Browsing by Author "Nakamura, Yoshitoshi"
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Item 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, YoshitoshiIn 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.Item 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.Item Bioconversion of Lignocellulosic Waste from Selected Dumping Sites in Dar es Salaam, Tanzania(2004-11) Mtui, Godliving Y. S.; Nakamura, YoshitoshiThe 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.Item 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.Item Continuous Production of Lignin-degrading Enzymes by Bjerkandera Adusta Immobilized on Polyurethane Foam(2002-11) Mtui, Godliving Y. S.; Nakamura, YoshitoshiContinuous 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.Item 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, YoshitoshiThe 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.Item 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, YoshitoshiThe 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.Item 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, HiromichiProduction 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.Item Lignin-degrading Enzyme Production by Bjerkandera Adusta Immobilized on Polyurethane Foam(1999-10) Nakamura, Yoshitoshi; Mtui, Godliving Y. S.; Sawada, Tatsuro; Kuwahara, MasaakiProduction 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.Item Lignin-Degrading Enzymes from Mycelial Cultures of Basidiomycete Fungi Isolated in Tanzania(2004-06) Mtui, Godliving Y. S.; Nakamura, YoshitoshiThis 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%.Item Manufacturing Method of Okara-Containing Soybean Curd Using Steam Explosion(2008) Nakamura, Yoshitoshi; Kurosumi, Akihiro; Mtui, Godliving Y. S.Development of novel manufacturing method of soybean curd including Okara using steam explosion was attempted. Furthermore, the main contents (i.e. moisture, crude fiber, protein lipid and ash) and rupture stress of the soybean curd produced by novel manufacturing method were investigated. It was able to produce the soybean curd which included a lot of crude fiber by the miniaturization of crude fiber in Okara using steam explosion. By addition of the steam exploded Okara to soybean curd not only the utilization of Okara but also the possibility of the high-nutrition soybean curd production was suggested.Item 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, YoshitoshiAntioxidant 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.Item Physicochemical and Microbiological Water Quality of Lake Sagara in Malagarasi Wetlands(2006) Mtui, Godliving Y. S.; Nakamura, YoshitoshiThe 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.Item 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, TomooSteam 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.