Browsing Department Of Microbiology by Issue Date
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- ItemOpen AccessSurvival of Escherichia Coli in Lagos Lagoon(1981) Amund, O.O; Ekundayo, J.A; Ogunsanya, C.O; Akpata, T.V.IThere was a gradual decrease in the population of Escherichia coli incubated in autoclaved and unautoclaved (raw) water samples obtained from three different sampling stations of the Lagos lagoon. The survival period of the bacterium was generally shorter in the unautoclaved than in the autoclaved water sample; and also varied with the season. In November, 1976, the survival periods in unautoclaved (raw) samples were 6 and 8 days respectively; while in February, 1977 they were 12 days for all three water samples. For the autoclaved water samples the survival periods in November 1976 were 12 and 14 days; while in February, 1977 they were 22, 24 and 32 days. The survival period was also affected by seasonal variations in some physic-chemical parameters of the lagoon.
- ItemOpen AccessIncreased L-Ornithine Production by an Arg Mutant of Acinetobacter Iwoffi(Springer-Verlag, 1983) Amund, O.O; Mackinnon, G; Higgins, I.JThe metabolic production of L-ornithine by an arg mutant of Acinetobacter Iwoffi using n-hexadecane as sole carbon source was studied. Time course experiments under optimised conditions showed that L-ornithine production was growth related, with maximum concentrations (10.5gl-1) accumulating in the late exponential phase of growth.
- ItemOpen AccessObservations on the Degradation of Crude Mineral Oil by an Estuarine Microbial Community.(The Nigerian Society for Microbiology, 1984) Amund, O.OAn oil-degrading bacterium identified as Acinetobacter lwoffi. S2 was isolated by enrichment on the North Sea Forties oil from a water sample collected from the Medway estuary, Kent, England. This organism metabolises a wide range of long-chain n-alkanes (C8–C28) through the corresponding n-alkan-1-ols and n-alkanoic acids. A mixed microbial population was shown to effect a more extensive degradation of crude oil than single species. Simultaneous growth of five estuarine bacterial isolates on crude oil resulted in the synthesis of novel alkanes of higher molecular weights than those originally founds in the crude oil sample. Results of further investigation however, showed that the novel alkane synthesis could be attributed to the synergistic relationship in the estuarine microbial community.
- ItemOpen AccessThe Degradation of I-Phenylalkanes by an Oil-Degrading Strain of Alinetobacter Iwoffi(1985) Amund, O.O; Higgins, I.JAn oil-degrading bacterium identified as Acinetobacter lwoffi was isolated by elective culture on North Sea Forties crude oil from an activated sludge sample. It grew on a wide range of n-alkanes (C12 – C28) and 1 –phenylalkanes, including 1-pheny1dodecane, 1-pheny1tridecane and 1-pheny1tetradecane. The organism degraded 1-pheny1dodecane to phenylacetic acid which was further metabolized via homogentisic acid, whilst 1-phenyltridecane was transformed to trans-cin-namic and 3-pheny1propionic acid which were not further metabolized. Evidence is presented for a relationship between aromatic amino acid catabolism and 1-pheny1dodecane degradation in this organism.
- ItemOpen AccessA study of bacteria from the digestive system of two advanced termites (Isoptera, Termitidae) in Nigeria(1986) Amund, O.O; Yakubu, O.S; Malaka, S.L.OThe total heterotrophic counts of bacteria present in the digestive system of Macrotermes bellicosus Smeathman and Amitermes evuncifer Silvestri were carried out. The populations of bacteria in the guts of workers were generally higher than in those of soldiers. A total of nineteen bacterial strains belonging to four main genera, namely Cytophaga, Micrococcus, Bacillus and Sarcina were isolated; six of these organisms were capable of producing cellulose-digesting enzymes. The possible role of these cellulolytic bacteria in termite nutrition was discussed.
- ItemOpen AccessA Study of Bacteria from the Digestive Systems of Two Advanced Termites (Isoptera, Termitidae) in Nigeria(1986) Amund, O.O; Yakubu, O.S; Malaka, L.S.O1. The total heterotrophic counts of bacteria present in the digestive system of Macrotermes bellicosus Smeathman and Amitermes evuncifer Silvestri were carried out. 2. The populations of bacteria in the guts of workers were generally higher than in those of soldiers. 3. A total of nineteen bacterial strains belonging to four main genera, namely Cytophaga, Micrococcus, Bacillus and Sarcina were isolated; six of these organisms were capable of producing cellulose-digesting enzymes. 4. The possible role of these cellulolytic bacteria in termite nutrition was discussed.
- ItemOpen AccessOccurence and Characteristics of HydroCarbon-Utilizing Bacteria in Nigerian Soils Contaminated with Spent Motor Oil(1987) Amund, O.O; Adebowale, A.A; Ugoji, E.OSoil samples were collected from four different oil-contaminated sites in Lagos, Nigeria, Enrichment of soil samples in a mineral salts medium containing SAE 40 motor oil as carbon source resulted in the isolation of eleven bacterial species. These organisms were identified as species of Corynebacterium, Acinetobacter, Pseudomonas, Bacillus, Arthrobacter, Gemella, Flavobacterium and Micrococcus. Substrate specificity tests showed that the organisms could utilize long chain n-alkanes including dodecane, tetradecane and hexadecane. Some species grew on some aromatic hydrocarbons, such as naphthalene, anthracene and phenanthrene. However, all the isolates grew on crude oil as well as motor oil. The growth of a Pseudomonas sp on motor oil resulted in the extensive degradation of the oil and in the synthesis of a new compound.
- ItemOpen AccessExtracellular Amylase Production by Cassava-Fermenting Bacteria(Elservier, 1987) Amund, O.O; Ogunsina, O.AFermentation of cassava tubers was accompanied by a gradual decrease in pH, increased amylase activity in the steep liquor, and increased microbial load and lactic acid concentration. Amylase-producing bacterial strains associated with cassava fermentation were isolated and identified as Bacillus subtilis, Bacillus licheniformis and Bacillus cereus. The pH optima for the partially purified enzymes of these organisms were 7.0, 5.5 and 7.5, whilst their temperature optima were 30, 37 and 80 oC. There was no significant difference in amylase activities when starch, dextrin, amylopectin, glucose and maltose were used as growth substrates.
- ItemOpen AccessMicrobial Rotting and Preservation of Banana Fruits (Musa Sapientum L.) in Nigeria(The faculty press, Cambridge, 1990) Okonkwo, S.N; Amund, O.O; Ogunsanya, C.OThe bacterial and fungal pathogens associated with the watery rot of banana fruits were isolated and identified. The bacterial pathogens were Pediococcus sp., Propionibacterium sp. and Pseudomonas aeruginosa. The fungal pathogens which also showed cellulolytic activities were Botryodiplodia theobromae, Aspergillus niger and Rhizopus sp. These organisms caused rot at room temperature but were unable to cause rot at 5 oC and 10 oC. Banana fruit rot was generally prevented at relative humidities of 10, 50, 80, 90 and 100 %, except that Botryodiplodia theobromae caused rot at 10, 50, and 80% RH. Microbial infection of healthy fruit resulted in a depletion of the total carbohydrate, crude protein, reducing sugar, free fatty acid and ascorbic acid contents. There was an increase in the total lipid and moisture contents of spoilt fruits. Preservation of banana fruits with fungicides and chemical preservatives was investigated. The use of fungicidal wax emulsion was observed to delay fruit ripening and prevented moisture loss thereby controlling the onset of rot.
- ItemOpen AccessPurification and Properties of a Neutral Protease Produced by Lactobaccillus Brevis(Elservier, 1990) Amund, O.O; Omidiji, O; Ilori, M.OAn 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 oC and pH 6.5. Its Km value for starch was 0.27 mg ml-1 and its M, was approx. 75,900 Da. The activity of the enzyme was enhanced by Ca2+, Mg2+, Na+ or K+ and inhibited by EDTA, KCN, citric acid and L-cysteine.
- ItemOpen AccessBiodegradation of Petroleum Hydrocarbons Under Tropical Estuarine Conditions(Rapid Communications of Oxford Limited., 1990-09) Amund, O.O; Igiri, C.OThe physic-chemical parameters of water samples collected from three points in the Lagos lagoon were studied for 12 months. Salinity varied seasonally but the temperature, pH, dissolved O2, conductivity, NO3 and HPO42- concentrations were relatively constant. There was a direct proportionality between the population density of hydrocarbon-utilizing bacteria and the oil content of water samples. Twelve hydrocarbon-utilizing bacteria were isolated by selective enrichment and characterized as species of Pseudomonas, Alcaligenes, Acinetobacter and Bacillus. The organisms grew mainly on long-chain aliphatic hydrocarbons. Laboratory and field biodegradation studies showed both quantitative and qualitative changes in the hydrocarbon content of crude oil due to microbial degradative activities and a faster rate of oil depletion from the Lagos lagoon during the rainy season. The results obtained could offer a predictive model for estimating the rate of disappearance of petroleum hydrocarbons from the tropical estuarine environment.
- ItemOpen AccessOccurrence and Distribution of Sulphate-Reducing Bacteria in a Polluted Lagoon(The faculty press, Cambridge, 1991-01) Esiobu, N; Amund, O.O; Fakile, O.O; Popoola, O.HThe presence and distribution of sulphate-reducing bacteria (SRB) in the sediment and water from four strategic points on the Lagos Lagoon were assessed using the most probable number technique. All the samples were positive for the dissimilatory sulphate reducers. The relative occurrence varied markedly with the site and pollution status. The least polluted end of the lagoon recorded the lowest number of SRB in both sediment (4.23x102 SRB/ml) and water (28 SRB/ml) while the most polluted site receiving sewage and domestic wastes harboured numbers as high as 5.71x103 and 7.6x104 SRB/ml for water and sediment sasmples, respectively. The occurrence of sulphate-reducing bacteria in such numbers indicated that this environment favoured biocorrosion of buried and immersed metals. The active involvement of these organisms in the syngenesis of sulphur, metallic sulphides and the general biodegradation of pollutants in this ecosystem is discussed.
- ItemOpen AccessEffect of Viscosity on the biodegradability of Automotive Lubricating Oils(Butterworth- Heinemann Limited, 1991-08) Amund, O.O; Adebiyi, A.GHydrocarbon-utilizing bacteria were isolated by enrichment from water samples collected from the Lagos lagoon and identified as species of Achromobacter, Acinetobacter, Alcaligenes, Arthrobacter, Bacillus, Flavobacterium, Micrococcus and Pseudomonas. The growth potentials of these isolates were evaluated using lubricating oils of different viscosities as substrates. All the organisms grew without lag on oils of low viscosity while they grew with pronounced lag phases on the highly viscous lubricating oil (bright stock). The biodeterioration potential of lubricating oils therefore appears to be closely related to their viscosities.
- ItemOpen AccessHydrocarbon Degradation Potentials of Yeast Isolates from a Polluted Lagoon(1993) Amund, O.O; Nwokoye, NThe population counts of heterotrophic and hydrocarbon-utilising yeasts were monitored at six sampling stations in the Lagos lagoon over a four-week period. Although the population counts were relatively constant in each locality, the highest counts occurred in areas heavily polluted by domestic and industrial effluents. A total of thirty-two hydrocarbon-degrading yeasts were isolated from water at the sampling stations using n-hexadecane as sole carbon source. The isolates were identified as belonging to the genera Candida (25 strains), Endomycopsis (4 strains) and Schizosaccharomyces (3 strains). All the organisms grew on long-chain n-alkane, kerosene, diesel oil and crude oil but failed to grow on short-chain n-alkane, aromatic and alicyclic hydrocarbons. Measurement of growth attributes of the isolates using n-hexadecane, diesel oil oil and crude oil as substrates showed that the Candida species were better utilizers of hydrocarbon substrates relative to Endomycopsis and Schizosaccharomyces species.
- ItemOpen AccessMicrobial Degradation of Four Nigerian Crude Oils in an Estuarine Microcosm.(1993) Amund, O.O; Akangbou, T.SFour Nigerian crude oils (Bonny Light, Bonny Medium, Escravos Light and Forcados Blend) that differ substantially in fractional composition were exposed to the Lagos Lagoon waters in microcosm experiments with oil-impregnated membrane filters. Changes in microbial numbers on the membranes and in the residual oil concentration showed a relationship between the fractional composition and the biodegradation rates of the oils, with the lighter oils disappearing more rapidly. After 10 weeks exposure in the lagoon, only 15 % (w/w) of the Bonny Light crude remained on the filters as compared with 20, 32 and 45 % (w/w) for Escravos Light, Bonny Medium and Forcados Blend respectively. The hydrocarbon-utilizing microbial colonizers of the oil-impregnated membranes were Micrococcus, Bacillus, Pseudomonas, Flavobacterium, Alcaligenes and Aspergillus niger.
- ItemOpen AccessEffects of Waste Engine Oil Spillage on Soil Physico-Chemical and Microbiological Properties(1993) Amund, O.O; Omole, C.A; Esiobu, N; Ugoji, E.OChanges in physic-chemical and microbial properties of soils contaminated with waste motor oil were monitored over a 24 week period. Oil application to soils resulted in a decrease in moisture content but brought about increase in organic matter, total nitrogen and available phosphorus contents. There was an initial decrease in microbial counts followed by a subsequent increase in population levels after four weeks. Microbial species diversity was however reduced in oil-contaminated sites relative to the control sites. Hydrocarbon-utilizing bacteria isolated from the experimental sites were identified as Pseudomonas, Acinetobacter, Alcaligenes, Flavobacterium and Corynebacterium. The organisms grew on long-chain n-alkanes, crude oil and fresh engine oil while a few species grew on aromatic hydrocarbons. Laboratory biodegradation studies of fresh engine oil using strains of Pseudomonas, Acinetobacter, and Corynebacterium showed a progressive decrease in oil concentration and pH of the medium due to the production of acidic metabolites.
- ItemOpen AccessShort Communication: Purification and Properties of a Glucose-Forming Amylase of Lactobacillus Brevis(Rapid Science Publishers, 1995) Ilori, M.O; Amund, O.O; Omidiji, O.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 oC and pH 6.5. Its Km value for starch was 0.27 mg ml-1 and its M, was approx. 75,900 Da. The activity of the enzyme was enhanced by Ca2+, Mg2+, Na+ or K+ and inhibited by EDTA, KCN, citric acid and L-cysteine.
- ItemOpen AccessCharacterisation of a Neutral Protease Produced by Micrococcus Luteus(1995-05-26) Ilori, M.O; Amund, O.O; Omidiji, OA proteolytic enzyme produced by a cassava-fermenting strain of Micrococcus luteus was extracted and purified 50-fold by gel filtration and ion exchange chromatography. The optimum pH for the enzyme was 7.0, the optimum temperature 25o C, the apparent molecular weight 42 kDa and the Km value, 0.45 mg ml-1 with casein as substrate. The enzyme was stimulated by Ca2+ and Mg2+ but inhibited by Zn2+ and Co2+ ions. Other inhibitors were EDTA, KCN, citric acid and L-cysteine indicating the enzyme to be a metalloprotease.
- ItemOpen AccessGenetic Transfer of Auxotrophic Markers in Hydrocarbon-Utilizing Strains of Acinetobacter Lwoffi(1996) Amund, O.OConjugal transfer of chromosomal genes was shown to occur in oil-degrading strains of Acinetobacter lwoffi. High co-inheritance frequencies of auxotrophic makers inconjugation experiments suggested linkage relationships amongst the, trp and arg loci. The significance of gene transfer in Acinetobacter species was discussed.
- ItemOpen AccessUtilization and Degradation of an Ester-Based Synthetic Lubricant by Acinetobacter lwoffi(Kluwer Academic Publishers, 1996) Amund, O.OAn oil-degrading bacterium, Acinetobacter lwoffi, isolated by elective culture from the Medway estuary, utilized an ester-based synthetic lubricating oil EMKARATE DE 155 as sole carbon and energy source. Analysis of culture supernatants by gas chromatography showed the accumulation of a nondegradable metabolite 1,1,1 Tris (hydroxymethyl) propane in addition to two metabolizable fatty acids, octanoic and decanoic acids as products of the synthetic oil degradation. Esterase activities were subsequently demonstrated in oil and acetate-grow cells. The synthetic oil therefore appears to be partially biodegradable in the environment.