Effects of glucose as carbon catabolite repressor on alpha-amylase and glucoamylase production in Indonesian indigenous fungi

Aims@#The study aimed to investigate the effect of glucose on alpha-amylase and glucoamylase production in some Indonesian indigenous fungi.@*Methodology and results@#Fungi were screened for their ability to produce alpha-amylase and glucoamylase in the presence of glucose. The strains were grown in a medium containing starch and glucose as carbon sources with glucose concentrations varying from 0 to 5% for four days, and the alpha-amylase and glucoamylase were analyzed at the end of the growth period. Most strains showed repression on the amylases production when glucose was added to the medium. However, some strains showed no repression on amylases production when glucose was supplemented to the medium. The addition of glucose repressed glucoamylase production, but no repression on alpha-amylase was noted for strain KKB4, vice versa, there was repression on alpha-amylase production but no repression on glucoamylase production for strain FIG1. Strains FNCC 6151 and MLT1J1 showed no repression on both alpha-amylase and glucoamylase production when glucose was added to the medium up to 5%. The occurrence of repression in the production of alpha-amylase and glucoamylase was strain-specific.@*Conclusion, significance and impact of study@#Out of the nine indigenous fungi strains examined, strains FNCC 6151 and MLT1J1 showed no repression on both alpha-amylase and glucoamylase production when glucose was added to the medium up to 5%. Those two strains have the potential to be improved further to produce both alpha-amylase and glucoamylase.

Characterization and structure of a novel thermostable glucoamylase from Talaromyces leycettanus JCM12802 / 生物工程学报

Glucoamylase is a critical ingredient for saccharification in the starch decomposition, and widely used in food, pharmaceutical and fermentation industries. Glucoamylases are usually thermostable and have peak activities at high temperature, as required for the industrial process of glucose production. In this study, a glucoamylase gene belonging to the glycoside hydrolase (GH) family 15, Tlga15A, was cloned from Talaromyces leycettanus JCM12802, and successfully expressed in Pichia pastoris GS115. Recombinant glucoamylase TlGA showed optimal activities at pH 4.5 and 75 °C. The result of thermostability analysis showed that TlGA retained above 70% activity after incubating for 1 h at 65 °C, and 43% residual activity after 30 min at 70 °C. Moreover, TlGA had high resistance to most metal ions and chemical reagents tested. Various starch substrates could be hydrolyzed by TlGA, including soluble starch (255.6±15.3) U/mg, amylopectin (342.3±24.7) U/mg, glycogen (185.4±12.5) U/mg, dextrin (423.3±29.3) U/mg and pullulan (65.7±8.1) U/mg. The primary, secondary and tertiary structures of glucoamylase were further analyzed. The low ratio of Gly in the primary structure and low exposed nonpolarity solvent accessible surface in the tertiary structure may be the main reasons for TlGA's thermostability. These results show that TlGA is great promising for potential use in the commercial production of glucose syrups. Moreover, this research will provide knowledge and innovating ideas for the improvement of glucoamylase thermostability.

Antidiabetic potential of methanol extracts from leaves of Piper umbellatum L. and Persea americana Mill

Objective: To determine inhibitory activity of methanolic leaf extract of Piper umbellatum and Persea americana (P. americana) (traditionally used in Cameroon against diabetes) on α-glucosidase, β-glucosidase, maltase-glucoamylase, aldose reductase and aldehyde reductase activities, enzymes involved in starch digestion or diabetic complications. Methods: The methanol extracts from Piper umbellatum and P. americana were prepared by maceration. To assess relative efficacy of these extracts, the determination of concentrations that were needed to inhibit 50% of enzyme activity was done, whereas, gas chromatography-mass spectrum was used to identify components from extracts that may be responsible for the activities. Results: The tested extracts strongly inhibited α-glucosidase, maltase-glucoamylase, aldose reductase and aldehyde reductase activities with IC

Antidiabetic potential of methanol extracts from leaves of Piper umbellatum L.and Persea americana Mill

Objective:To determine inhibitory activity of methanolic leaf extract of Piper umbellatum and Persea americana (P.americana) (traditionally used in Cameroon against diabetes) on α-glucosidase,β-glucosidase,maltase-gluconmylase,aldose reductase and aldehyde reductase activities,enzymes involved in starch digestion or diabetic complications.Methods:The methanol extracts from Piper umbellatum and P.americana were prepared by maceration.To assess relative efficacy of these extracts,the determination of concentrations that were needed to inhibit 50％ of enzyme activity was done,whereas,gas chromatography-mass spectrum was used to identify components from extracts that may be responsible for the activities.Resullts The tested extracts strongly inhibited α-glucosidase,maltase-glucoamylase,aldose reductase and aldehyde reductase activities with IC50 ranging from (1.07 ± 0.03) to 01.77 + 1.17) μg/mL.Among the tested extracts,P.americana was the most active against sensitive enzymes (IC50 of 1.07 ± 0.03 to 15.63 ± 1.23).But,none of the extracts showed interesting inhibitory effect against β-glucosidase as their percentage inhibitions were less than 16％.From gas chromatographymass spectrum analysis,10 and 8 compounds were identified in Piper umbellatum and P.americana extracts respectively,using NIST library 2014.Conclusions:Results of this study provide the scientific credential for a prospective usage of these plants to treat diabetes.

Bioprospection and characterization of the amylolytic activity by filamentous fungi from Brazilian Atlantic Forest / Bioprospecção e caracterização da atividade amilolítica de fungos filamentosos da Mata Atlântica Brasileira

Abstract Filamentous fungi are widely diverse and ubiquitous organisms. Such biodiversity is barely known, making room for a great potential still to be discovered, especially in tropical environments - which are favorable to growth and species variety. Filamentous fungi are extensively applied to the production of industrial enzymes, such as the amylases. This class of enzymes acts in the hydrolysis of starch to glucose or maltooligosaccharides. In this work twenty-five filamentous fungi were isolated from samples of decomposing material collected in the Brazilian Atlantic Forest. The two best amylase producers were identified as Aspergillus brasiliensis and Rhizopus oryzae. Both are mesophilic, they grow well in organic nitrogen-rich media produce great amounts of glucoamylases. The enzymes of A. brasiliensis and R. oryzae are different, possibly because of their phylogenetical distance. The best amylase production of A. brasiliensis occurred during 120 hours with initial pH of 7.5; it had a better activity in the pH range of 3.5-5.0 and at 60-75°C. Both fungal glucoamylase had wide pH stability (3-8) and were activated by Mn2+. R. oryzae best production occurred in 96 hours and at pH 6.5. Its amylases had a greater activity in the pH range of 4.0-5.5 and temperature at 50-65ºC. The most significant difference between the enzymes produced by both fungi is the resistance to thermal denaturation: A. brasiliensis glucoamylase had a T50 of 60 minutes at 70ºC. The R. oryzae glucoamylase only had a residual activity when incubated at 50°C with a 12 min T50.

Resumo Fungos filamentosos são organismos amplamente diversificados e ubíquos. Esta biodiversidade ainda é pouco caracterizada, desta forma, há um grande potencial a ser descoberto, sobretudo em biomas tropicais, que favorecem o crescimento e diversificação de espécies. Fungos filamentosos são extensivamente utilizados para a produção industrial de enzimas, como as amilases. Esta classe de enzimas atua na hidrólise do amido em glicose ou maltooligossacarídeos. Neste trabalho 25 cepas de fungos filamentosos foram isoladas a partir de amostras de material em decomposição coletados na Mata Atlântica Brasileira. As duas cepas que produziram mais amilases foram identificadas como Aspergillus brasiliensis e Rhizopus oryzae. Ambos os fungos são mesofílicos, crescem bem em meio de cultivo rico em nitrogênio orgânico, e produziram grande quantidade de glucoamilase. As enzimas de A. brasiliensis e R. oryzae possuem características distintas, possivelmente devido à distância filogenética das espécies. A produção de amilase mais expressiva de A. brasiliensis ocorreu em 120 horas de cultivo e pH inicial de 7,5; possui maior atividade em temperaturas entre 60-75ºC e pH entre 3,5-5,0. Ambas glucoamilases fúngicas obtiveram ampla estabilidade de pH (3-8) e foram ativadas por Mn2+. A melhor produção de R. oryzae ocorreu em 96 horas de cultivo e pH 6,5. Suas amilases são mais ativas na faixa de pH de 4,0-5,5 e temperatura entre 50-60ºC. A diferença mais significativa dentre as enzimas produzidas pelos fungos selecionados é a resistência à desnaturação térmica, tendo a glucoamilase de A. brasiliensis um T50 de 60 minutos a 70ºC, já a glucoamilase de R. oryzae somente obteve atividade residual quando incubada a 50°C, com um T50 de apenas 12 minutos.

Three new shuttle vectors for heterologous expression in Zymomonas mobilis

Background: Zymomonas mobilis, as a novel platform for bio-ethanol production, has been attracted more attention and it is very important to construct vectors for the efficient expression of foreign genes in this bacterium. Results: Three shuttle vectors ( pSUZM 1, pSUZM2 and pSUZM3 ) were first constructed with the origins of replication from the chromosome and two native plasmids (pZZM401 and pZZM402) of Z. mobilis ZM4, respectively. The three shuttle vectors were stable in Z. mobilis ZM4 and have 3,32 and 27 copies, respectively. The promoter Ppdc (a), from the pyruvate decarboxylase gene, was clonedinto the shuttle vectors, generatingthe expressionvectors pSUZM1(2, 3)a. The codon-optimized glucoamylase gene from Aspergillus awamori combined with the signal peptide sequence from the alkaline phosphatase gene of Z. mobilis was cloned into pSUZM1(2, 3)a, resulting in the plasmids pSUZM1a-GA, pSUZM2a-GA and pSUZM3a-GA, respectively. After transforming these plasmids into Z. mobilis ZM4, the host was endowed with glucoamylase activity for starch hydrolysis. Both pSUZM2a-GA and pSUZM3a-GA were more efficientatproducingglucoamylase thanpSUZM1a-GA. Conclusions: These results indicated that these expression vectors are useful tools for gene expression in Z. mobilis and this could provide a solid foundation for further studies of heterologous gene expression in Z. mobilis.

Electrophoresis separation and MS analysis of proteins in fermentation broth of Poria cocos / 中草药

Objective: In order to carry out the study on proteins from Poria cocos fermentation broth, the proteins in the fermentation broth were separated and identified. Methods: Proteins were obtained by organic acid precipitation from the fermentation broth and the protein concentration was determined by Bradford method. The obtained P. cocos secreted proteins were separated on SDS-PAGE electrophoresis, subjected to in-gel digestion, then identified by mass spectrometric analysis followed by database searching. Results: The protein concentration in the fermentation broth was around 74.01 μg/mL, with the apparent molecular weight ranged from 2.8 × 104 to 1.3 × 105. A total of 52 P. cocos secreted proteins were identified, including catalase, protein kinase, alkaline protease, glucoamylase, lysozyme, and so on. Conclusion: P. cocos fermentation broth has abundant proteins, which could be a good material for the study of P. cocos protein and also a potential healthy food and beverage.

Determination of polysaccharide in Lycium barbarum L. extract powder containing malt dextrin / 国际药学研究杂志

Objective To establish a method for determination of polysaccharide in Lycium barbarum L. extract powder containing with malt dextrin. Method Maltodextrin was treated with glucoamylase hydrolysis and ethanol precipitation successively; then the phenol-sulfuric acid method was used to determine the content of polysaccharide. The glucoamylase hydrolysis technolgy of malt dextrin was optimized, and the variation of polysaccharide content before and after hydrolysis, the difference of polysaccharide contents between direct determination and truth were compared. Morever, the hydrolysis effect of glucoamylase on Lycium barbarum L. was investigated. Results The optimum hydrolysis condition was: temperature 60" , the ratio of enzyme to substrate 1 #5, hydrolysis time 30 min. The polysaccharide content determined directly was significantly higher than the real value (P0.05). Glucoamylase showed no hydrolysis effects on Lycium barbarum L. polysaccharide. Conclusion Glucoamylase hydrolysis can deplete the influence of malt dextrin on determination of polysaccharide in Lycium barbarum L. extract powder, the procedure is simple and effective.

Determination of polysaccharide in Lycium barbarum L. extract powder containing malt dextrin / 国际药学研究杂志

Objective To establish a method for determination of polysaccharide in Lycium barbarum L . extract powder containing with malt dextrin. Method Maltodextrin was treated with glucoamylase hydrolysis and ethanol precipitation successively;then the phenol-sulfuric acid method was used to determine the content of polysaccharide. The glucoamylase hydrolysis technolgy of malt dextrin was optimized, and the variation of polysaccharide content before and after hydrolysis, the difference of polysaccharide contents between direct determination and truth were compared. Morever, the hydrolysis effect of glucoamylase on Lycium barbarum L. was investigated. Results The optimum hydrolysis condition was: temperature 60℃, the ratio of enzyme to substrate 1∶5, hydrolysis time 30 min. The polysaccharide content determined directly was significantly higher than the real value (P0.05). Glucoamylase showed no hydrolysis effects on Lycium barbarum L. polysaccharide. Conclusion Glucoamylase hydrolysis can deplete the influence of malt dextrin on determination of polysaccharide in Lycium barbarum L. extract powder, the procedure is simple and effective.

Antimicrobial screening of Garlic (Allium sativum) extracts and their effect on Glucoamylase activity in-vitro.

Amongst the various extracts, Petrol-ether and Chloroform extracts of garlic were found to be good antimicrobial agents against Escherechia coli, Pseudomonas Aeruginosa, Bacilli Subtilis and Staphylococcus Aureus, and moderate inhibitors of Glucoamylase, an enzyme prominent in carbohydrate metabolism. Whereas, the Ethyl acetate and Methanolic extracts did not exhibit antimicrobial activity and found moderate to good activators of Glucoamylase.

Effect of Epigallocatechin gallate isolated from Terminalia Bellerica fruit rind on glucoamylase activity in vitro.

Chloroform-Ethyl Acetate fraction of Terminalia bellerica fruit rind powder showed maximum antimicrobial activity. This fraction on further purification by column chromatography gave a single spot compound, which after characterisation was found to be Epigallocatechin gallate. Epigallo catechin gallate showed significant antimicrobial activity against E.coli, B. subtilis and S. Aureus. Epigallocatechin gallate inhibits 23.13 to 46.24 % activity of glucoamylase at very low concentrations, therefore may be used as hypoglycaemic agent showing good agreement with the earlier literature.

Biochemical characterisation of a glucoamylase from Aspergillus niger produced by solid-state fermentation

In this work, glucoamylase was produced by Aspergillus niger in solid-state fermentation. The enzyme was partially purified by ammonium sulphate precipitation and ion exchange and gel filtration chromatographies. Its molecular mass was estimated as 118.17 kDa by electrophoresis. The partially purified enzyme had an optimum pH range of 4.5-5.0 and an optimum temperature of 60 °C, with average activity 152.85 U mL-1. Thermal and pH stability assays with the crude extract showed that more than 60 percent of the activity remained at pH 4.6 and 60 °C, even after an exposition to these conditions longer than 24 h. Yet, after purification, the enzyme was stable at these for at least 4 h, which indicated that its purification for use in starch saccharification was inadvisable. K M and Vmax were 0.34 mg mL-1 and 160.22 U mL-1, respectively.

Localization and partial characterization of thermostable glucoamylase produced by newly isolated Thermomyces lanuginosus TO3 in submerged fermentation

Thermophilic Thermomyces lanuginosus strain TO3 was isolated from compost pile samples and was used for its ability to produce considerable glucoamylase activity when growing in liquid medium at 45ºC with starch as the sole carbon source. Enzyme productivity was high in submerged fermentation (SmF) with maximum activity of 13 U/mL after 168 h of fermentation. Higher quantities of glucose were released when the substrate for enzyme was soluble starch than maltose or maltooligosaccharides were used. The distribution of glucoamylase between the extracellular and cell-associated fractions varied according to fermentation time. Glucoamylase produced from T. lanuginosus TO3 had optimum activity at 65 ºC and good thermostability in the absence of substrate, with a half-life of 6 h at 60 ºC. The enzyme was stable over a wide pH range (4.0-10.0).

O fungo termofílico Thermomyces lanuginosus TO3 foi isolado a partir de amostras de material de pilhas de compostagem, com base em sua capacidade de crescer em meio líquido contendo amido como única fonte de carbono, a 45 ºC, e produzir considerável quantidade de glucoamilase. A produção da enzima por fermentação submersa FSm foi alta, com um máximo de 13 U/mL em 168 h de fermentação. A atividade enzimática foi maior sobre amido do que sobre a maltose e maltooligosacarideos. As atividades de glucoamilase extra e intracelular variaram com o tempo de fermentação. A glucoamilase produzidas por T. lanuginosus TO3 apresentou elevada temperatura ótima de atividade (65 -70 ºC) com boa termoestabilidade em ausência de substrato, apresentando uma meia vida de 6 h a 60ºC, além de estabilidade em ampla faixa de pH. Os resultados apresentados indicam uma importante fonte alternativa de glucoamilase para uso no processamento industrial de amido.

Mycelial glucoamylases produced by the thermophilic fungus Scytalidium thermophilum strains 15.1 and 15.8: purification and biochemical characterization / Glucoamilases miceliais produzidas pelas linhagens 15.1 e 15.8 do fungo termofílico Scytalidium thermophilum: purificação e caracterização bioquímica

Two strains (15.1 and 15.8) of the thermophilic fungus Scytalidium thermophilum produced high levels of intracellular glucoamylases, with potential for industrial applications. The isoform I of the glucoamylase produced by 15.1 strain was sequentially submitted to DEAE-Cellulose and CM-Cellulose chromatography, and purified 141-fold, with 5.45 percent recovery. The glucoamylase of strain 15.8 was purified 71-fold by CM-Cellulose and Concanavalin A-Sepharose chromatography, with 7.38 percent recovery. Temperature and pH optima were in the range of 50-60ºC and 5.0-6.0, respectively, using starch and maltose as substrates. The glucoamylase of S. thermophilum 15.8 was more stable (t50 > 60 min) than that of S. thermophilum 15.1 (t50= 11-15 min), at 60ºC. The glucoamylase activities were enhanced by several ions (e.g. Mn2+ and Ca2+) and inhibited by β-mercaptoethanol. The glucoamylase from 15.1 strain showed a Km of 0.094 mg/ml and 0.029 mg/ml and Vmax of 202 U/mg prot and 109 U/mg prot, for starch and maltose, respectively. The hydrolysis products of starch and maltose, analyzed by TLC, demonstrated glucose as end product and confirming the character of the enzyme as glucoamylase. Differences were observed in relation to the products formed with maltose as substrate between the two strains studied. S. thermophilum 15.8 formed maltotriose in contrast with S. thermophilum 15.1.

Duas linhagens (15.1 e 15.8) do fungo termofílico Scytalidium thermophilum se mostraram produtoras de grandes quantidades de glucoamilases, com potencial aplicação industrial. A isoforma I de glucoamilase produzida pela linhagem 15.1 foi submetida seqüencialmente a cromatografia em colunas de DEAE-celulose e CM-celulose, sendo purificada 141 vezes com porcentagem de recuperação de 5,45 por cento. A glucoamilase da linhagem 15.8 foi purificada 71 vezes através do uso de colunas de cromatografia de CM-celulose e Concanavalina A-sepharose com porcentagem de recuperação de 7,38 por cento. Temperatura e pH ótimo foram de 50-60ºC e 5,0-6,0 respectivamente, utilizando-se amido e maltose como substratos. A glucoamilase de S. thermophilum 15.8 se mostrou mais estável (t50 > 60 min) que a de S. thermophilum 15.1 (t50 =11-15min) a 60ºC. As glucoamilases tiveram suas atividades enzimáticas aumentadas na presença de vários íons (ex: Mn2+, e Ca2+) e inibidas por β-mercaptoetanol. A glucoamilase da linhagem 15.1 apresentou um Km de 0,094 mg/ml e 0,029 mg/ml and Vmax de 202U/mg prot e 109U/mg prot, para amido e maltose respectivamente. A análise do produto da hidrólise de amido e maltose por TLC, demonstrou que o produto final era glucose, confirmando as características da enzima como glucoamilase. Diferenças entre as duas linhagens foram observadas com relação aos produtos formados tendo maltose como susbstrato, a linhagem 15.8 de S. thermophilum produziu maltotriose como produto final em contrate com a linhagem 15.1.

Production and characterization of glucoamylase from fungus Aspergillus awamori expressed in yeast Saccharomyces cerevisiae using different carbon sources

Glucoamylase is widely used in the food industry to produce high glucose syrup, and also in fermentation processes for production beer and ethanol. In this work the productivity of the glucoamylase of Aspergillus awamori expressed by the yeast Saccharomyces cerevisiae, produced in submerged fermentation using different starches, was evaluated and characterized physico-chemically. The enzyme presented high specific activity, 13.8 U/mgprotein or 2.9 U/mgbiomass, after 48 h of fermentation using soluble starch as substrate. Glucoamylase presented optimum activity at temperature of 55ºC, and, in the substratum absence, the thermostability was for 1h at 50ºC. The optimum pH of activity was pH 3.5 - 4.0 and the pH stability between 5.0 and 7.0. The half life at 65ºC was at 30.2 min, and the thermal energy of denaturation was 234.3 KJ mol-1. The hydrolysis of different substrate showed the enzyme's preference for the substrate with a larger polymerization degree. The gelatinized corn starch was the substratum most susceptible to the enzymatic action.

A glucoamilase é amplamente utilizada na indústria de alimentos no processamento do amido para a produção de xarope com alto teor de glicose e também muito empregada nos processos de fermentação para produção de cerveja e etanol. Neste trabalho a glucoamilase de Aspergillus awamori expressa em Saccharomyces cerevisiae produzida sob fermentação líquida foi avaliada quanto à produtividade em diferentes amidos e caracterizada físico-quimicamente. A enzima apresentou alta atividade específica de 13,8 U/mg proteína e de 2,9 U/mg biomassa ao final de 48 h de fermentação em meio contendo amido solúvel. A glucoamilase apresentou temperatura ótima de atividade a 55ºC, e temperatura de desnaturação térmica na ausência de substrato por 1h a 50ºC. O pH ótimo de atividade foi na faixa de 3,5 - 4,0 e a estabilidade ao pH entre os valores 5,0 e 7,0. A meia vida a 65ºC foi 30,2 min., e a energia de desnaturação foi de 234.3 KJ mol-1. A hidrólise em diferentes substratos mostrou a preferência da enzima pelos substratos com maior grau de polimerização, sendo o amido de milho gelatinizado o substrato preferencial à ação enzimática.

Characteristics of the Amylase and its Related Enzymes Produced by Ectomycorrhizal Fungus Tricholoma matsutake

Extracellular amylase properties were examined with the mycelium of Tricholoma matsutake isolated from ectomycorrhizal roots of Pinus densiflora. The molecular weights of alpha-amylase and glucoamylase were estimated as 34.2 kD and 11.5 kD, respectively, after eluted through Superdex 75 column. The optimum pH of the purified enzyme was found in a range of pH 5.0~6.0, with a peak at pH 5.0. The activities of these enzymes were stable from 4degrees C to 30degrees C. The alpha-amylase of T. matsutake readily hydrolyzed soluble starch and amylose-B, while it weakly hydrolyzed glycogen, dextrin, amylose and amylose-A. The main products of hydrolysis were confirmed to be glucose, maltose and maltotriose on the basis of the similarities in the thin layer chromatographic mobility.

Amylases of the thermophilic fungus Thermomyces lanuginosus: Their purification, properties, action on starch and response to heat.

A thermophilic fungus Thermomyces la nuginosus, strain IISc 91, secreted one form each of α-amylase and glucoamylase during growth. Both enzymes were purified to homogeneity by ion-exchange and gel-filtration chromatography and obtained in mg quantities. α-Amylase was considered to be a dimeric protein of ~ 42 kDa and contained 5% (by mass) carbohydrate. It was maximally active at pH 5·6 and at 65°C. It had an activation energy of 44 kJ mol–1. The apparent Km for soluble starch was 2·5 mg ml–1. The enzyme produced exceptionally high levels of maltose from raw potato starch. At 50°C, the enzyme was stable for > 7h. At 65°C, α-amylase was nearly 8-times more stable in the presence of calcium. Addition of calcium increaed the melting temperature of α-amylase from 66°C to 73°C. Upon incubation at 94°C, α-amylase was progressively and irreversibly inactivated, and converted into an inactive 72 kDa trimeric species. Glucoamylase was a monomeric glycoprotein of ~ 45 kDa with a carbohydrate content of 11% (by mass). It effected up to 76% conversion of starch in 24 h producing glucose as the sole product. Its apparent Km for soluble starch was 0·04 mg ml–1 and Vmax was 660 μmol glucose min–1 mg protein–1. It also hydrolyzed maltose. Its activity on maltooligosaccharides increased with the chain length of the substrates. Glucoamylase was stable at 60°C for over 7h. Its activation energy was 61 kJ mol–1 Glucoamylase did not show synergistic effect with α- amylase. The properties of α-amylase and glucoamylase of Thermo my ces lanuginosus strain IISc 91 suggest their usefulness in the commercial production of maltose and glucose syrups.

SCREENING AND MUTATING A RAW STARCH-DIGESTING GLUCOAMYLASE STRAIN / 微生物学通报

strains that could produce raw starch-digesting glucoamylase were isolated from soil and mildewed rice.The highest raw starch-digesting glucoamylase activity strain named OR-1 was identified as Rhizopus.sp.The raw starch-digesting glucoamylase activity of the strain is 90U/mL.Through UV and NTG mutagenesis,the raw starch-digesting glucoamylase activity raised to 200U/mL and 325U/mL respectively.The RDA were 70% and 65% respectively.

THE CHEMICAL COMPOSITION AND SPECTRUM CHARACTERISTICS OF GLUCOAMYLASE FROM AN ASPERGILLUS NIGER MUTANT / 微生物学通报

Purified GAI, one form of glucoamylase obtained from Aspergillus niger mutant T21 contained 17.6% total carbohydrate. Analyses of amino acid composition showed that GAI contained about 25% Ser and Thr, 20.3% Asx and Glx and 6% basic amino acids. The UV absorption and fluorescence spectra of GAI were determined. The maximum absorption wavelength was at 278nm and minimum at 250nm. For fluorescent analyses the excitation and maximum emission spectra were at 284nm and 342nm respectively. The CD-spectrum determined showed two negative peaks. Its dispersion of secondary structure in solution showed 10.6% ?-helix, 16.3% ?-form and 73.1% unordered.

Production of High Ethanol Concentration from Raw Corn Flour Using Rhizopus sp. and Saccharomyces cerevisiae / 微生物学通报

A novel raw-starch-digesting glucoamylase producer,Rhizopus sp.W-08,was used in a novel fermentation system of solid-state followed by submerged,and high enzyme activity of 72 IU/mL was obtained.In the following simultaneous saccharification and fermentation process, Saccharomyces cerevisiae Z-06 directly converted raw corn flour to ethanol with the concentration of 21 % (V/V) at 30℃ after 48h.The conversion efficiency of raw corn flour to ethanol was 94.5 % of the theoretical ethanol yield.