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Volume 30 (1) 2016

  • Authors: Akinnibosun F. I. and Lappin-Scott H. M.

    Abstract: Phylogenetic analysis of sulphidogenic bacterial isolates from Nigerian Bonny light crude oil and its produce water samples was carried out following preliminary detection of the bacterial species. Samples were enriched in mixed carbon postgate’s (MCP) medium and incubated at 55 ºC for 28 days. DNA was extracted from isolated culture and amplified by Polymerase Chain Reaction (PCR) using 16S rRNA eubacterial primers with a GC–clamp. Successful amplification was confirmed by ethidium bromide fluorescence in 1 % agarose gelafter agarose gel electrophoresis. PCR-amplified DNA was separated by Denaturing Gradient Gel Electrophoresis (DGGE) analysis, to show the relationship between samples based on their GC content. Following successful DGGE analysis, DGGE bands were excised, purified and sequenced to display sequence homology and affiliation to related genera of sulphide producers. The DGGE products sequencing was successful, displaying 98 % and 99 % similarity and homology to Petrotogamexicana (AY125964.1) and Petrotogaolearia (AJ311703.1) respectively. Phylogenetic analysis showed a relationship between the sulphidogenic bacteria with other members of the Thermotogales.

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  • Authors: Onugbolu C. D. and Adieze I. E.

    Abstract: Biosurfactant production potentials of hydrocarbon utilizing bacterial species isolated from petroleum hydrocarbon polluted environments were assessed. Twelve isolates were obtained from oil polluted environments (three soil samples and two water samples), these were assayed for biosurfactant production. The isolates were identified as Micrococcus sp.C1, Staphylococcus sp.C2, Acinetobactersp.D1, Staphylococcus sp. D2, Corynebacteria sp.E1, Bacillus sp.E2, Pseudomonas sp.F1, Bacillus sp.F2, Bacillus sp.F3, Micrococcus sp.G1, Pseudomonas sp.G2 and Pseudomonas sp.G3. The isolates were screened for blood haemolysis potential, and for biosurfactant production using drop collapse test and oil displacement test. Emulsification activities of crude biosurfactants from isolates were also determined. From the test results obtained, the isolates produced biosurfactants to varying degree, with the highest production from Bacillus sp.F3, Pseudomonas sp.G2 and Pseudomonas sp.G3. These isolates can be harnessed in the cleanup of petroleum hydrocarbon polluted media.

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  • Authors: Akinnibosun F. I and Iriakpe H. J

    Abstract: The prevalence of bacteria causing UTI in diabetic patients, as well as their susceptibility to commonly used antibiotics was investigated in Benin City. Bacteriological analysis involved standard biochemical tests and comparison of isolates’ characteristics with known taxa. Species isolated from the urine samples analysed were Escherichia coli, Staphylococcus aureus, Staphylococcus saprophyticus, Proteus mirabilis and Pseudomonas aeruginosa. Gram-negative isolates had a prevalence of 60 %, while Gram-positive isolates had 40 %. E. coli were found to be the most prevalence (44.4 %), while the least prevalent were P. aeruginosa(11.1 %),S. aureus(11.1 %) and S. saprophyticus (11.1 %). Isolates were found to be more in females than males. Three out of the six male diabetics sampled had uropathogens, while six out of the fifteen female diabetics sampled had uropathogens. Susceptibility tests were performed by Bauer-Kirby disc-diffusion method with standard antibiotics. The results were expressed as susceptible or resistant. All the isolates were found to be susceptible to ciprofloxacin and gentamicin. They were also found to be multi-drug resistant. This study showed that diabetic patients had increased risk of urinary tract infections due to the presence of uropathogens.

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  • Authors: Chikere Chioma B. , Amara Okoye Ukamaka, Gideon Okpokwasili Chijioke

    Abstract: In this study, culture-dependent method and other bioremediation indices were used to monitor oil-polluted sediment sample collected from Bodo Community, Gokana Local Government Area of Rivers State, Nigeria. The sample was amended with either organic or inorganic nutrients (Cow dung, Poultry litter, NPK fertilizer, Urea fertilizer), while unamended served as control and monitored over a 64-day period in five bioreactors. Four bioreactors each contained, 1 kg (wet weight) sediment amended with 1 litre sea water spiked with 20 ml and 20 mg of crude oil and anthracene respectively. The unamended treatment (control) was only spiked with the hydrocarbons. The gas chromatography-mass spectrometry (GC-MS) analysis for total petroleum hydrocarbons (TPH) was 115.9 ppm in all spiked sediment slurry and polycyclic aromatic hydrocarbon (PAH) of 61.03 ppm on day 0. By day 64, TPH in the biodegradation treatments ranged between 1.48 to 6.40 ppm while PAH ranged between 1.62 to 5.1 ppm. Amendment with NPK fertilizer (BNPK) gave the highest counts for both total culturable heterotrophic bacterial (TCHB) and total culturable hydrocarbon utilizing bacterial (TCHUB) with a value of 19.5 x 107 cfu/g and 8.29 x 107 cfu/g respectively. Forty hydrocarbon utilizing bacteria were isolated and characterized as Bacillus spp., Pseudomonas spp., Corynebacterium spp., Klebsiella sp., Micrococcus spp., Rhodococcus spp., Citrobacter sp., Aeromonas spp., Serratia spp., Acinetobacter spp., Vibrio sp., Streptococcus sp. Result revealed presence of diverse extant indigenous bacterial populations and biostimulation enhanced their ability to degrade hydrocarbons.

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  • Authors: Uzeh Roseline Ekiomado and Nwaeze Chinenye Cynthia

    Abstract: Vegetables harbour a diverse range of microorganisms. Effect of washing salad vegetables- cabbage and lettuce in vinegar and sodium chloride solutions at 0.5%, 1.5% 2.5% concentration for <1min, 2mins and 4mins contact time on their bacterial load was determined. The effect of sterilized and unsterilized water was also evaluated. Bacteria isolated from lettuce included Escherichia coli, Salmonella spp., Staphylococcus aureus, Klebsiella spp., Pseudomonas aeruginosa, and Enterobacter, while from cabbage we got Bacillus cereus, Escherichia coli, Staphylococcus aureus and Proteus vulgaris. Total viable bacterial count for unwashed cabbage and lettuce was 1.97×106 and 2.31×106 cfu/g respectively, while coliform count was 1.43×106 and 1.97×106 cfu/g respectively. Bacterial load of washed vegetables decreased compared with unwashed samples, especially with increase in contact time and concentration of the wash solutions. After washing cabbage with vinegar total bacteria and coliform reduced to 1.2×105 cfu/g and 7.0×104 cfu/g respectively, with sodium chloride, counts reduced to 2.0×105 cfu/g and 9.0×104 cfu/g respectively, with sterilized water, counts reduced to 1.31×106 cfu/g and 8.7×105 cfu/g respectively and washing with unsterilized water reduced the count to 1.59×106 cfu/g and 1.05×106 cfu/g respectively. For lettuce, total bacterial and coliform count reduced to 1.5×105 cfu/g and 1.0×105 cfu/g respectively after washing with vinegar. With sodium chloride, count reduced to 2.1×105 cfu/g and 1.7×105 cfu/g respectively, washing with sterilized water reduced the total bacterial and coliform count to 1.39×106 cfu/g and 1.21×105 cfu/g respectively, with unsterilized water it was 1.46×106 cfu/g and 1.31×106 cfu/g respectively. Least bacterial load was obtained when the salad vegetables were washed with 2.5% vinegar at contact time of 4mins. Statistical analysis using ANOVA revealed that counts obtained at 4 mins contact time were significantly different from those at <1 and 2 mins. at 0.05 significance level. But there was no significant difference between the use of vinegar and sodium chloride; sterilized water and unsterilized water as washing agents for cabbage and lettuce and even at different concentrations. The importance of washing salad vegetables before consumption, especially with vinegar and sodium chloride solutions at contact time of at least 4 mins. is recommended.

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  • Authors: A. R. Oloyede, E. O. Ayedun, O. I. Sonde and P.A. Akinduti

    Abstract: Silver nanoparticles (SNPs) are nanoparticles of silver that are in the range of 1.0 and 100nm in size. They have unique antimicrobial properties which help in water sanitation and medical industries, but their potentials in agriculture have not been utilized. This study was conducted to investigate the effectiveness of SNPs synthesized using different concentrations of bitter leaf (Vernonia amygdalina) extracts in inhibiting the growth of three plant pathogenic fungi; Fusarium oxysporum, F. solani and Cercospora canescens isolated from diseased plants and identified using molecular method. Synthesized SNPs were characterized using UV-Vis absorption spectroscopy. The antifungal activity of SNPs synthesized at 0, 2, 5 and 10 mins using 0.10g/ml and 0.20g/ml of bitter leaf extracts were evaluated on the basis of colony formation by in-vitro assays. UV-visible spectroscopic analyses revealed rapid reduction of silver ions (Ag+) by bitter leaf extracts where surface Plasmon absorption maxima were observed from the UV-vis spectra. The growth of pathogenic fungi on agar plates were significantly decreased or totally inhibited by treatment with the SNPs depending on the concentrations of the plant extracts and the time of reaction. SNPs synthesized with 0.20g/ml of the extract for 10 mins completely inhibited the growth of the tested fungal pathogens while other SNPs significantly reduced their growth (60 – 90% reduction). The results of this study indicated that the silver nanoparticles synthesized using bitter leaf extracts have potentials to be used as control agents against fungal plant diseases to replace the use of chemical fungicides.

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  • Authors: Obueh H.O, Ikenebomeh M. J and Oshoma C.E

    Abstract: Optimization of fermentation process for 72 h was carried out to determine the effect of pH (3 – 8), temperature (30°C – 50°C) and agitation rate (200 rpm – 500 rpm) on bioethanol production and microbial count using cassava variety samples. Bioethanol yield and microbial count were highest at pH 6, temperature 35°C and agitation rate of 300 rpm. The bacterial species had highest population counts of 5. 21 x 105 cfu/g at pH 6, 4.62 x 105 cfu/g at temperature 35°C and 4.84 x 105 cfu/g at pH 6, 3.94 x 105 cfu/g at temperature 35 °C for sweet and bitter cassava varieties respectively. The fungal species had highest counts of 5.60 x 104 cfu/g at pH 6, 2.53 x 104 cfu/g at temperature 35°C and 5.20 x 104 cfu/g at pH 6, 2.11 x 104 cfu/g at temperature 35°C for sweet and bitter cassava varieties. Bioethanol yield was 56% and 44% resulting in a significant increase of 75% and 63% for the sweet and bitter cassava varieties respectively. The optimization of the fermentation process yielded maximum bioethanol and also detoxified the cassava processing wastes which are environmental pollutants.

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