Browsing by Author "Abdulrasheed Mansur"

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    Effect of Soil pH on Composition and Abundance of Nitrite-oxidising Bacteria
    (Hibiscus Publisher, 2018-02-02) Abdulrasheed Mansur; Hussein I. Ibrahim; Fatima Umar Maigari; Ahmed F. Umar; Salihu Ibrahim
    Nitrification, the microbial oxidation of ammonia to nitrate (NO3-) via nitrite (NO2-) is a vital process in the biogeochemical nitrogen cycle and is performed by two distinct functional groups; ammonia oxidisers [comprised of ammonia oxidising bacteria (AOB) and ammonia oxidising archaea (AOA)] and nitrite oxidising bacteria. Autotrophic nitrification is said to occur in acidic soils, even though most laboratory cultures of isolated ammonia and nitrite oxidising bacteria fail to grow below neutral pH. Published studies revealed that soil pH is a major driver for determining the distribution and abundance of AOB and AOA. To determine whether distinct populations of nitrite oxidising bacteria within the lineages of Nitrospira and Nitrobacter are adapted to a particular range of pH as observed in ammonia oxidising organisms, the community structure of Nitrospira-like and Nitrobacter-like NOB were determined across a pH gradient (4.5 – 7.5) by amplifying nitrite oxidoreductase (nxrA) and 16S rRNA genes followed by denaturing gradient gel electrophoresis (DGGE). The community structure of both Nitrospira and Nitrobacter changed with soil pH, with distinct populations observed in acidic and neutral soils. The abundance of Nitrospira-like 16S rRNA and Nitrobacter-like nxrA gene copies contrasted across the pH gradient. Nitrobacter-like nxrA gene abundance decreased with increasing soil pH, whereas Nitrospira-like 16S rRNA gene abundance increased with increasing pH. Nitrification activity of both Nitrospira-like and Nitrobacter-like NOB in acidic and neutral pH soil was investigated in a microcosm experiment incubated at 30 oC for 21 days, with high rates of nitrification observed in both soils. Findings indicated that abundance and distributions of soil NOB is influence by soil pH.
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    Effect of Varying Drying Temperature on the Antibacterial Activity of Moringa oleifera Leaf (Lam)
    (IOSR Journals (International Organization of Scientific Research Journals), 2015-02-02) Ibrahim I. Hussein; Miriam Mamman; Abdulrasheed Mansur
    The use of herbal and medicinal plant for traditional therapeutic measure and health care services began since pre-historical time and currently exploited especially in modern medicine. This study investigated the effects of different drying temperature on the antibacterial activity of ethanolic extract of M. oleifera leaf. Fresh leaves of M. oleifera were dried separately at varying temperature by sun drying, oven drying and air drying methods, grinded into powdered form and extracted with ethanol. The ethanolic extracts were used for antibacterial susceptibility test using agar disc diffusion method. All the three clinical bacterial isolates such as E. coli, S. aureus and S. typhiwere susceptible to the ethanolic extract of M. oleifera leaf which signified its antibacterial potency. The air dried extract produced the highest zones of inhibition than the sun dried and oven dried ethanolic extract with 13 mm and 19 mm, 13 mm and 21 mm, 11 mm and 20 mm as the lowest and highest inhibition zones for E. coli, S. aureus and S. typhi respectively. This study inferred that drying temperature especially higher temperature has profound effects on the antibacterial activity of M. oleifera leaf as active component are depreciated