnesium was the most abundant mineral in both RSSG and WSSG--185 and 140 mg/kg, respectively. Calcium, zinc, iron and copper were generally low. Both samples contained cadmium 1.12 (WSSG), 1.19 (RSSG) and lead at 1.38 mg/kg. Lysine was the limiting amino acid (chemical score 0.55) in both samples. Other essential amino acids were adequate or surplus. Stearic acid was the predominant fatty acid with varying levels of lauric, myristic, palmitic, and oleic acids in both samples. Feed intake and weight gain were highest in rats fed 26.3% WSSG (contributing 50% of the diet protein) but protein efficiency ratio (PER) and net protein retention (NPR) were highest in diets where spent grains contributed just 25% of the diet protein. True digestibility of diets decreased as dietary fiber content increased such that animals on diets containing 100% spent grain protein (above 20% NDF) lost weight.

Effect of chemical treatments on the micro-organisms associated with malting of sorghum grains and sorghum malt.

The effect of five chemical preservatives on the micro-organisms associated with sorghum grain and malts was investigated. Sorbic acid, sodium benzoate, nisin, formaldehyde and lime at concentrations up to 500, 100, 1000, 1500 and 2000 ppm, respectively did not adversely affect the malting properties of sorghum grain. Only HCHO and Ca(OH)2, each of which prevented bacteria and mould growth at 500 and 2000 ppm, respectively, were sufficiently effective at maximum practicable concentrations to control microbial contamination during malting.