Browsing by Author "Muruke, Masoud S. H."

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    Cyanobacteria Composition and Impact of Seasonality on Their In Situ Nitrogen Fixation Rate in a Mangrove Ecosystem Adjacent to Zanzibar Town
    (2004) Kyaruzi, Jasson J.; Kyewalyanga, M. S.; Muruke, Masoud S. H.
    To investigate the input of combined nitrogen by cyanobacteria in mangrove ecosystems and the seasonal fluctuation of this biological process, in situ nitrogen fixation activity was measured in day and night experiments carried out at Maruhubi mangrove ecosystem adjacent to Zanzibar town. Sampling was done for 12 months at two stations: Station I covering sandy sediments and Station II muddy sediments. Associated cyanobacteria genera were identified and environmental variables were measured throughout the study period. A total of 10 genera of cyanobacteria were encountered, two of which were the heterocystous cyanobacteria genera Anabaena and Rivularia and eight the non-heterocystous genera Aphanocapsa, Merismopedia, Lyngbya, Microcoleus, Oscillatoria, Phormidium, Schizothrix and Spirulina. At both stations N2 fixation during the night was significantly higher (P ≤ 0.05) than during the day. The average N2-fixation rates at stations I and II were 1.64 and 1.34 nmole N2/hr/m2 respectively, with no significant differences (P ≤ 0.05) observed between seasons at both stations, or between stations in the rainy season. There was no significant correlation (P ≤ 0.05) between nitrogen fixation and physical-chemical variables, except sediment temperature, which showed a significant direct relationship with N2 fixation rate at Station I only. The results suggest that in the investigated ecosystem cyanobacterial diversity and nitrogen fixation are high; and generally seasonal changes do not have a significant influence on nitrogen fixation. It is therefore concluded that cyanobacterial diversity and nitrogen fixation process may contribute in the promotion of primary productivity in the mangrove ecosystem adjacent to Zanzibar town.
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    Cyanobacterial Occurrence and Diversity in Seagrass Meadows in Coastal Tanzania
    (2007) Hamisi, Mariam; Lyimo, Thomas J.; Muruke, Masoud S. H.
    We report on the occurrence and diversity of cyanobacteria in intertidal seagrass meadows at Ocean Road and Mjimwema, Dar es Salaam, Tanzania. Nutrients, temperature and salinity were measured as comparative environmental factors. A total of 19 different cyanobacteria taxa were encountered, out of which eight were found exclusively in Mjimwema, four exclusively in Ocean Road and seven were common to both sites. Oscillatoria, Lyngbya and Spirulina were the dominant cyanobacterial genera. Cyanobacterial coverage was higher in Mjimwema (31–100%) than in Ocean Road (0–60%). The levels of nutrients in tidal pool waters at Ocean Road ranged from 0.45–1.03 μmol NO3 -N/l, 0.19–0.27 μmol NO2 -N/l and 0.03–0.09 μmol PO4 -P/l. At Mjimwema the nutrient concentration ranges were 0.14–0.93 μmol NO3 -N/l, 0.20–0.30 μmol NO2 -N/l and 0.01-0.07 μmol PO4 -P/l . The nutrient levels were significantly higher at Ocean Road than at Mjimwema (P = 0.001 for nitrate and P = 0.025 for phosphate). There was no significant difference in nitrite levels between the study sites (P = 0.83). The low cyanobacterial diversity and coverage in Ocean Road is related to the high levels of nutrients and physical disturbance from sewage discharge and the harbour in the area.
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    The Level of Enzymes Involved In the Allantoin Metabolism of Bacillus Fastidiosus Grown under Different Conditions
    (Springer Link, 1995) Muruke, Masoud S. H.; den Camp, Huub J. M. O.; Semesi, Amelia K.; van der Drift, Chris
    Bacillus fastidiosus was cultivated in batch and continuous culture on various carbon and nitrogen sources. The enzymes involved in allantoin degradation (allantoinase, urease, carboligase) of B. fastidiosus were hardly affected by either carbon or nitrogen source. In contrast, the enzymes involved in glycerol utilization (glycerol kinase, glycerol 3-phosphate dehydrogenase) were induced during growth on glycerol, but were not affected by the amount of allantoin present.
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    Novel Nitrogen Sources for Growth of Bacillus Fastidiosus and their Effect on the Activity of NADP-Dependent Glutamate Dehydrogenase
    (1993) Muruke, Masoud S. H.; den Camp, Huub J. M. O.; van der Drift, Chris
    Although Bacillus fastidiosus assimilates ammonium formed internally during growth on urate, allantoin or allantoate via NADP-dependent glutamate dehydrogenase (NADP-GDH), growth on exogenous ammonium as nitrogen source has not been observed. Growth on ammonium, urea and ureidoglycolate, intermediates of the urate degradative pathway, was found to occur if the mineral growth medium containing glycerol as a carbon source was supplemented with both allantoin (0.5 mM) and brain heart infusion (BHI, 0.1%, w/v) or yeast extract. Neither allantoin nor BHI supported growth alone or in combination unless ammonium was present. NADP-GDH activity appeared to be regulated only by the extracellular concentration of allantoin or allantoate. Enzyme activity was not influenced by other nitrogen sources or the intracellular ammonium concentration.
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    A Rapid PCR‐RFLP Method for Monitoring Genetic Variation among Commercial Mushroom Species*
    (Wiley, 2004) Martin, Presley; Muruke, Masoud S. H.; Hosea, Ken M.; Kivaisi, Amelia K.; Zerwas, Nick; Bauerle, Cynthia
    We report the development of a simplified procedure for restriction fragment length polymorphism (RFLP) analysis of mushrooms. We have adapted standard molecular techniques to be amenable to an undergraduate laboratory setting in order to allow students to explore basic questions about fungal diversity and relatedness among mushroom species. The streamlined protocols allowed students to practice important molecular techniques within the context of self-designed investigative projects. This laboratory experience provided opportunities for students to practice strategies for examining molecular diversity among species.
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    Rapid Purification of Uricase from Bacillus Fastidiosus
    (1996) Muruke, Masoud S. H.; den Camp, Huub J. M. O.; van der Drift, Chris
    A simple, rapid procedure was developed for the purification of uricase from Bacillus fastidiosus. The enzyme was purified to homogeneity in a two-step procedure with the aid of fast-flow column chromatography. In this way high yields (37 %) of pure uricase with a specific activity of 78.3 U/mg were obtained in a short time.