Production of amylases by Aspergillus tamarii

The glucoamylase from Aspergillus wentii: Purification and characterization

This study describes for the first time the purification and characterization of a glucoamylase from Aspergillus wentii (strain PG18), a species of the Aspergillus genus Cremei section. Maximum enzyme production (∼3.5 U/ml) was obtained in submerged culture (72 h) with starch as the carbon source, at 25°C, and with orbital agitation (100 rpm). The enzyme was purified with one-step molecular exclusion chromatography. The 86 kDa purified enzyme hydrolyzed starch in a zymogram and had activity against p-nitrophenyl α- d-glucopyranoside. The optimal enzyme pH and temperature were 5.0 and 60°C (at pH 5.0), respectively. The T_m of the purified enzyme was 60°C, at pH 7.0. The purified glucoamylase had a K_M for starch of 1.4 mg/ml and a V_max of 0.057 mg/min of hydrolyzed starch. Molybdenum activated the purified enzyme, and sodium dodecyl sulfate inhibited it. A thin layer chromatography analysis revealed glucose as the enzyme's main starch hydrolysis product. An enzyme's peptide sequence was obtained by mass spectrometry and used to retrieve a glucoamylase within the annotated genome of A. wentii v1.0. An in silico structural model revealed a N-terminal glycosyl hydrolases family 15 (GH15) domain, which is ligated by a linker to a C-terminal carbohydrate-binding module (CBM) from the CBM20 family.

Filamentous fungi with high paraquat-degrading activity isolated from contaminated agricultural soils in northern Thailand

The contamination of paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride) herbicide from the farming area has become a public concern in many countries. This herbicide harms to human health and negatively effects the soil fertility. Several methods have been introduced for the remediation of paraquat. In this study, 20 isolates of the paraquat-tolerant fungi were isolated from the contaminated soil samples in northern Thailand. We found that isolate PRPY-2 and PFCM-1 exhibited the highest degradation activity of paraquat on synthetic liquid medium. About 80 and 68% of paraquat were removed by PRPY-2 and PFCM-1 respectively after 15 days of cultivation. Based on the morphological characteristic and molecular analysis, the fungal isolate PRPY-2 and PFCM-1 were identified as Aspergillus tamarii and Cunninghamella sp. respectively. The biosorption of paraquat on these fungal mycelia was also investigated. It was found that only 8-10% of paraquat could be detected on their mycelia, while 24-46% of paraquat was degraded by fungal mycelia. This is the first report on paraquat degrading ability by A. tamarii and Cunninghamella sp. It is demonstrated that these filamentous fungi are promising microorganisms available for remediation of paraquat contaminated environment.

Evolutionary Trends in Industrial Production of α-amylase

BACKGROUND

Amylase catalyzes the breakdown of long-chain carbohydrates to yield maltotriose, maltose, glucose and dextrin as end products. It is present in mammalian saliva and helps in digestion.

OBJECTIVE

Their applications in biotechnology include starch processing, biofuel, food, paper, textile and detergent industries, bioremediation of environmental pollutants and in clinical and medical applications. The commercial microbial strains for production of α-amylase are Bacillus subtilis, B. licheniformis, B. amyloliquefaciens and Aspergillus oryzae. Industrial production of enzymes requires high productivity and cannot use wild-type strains for enzyme production. The yield of enzyme from bacteria can be increased by varying the physiological and genetic properties of strains.

RESULTS

The genetic properties of a bacterium can be improved by enhancing the expression levels of the gene and secretion of the enzyme outside the cells, thereby improving the productivity by preventing degradation of enzymes. Overall, the strain for specific productivity should have the maximum ability for synthesis and secretion of an enzyme of interest. Genetic manipulation of α-amylase can also be used for the production of enzymes with different properties, for example, by recombinant DNA technology.

CONCLUSION

This review summarizes different techniques in the production of recombinant α- amylases along with the patents in this arena. The washing out of enzymes in reactions became a limitation in utilization of these enzymes in industries and hence immobilization of these enzymes becomes important. This paper also discusses the immobilization techniques for used α-amylases.

Marine Microbial Amylases: Properties and Applications

Amylases are crucial enzymes which hydrolyze internal glycosidic linkages in starch and produce as primary products dextrins and oligosaccharides. Amylases are classified into α-amylase, β-amylase, and glucoamylase based on their three-dimensional structures, reaction mechanisms, and amino acid sequences. Amylases have innumerable applications in clinical, medical, and analytical chemistries as well as in food, detergent, textile, brewing, and distilling industries. Amylases can be produced from plants, animals, and microbial sources. Due to the advantages in microbial production, it meets commercial needs. The pervasive nature, easy production, and wide range of applications make amylase an industrially pivotal enzyme. This chapter will focus on amylases found in marine microorganisms, their potential industrial applications, and how these enzymes can be improved to the required bioprocessing conditions.

Production of raw starch-saccharifying thermostable and neutral glucoamylase by the thermophilic mold Thermomucor indicae-seudaticae in submerged fermentation

Among physical and nutritional parameters optimized by "one variable at a time" approach, four cultural variables (sucrose, MgSO4 .7H2O, inoculum size, and incubation period) significantly affected glucoamylase production. These variables were, therefore, selected for optimization using response surface methodology. The p-values of the coefficients for linear effect of sucrose and inoculum size were less than 0.0001, suggesting them to be the key experimental variables in glucoamylase production. The enzyme production (34 U/ml) attained under optimized conditions (sucrose, 2%; MgSO4 .7H2O, 0.13%; yeast extract, 0.1%; inoculum size, 5 x 10(6) spores per 50 ml production medium; incubation time, 48 h; temperature, 40 degrees C; and pH 7.0) was comparable with the value predicted by polynomial model (34.2 U/ml). An over all 3.1-fold higher enzyme titers were attained due to response surface optimization. The experimental model was validated by carrying out glucoamylase production in shake flasks of increasing capacity (0.25-2.0 l) and 22-l laboratory bioreactors (stirred tank and airlift), where the enzyme production was sustainable. Furthermore, the fermentation time was reduced from 48 h in shake flasks to 32 h in bioreactors.

Production and properties of alpha-amylase from Penicillium chrysogenum and its application in starch hydrolysis

Fungi were screened for their ability to produce alpha-amylase by a plate culture method. Penicillium chrysogenum showed high enzymatic activity. Alpha-amylase production by P. chrysogenum cultivated in liquid media containing maltose (2%) reached its maximum at 6-8 days, at 30 degrees C, with a level of 155 U ml(-1). Some general properties of the enzyme were investigated. The optimum reaction pH and temperature were 5.0 and 30-40 degrees C, respectively. The enzyme was stable at a pH range from 5.0-6.0 and at 30 degrees C for 20 min and the enzyme's 92.1% activity's was retained at 40 degrees C for 20 min without substrate. Hydrolysis products of the enzyme were maltose, unidefined oligosaccharides, and a trace amount of glucose. Alpha-amylase of P. chrysogenum hydrolysed starches from different sources. The best hydrolysis was determined (98.69%) in soluble starch for 15 minute at 30 degrees C.