Department of Molecular Biology and Biotechnology

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    Rooting Ability of Leucaena Leucocephala Stem Cuttings
    (1998-08) Dick, J.; Magingo, Francis S.; Smith, R. I.; McBeath, C.
    Single-node leafy and leafless cuttings harvested from one-year-old, 1.3 to 1.5 m tall Leucaena leucocephala seedlings were successfully rooted in a non-mist propagator which is suitable for use in the rural tropics. Cuttings with a leaf attached rooted more successfully than those without a leaf (71% and 39% respectively) and clones differed significantly (43% to 71%). There was also a clear pattern in rooting ability of cuttings collected sequentially down the main stem. Cuttings rooted most successfully when taken from node five to 13, counting from the apex; this was the region where internodes were longest (64 to 109 mm) of moderate diameter (2.9 to 5.5 mm) and all cuttings had a leaf attached.
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    Influence of Hydraulic Retention Time on Start-Up and Process Stability of Polyurethane Carrier Reactions
    (1992) Rubindamayugi, M. S. T.; Op Den Camp, H. J. M.; Lubberding, H. J.; Gijzen, H. J.; Vogels, G. D.
    Influence of hydraulic retention time (HRT) on start-up of Polyurethane Carrier Reactors treating Volatile Fatty Acids (VFA) based wastewater, at constant organic loading rate (OLR) was investigated. OLR was increased stepwise after start-up to evaluate the influence of HRT on process stability. Four parallel experiements were conducted at HRTs of 48, 24, 18 and 12 hours. Results indicate an influence of HRT on duration of start-up period, and process stability after start-up. The reactor operating at HRT of 24 hours required only a relatively stort start-up period and showed higher process stability under steady-state condition. Analysis of individual VFA degradation indicated that butyrate and propionate consuming acetogenic bacteria increased in sigmoid fashion during start-up. Changes in acetate degradation do not show the true increase of acetoclastic population. Instead they reflect concomitant activity of VFA catabolizing acetogens and aceloclastic methanogens . Immobilized biomass increased exponentially during the first three weeks of start-up. The differences in start-up periods between reactors was probably due to differences in quality and activity of biomass immobilized at different HRTs. The HRT of 24 hours was most optimal to obtain stable reactor performance within a short startup period.
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    Novel Extraction Method of Antioxidant Compounds from Sasa Palmata (Bean) Nakai using Steam Explosion
    (2007-10) Kurosumi, Akihiro; Sasaki, Chizuru; Kumada, Kentaro; Kobayashi, Fumihisa; Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    Antioxidant compounds were extracted from various parts of Sasa palmata (Bean) Nakai, a bamboo plant whose leaves are commonly used to wrap foodstuffs such as Sushi in Japan. Highest concentrations of antioxidant compounds existed in the leaf part of S. palmata. Steam explosion treatment followed by hot water and methanol extractions was used for separating the antioxidant compounds from S. palmata leaf. The steam explosion treatment is the physical–chemical treatment which crushes a sample by sudden reduction of the pressure in reactor to atmospheric pressure after steaming the sample at high temperature and pressures. Sasa palmata leaf was hydrolyzed by steaming and crushed by the rapid decompression. The optimal condition of steam explosion for the effective extraction of antioxidant compounds from S. palmata was determined as a steam of temperature of 250 °C and a steaming time of 1 min. In these conditions 217.41 mg/(g-Sasa leaf) of phenolic compounds and 142.81 mg/(g-Sasa leaf) of radical scavenging activity, that was expressed as butylated hydroxyanisole (BHA), were obtained.
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    Trends in Industrial and Environmental Biotechnology Research in Tanzania
    (2007-12) Mtui, Godliving Y. S.
    This paper reviews the trends in industrial and environmental biotechnology research in Tanzania for the past 20 years. Researches on production of bio-energy, enzymes and organic acids are reviewed. Furthermore, researches related to wastewater treatment systems including water stabilization ponds and constructed wetlands are covered. Brief highlights are made on researches related to bioprospecting and molecular biology techniques used in identification of organisms. In critically reviewing the research done so far, an attempt is made to pinpoint significant research gaps in areas such as single cell protein, biomining, biocomposting and bioengineering. This paper, therefore, provides an overview of the renewable raw materials available in the developing countries and outlines the researches that have been done to convert them to bio-products, while reducing bio-wastes. The identified gaps will serve as guidance to scientists who are interested in doing research in untapped areas of biotechnology.
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    Degradation of 2,4-Dichlorophenoxyacetic Acid (2,4-D) by Ozonation and TiO2/UV Treatment
    (2007-04) Daidai, Masakazu; Kobayashi, Fumihisa; Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    The degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was conducted by ozonation, TiO2/UV treatment only, and two-stage treatment of ozonation followed by TiO2/UV treatment. In the case of ozonation, 2,4-D could be degraded and vanished within about 10 min at pH 9 and 20°C, but the TOC value was reduced by only about 40% by 30 min ozonation. In the case of TiO2/UV treatment, about 5 d was needed for complete disappearance of 2,4-D at pH 5 and 20°C. On the other hand, when the two-stage treatment of ozonation plus TiO2/UV treatment was applied, 90% decline of TOC was achieved within about 20 h, i.e., 30 min ozonation and 20 h TiO2/UV treatment thereafter. Furthermore, 90% of chloride ions in 2,4-D were liberated by the two-stage treatment. From a bioassay test of the two-stage treated water by the use of an osteoclasts of goldfish scales or Daphnia magna, it was found that 2,4-D was degraded into harmless substances with little estrogen activity and toxicity.
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    Lignin-Degrading Enzymes from Mycelial Cultures of Basidiomycete Fungi Isolated in Tanzania
    (2004-06) Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    This research involved field surveys in different geographical locations in Tanzania for collection of fungi species, identification of the isolates, and screening for lignin-degrading enzyme production. Out of 18 saprophytic fungi (both wood and non-wood inhabiting) isolates, 17 were positive in the rhemazol brilliant blue-R (RBBR) decolorization test; 15 of the isolates oxidized guaiacol while 7 and 12 oxidized α-naphthol and pyrogallol, respectively. The cultures with 1% glucose concentration showed the fastest growth of mycelia and highest MnP, LiP, and Lac activities. MnP was found to be dominant among the tested isolates and Laetiporus sulphurae had the highest LiP activity of 65.2 U/ml. Most of the fungi isolates produced more than two extracellular enzymes, suggesting that these isolates possess the ability to degrade lignin or related polyphenolic compounds, and thus they can be used in upgrading low quality animal feed. The selected fungi isolates reduced cellulose and hemicellulose contents in rice straw by an average of 10% and 35%, respectively, delignification ratio of 23% and increased its relative crude protein content by more than 50%.
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    Biodegradation of Endocrine-disrupting Phenolic Compounds Using Laccase Followed by Activated Sludge Treatment
    (2003-07) Nakamura, Yoshitoshi; Mtui, Godliving Y. S.
    Endocrine-disrupting phenolic compounds in the water were degraded by laccase fromTrametes sp. followed by activated sludge treatment. The effect of temperature on the degradation of phenolic compounds and the production of organic compounds were investigated using endocrine-disrupting chemicals such as bisphenol A, 2,4-dichlorophenol, and diethyl phthalate. Bisphenol A and 2,4-dichlorophenol disappeared completely after the laccase treatment, but no disappearance of diethyl phthalate was observed. The Michaelis-Menten type equation was proposed to represent the degradation rate of bisphenol A by the lacasse under various temperatures. After the laccase treatment of endocrine-disrupting chemicals, the activated sludge treatment was attempted and it could convert about 85 and 75% of organic compounds produced from bisphenol A and 2,4-dichlorophenol into H2O and CO2, respectively.
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    Anaerobic Fermentation of Woody Biomass Treated by Various Methods
    (2003-06) Nakamura, Yoshitoshi; Mtui, Godliving Y. S.
    Anaerobic fermentation was attempted to produce methane from the wood chip (Eucalyptus globulus). By the pretreatment of the wood chip using hot water with high temperature, NaOH, and steam explosion, the production of methane gas was enhanced. The pretreatment using steam explosion resulted in more amount of methane gas produced than the treatment using either hot water or 1% (w/w) NaOH with high temperature, and the steam explosion at a steam pressure of 25 atm and a steaming time of 3 min was the most effective for the methane production. The amount of methane gas produced depended on the ratio of weight of Klason lignin, a high molecular weight lignin, in the treated wood chip.
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    Microbial Treatment of Kraft Pulp Wastewater Pretreated with Ozone
    (1997-02) Nakamura, Y.; Sawada, T.; Kobayashi, F.; Mtui, Godliving Y. S.
    Kraft pulp wastewater was treated with a combination of ozone and activated sludge. The effects of pH on the degradation of lignin and the production of organic acids were examined experimentally in the ozonolysis of wastewater. The strong alkaline condition enhanced not only the degradation of lignin but also the production of organic acids. The dynamic behaviours of microbial growth and substrate consumption were investigated in the biodegradation of organic acids using activated sludge. Maleic acid and oxalic acid in the ozonized wastewater were degraded completely by the activated sludge. The immobilized activated sludge culture using polyurethane foam was effective in degrading organic acids.
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    Additive Effect of Soybean Curd Residue, Okara, for Enhancement of Methane Production from Pretreated Woody Waste
    (2005) Take, Harumi; Mtui, Godliving Y. S.; Kobayashi, Fumihisa; Nakamura, Yoshitoshi
    In order to convert woody waste into methane gas efficiently, the pretreatment effect of steam explosion and the additive effect of soybean curd residue, okara, were clarified. 180 mL of methane gas was obtained from 1 g of steam-exploded Japanese cedar chips at a steam pressure of 4.51 MPa and a steaming time of 5 min while no methane gas was produced from untreated chips. The addition of okara into the chips was attempted and the optimal condition, i.e. C/N of 18, increased the methane gas produced to 315 mL.
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    Lignin Peroxidase Production by Phanerochaete Chrysosporium Immobilized on Polyurethane Foam
    (2005-02) Nakamura, Yoshitoshi; Sawada, Tatsuro; Mtui, Godliving Y. S.; Kobayashi, Fumihisa; Kuwahara, Masaaki; Ito, Hiromichi
    Production of lignin peroxidase by a white-rot basidiomycete, Phanerochaete chrysosporium, was investigated experimentally using polyurethane foam as a carrier of immobilized fungal mycelia. The immobilized cell culture using polyurethane foam as a carrier of mycelia yielded significantly greater lignin peroxidase activity than the conventional stationary liquid culture. The effects of operational conditions, such as the kind and number of polyurethane foam cubes, glucose concentration and temperature, on the lignin peroxidase production were examined. Addition of 0.05% Tween 80, 1 mM veratryl alcohol and 1 mM FeSO4-·7H2O greatly improved the production of lignin peroxidase up to 2,700 units/ml culture medium. The lignin peroxidase activity in this culture was about three times larger than that obtained from the culture cultivated in the absence of these additives. Step change incubation lowering the temperature from 37°C to 30°C over an incubation time of three days was carried out for the large scale production of lignin peroxidase, and this incubation gave the highest lignin peroxidase activity 3,800 units/ml culture medium.
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    Continuous Production of Lignin-degrading Enzymes by Bjerkandera Adusta Immobilized on Polyurethane Foam
    (2002-11) Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    Continuous production of lignin-degrading enzymes by Bjerkandera adusta immobilized on polyurethane foam gave maximum activities of 220 U lignin peroxidase ml−1, 150 U manganese peroxidase ml−1, 50 U laccase ml−1 and 6.2 U protease ml−1 at the retention time of 24 h for 60 days. Protease secretion destabilized the produced lignin peroxidase, manganese peroxidase and laccase.
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    Biosafety Systems in Eastern and Central Africa
    (2012-02) Mtui, Godliving Y. S.
    This review examines the biosafety systems of selected countries in the Eastern and Central Africa. The biosafety systems are meant to safeguard human health, animal health and the environment against any possible risks posed by development and application of modern biotechnology. Though the focus is in the Eastern and Central African region, the study gives an overview of worldwide biosafety frameworks as guided by the Cartagena protocol on biosafety. The Eastern and Central African countries covered in this study are Tanzania, Kenya, Uganda, Rwanda, Burundi, Ethiopia and the Democratic Republic of Congo (DRC). An attempt is made to assess the current status on the countries’ compliance to biosafety international conventions, institutional arrangements and regulatory regimes. A critical look is given to the existing biosafety frameworks, pinpointing their weaknesses and giving suggestions on what could be done to address the shortfalls. The study shows that Kenya is leading the group by having all the requirements in place, followed by Uganda. Tanzania has cleared the legal frameworks hurdles, but it is rather slow in processing applications of genetically modified organisms (GMOs) for containment and confined trials. Ethiopia, Rwanda, Burundi and DRC are still in the process of formulating their biosafety laws. The challenges facing the operationalization of the biosafety systems are financial constraints, insufficient trained human resources, poor facilities, low awareness and insufficient political will by some governments. It is argued that while biosafety frameworks stand to safeguard safe application of modern biotechnology, they should not have too stringent regulations, lest they impede the development of modern biotechnology in the Eastern and Central African region.
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    Combined Chemical and Biological Treatment of Recalcitrant Industrial Effluents: A Case Study on Kraft Pulp Wastewater.
    The chemical degradation of lignin-rich kraft pulp wastewater was carried out by ozonation process flowed by biological treatment using activated sludge. The effects of pH on the degradation of lignin and the production of organic acids were examined experimentally in the ozonolysis of wastewater. The strong alkaline condition enhanced not only the degradation of lignin but also the production of organic acids. The maximum value of BOD5/COD obtained after 12 hours of ozonation was 0.41, indicating that ozone treatment improved the biodegradability of the kraft pulp wastewater. The dynamic behaviours of microbial growth and substrate consumption were investigated in the biodegradation of organic acids using activated sludge. Maleic acid and oxalic acid in the ozonized wastewater were degraded completely by the activated sludge in shake-flasks and bench-scale aerated bioreactor experiments. The immobilized activated sludge culture using polyurethane foam (PUF) was most effective in degrading organic acids in continuous culture condition at an optimum hydraulic retention time (HRT) of 14 hours. The study confirmed that consecutive treatments by ozone and activated sludge are effective methods to treat industrial effluents containing recalcitrant environmental pollutants such as kraft pulp wastewater.
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    Lignin-degrading Enzyme Production by Bjerkandera Adusta Immobilized on Polyurethane Foam
    (1999-10) Nakamura, Yoshitoshi; Mtui, Godliving Y. S.; Sawada, Tatsuro; Kuwahara, Masaaki
    Production of the lignin-degrading enzymes lignin peroxidase (Lip), manganese peroxidase (MnP), and laccase (Lac) by the white-rot fungus Bjerkandera adusta was investigated experimentally using polyurethane foam (PUF) as a carrier of immobilized fungal mycelia. An immobilized cell culture with a low-nitrogen medium yielded significantly greater LiP, MnP, and Lac activities in comparison with those obtained in a liquid culture. The maximum activities of the three enzymes were 450, 370, and 100 U/ml, respectively, under the following incubation condition: glucose concentration, 20 g/l; temperature, 30°C; pH 4.5. The activities of MnP and Lac were significantly higher than those reported using other incubation methods. Lignin was degraded to the extent of 40% and its decolorization ratio was about 70% at an incubation time of 40 h using lignin-degrading enzymes from B. adusta. Six different isozymes of MnP were synthesized by B. adusta, two of which exhibited high MnP activity. Our preliminary finding that extracellular enzymes from B. adusta are capable of degrading and decoloring lignin makes these enzymes attractive for further research aimed at their large-scale application in lignin depolymerization, pulp biobleaching, and the degradation of toxic pollutants.
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    Bioconversion of Lignocellulosic Waste from Selected Dumping Sites in Dar es Salaam, Tanzania
    (2004-11) Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    The poor management of solid wastes in Tanzania urban centers is a chronic problem that has increasingly become a source of environmental pollution. Bioconversion offers a cheap and safe method of not only disposing these wastes, but also it has the potential to convert lignocellulosic wastes into usable forms such as reducing sugars that could be used as food. This paper reports a preliminary study on the physical characteristics, acid pretreatment, saccharification by cellulase from Trichoderma reesei and fermentation by Saccharomyces cerevisiae of the lignocellulosic component of the solid wastes collected from various dumping sites located in Kinondoni Municipality, Dar es Salaam city. The results showed that overall, the lignocellulosic component constitute about 50% of solid wastes dumped in the study areas. Maximum production of reducing sugars was obtained after 6 h of saccharification while highest concentrations of bioethanol were achieved after 48 h of fermentation. Microbial bioconversion of lignocellulose component yielded up to 21% bioethanol.
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    Saccharification and Alcohol Fermentation in Starch Solution of Steam-exploded Potato
    (1996-12) Kobayashi, Fumihisa; Sawada, Tatsuro; Nakamura, Yoshitoshi; Ohnaga, Makoto; Mtui, Godliving Y. S.; Ushiyama, Tomoo
    Steam explosion pretreatment of potato for the efficient production of alcohol was experimentally studied. The amount of water-soluble starch increased with the increase of steam pressure, but the amounts of methanol-soluble material and Klason lignin remained insignificant, regardless of steam pressure. The potatoes exploded at high pressure were hydrolyzed into a low molecular liquid starch, and then easily converted into ethanol by simultaneous saccharification and fermentation using mixed microorganisms: an amylolytic microorganism,Aspergillus awamori, and a fermentation microorganism,Saccharomyces cerevisiae. The maximal ethanol concentration was 4.2 g/L in a batch culture at 15 g/L starch concentration, and 3.6 g/L in a continuous culture fed the same starch concentration. In the fed-batch culture, the maximal ethanol concentration increased more than twofold, compared to the batch culture.
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    Influence of Sampling Depth and Post-sampling Analysis Time on the Occurrence of Coliforms and Vibrio in Water and Shellfish
    (2005) Sallema, R.E; Mtui, Godliving Y. S.
    The bacteriological quality was examined at the water surface, 3 m depth and in the shellfish flesh, and the results were compared to other potential pathogenic indicator organisms. The study was conducted at Long Harbour (mussel farm), St. John's and Outer Cove sites of Newfoundland, Canada. Bacteriological analysis was carried out for samples taken at water depth and at 1, 6, 12 and 24 hours post-sampling. It was observed that the total and faecal coliform bacteria were significantly higher in the 3 m water depth samples than in the surface water samples (ANOVA, F = 59.41, 26.751, 9.82 (T.C); 46.41, 26.81, 10.72 (F.C); P <0.001). In addition, shellfish tissues had substantial amounts of coliform bacteria levels, which varied significantly with station and date of sampling (F = 128.21,37.42 (T.C); 1281, 37.42 (F.C); P <0.05). The higher levels reflect bioaccumulation. There were no correlations between estimates of total or faecal coliforms with potential pathogenic Vibrio groups. Furthermore, there were no significant differences in total and faecal coliforms among the post-sampling time intervals. The results suggest that sampling and bacteriological analysis of water and shellfish for quality control should consider both the water surface and depths proximal to the shellfish. Moreover, adoption of extended post-sampling time may lead to a more convenient and less costly approach to monitoring of bacteriological impact on the coastal marine environments.
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    Development of optimal Culture Method of Sparassis crispa mycelia and new extraction method of Antineoplastic Constituent.
    (2006-05) Kurosumi, Akihiro; Kobayasi, Fumihisa; Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    The optimal culture condition of basidiomycete Sparassis crispa mycelia was determined for producing a large amount of antineoplastic constituent, i.e. β-1,3-glucan. Furthermore, a new extraction method with steam explosion as a pretreatment was attempted to increase the amount of antineoplastic constituent extracted from S. crispa mycelia. The shake-flask liquid culture of fungal mycelia could shorten a culture time up to about 1/3 compared with the conventional stationary liquid culture. The productivity of S. crispa mycelia reached its maximum at an initial glucose concentration of 30 g/L, a culture temperature of 25–30 °C, and pH 5. Steam explosion at a steam temperature of 225 °C for 5 min not only enhanced the amount of antineoplastic constituent extracted from the mycelia but also shortened the extraction time significantly.
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    Physicochemical and Microbiological Water Quality of Lake Sagara in Malagarasi Wetlands
    (2006) Mtui, Godliving Y. S.; Nakamura, Yoshitoshi
    The physicochemical and microbiological water quality parameters of Lake Sagara in the Malagarasi ecosystem, Tanzania, were studied between September 2003 and January 2004. Standard methods of analysis were used to elucidate the levels of the main water quality parameters. The Lake was found to be shallow (maximum depth 6.5 m) with encroaching hydrophytes and floodplain grasslands. High turbidity values ranging from 20-126.5 NTU recorded in the studied sites was attributed to vigorous wind mixing of the Lake water. The temperature, pH and chlorides values were 24.4-27.0 C, 6.8-8.8, 7.9-17.4 mg L-1), respectively. These values are within the standard water quality requirements. The values of conductivity (89-212 ìs/cm), phosphates (1.0-4.5 mg L-1), organic nitrogen (0.8-2.2 mg L-1); abundant sediments and algal blooms suggest that Lake Sagara is eutrophic. Values of dissolved oxygen (6.2-7.3 mg L-1), COD (22.1-42.6 mg L-1) and BOD (3.8-7.1 mg L-1) show that so far, the levels of oxygen-demanding wastes in Lake Sagara can still sustain aquatic life. The high counts of enteric pathogenic microorganisms including fecal coiliform (10-66 MPN/100m), Vibrio sp. (2-6 CFU mL-1) and Salmonella sp. (1-4 CFU mL-1) as a result of surface runoff and direct contamination depict poor hygienic practices by the local fishermen and the surrounding communities. This work provides the first ever scientific research on the microbiological status of Malagarasi-Muyovozi wetland ecosystem.