Biodegradation of Bonny light crude oil in soil microcosm by some bacterial strains isolated from crude oil flow stations saver pits in Nigeria

In an effort at developing an active indigenous bacterial consortium that could be of relevance in bioremediation of petroleum contaminated systems in Nigeria, four hydrocarbon degrading bacteria strains were isolated. Partial sequencing of the 16S rDNA of the isolates suggests that they are all strains of Pseudomonas aeruginosa. Axenic cultures of the isolates biodegraded Bonny light crude oil in soil microcosm. Amount of crude oil biodegraded in 15 days ranged significantly (P < 0.05) from 4.9% to 29.6%. Degradation rates and specific growth rates varied significantly (P < 0.05) between 0.049 and 0.351 day-1 and 0.017 and 0.028 hour-1 respectively. Major peak components of the oil were reduced by between 6.5% and 70.6%. It would appear that oil degradation capability of axenic cultures of at least three of these isolates was not different from that of their consortium. Also, the multiple antibiotic resistance observed in the isolates is an important factor to consider in their eventual use in bioremediation exercises. (African Journal of Biotechnology: 2003 2(5): 1014-108

Developing an ionospheric map for South Africa

The development of a map of the ionosphere over South Africa is presented in this paper. The International Reference Ionosphere (IRI) model, South African Bottomside Ionospheric Model (SABIM), and measurements from ionosondes in the South African Ionosonde Network, were combined within their own limitations to develop an accurate representation of the South African ionosphere. The map is essentially in the form of a computer program that shows spatial and temporal representations of the South African ionosphere for a given set of geophysical parameters. A validation of the map is attempted using a comparison of Total Electron Content (TEC) values derived from the map, from the IRI model, and from Global Positioning System (GPS) measurements. It is foreseen that the final South African ionospheric map will be implemented as a Space Weather product of the African Space Weather Regional Warning Centre

Flocculating Properties of a Bioflocculant Produced by Bacillus sp. Isolated from a Marine Environment in South Africa

We assessed the bioflocculant production by a bacteria isolated from a marine environment in South Africa. The 16S rDNA nucleotide sequence analyses revealed the bacteria to have a 99 % similarity to Bacillus sp. A-5A and the sequence was deposited in the Genbank as Bacillus sp. MAYA (accession number JF799093). Bioflocculant production by the bacteria was optimal when glucose (95.6 % flocculating activity) and ammonium nitrate (83.3 % flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 % (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis reveals the presence of methoxyl, hydroxyl, carboxyl and amino-groups in the compound bioflocculant. The bioflocculant is thermostable with about 65.6 % residual flocculating activity retained after heating the bioflocculant at 100 °C for 25 minutes

Commensal Staphylococcus spp., Acinetobacter spp. and Stenotrophomonas maltophilia as reservoirs of antibiotic resistance genes

Staphylococcus species, Acinetobacter species and Stenotrophomonas maltophilia are of particular importance as they sometimes reside as flora on the intact skin and nasal passages of man and farm animals. Studies around the globe have shown them as “friends and foes” especially in immunocompromised individuals as they occur as commensals but sometimes as pathogens that infect, causing morbidity and consequently higher therapeutic cost. The occurrence of antibiotic resistance gene(s) in their genomes and their phenotypic display of resistance make them difficult to control and places a high demand on the assessment of such genes in the bacteria. In doing this, the less considered (commensals) have been described more recently as a reservoir for antibiotic resistance genes. The transfer of heavy metal and antibiotic resistance genes from Staphylococcus spp., a Gram positive bacterium to S. maltophilia and Acinetobacter species, Gram negative bacteria confer the resilience to control measures that is peculiar with the former on the latter. This attribute in Acinetobacter spp. and S. maltophilia have encouraged their inclusion in drug screening research. Intermittent assessment of resistance genes in the ecosystem should be embraced to foster appropriate measures against their spread.Keyword: Commensal, resistance genes, Staphylococcus, Acinetobacter, Stenotrophomonas maltophili

Moisture Sorption Isotherms of the Wood and Inner Bark of Ten Southern U.S. Hardwoods

The adsorption isotherms of the woods and inner barks of ten hardwoods, measured at 25 C and atmospheric pressure, were essentially identical, but the desorption isotherms for the barks were consistently lower than those for the woods. Three fundamental constants were required to evaluate the isotherms in terms of the Dent (1977) model, a modification of the classical BET surface model, and of the Hailwood-Horrobin (1946) single-hydrate solution model. Two of these constants are identical for the two models, but the third is somewhat lower for the Dent model. Both models divide the sorbed water into two components, one strongly bonded and the other more weakly bonded to the wood or bark substrate. Also both models predict an identical parabolic relationship giving the ratio of the relative humidity to the moisture content as a function of relative humidity

Petroleum Hydrocarbon Fingerprints of Water and Sediment Samples of Buffalo River Estuary in the Eastern Cape Province, South Africa

. Surface water and sediment samples were collected from five points in the estuary and extracted using standard methods. The extracts were subsequently analyzed by gas chromatography-flame ionization detection. Results showed that total petroleum hydrocarbon (TPH) varied from 7.65 to 477 g/L in the water and 12.59 to 1,100 mg/kg in the sediments, with mean values of 146.50 ± 27.96 g/L and 209.81 ± 63.82 mg/kg, respectively. Concentrations of TPH in the sediments correlated significantly with organic carbon (OC) in both seasons. TPH and OC levels were slightly lower in summer than in autumn in the two environmental matrices, and the average amount of TPH in the water samples collected from all the sampling stations was generally lower than the EU standard limit of 300 g/L. However, the levels in the sediments exceeded the EGASPIN target value (50 mg/kg) for mineral oil but were below the intervention value (5,000 mg/kg), indicating a serious impact of industrial growth and urbanization on the area, although the n-alkane ratios and indexes used for source tracking revealed excessive flow from both natural and anthropogenic sources

Synthesis, characterization and antibacterial studies of metal complexes of sulfadiazine with N-alkyl-N-phenyldithiocarbamate

Co(II), Cu(II), Pd(II) and Pt(II) complexes of 4-amino-N-(2-pyrimidinyl)benzene sulfonamide (sulfadiazine) with some N-alkyl-N-phenyl dithiocarbamate have been synthesized and characterized by elemental analysis, conductivity measurements, UV-Vis and FTIR spectroscopy. The complexes are formulated as four coordinate MN2S2 species in which the metal ions are coordinated to one molecule of sulfadiazine through the pyrimidinyl and sulfulnamido nitrogen atoms and one molecule of dithiocarbamate through two sulfur atoms with both molecules acting as bidentate chelating ligands. The in vitro antibacterial activities of the complexes and sulfadiazine were evaluated against eight bacteria strains using the agar well diffusion method. The metal complexes showed varied antibacterial properties and their minimum inhibitory concentration (MIC) and maximum bactericidal concentration (MBC) were determined. KEY WORDS: Sulfadiane, Dithiocarbamate, Metal complexes, Antibacterial, Drug resistance Bull. Chem. Soc. Ethiop. 2013, 27(1), 77-84.DOI: http://dx.doi.org/10.4314/bcse.v27i1.

Synthesis, characterization and antibacterial screening of 2,4-diaminopyrimidine pyrimethamine and trimethoprim silver complexes

Air stable silver Ag(I) complexes of pyrimethamine and trimethoprim drugs have been synthesized and characterized by elemental analysis, Fourier transform infrared (FTIR) and ultraviolet visible (UV-Vis) spectroscopy, and conductivity measurement. The metal complexes formed a three and four coordinate geometry with the ligands acting as a monodentate molecule bonding to the silver ion in each case through the pyrimidine N (1) nitrogen. The complexes have non-electrolyte behaviour in dimethylformamide (DMF) solution with its low conductivity values. Silver complexes, their free ligands alongside the corresponding silver salts were screened against selected bacterial isolates. All the silver complexes showed enhanced antibacterial activities compared to their free ligands and potential antibacterial agents have been identified.Key words: Pyrimethamine, trimethoprim, silver complexes, antibacterial screening, minimum inhibitory concentration

Identification of the Anti Listerial

Partially purified fractions of the n-hexane extract of Garcinia kola seeds were obtained through column chromatography and their constituents were identified through the use of gas chromatography coupled to mass spectrometry (GC-MS). Three fractions were obtained by elution with benzene as the mobile phase and silica gel 60 as the stationery phase and these were named Benz1, Benz2, and Benz3 in the order of their elution. The antiListerial activities of these fractions were assessed through MIC determination and only Benz2 and Benz3 were found to be active with MIC’s ranging from 0.625 to 2.5 mg/mL. The results of the GC-MS analysis showed Benz2 to have 9 compounds whilst Benz3 had 7 compounds, with the major compounds in both fractions being 9,19-Cyclolanost-24-en-3-ol, (3.β.) and 9,19-Cyclolanostan-3-ol,24-methylene-, (3.β.). The Benz2 fraction was found to have mainly indifferent interactions with ampicillin and penicillin G whilst mainly additive interactions were observed with ciprofloxacin. The Benz3 fraction’s interactions were found to be 50% synergistic with penicillin G and 25% synergistic with ciprofloxacin and ampicillin. A commercially available 9,19-Cyclolanost-24-en-3-ol, (3.β.) was found not to exhibit any antiListerial activities at maximum test concentrations of 5 mg/mL, suggesting that the compound could be acting in synergy with the other compounds in the eluted fractions of Garcinia kola seeds

Regulatory mutations affecting the synthesis of cellulase in Pseudomonas fluorescens

Pseudomonas fluorescens, was cultured in basal medium containing carboxymethyl-cellulose (CMC) as inducer and glucose or glycerol as carbon and energy sources. Ethylmethanesulphonate (EMS) was used to mutagenize the wild-type organism to produce mutants. The isolated mutants were screened for the isolation of catabolite repression resistant mutants in the presence of 1% (w/v) glucose as carbon source. A total of fifty mutants were isolated. All the mutants produced cellulase in the presence of CMC as an inducer with specific activity of 0.057, 0.088 and 0.074 units/mg protein for the wild-type, catabolite repression resistant mutant4 (CRRmt4) and catabolite repression resistant mutant24 (CRRmt24), respectively. It was observed that addition of glucose or glycerol as carbon and energy sources to the culture medium resulted into considerable reduction in the cellulolytic activity. However, glycerol appeared to be a better carbon and energy source than glucose which inhibited enzyme expression in most of the strains used in this study. It was also observed that potent cellulase production occurred at the exponential growth phase of the organism. The isolated mutants were grouped into three classes based on their induction ratios namely; unimproved mutants, catabolite repression resistant mutants and mutants with highest induction ratio but sensitive to catabolite repression in the presence of high glucose concentration. The overall results obtained showed that cellulolytic activity in P. fluorescens was regulated by catabolite repression.Key words: Pseudomonas fluorescens, ethylmethanesulphonate, mutants, cellulose, catabolite repression, induction ratio.African Journal of Biotechnology Vol. 4 (8), pp. 838-84