Production of amylase by Aspergillus fumigatus utilizing alpha-methyl-D-glycoside, a synthetic analogue of maltose, as substrate

Kinetics of improved 1,4-alpha-D-glucan glucohydrolase biosynthesis from a newly isolated Aspergillus oryzae IIB-6 and parameter significance analysis by 2-factorial design

Sixteen different mould cultures viz. Aspergillus, Alternaria, Arthroderma, Trichoderma, Fusarium, Penicillium, Rhizopus and Chochliobolus were isolated from the soil samples of Qatar by serial dilution method. The preliminary screening of isolates was done by selecting initial colonies showing relatively bigger zones of starch hydrolysis on nutrient agar plates. The isolates were then subjected to secondary screening by submerged fermentation (SmF). The 1,4-α-D-glucan glucohydrolase (GGH) activity ranged from 1.906-12.675 U/ml/min. The product yield was analysed in dependence of mycelial morphology, biomass level and protein content. The isolate Aspergillus oryzae llB-6 which gave maximum enzyme production was incubated in M3 medium containing 20 g/l starch, 10 g/l lactose, 8.5 g/l yeast extract, 6 g/l corn steep liquor (CSL), 1.2 g/l MgSO₄.7H₂O, 1.3 g/l NH₄Cl, 0.6 g/l CaCl₂.2H₂O, pH 5 at 30±2°C and 200 rpm. On the basis of kinetic variables, notably Q_p (0.058±0.01^a U/g/h), Y_p/s (0.308±0.03^ab U/g) and q_p (0.210±0.032^abc U/g fungal biomass/h), A. oryzae IIB-6 was found to be a hyper producer of GGH (LSD 0.0345) compared to A. kawachii IIB-2. A noticeable enhancement in enzyme activity of over 30% was observed (13.917±1.01 U/ml/min) when the process parameters viz. cultural conditions (pH 5, incubation period 72 h) and nutritional requirements (6 g/l CSL, 9.5 g/l yeast extract, 10 g/l starch, 20 g/l lactose) were further optimized using a 2-factorial Plackett-Burman design. The model terms were found to be highly significant (HS, p≤0.05), indicating the potential utility of the culture (dof~3).

Indigestible dextrin stimulates glucoamylase production in submerged culture of Aspergillus kawachii

Submerged batch cultures of Aspergillus kawachii grown on indigestible dextrin were investigated for potential improvements in glucoamylase (GA) production. In flask culture, specific GA productivities per dry weight biomass using dextrin and indigestible dextrin were 11.0 and 56.1 mU/mg-DW, respectively. Indigestible dextrin was a poor substrate for enzymatic hydrolysis. Rates of glucose formation from dextrin and indigestible dextrin by enzymatic hydrolysis were 0.477 and 0.100 mg-glucose/ml/h, respectively. For this reason, residual glucose concentrations in batch cultures grown on indigestible dextrin remained below 1.32 mg/ml where glucose-limiting conditions were easily maintained. Batch culture using indigestible dextrin had the same residual glucose profile as dextrin fed-batch culture, and nearly the same GA activity was obtained after 42.5 h of growth. However, between 42.5 and 66 h, the GA production rate of the indigestible dextrin batch culture (11.5 mU/ml/h) was higher than that of the dextrin fed-batch culture (6.5 mU/ml/h). During this period, a high amount of residual maltooligosaccharide was detected in the culture supernatant grown on indigestible dextrin. The high GA productivity observed in the indigestible dextrin batch culture may have resulted from the absence of glucose and the simultaneous presence of maltooligosaccharides throughout growth.

Biochemical and Structural Characterization of Amy1: An Alpha-Amylase from Cryptococcus flavus Expressed in Saccharomyces cerevisiae

An extracellular alpha-amylase (Amy1) whose gene from Cryptococcus flavus was previously expressed in Saccharomyces cerevisiae was purified to homogeneity (67 kDa) by ion-exchange and molecular exclusion chromatography. The enzyme was activated by NH₄⁺ and inhibited by Cu⁺² and Hg⁺². Significant biochemical and structural discrepancies between wild-type and recombinant α-amylase with respect to K_m values, enzyme specificity, and secondary structure content were found. Far-UV CD spectra analysis at pH 7.0 revealed the high thermal stability of both proteins and the difference in folding pattern of Amy1 compared with wild-type amylase from C. flavus, which reflected in decrease (10-fold) of enzymatic activity of recombinant protein. Despite the differences, the highest activity of Amy1 towards soluble starch, amylopectin, and amylase, in contrast with the lowest activity of Amy1_w, points to this protein as being of paramount biotechnological importance with many applications ranging from food industry to the production of biofuels.

Application of microbial α-amylase in industry - A review

Amylases are one of the main enzymes used in industry. Such enzymes hydrolyze the starch molecules into polymers composed of glucose units. Amylases have potential application in a wide number of industrial processes such as food, fermentation and pharmaceutical industries. α-Amylases can be obtained from plants, animals and microorganisms. However, enzymes from fungal and bacterial sources have dominated applications in industrial sectors. The production of α-amylase is essential for conversion of starches into oligosaccharides. Starch is an important constituent of the human diet and is a major storage product of many economically important crops such as wheat, rice, maize, tapioca, and potato. Starch-converting enzymes are used in the production of maltodextrin, modified starches, or glucose and fructose syrups. A large number of microbial α-amylases has applications in different industrial sectors such as food, textile, paper and detergent industries. The production of α-amylases has generally been carried out using submerged fermentation, but solid state fermentation systems appear as a promising technology. The properties of each α-amylase such as thermostability, pH profile, pH stability, and Ca-independency are important in the development of fermentation process. This review focuses on the production of bacterial and fungal α-amylases, their distribution, structural-functional aspects, physical and chemical parameters, and the use of these enzymes in industrial applications.

Enhancement of acid amylase production by an isolated Aspergillus awamori

AIMS

Evaluation of the influence of fermentation components on extracellular acid amylase production by an isolated fungal strain Aspergillus awamori.

METHODS AND RESULTS

Eight fungal metabolic influential factors, viz. soluble starch, corn steep liquor (CSL), casein, potassium dihydrogen phosphate (KH(2)PO(4)) and magnesium sulfate (MgSO(4) x 7H(2)O), pH, temperature and inoculum level were selected to optimize amylase production by A. awamori using fractional factorial design of Taguchi methodology. Significant improvement in acid amylase enzyme production (48%) was achieved. The optimized medium composition consisted of soluble starch--3%; CSL--0.5%; KH(2)PO(4)--0.125%; MgSO(4) x 7H(2)O--0.125%; casein--1.5% at pH 4.0 and temperature at 31 degrees C.

CONCLUSION

Optimization of the components of the fermentation medium was carried out using fractional factorial design of Taguchi's L-18 orthogonal array. Based on the influence of interaction components of fermentation, these could be classified as the least significant and the most significant at individual and interaction levels. Least significant factors of individual level have higher interaction severity index and vice versa at enzyme production in this fungal strain. The pH of the medium and substrate (soluble starch) showed maximum production impact (60%) at optimized environment. Temperature and CSL were the least influential factors for acid amylase production.

SIGNIFICANCE AND IMPACT OF THE STUDY

Acid amylase production by isolated A. awamori is influenced by the interaction of fermentation factors with fungal metabolism at individual and interaction levels. The pH of the fermentation medium and substrate concentration regulates maximum enzyme production process in this fungal strain.

l-asparaginase production by isolated Staphylococcus sp. ? 6A: design of experiment considering interaction effect for process parameter optimization

AIMS

Evaluation of fermentation process parameter interactions for the production of l-asparaginase by isolated Staphylococcus sp. - 6A.

METHODS AND RESULTS

Fractional factorial design of experimentation (L18 orthogonal array of Taguchi methodology) was adopted to optimize nutritional (carbon and nitrogen sources), physiological (incubation temperature, medium pH, aeration and agitation) and microbial (inoculum level) fermentation factors. The experimental results and software predicted enzyme production values were comparable.

CONCLUSION

Incubation temperature, inoculum level and medium pH, among all fermentation factors, were major influential parameters at their individual level, and contributed to more than 60% of total l-asparaginase production. Interaction data of selected fermentation parameters could be classified as least and most significant at individual and interactive levels. Aeration and agitation were most significant at interactive level, but least significant at individual level, and showed maximum severity index and vice versa at enzyme production.

SIGNIFICANCE AND IMPACT OF THE STUDY

All selected factors showed impact on l-asparaginase enzyme production by this isolated microbial strain either at the individual or interactive level. Incubation temperature, inoculum concentration, pH of the medium and nutritional source (glucose and ammonium chloride) had impact at individual level, while aeration, agitation and incubation time showed influence at interactive level. Significant improvement (ninefold increase) in enzyme production by this microbial isolate was noted under optimized environment.