Browsing by Author "Mtui, Godliving"

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    Comparison of Escherichia Coli KO11 and Saccharomyces Cerevisiae ATCC 96581 in Fermenting Pinus Patula Hydrolysate Pretreated at Different Steam Explosion Severity
    (2012) Chacha, Nyangi; Dyrset, Nils; Mtui, Godliving; Katima, Jamidu H. Y.; Mrema, Godwill
    Bioconversion of wood residues to biofuels such as ethanol is one of the feasible initiatives towards production of renewable energy. This work compares the effectiveness of Escherichia coli KO11 and Saccharomyces cerevisiae ATCC 96581 in fermenting Pinus patula (pine) hydrolysate pretreated by acid-catalyzed steam explosion. The results show no significant difference in terms of the ethanol yield when E. coli KO11 and S. cerevisiae ATCC 96581 were used. The maximum ethanol concentration obtained in test tubes fermentation were 18.30 and 19.41 g/l for E. coli KO11 and S. cerevisiae ATCC 96581, respectively, from samples pretreated at 225°C/5 min. The ethanol yields obtained using bioreactors for samples pretreated at 225°C, 0.5% SO2, and 5 min, were 21.30 and 19.63 g/l for E. coli and S. cerevisiae, respectively. Overall, ethanol yields were higher in bioreactors than in test tubes for both strains. In comparison, S. cerevisiae consumed the substrate faster than E. coli, thus making S. cerevisiae the most preferred strain in fermentation of hydrolysates from steam pretreated P. patula.
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    Optimization of Laccase and Manganese Peroxidase Production in Submerged Culture of Pleurotus Sajor-caju
    (2013) Patrick, Ferdinandi; Mtui, Godliving; Mligo, Anthony M.; Kivaisi, Amelia K.
    A white-rot fungus, Pleurotus sajor-caju, was isolated from coastal Tanzania and screened for crude lignolytic enzymes production using rhemazol brilliant blue R (RBBR) dye, 2,2-azino-bis (3- ethylbenzthiazoline)-6-sulfonate (ABTS) and guaiacol in a semi-solid medium. Laccase (Lac) and manganese peroxidase (MnP) were detected by α-napthol and pyrogallol solutions, respectively, on the guaiacol supplemented semi-solid media. The effect of temperature, pH, carbon, nitrogen, Cu2+, 2,5- xylidine, ferulic acid, Mn2+ and immobilization using Luffa cylindrica sponges in submerged culture fermentations were investigated for maximum enzymes production. After 7 days of incubation, 83 to 100% oxidation of RBBR, ABTS and guaiacol was observed. With optimized culture conditions, the fungal filtrate had maximum Lac and MnP activities of 80 and 0.94 U/ml, respectively compared to 0.62 and 0.0003 U/ml obtained with non-optimized ones; amounting to 129 and 3133 times increase in Lac and MnP activities, respectively. The improved crude enzymes activities, RBBR decolourization, ABTS and guaiacol oxidation capabilities of P. sajor-caju show its potential as a source of industrial enzymes for biotechnological applications.
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    Purification and Characterization of a Laccase from the Basidiomycete Funalia Trogii (Berk.) Isolated in Tanzania
    (2009) Patrick, Ferdinandi; Mtui, Godliving; Mshandete, Anthony M.; Johansson, Gunnar; Kivaisi, Amelia K.
    A lignolytic basidiomycete fungus, Funalia trogii (Berk.), was isolated from decayed wood in coastal Tanzania and cultivated in submerged culture. Initially screened crude enzyme filtrate showed complete rhemazol brilliant blue - R (RBBR) decolorization 2,2’-azino-bis (3-ethylbenzthiazoline)-6-sulfonate and guaiacol oxidation after 7 days of incubation. The fungal filtrate had maximum laccase activity of 593 U/ml after 15 days of incubation. A laccase was purified by anion exchange and size exclusion chromatography to good purity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF). The isolated main component had a molecular weight of ca 58 kDa as determined by MS and an isoelectric point (pI) of 3.8. The optimal pH and temperature range for the purified laccase were 4.0 - 5.0 and 50 - 70 ºC, respectively, using 2, 6- dimethoxyphenol as a substrate.
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    Steam Pretreatment of Pine (Pinus Patula) Wood Residue for the Production of Reducing Sugars
    (2011) Chacha, Nyangi; Toven, Kai; Mtui, Godliving; Katima, Jamidu H. Y; Mrema, Godwill
    The study explores the production of reducing sugars from Pinus patula wood residual chips based on steam pretreatment technology. The severity of the steam pretreatment was altered by using two levels of temperature and time and three levels of sulphur dioxide impregnation. The results show that the efficiency of enzymatic hydrolysis depends on the severity of steam pretreatment. On a given cellulose content, the reducing sugar yield increased from 29% (15.6 g/L) under the mildest steam pretreatment conditions (180 °C, 1.5% SO2) to 91% (42.3 g/L) under the most severe steam pretreatment conditions (225 °C, 3% SO2). In all cases, the enzymatic hydrolysis yield is dependent on enzyme accessibility to the cellulose chains, as the steam pretreatment severity strongly affects biomass fragmentation.