Abstract Xylitol is a widely marketed sweetener with good functionality and health-promoting prop... more Abstract Xylitol is a widely marketed sweetener with good functionality and health-promoting properties. It can be synthetized by many yeast species in a one-step reduction of xylose. Arabinose is a common contaminant found in xylose and there is ongoing interest in finding biocatalysts that selectively produce xyltiol. From a screen of 99 yeasts, Barnettozyma populi Y-12728 was found to selectively produce xylitol from both mixed sugars and corn stover hemicellulosic hydrolysate. Here, fermentation conditions for xylitol production from xylose by B. populi were optimized. The medium for xylitol production was optimized through response surface methodology. The yeast produced 31.2 ± 0.4 g xylitol from xylose (50 g L−1) in 62 h using the optimized medium. The optimal pH for xylitol production was 6.0. Glucose (10 g L−1), acetic acid (6.0 g L−1), HMF (4 mM) and ethanol (2.0 g L−1) inhibited the xylitol production. The glucose inhibition was entirely mitigated by using a 2-stage aeration strategy, indicating that the yeast was inhibited by ethanol produced from glucose under low aeration. This culture strategy will greatly benefit xylitol production from hemicellulosic hydrolysates, which often contain glucose. This is the first report on optimization of xylitol production by a Barnettozyma species.
Biocatalysts play important roles in various biotechnology products and processes in the food and... more Biocatalysts play important roles in various biotechnology products and processes in the food and beverage industries and have already been recognized as valuable catalysts for various organic transformations and production of fine chemicals and pharmaceuticals. At present, the most commonly used biocatalysts in biotechnology are hydrolytic enzymes which catalyze the breakdown of larger biopolymers into smaller units. Enzymes catalyze reactions in a selective manner, not only regio-but also stereoselectively and have been used both for asymmetric synthesis and racemic resolutions. The chiral selectivity of enzymes has been employed to prepare enantiomerically pure pharmaceuticals, agrochemicals and food additives. Biocatalytic methods have already replaced some conventional chemical processes. Biocatalytic routes, in combination with chemical synthesis, are finding increased use in the synthesis of novel polymeric materials. The present global market for enzymes is estimated to be more than US $1.5 billion. The discovery of new and improved enzymes and their use in various processes and products will create new market opportunities for biocatalysts and helps solve environmental problems. Applied biocatalysis can be defined as the application of biocatalysts to achieve a desired conversion under controlled conditions in a bioreactor (/). A biocatalyst can be an enzyme, an enzyme complex, a cell organelle or whole cells. The source of biocatalyst can be of microbial, plant or animal origin. Catalysis by an enzyme offers 2
Journal of the Association for Laboratory Automation, 2009
Commercialization of fuel ethanol production from lignocellulosic biomass has focused on engineer... more Commercialization of fuel ethanol production from lignocellulosic biomass has focused on engineering the glucose-fermenting industrial yeast Saccharomyces cerevisiae to use pentose sugars. Because S. cerevisiae naturally metabolizes xylulose, one approach involves introducing xylose isomerase (XI), which catalyzes conversion of xylose to xylulose. In this study, an automated two-hybrid interaction protocol was used to find yeast genes encoding proteins that bind XI to identify potential targets for improving xylose utilization by S. cerevisiae. A pDEST32 vector re-engineered for TRP selection and containing the Gal4 binding domain fused with the Piromyces sp. E2 XI open reading frame (ORF) was used as bait with a library of LEU-selectable pOAD vectors containing the Gal4 activation domain in fusion with members of the S. cerevisiae genome ORF collection. Binding of a yeast ORF protein to XI activates two chromosomally located reporter genes in a PJ69–4 yeast strain to give selective...
Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the pot... more Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the potential to serve as a low cost feedstock for production of fuel ethanol. Currently, the use of corn fiber to produce fuel ethanol faces significant technical and economic challenges. Its success depends largely on the development of environmentally friendly pretreatment procedures, highly effective enzyme systems for conversion of pretreated corn fiber to fermentable sugars, and efficient microorganisms to convert multiple sugars to ethanol. Several promising pretreatment and enzymatic processes for conversion of corn fiber cellulose, hemicellulose, and remaining starch to fermentable sugars were evaluated. These hydrolyzates were then examined for ethanol production in bioreactors, using genetically modified bacteria and yeast. Several novel enzymes were also developed for use in pretreated corn fiber saccharification. Index Entries: Fuel ethanol; corn fiber; pretreatment; enzymatic saccharification; fermentation. * Author to whom all correspondence and reprint requests should be addressed. ** Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.
Utilization of pentose sugars (o-xylose and L-arabinose) derived from hemicellulose is essential ... more Utilization of pentose sugars (o-xylose and L-arabinose) derived from hemicellulose is essential for the economic conversion of biomass to ethanol. Xvlosefermenting yeasts were discovered in the 1980s, but to date, no yeasts hav~been found that ferment L-arabinose to ethanol in significant quantities. We have screened 116 different yeasts for the ability to ferment L-arabinose and have found the following species able to ferment the sugar: Candida auringiensis, Candida succiphila, Ambrosiozyma monospol"a, and Candida sp. (YB-2248). Though these yeasts produced ethanol concentrations of 4.1 giL or less, they are potential candidates for mutational enhancement of L-arabinose fermentation. These yeasts were also found to ferment o-xylose. Index Entries: L-arabinose; pentose; ethanol; fermentation; yeasts. *Author to whom all correspondence and reprint requests should be addressed. tNames are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.
Mannitol biosynthesis in Candida magnoliae HH-01 (KCCM-10252), a yeast strain that is currently u... more Mannitol biosynthesis in Candida magnoliae HH-01 (KCCM-10252), a yeast strain that is currently used for the industrial production of mannitol, is catalyzed by mannitol dehydrogenase (MDH) (EC 1.1.1.138). In this study, NAD(P)H-dependent MDH was purified to homogeneity from C. magnoliae HH-01 by ion-exchange chromatography, hydrophobic interaction chromatography, and affinity chromatography. The relative molecular masses of C. magnoliae MDH, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography, were 35 and 142 kDa, respectively, indicating that the enzyme is a tetramer. This enzyme catalyzed both fructose reduction and mannitol oxidation. The pH and temperature optima for fructose reduction and mannitol oxidation were 7.5 and 37°C and 10.0 and 40°C, respectively. C. magnoliae MDH showed high substrate specificity and high catalytic efficiency (k cat = 823 s−1, K m = 28.0 mM, and k cat /K m = 29.4 mM−1 s−1) for fructose, which m...
Itaconic acid (IA), an unsaturated 5-carbon dicarboxylic acid, is a building block platform chemi... more Itaconic acid (IA), an unsaturated 5-carbon dicarboxylic acid, is a building block platform chemical that is currently produced industrially from glucose by fermentation with Aspergillus terreus. However, lignocellulosic biomass has potential to serve as low cost source of sugars for production of IA. Research needs to be performed to find a suitable A. terreus strain that can use lignocellulose derived pentose sugars and produce IA. One hundred A. terreus strains were evaluated for the first time for production of IA from xylose and arabinose. Twenty strains showed good production of IA from the sugars. Among these, 6 strains (NRRL strains 1960, 1961, 1962, 1972, 66125 and DSM 23081) were selected for further study. One of these strains NRRL 1961 produced 49.8±0.3, 38.9±0.8, 34.8±0.9 and 33.2±2.4 g IA from 80 g glucose, xylose, arabinose and their mixture (1:1:1), respectively, per L at initial pH 3.1 and 33°C. This is the first report on the production of IA from arabinose and mixed sugar of glucose, xylose and arabinose by A. terreus. The results presented in the paper will be very useful in developing a process technology for production of IA from lignocellulosic feedstocks. This article is protected by copyright. All rights reserved.
AbstractofAnnualMeeting, Soc. Ind Microbiol.,Toronto, Ontario, 1993, p. 49.16. Sirisansaneeyakul,... more AbstractofAnnualMeeting, Soc. Ind Microbiol.,Toronto, Ontario, 1993, p. 49.16. Sirisansaneeyakul, S.; Staniszewski, M.; Rizzi, M. J. Ferment. Biotechnol. 1995,80, 565-570.17. Roseiro, J. C.; Peito, M A.; Girio, F. M; Amaral-Collaco,M. T. Arch. Microbiol.1991, 484-490.18. Saha, B. C.; Bothast, R. 1. Appl. Microbiol. Biotechnol. 1996,45,299-306.19. Dien, B. D.; Kurtzman, C. P.; Saha, B. C.; Bothast, R. 1. Appl. Biochem.Biotechnol. 1996,57/58,233-242.20. McMillan, J. D.; Boynton, B. L. Appl. Biochem. Biotechnol. 1994,45/46,569-584.21. Schvester, P.; Robinson, C. W.; Moo-Young,M. Biotechnol. Bioeng. Symp. 1983,13,131-152.22. Dekker, R. F. H. Biotechnol. Letts. 1982,4,411-416.23. Morikawa, Y; Takasawa, S.; Masunaga, 1.; Takayama, K Biotechnol. Bioeng.1985,27,509-513.24. McCracken, L. D.; Gong, C-S.Biotechnol. Bioeng. Symp. 1982, 12,91-102.25. Dahiya,1. S. Can 1. Microbiol. Can J. Microbiol. 1991,37, 14-18.26. Yoshitake, 1.; Ishizaki, H.; Shimamura, M.; Imai, T. Agric. BioI. Chem. 1973,37...
By and large most studies on biocatalysis deal with enzymes derived from animal, plant, or microb... more By and large most studies on biocatalysis deal with enzymes derived from animal, plant, or microbial sources that grow under “normal physiological” conditions, that is, those environmental conditions that would describe the discovery of physiological biochemistry in the 1930–1950s when normal enzyme environmental conditions (e.g., pH 7.0, 1.5% NaCl, 37°C) were representative of an animal cell as the model system of the times. In the 1970–1980s the vast physiobiochemical diversity of microbes has been extended by microbiologists who can now recognize microbes as living in both normal environments (e.g., human body flora) or in environments (e.g., thermal springs, hypersaline lakes, acidic peat bogs) that represent extreme conditions in relation to the origins of physiological chemistry and a normal animal or plant cell. This chapter will report on our laboratory’s efforts to understand biocatalysis in both obligate anaerobes and their enzymes that have adapted to extreme environmenta...
Itaconic acid (IA), a building block platform chemical, is produced industrially by Aspergillus t... more Itaconic acid (IA), a building block platform chemical, is produced industrially by Aspergillus terreus utilizing glucose. Lignocellulosic biomass can serve as a low cost source of sugars for IA production. However, the fungus could not produce IA from dilute acid pretreated and enzymatically saccharified wheat straw hydrolyzate even at 100‐fold dilution. Furfural, hydroxymethyl furfural and acetic acid were inhibitory, as is typical, but Mn2+ was particularly problematic for IA production. It was present in the hydrolyzate at a level that was 230 times over the inhibitory limit (50 ppb). Recently, it was found that PO43− limitation decreased the inhibitory effect of Mn2+ on IA production. In the present study, a novel medium was developed for production of IA by varying PO43−, Fe3+ and Cu2+ concentrations using response surface methodology, which alleviated the strong inhibitory effect of Mn2+. The new medium contained 0.08 g KH2PO4, 3 g NH4NO3, 1 g MgSO4·7H2O, 5 g CaCl2·2 H2O, 0.83 mg FeCl3·6H2O, 8 mg ZnSO4·7H2O, and 45 mg CuSO4·5H2O per liter. The fungus was able to produce IA very well in the presence of Mn2+ up to 100 ppm in the medium. This medium will be extremely useful for IA production in the presence of Mn2+. This is the first report on the development of Mn2+ tolerant medium for IA production by A. terreus.
Stepwise formulation of a versatile and cost-effective medium based on barley straw hydrolysate a... more Stepwise formulation of a versatile and cost-effective medium based on barley straw hydrolysate and egg shell for efficient polymalic acid production by A. pullulans NRRL Y-2311-1 was carried out for the first time. The strain did not grow and produce polymalic acid when dilute acid pretreated barley straw hydrolysate (total fermentable sugars: 94.60 g/L; furfural: 1.01 g/L; hydroxymethylfurfural: 0.55 g/L; acetic acid: 5.06 g/L) was directly used in medium formulation without detoxification (e.g. charcoal pretreatment). When CaCO3 in the medium formulation was substituted with egg shell powder, efficient production of polymalic acid was achieved without a detoxification step. Utilization of 40 g/L of egg shell powder led to 43.54 g polymalic acid production per L with the productivity of 0.30 g/L/h and yield of 0.48 g/g. The bioprocess strategy used in this study can also be utilized for mass production of several other industrially important microbial organic acids and biomaterials.
Aus den Versuchsergebnissen geht folgendes hervor : Die Einrichtungen zur Kartoffelstarkegewinnun... more Aus den Versuchsergebnissen geht folgendes hervor : Die Einrichtungen zur Kartoffelstarkegewinnung sollten eine moglichst groDe Leistungskapazitat haben. Diese Kapazitat sol1 max. ausgenutzt werden, weil dies zur Senkung des Energieaufwandes bei Erhaltung der entsprechenden Qualitat des Endproduktes fuhrt. Heutzutage verwendete Einrichtungen verbrauchen zu vie1 Wasser und verursachen deshalb neben den allzu groDen Energieverlusten Schwierigkeiten bezuglich der Reinigung. Den Hydrozyklonen im Auswasch-und Raffinationsverfahren sollte im Hinblick auf ihre universelle Verwendbarkeit und den verhaltnismaBig niedrigen Energieverbrauch eine groDere Bedeutung zugemessen werden. Die Untersuchungsergebnisse erlauben grundsatzlich h d erungen im Auswasch-und RaffinationsprozeD, die bei Berucksichtigung durch die Untersuchung der ermittelten optimalen Parameter eine neue technische Anordnung der untersuchten Einrichtungen in der Kartoffelstarkeproduktion gestatten.
Some highly thermostable pullulanases from thermophiles belong to a new class of pullulanase that... more Some highly thermostable pullulanases from thermophiles belong to a new class of pullulanase that cleaves oc 1-4 linkages from starch. Some of these enzymes are stable and active above 90°C. The enzymes have great potential for use directly, both in starch liquefaction (with or without o~-amylase) and in saccharification processes. More highly thermostable and thermoactive pullulanases may yet be isolated from thermophiles. This new class of pullulanase may prove superior to the commercial thermostable o~-amylase from Bacillus Hcheniformis used for industrial starch liquefaction processes. The novel pullulanases may also be useful for single-step starch conversion into various maltodextrins. Pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41) is usually considered as a debranching enzyme that specifically cleaves 0~1-6 linkages in pullulan, starch, amylopectin and related oligosaccharidesL It is an industrially important enzyme; it is generally used in combination with saccharifying (see Glossary) amylases such as glucoamylase, fungal o~-amylase or ~-amylase for the production of various sugar syrups because it improves saccharification rate and yield 2. Moreover, it is a useful tool for structural studies of carbohydrates 3. Pullulan-degrading enzymes Pullulan is a linear glucan of about 480 maltotriosyl units linked through B.
Various commodity chemicals such as alcohols, polyols, organic acids, amino acids, polysaccharide... more Various commodity chemicals such as alcohols, polyols, organic acids, amino acids, polysaccharides, biodegradable plastic components, and industrial enzymes can be produced by fermentation. This overview focuses on recent research progress in the production of a few chemicals: ethanol, 1,3-propanediol, lactic acid, polyhydroxyalkanoates, exopolysaccharides and vanillin. The problems and prospects of cost-effective commodity chemical production by fermentation and future directions of research are presented. During the last two decades, tremendous improvements have been made in fermentation technology for the production of commodity chemicals and high value pharmaceuticals. In addition to classical mutation, selection, media design, and process optimization, metabolic engineering plays a significant role in the improvement of microbial strains and fermentation processes. Classical mutation includes random screening and rationalized selection. Rationalized selection can be based on developing auxotropic strains, deregulated mutants, mutants resistant to feedback inhibition and mutants resistant to repression (/). In addition to the
Abstract Xylitol is a widely marketed sweetener with good functionality and health-promoting prop... more Abstract Xylitol is a widely marketed sweetener with good functionality and health-promoting properties. It can be synthetized by many yeast species in a one-step reduction of xylose. Arabinose is a common contaminant found in xylose and there is ongoing interest in finding biocatalysts that selectively produce xyltiol. From a screen of 99 yeasts, Barnettozyma populi Y-12728 was found to selectively produce xylitol from both mixed sugars and corn stover hemicellulosic hydrolysate. Here, fermentation conditions for xylitol production from xylose by B. populi were optimized. The medium for xylitol production was optimized through response surface methodology. The yeast produced 31.2 ± 0.4 g xylitol from xylose (50 g L−1) in 62 h using the optimized medium. The optimal pH for xylitol production was 6.0. Glucose (10 g L−1), acetic acid (6.0 g L−1), HMF (4 mM) and ethanol (2.0 g L−1) inhibited the xylitol production. The glucose inhibition was entirely mitigated by using a 2-stage aeration strategy, indicating that the yeast was inhibited by ethanol produced from glucose under low aeration. This culture strategy will greatly benefit xylitol production from hemicellulosic hydrolysates, which often contain glucose. This is the first report on optimization of xylitol production by a Barnettozyma species.
Biocatalysts play important roles in various biotechnology products and processes in the food and... more Biocatalysts play important roles in various biotechnology products and processes in the food and beverage industries and have already been recognized as valuable catalysts for various organic transformations and production of fine chemicals and pharmaceuticals. At present, the most commonly used biocatalysts in biotechnology are hydrolytic enzymes which catalyze the breakdown of larger biopolymers into smaller units. Enzymes catalyze reactions in a selective manner, not only regio-but also stereoselectively and have been used both for asymmetric synthesis and racemic resolutions. The chiral selectivity of enzymes has been employed to prepare enantiomerically pure pharmaceuticals, agrochemicals and food additives. Biocatalytic methods have already replaced some conventional chemical processes. Biocatalytic routes, in combination with chemical synthesis, are finding increased use in the synthesis of novel polymeric materials. The present global market for enzymes is estimated to be more than US $1.5 billion. The discovery of new and improved enzymes and their use in various processes and products will create new market opportunities for biocatalysts and helps solve environmental problems. Applied biocatalysis can be defined as the application of biocatalysts to achieve a desired conversion under controlled conditions in a bioreactor (/). A biocatalyst can be an enzyme, an enzyme complex, a cell organelle or whole cells. The source of biocatalyst can be of microbial, plant or animal origin. Catalysis by an enzyme offers 2
Journal of the Association for Laboratory Automation, 2009
Commercialization of fuel ethanol production from lignocellulosic biomass has focused on engineer... more Commercialization of fuel ethanol production from lignocellulosic biomass has focused on engineering the glucose-fermenting industrial yeast Saccharomyces cerevisiae to use pentose sugars. Because S. cerevisiae naturally metabolizes xylulose, one approach involves introducing xylose isomerase (XI), which catalyzes conversion of xylose to xylulose. In this study, an automated two-hybrid interaction protocol was used to find yeast genes encoding proteins that bind XI to identify potential targets for improving xylose utilization by S. cerevisiae. A pDEST32 vector re-engineered for TRP selection and containing the Gal4 binding domain fused with the Piromyces sp. E2 XI open reading frame (ORF) was used as bait with a library of LEU-selectable pOAD vectors containing the Gal4 activation domain in fusion with members of the S. cerevisiae genome ORF collection. Binding of a yeast ORF protein to XI activates two chromosomally located reporter genes in a PJ69–4 yeast strain to give selective...
Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the pot... more Corn fiber, which consists of about 20% starch, 14% cellulose, and 35% hemicellulose, has the potential to serve as a low cost feedstock for production of fuel ethanol. Currently, the use of corn fiber to produce fuel ethanol faces significant technical and economic challenges. Its success depends largely on the development of environmentally friendly pretreatment procedures, highly effective enzyme systems for conversion of pretreated corn fiber to fermentable sugars, and efficient microorganisms to convert multiple sugars to ethanol. Several promising pretreatment and enzymatic processes for conversion of corn fiber cellulose, hemicellulose, and remaining starch to fermentable sugars were evaluated. These hydrolyzates were then examined for ethanol production in bioreactors, using genetically modified bacteria and yeast. Several novel enzymes were also developed for use in pretreated corn fiber saccharification. Index Entries: Fuel ethanol; corn fiber; pretreatment; enzymatic saccharification; fermentation. * Author to whom all correspondence and reprint requests should be addressed. ** Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.
Utilization of pentose sugars (o-xylose and L-arabinose) derived from hemicellulose is essential ... more Utilization of pentose sugars (o-xylose and L-arabinose) derived from hemicellulose is essential for the economic conversion of biomass to ethanol. Xvlosefermenting yeasts were discovered in the 1980s, but to date, no yeasts hav~been found that ferment L-arabinose to ethanol in significant quantities. We have screened 116 different yeasts for the ability to ferment L-arabinose and have found the following species able to ferment the sugar: Candida auringiensis, Candida succiphila, Ambrosiozyma monospol"a, and Candida sp. (YB-2248). Though these yeasts produced ethanol concentrations of 4.1 giL or less, they are potential candidates for mutational enhancement of L-arabinose fermentation. These yeasts were also found to ferment o-xylose. Index Entries: L-arabinose; pentose; ethanol; fermentation; yeasts. *Author to whom all correspondence and reprint requests should be addressed. tNames are necessary to report factually on available data. However, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by USDA implies no approval of the product to the exclusion of others that may also be suitable.
Mannitol biosynthesis in Candida magnoliae HH-01 (KCCM-10252), a yeast strain that is currently u... more Mannitol biosynthesis in Candida magnoliae HH-01 (KCCM-10252), a yeast strain that is currently used for the industrial production of mannitol, is catalyzed by mannitol dehydrogenase (MDH) (EC 1.1.1.138). In this study, NAD(P)H-dependent MDH was purified to homogeneity from C. magnoliae HH-01 by ion-exchange chromatography, hydrophobic interaction chromatography, and affinity chromatography. The relative molecular masses of C. magnoliae MDH, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and size-exclusion chromatography, were 35 and 142 kDa, respectively, indicating that the enzyme is a tetramer. This enzyme catalyzed both fructose reduction and mannitol oxidation. The pH and temperature optima for fructose reduction and mannitol oxidation were 7.5 and 37°C and 10.0 and 40°C, respectively. C. magnoliae MDH showed high substrate specificity and high catalytic efficiency (k cat = 823 s−1, K m = 28.0 mM, and k cat /K m = 29.4 mM−1 s−1) for fructose, which m...
Itaconic acid (IA), an unsaturated 5-carbon dicarboxylic acid, is a building block platform chemi... more Itaconic acid (IA), an unsaturated 5-carbon dicarboxylic acid, is a building block platform chemical that is currently produced industrially from glucose by fermentation with Aspergillus terreus. However, lignocellulosic biomass has potential to serve as low cost source of sugars for production of IA. Research needs to be performed to find a suitable A. terreus strain that can use lignocellulose derived pentose sugars and produce IA. One hundred A. terreus strains were evaluated for the first time for production of IA from xylose and arabinose. Twenty strains showed good production of IA from the sugars. Among these, 6 strains (NRRL strains 1960, 1961, 1962, 1972, 66125 and DSM 23081) were selected for further study. One of these strains NRRL 1961 produced 49.8±0.3, 38.9±0.8, 34.8±0.9 and 33.2±2.4 g IA from 80 g glucose, xylose, arabinose and their mixture (1:1:1), respectively, per L at initial pH 3.1 and 33°C. This is the first report on the production of IA from arabinose and mixed sugar of glucose, xylose and arabinose by A. terreus. The results presented in the paper will be very useful in developing a process technology for production of IA from lignocellulosic feedstocks. This article is protected by copyright. All rights reserved.
AbstractofAnnualMeeting, Soc. Ind Microbiol.,Toronto, Ontario, 1993, p. 49.16. Sirisansaneeyakul,... more AbstractofAnnualMeeting, Soc. Ind Microbiol.,Toronto, Ontario, 1993, p. 49.16. Sirisansaneeyakul, S.; Staniszewski, M.; Rizzi, M. J. Ferment. Biotechnol. 1995,80, 565-570.17. Roseiro, J. C.; Peito, M A.; Girio, F. M; Amaral-Collaco,M. T. Arch. Microbiol.1991, 484-490.18. Saha, B. C.; Bothast, R. 1. Appl. Microbiol. Biotechnol. 1996,45,299-306.19. Dien, B. D.; Kurtzman, C. P.; Saha, B. C.; Bothast, R. 1. Appl. Biochem.Biotechnol. 1996,57/58,233-242.20. McMillan, J. D.; Boynton, B. L. Appl. Biochem. Biotechnol. 1994,45/46,569-584.21. Schvester, P.; Robinson, C. W.; Moo-Young,M. Biotechnol. Bioeng. Symp. 1983,13,131-152.22. Dekker, R. F. H. Biotechnol. Letts. 1982,4,411-416.23. Morikawa, Y; Takasawa, S.; Masunaga, 1.; Takayama, K Biotechnol. Bioeng.1985,27,509-513.24. McCracken, L. D.; Gong, C-S.Biotechnol. Bioeng. Symp. 1982, 12,91-102.25. Dahiya,1. S. Can 1. Microbiol. Can J. Microbiol. 1991,37, 14-18.26. Yoshitake, 1.; Ishizaki, H.; Shimamura, M.; Imai, T. Agric. BioI. Chem. 1973,37...
By and large most studies on biocatalysis deal with enzymes derived from animal, plant, or microb... more By and large most studies on biocatalysis deal with enzymes derived from animal, plant, or microbial sources that grow under “normal physiological” conditions, that is, those environmental conditions that would describe the discovery of physiological biochemistry in the 1930–1950s when normal enzyme environmental conditions (e.g., pH 7.0, 1.5% NaCl, 37°C) were representative of an animal cell as the model system of the times. In the 1970–1980s the vast physiobiochemical diversity of microbes has been extended by microbiologists who can now recognize microbes as living in both normal environments (e.g., human body flora) or in environments (e.g., thermal springs, hypersaline lakes, acidic peat bogs) that represent extreme conditions in relation to the origins of physiological chemistry and a normal animal or plant cell. This chapter will report on our laboratory’s efforts to understand biocatalysis in both obligate anaerobes and their enzymes that have adapted to extreme environmenta...
Itaconic acid (IA), a building block platform chemical, is produced industrially by Aspergillus t... more Itaconic acid (IA), a building block platform chemical, is produced industrially by Aspergillus terreus utilizing glucose. Lignocellulosic biomass can serve as a low cost source of sugars for IA production. However, the fungus could not produce IA from dilute acid pretreated and enzymatically saccharified wheat straw hydrolyzate even at 100‐fold dilution. Furfural, hydroxymethyl furfural and acetic acid were inhibitory, as is typical, but Mn2+ was particularly problematic for IA production. It was present in the hydrolyzate at a level that was 230 times over the inhibitory limit (50 ppb). Recently, it was found that PO43− limitation decreased the inhibitory effect of Mn2+ on IA production. In the present study, a novel medium was developed for production of IA by varying PO43−, Fe3+ and Cu2+ concentrations using response surface methodology, which alleviated the strong inhibitory effect of Mn2+. The new medium contained 0.08 g KH2PO4, 3 g NH4NO3, 1 g MgSO4·7H2O, 5 g CaCl2·2 H2O, 0.83 mg FeCl3·6H2O, 8 mg ZnSO4·7H2O, and 45 mg CuSO4·5H2O per liter. The fungus was able to produce IA very well in the presence of Mn2+ up to 100 ppm in the medium. This medium will be extremely useful for IA production in the presence of Mn2+. This is the first report on the development of Mn2+ tolerant medium for IA production by A. terreus.
Stepwise formulation of a versatile and cost-effective medium based on barley straw hydrolysate a... more Stepwise formulation of a versatile and cost-effective medium based on barley straw hydrolysate and egg shell for efficient polymalic acid production by A. pullulans NRRL Y-2311-1 was carried out for the first time. The strain did not grow and produce polymalic acid when dilute acid pretreated barley straw hydrolysate (total fermentable sugars: 94.60 g/L; furfural: 1.01 g/L; hydroxymethylfurfural: 0.55 g/L; acetic acid: 5.06 g/L) was directly used in medium formulation without detoxification (e.g. charcoal pretreatment). When CaCO3 in the medium formulation was substituted with egg shell powder, efficient production of polymalic acid was achieved without a detoxification step. Utilization of 40 g/L of egg shell powder led to 43.54 g polymalic acid production per L with the productivity of 0.30 g/L/h and yield of 0.48 g/g. The bioprocess strategy used in this study can also be utilized for mass production of several other industrially important microbial organic acids and biomaterials.
Aus den Versuchsergebnissen geht folgendes hervor : Die Einrichtungen zur Kartoffelstarkegewinnun... more Aus den Versuchsergebnissen geht folgendes hervor : Die Einrichtungen zur Kartoffelstarkegewinnung sollten eine moglichst groDe Leistungskapazitat haben. Diese Kapazitat sol1 max. ausgenutzt werden, weil dies zur Senkung des Energieaufwandes bei Erhaltung der entsprechenden Qualitat des Endproduktes fuhrt. Heutzutage verwendete Einrichtungen verbrauchen zu vie1 Wasser und verursachen deshalb neben den allzu groDen Energieverlusten Schwierigkeiten bezuglich der Reinigung. Den Hydrozyklonen im Auswasch-und Raffinationsverfahren sollte im Hinblick auf ihre universelle Verwendbarkeit und den verhaltnismaBig niedrigen Energieverbrauch eine groDere Bedeutung zugemessen werden. Die Untersuchungsergebnisse erlauben grundsatzlich h d erungen im Auswasch-und RaffinationsprozeD, die bei Berucksichtigung durch die Untersuchung der ermittelten optimalen Parameter eine neue technische Anordnung der untersuchten Einrichtungen in der Kartoffelstarkeproduktion gestatten.
Some highly thermostable pullulanases from thermophiles belong to a new class of pullulanase that... more Some highly thermostable pullulanases from thermophiles belong to a new class of pullulanase that cleaves oc 1-4 linkages from starch. Some of these enzymes are stable and active above 90°C. The enzymes have great potential for use directly, both in starch liquefaction (with or without o~-amylase) and in saccharification processes. More highly thermostable and thermoactive pullulanases may yet be isolated from thermophiles. This new class of pullulanase may prove superior to the commercial thermostable o~-amylase from Bacillus Hcheniformis used for industrial starch liquefaction processes. The novel pullulanases may also be useful for single-step starch conversion into various maltodextrins. Pullulanase (pullulan 6-glucanohydrolase, EC 3.2.1.41) is usually considered as a debranching enzyme that specifically cleaves 0~1-6 linkages in pullulan, starch, amylopectin and related oligosaccharidesL It is an industrially important enzyme; it is generally used in combination with saccharifying (see Glossary) amylases such as glucoamylase, fungal o~-amylase or ~-amylase for the production of various sugar syrups because it improves saccharification rate and yield 2. Moreover, it is a useful tool for structural studies of carbohydrates 3. Pullulan-degrading enzymes Pullulan is a linear glucan of about 480 maltotriosyl units linked through B.
Various commodity chemicals such as alcohols, polyols, organic acids, amino acids, polysaccharide... more Various commodity chemicals such as alcohols, polyols, organic acids, amino acids, polysaccharides, biodegradable plastic components, and industrial enzymes can be produced by fermentation. This overview focuses on recent research progress in the production of a few chemicals: ethanol, 1,3-propanediol, lactic acid, polyhydroxyalkanoates, exopolysaccharides and vanillin. The problems and prospects of cost-effective commodity chemical production by fermentation and future directions of research are presented. During the last two decades, tremendous improvements have been made in fermentation technology for the production of commodity chemicals and high value pharmaceuticals. In addition to classical mutation, selection, media design, and process optimization, metabolic engineering plays a significant role in the improvement of microbial strains and fermentation processes. Classical mutation includes random screening and rationalized selection. Rationalized selection can be based on developing auxotropic strains, deregulated mutants, mutants resistant to feedback inhibition and mutants resistant to repression (/). In addition to the
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