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Bioethanol Production from Molasses by Yeasts with Stress-Tolerance Isolated from Aquatic Environments in Japan

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Advances in Microbiology 2019年第12期9卷 1000-1011页

作者： Yuka Naito Masahiko Okai Masami Ishida Masachika Takashio naoto urano Laboratory of Marine Biochemistry Department of Ocean Sciences Tokyo University of Marine Science and Technology Konan Minato-ku Tokyo Japan Zensho Laboratories of Food Technology Zensho Holdings Co. Ltd. Konan Minato-ku Tokyo Japan

Bioethanol is a safe and renewable source of energy that continues to be a research focus, since fossil fuels have been linked to global warming and nuclear energy sources are affected by the increased safety concerns following the 2011 nuclear power plant accident in Japan. In general, bioethanol is converted from a biomass by yeast fermentation. The production efficiency of this bioethanol is not sufficiently high, and its practical use as a substitute for fossil fuels and nuclear energy is thus limited. For the industrial production of bioethanol, the yeast fermentation of biomass cultures containing high concentration sugar, NaCl, and ethanol is necessary, but this might induce phenomena in which the stresses arising in the yeasts weaken their cells during fermentation. As described herein, we isolated 1028 strains of yeasts from natural aquatic environments: Japan’s Tama River and Lake Kasumigaura. Among them, 412 strains were fermentative yeasts and 31 strains showed high fermentation ability under a 30% sorbitol + 10% ethanol condition. These strains were identified as Torulaspola delbrueckii, Wickerhamomyces anomalus, Candida glabrata, Pichia kudriavzevii, Saccharomyces cf. cerevisiae/paradoxus, and Lachancea kluyveri. The strains T. delbrueckii, W. anomalus, and C. glabrata also showed tolerance against 15% NaCl. Most importantly, S. cf. cerevisiae/paradoxus H28 and L. kluyveri F2-67 produced 57.4 g/L and 53.9 g/L ethanol from molasses (sucrose 104.0 g/L, fructose 33.4 g/L, and glucose 24.8 g/L) within 48 hrs at 25°C, respectively.

关键词： Stress-Tolerance Molasses Yeast Species Aquatic Environment Fermentation

Characterization of Yeasts Capable of Neutralizing Acidic Media from Natural Neutral Environments

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Advances in Microbiology 2017年第12期7卷 887-897页

作者： Shintaro Nagaoka Takako Kobayashi Yuko Kajiwara Masahiko Okai Masami Ishida naoto urano Laboratory of Marine Biochemistry Department of Ocean Sciences Tokyo University of Marine Science and Technology Tokyo Japan

Acid-tolerant yeasts often inhabit extremely acidic environments: mine drain-ages, hot springs, and even fermented foods. Some of them also possess the ability to neutralize acidic media. However, the examples of these yeasts that are already known were isolated from acidic environments. In this study, the isolation of acid-tolerant yeasts from natural neutral aquatic environments and the identification of yeasts able to neutralize an acidic medium (acid-neutralizing yeast) in Japan were carried out. Various kinds of acid-tolerant and acid-neutralizing yeasts were obtained. In a neutralizing test using an acidic casamino acid solution adjusted to a pH of 4.0 with sulfuric acid, the obtained acid-neutralizing yeasts elevated the pH to approximately 7.0, and their neutralizing abilities were similar to those of previously reported yeasts that had been isolated from acidic environments. These results showed that acid-tolerant yeasts and acid-neutralizing yeasts exist widely in neutral environments, and little difference was found in the neutralizing abilities of yeasts obtained from neutral environments in comparison to those obtained from acidic environments.

关键词： Acid-Tolerant Yeast Acidic Environment Hydrosphere Neutralization Yeast Species

Molecular Phylogeny and Phenotypic Characterization of Yeasts with a Broad Range of pH Tolerance Isolated from Natural Aquatic Environments

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Advances in Microbiology 2019年第1期9卷 56-73页

作者： naoto urano Ayaka Shirao Yuka Naito Masahiko Okai Masami Ishida Masachika Takashio Department of Ocean Sciences Laboratory of Marine Biochemistry Tokyo University of Marine Science and Technology Tokyo Japan Zensho Laboratories of Food Technology Zensho Holdings Co. Ltd. Tokyo Japan

In this study, yeasts with broad range of pH tolerance were isolated and characterized from natural aquatic environments in Japan. Only a few basic and application studies of alkali-tolerant yeasts have been reported, despite the unmet industrial needs. First, we surveyed alkali-tolerant yeasts from natural aquatic environments at pH 7.6 - 9.4. We isolated 35 yeast strains that grew in pH 9.0 medium, from seven genera and nine species: 25 strains (N1, N2, through N6, N9, K1, K3 through K19) were Rhodotorula mucilaginosa;one (N7) was Rhodosporidium fluvial;one (N8) was Scheffersomyces spartinae;two (N10 and N13) were Wicherhamonyces anomalus;one (N11) was Cyberlindnera saturnus;one (S1) was Candida sp.;two (S2 and S4) were Candida intermedia;one (S3) was Candida quercuum;and one (K2) was Cryptococcus liquefacience. We examined the effects of pH on the growth of representative yeast strains. Strains K12 and S4 showed high growth at pH 3 - 10. Strains N7, N8, N10, N11, and S3 showed high growth at pH 3 - 9. Strains K2 and S1 showed high growth at pH 4 - 8. All nine of these strains had neutralizing activities from acidic media at pH 3 - 5 to pH 6 - 8. We previously isolated acid-tolerant yeasts (Cryptococcus sp. T1 [1] and Candida intermedia CeA16 [2]) from extremely acidified environments;they showed high growth at pH 3 - 9 and neutralizing activities of acidic media by releasing ammonium ions. Thus, alkali-tolerant yeasts and acid-tolerant yeasts were found to be similar species and have both high growth at a broad range of pH and neutralizing activities of acid media. Previously, we also isolated acid-tolerant, acid-neutralizing yeasts from neutral natural environments (26 strains, 12 species) [3]. Next, we constructed the phylogenetic trees of both acid-tolerant yeasts and alkali-tolerant yeasts. All were situated in the same classification position. Similar yeast species with a broad range of pH tolerance were living in natural aquatic environments at pH values fr

关键词： pH Tolerance Yeast Species Aquatic Environment Phylogenetic Tree Fermentation

Effect of Acid Species on <i>Cryptococcus</i>sp. T1 and Construction of Its Bioreactor System for Continuous Neutralization of Acidic Media

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Advances in Microbiology 2019年第1期9卷 74-86页

作者： Shintaro Nagaoka Yuko Yuko Kajiwara Sayaka Toyama Masahiko Okai Masami Ishida naoto urano Department of Ocean Science Laboratory of Marine Biochemistry Tokyo University of Marine Science and Technology Tokyo Japan Department of Life Science and Technology Tokyo Institute of Technology Yokohama Japan

Generally, the tolerance of yeasts to acid is stronger than that of bacteria. In addition, some of the yeasts are able to neutralize acidic media, which is called acid-neutralizing yeast. An acid-neutralizing yeast, Cryptococcus sp. strain T1, was previously isolated from Lake Tazawa in Japan. Here we investigated the effect of several types of acid on the neutralizing ability of strain T1, and we improved an existing bioreactor model to effectively neutralize acidic water. First we carried out a neutralizing test with strain T1 using casamino acid solution adjusted to pH 3.0 - 5.0 with each inorganic or organic acid. The solutions adjusted to pH 3.0 with nitric acid, phosphoric acid, sulfuric acid, and citric acid were neutralized by strain T1. The pH 3.0 solutions with lactic acid, formic acid, and acetic acid were not neutralized. These results demonstrated that some types of organic acid avoid neutralization by strain T1, and we hypothesized that this might be due to the sterilizing function of non-dissociative organic acid. We then constructed a bioreactor system with a column filled with T1-immobilized alginate beads. The previous research identified a problem in this bioreactor system: the high level of ammonium ions (NH+4) in the neutralized water might pollute water environments, and aluminum ions (Al3+) included in acidic water prevent the neutralization. Here, we used zeolite to get rid of the NH+4 and Al3+, and the addition of a zeolite reactor enabled the bioreactor system to neutralize the acidic water with a decrease of NH+4 in the water.

关键词： Acid-Tolerant Yeast Acid-Neutralizing Yeast Bioreactor Organic Acid Zeolite

Behavior of Antibiotic-Resistant Fecal Coliforms in the Stream of a Sewage Treatment Plant in Tokyo

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Advances in Microbiology 2020年第7期10卷 318-330页

作者： naoto urano Masahiko Okai Yusuke Tashiro Azusa Takeuchi Rintaro Endo Masami Ishida Masachika Takashio Laboratory of Marine Biochemistry Department of Ocean Sciences Tokyo University of Marine Science and Technology Tokyo Japan Zensho Laboratories of Food Technology Zensho Holdings Co. Ltd. Tokyo Japan

We are confronting a new threat in the prevalence of antibiotic-resistant bacteria followed by epidemic spread in aquatic environments in metropolitan areas because damage from river floods is increasing remarkably in Japan due to global extreme weather. The sewer penetration rate is about 100% in Tokyo and reclaimed water from sewage treatment plants accounts for over 50% of all water in both the down- and mid-stream areas of local rivers. The water quality of these rivers, which contain microflora, seems to be seriously affected by reclaimed water. In this study, we collected water samples on July 17, 2018 and examined the behavior of antibiotic-resistant fecal coliforms in the stream of a sewage treatment plant in Tokyo. Extended-spectrum β-lactamase (ESBL)-producing fecal coliforms with encoding genes were found;the CTX-M-1, CTX-M-9, TEM, and SHV groups were found to have survived in the final effluent to the river after sterilization with sodium hypochlorite.

关键词： Antibiotic-Resistant Bacteria (ARB) Extended-Spectrum β-Lactamase (ESBL) Fecal Coliforms Sewage Treatment Plant Reclaimed Water

Ethanol Fermentation by High-Stress-Tolerance Aquatic Yeasts and Their Mutants

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Advances in Microbiology 2021年第11期11卷 616-629页

作者： naoto urano Masami Ishida Yuka Naito Rintaro Endo Toshinori Takei Masachika Takashio Masahiko Okai Laboratory of Marine Biochemistry Department of Ocean Sciences Tokyo University of Marine Science and Technology Tokyo Japan Zensho Laboratories of Food Technology Zensho Holdings Co. Ltd. Tokyo Japan

Bioethanol is thought to be a renewable source of energy, because the biomasses used to make ethanol, such as sugar cane and its residual substance, molasses, are resources that can be continuously produced. But the practical use of ethanol to replace fossil fuels or atomic energy has been limited, because the production efficiencies of ethanol in relation to its substrates are not so high. Thus, for industrial production of the bioethanol, yeast fermentation would ideally be carried out in biomasses containing more highly concentrated carbohydrates. However, the environmental stresses in highly concentrated cultures might weaken the yeast’s physiological activities. From various kinds of aquatic yeast with stress tolerance, Torulaspora derbrueckii F2-11 and Wicherhamomyces anomalus AN2-64 were selected as candidates for high-sugar-tolerance yeasts as they showed remarkable growth in the YPD + sorbitol (600 g/L) medium at 25°C for 120 hrs. When the amounts and kinds of sugar alcohols in the cells of the two strains were measured in cultures containing 20 g/L or 400 g/L of D-glucose, maltose, or sucrose, the main two sugar alcohols that accumulated as the sugar concentration increased were glycerol and arabitol. Mutation by ethyl methanesulfonate of the parent strains T. derbrueckii F2-11 and W. anomalus AN2-64 induced mutants F2-11M or AN2-64M, which showed higher sugar, heat, and ethanol tolerances than their respective parents. Ethanol productivities and sugar assimilation activities of the mutants were also higher than those of the parents in the 25% (v/v) molasses.

关键词： Ethanol Fermentation Stress Tolerance Aquatic Yeast Mutant Ethyl

Continuous Saccharification of Laminarin by Immobilized Laminarinase ULam111 Followed by Ethanol Fermentation with a Marine-Derived Yeast

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Advances in Microbiology 2017年第5期7卷 387-403页

作者： Daisuke Mitsuya Masashi Yamamoto Masahiko Okai Akira Inoue Tomohiro Suzuki Takao Ojima naoto urano Laboratory of Marine Biochemistry Department of Ocean Sciences Tokyo University of Marine Science and Technology Tokyo Japan Laboratory of Marine Biotechnology and Microbiology Graduate School of Fisheries Sciences Hokkaido University Hakodate Japan

We isolated a novel laminarinase ULam111 from Flavobacterium sp. strain UMI-01. Purified ULam111 showed degradation activity against laminarin with the specific activity of 224 ± 18 U/mg at 30°C and pH 6.0. Its optimum temperature was 50°C, and degradation activities against laminarin were observed at 4°C - 80°C. With a laminarin degradation system, we investigated the preparation and properties of immobilized ULam111 with the use of the 11 types of carriers. The high activity recoveries of immobilized ULam111 were as follows: 19.4% for IB-S60P carrier beads (the non-ionic type), 15.6% for IB-S60S carrier beads (the non-ionic type), 11.9% for IB-150P carrier beads (the covalent type), and 7.1% for IB-C435 carrier beads (the cationic type). With the repeated use of immobilized ULam111, the enzyme activities immobilized on IB-S60S and those on IB-S60P remained at 40% and 30% respectively after the sixth trial. We selected IB-S60S as suitable beads for enzyme immobilization, and we attempted to construct a reactor system with ULam111 immobilized on IB-S60S beads. In this system, 1.2 - 1.9 g/L glucose was repeatedly produced from 30 mg/mL laminarin solutions after 20 hr when the reactor operation was repeated 10 times. We examined ethanol fermentation from the saccharified solutions with a marine-derived yeast (Saccharomyces cerevisiae C-19), and 0.51 - 0.58 g/L bioethanol was produced from the saccharified solution that contained 1.71 - 1.86 g/L of glucose.

关键词： Laminarin Laminarinase β-1 3-Glucanase Immobilization Ethanol Fermentation

Algorithm Selection Method Based on Coupling Strength for Partitioned Analysis of Structure-Piezoelectric-Circuit Coupling

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Computer Modeling in Engineering & Sciences 2024年第2期138卷 1237-1258页

作者： Daisuke Ishihara naoto Takayama Department of Intelligent and Control Systems Kyushu Institute of TechnologyIizuka820-8502Japan

In this study, we propose an algorithm selection method based on coupling strength for the partitioned analysis ofstructure-piezoelectric-circuit coupling, which includes two types of coupling or inverse and direct piezoelectriccoupling and direct piezoelectric and circuit coupling. In the proposed method, implicit and explicit formulationsare used for strong and weak coupling, respectively. Three feasible partitioned algorithms are generated, namely(1) a strongly coupled algorithm that uses a fully implicit formulation for both types of coupling, (2) a weaklycoupled algorithm that uses a fully explicit formulation for both types of coupling, and (3) a partially stronglycoupled and partially weakly coupled algorithm that uses an implicit formulation and an explicit formulation forthe two types of coupling, *** examples using a piezoelectric energy harvester,which is a typicalstructure-piezoelectric-circuit coupling problem, demonstrate that the proposed method selects the most costeffectivealgorithm.

关键词： Multiphysics coupling strength partitioned algorithm structure-piezoelectric-circuit coupling strongly coupled algorithm weakly coupled algorithm

Hybrid Strategy of Partitioned and Monolithic Methods for Solving Strongly Coupled Analysis of Inverse and Direct Piezoelectric and Circuit Coupling

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1371-1386页

作者： Daisuke Ishihara Syunnosuke Nozaki Tomoya Niho naoto Takayama Department of Intelligent and Control Systems Kyushu Institute of TechnologyFukuokaJapan

The inverse and direct piezoelectric and circuit coupling are widely observed in advanced electro-mechanical systems such as piezoelectric energy *** strongly coupled analysis methods based on direct numerical modeling for this phenomenon can be classified into partitioned or monolithic *** formulation has its advantages and disadvantages,and the choice depends on the characteristics of each coupled *** study proposes a new option:a coupled analysis strategy that combines the best features of the existing formulations,namely,the hybrid partitioned-monolithic *** analysis of inverse piezoelectricity and the monolithic analysis of direct piezoelectric and circuit interaction are strongly coupled using a partitioned iterative hierarchical *** a typical benchmark problem of a piezoelectric energy harvester,this research compares the results from the proposed method to those from the conventional strongly coupled partitioned iterative method,discussing the accuracy,stability,and computational *** proposed hybrid concept is effective for coupled multi-physics problems,including various coupling conditions.

关键词： Structure-piezoelectric-circuit interaction energy harvesting partitioned method monolithic method hybrid method