Journal of Microbiology

Journal Article

Characterization of Trichoderma reesei Endoglucanase II Expressed Heterologously in Pichia pastoris for Better Biofinishing and Biostoning: Sutanu Samanta , Asitava Basu , Umesh Chandra Halder , Soumitra Kumar Sen; J. Microbiol. 2012;50(3):518-525. Published online June 30, 2012; DOI: https://doi.org/10.1007/s12275-012-1207-5

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Abstract: The endoglucanase II of Trichoderma reesei is considered the most effective enzyme for biofinishing cotton fabrics and biostoning denim garments. However, the commercially available preparation of endoglucanase II is usually mixed with other cellulase components, especially endoglucanase I, resulting in hydrolysis and weight loss of garments during biofinishing and biostoning. We thus isolated the endoglucanase II gene from T. reesei to express this in Pichia pastoris, under the control of a methanol-inducible AOX1 promoter, to avoid the presence of other cellulase components. A highly expressible Mut+ transformant was selected and its expression in BMMH medium was found most suitable for the production of large amounts of the recombinant protein. Recombinant endoglucanase II was purified to electrophoretic homogeneity, and functionally characterized by activity staining. The specific activity of recombinant endoglucanase II was found to be 220.57 EU/mg of protein. Purified recombinant endoglucanase II was estimated to have a molecular mass of 52.8 kDa. The increase in molecular mass was likely due to hyperglycosylation. Hyperglycosylation of recombinant endoglucanase II secreted by P. pastoris did not change the temperature or pH optima as compared to the native protein, but did result in increased thermostability. Kinetic analysis showed that recombinant endoglucanase was most active against amorphous cellulose, such as carboxymethyl cellulose, for which it also had a high affinity.

Research Support, Non-U.S. Gov'ts

Identification of an Extracellular Thermostable Glycosyl Hydrolase Family 13 α-Amylase from Thermotoga neapolitana: Kyoung-Hwa Choi , Sungmin Hwang , Hee-Seob Lee , Jaeho Cha; J. Microbiol. 2011;49(4):628-634. Published online September 2, 2011; DOI: https://doi.org/10.1007/s12275-011-0432-7

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Abstract: We cloned the gene for an extracellular α-amylase, AmyE, from the hyperthermophilic bacterium Thermotoga neapolitana and expressed it in Escherichia coli. The molecular mass of the enzyme was 92 kDa as a monomer. Maximum activity was observed at pH 6.5 and temperature 75°C and the enzyme was highly thermostable. AmyE hydrolyzed the typical substrates for α-amylase, including soluble starch, amylopectin, and maltooligosaccharides. The hydrolytic pattern of AmyE was similar to that of a typical α-amylase; however, unlike most of the calcium (Ca2+)-dependent α-amylases, the activity of AmyE was unaffected by Ca2+. The specific activities of AmyE towards various substrates indicated that the enzyme preferred maltooligosaccharides which have more than four glucose residues. AmyE could not hydrolyze maltose and maltotriose. When maltoheptaose was incubated with AmyE at the various time courses, the products consisting of maltose through maltopentaose was evenly formed indicating that the enzyme acts in an endo-fashion. The specific activity of AmyE (7.4 U/mg at 75°C, pH 6.5, with starch as the substrate) was extremely lower than that of other extracellular α-amylases, which indicates that AmyE may cooperate with other highly active extracellular α-amylases for the breakdown of the starch or α-glucans into maltose and maltotriose before transport into the cell in the members of Thermotoga sp.

Characterization of Hyperthermostable Fructose-1,6-Bisphosphatase from Thermococcus onnurineus NA1: Yeol Gyun Lee , Sung Gyun Kang , Jung-Hyun Lee , Seung Il Kim , Young-Ho Chung; J. Microbiol. 2010;48(6):803-807. Published online January 9, 2011; DOI: https://doi.org/10.1007/s12275-010-0377-2

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Abstract: To understand the physiological functions of thermostable fructose-1,6-bisphosphatase (TNA1-Fbp) from Thermococcus onnurineus NA1, its recombinant enzyme was overexpressed in Escherichia coli, purified, and the enzymatic properties were characterized. The enzyme showed maximal activity for fructose-1,6- bisphosphate at 95°C and pH 8.0 with a half-life (t1/2) of about 8 h. TNA1-Fbp had broad substrate specificities for fructose-1,6-bisphosphate and its analogues including fructose-1-phosphate, glucose-1-phosphate, and phosphoenolpyruvate. In addition, its enzyme activity was increased five-fold by addition of 1 mM Mg2+, while Li+ did not enhance enzymatic activity. TNA1-Fbp activity was inhibited by ATP, ADP, and phosphoenolpyruvate, but AMP up to 100 mM did not have any effect. TNA1-Fbp is currently defined as a class V fructose-1,6-bisphosphatase (FBPase) because it is very similar to FBPase of Thermococcus kodakaraensis KOD1 based on sequence homology. However, this enzyme shows a different range of substrate specificities. These results suggest that TNA1-Fbp can establish new criterion for class V FBPases.

Production of Saccharogenic and Dextrinogenic Amylases by Rhizomucor pusillus A 13.36: Tony M. Silva , Derlene Attili-Angelis , Ana Flavia Azevedo Carvalho , Roberto Da Silva , Mauricio Boscolo , Eleni Gomes; J. Microbiol. 2005;43(6):561-568.; DOI: https://doi.org/2289 [pii]

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Abstract: A newly-isolated thermophilic strain of the zygomycete fungus Rhizomucor pusillus 13.36 produced highly active dextrinogenic and saccharogenic enzymes. Cassava pulp was a good alternative substrate for amylase production. Dextrinogenic and saccharogenic amylases exhibited optimum activities at a pH of 4.0-4.5 and 5.0 respectively and at a temperature of 75oC. The enzymes were highly thermostable, with no detectable loss of saccharogenic or dextrinogenic activity after 1 h and 6 h at 60oC, respectively. The saccharogenic activity was inhibited by Ca2+ while the dextrinogenic was indifferent to this ion. Both activities were inhibited by Fe2+ and Cu2+ Hydrolysis of soluble starch by the crude enzyme yielded 66% glucose, 19.5% maltose, 7.7% maltotriose and 6.6% oligosaccharides.

Cloning and Characterization of Thermostable Esterase from Archaeoglobus fulgidus: Seung-Bum Kim , Wonkyu Lee , Yeon-Woo Ryu; J. Microbiol. 2008;46(1):100-107.; DOI: https://doi.org/10.1007/s12275-007-0185-5

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Abstract: Thermostable esterase gene was cloned (Est-AF) from extremophilic microorganisms, Archaeoglobus fulgidus DSM 4304. The protein analysis result showed that Est-AF is monomer with total 247 amino acids and molecular weight of estimated 27.5 kDa. It also showed repeating units G-X-S-X-G (GHSLG) (residues 86~90) which is reported as active site of known esterases, and the putative catalytic triad composed of Ser88, Asp198 and His226. The esterase activity test with various acyl chain length of ρ-nitrophenol resulted that Est-AF showed highest specific activity with ρ-nitrophenylbutyrate (pNPC4) and rapidly decrease with ρ-nitrophenyl ester contain more than 8 carbon chain. These results represent that cloned enzyme is verified as a carboxylesterase but not a lipase because esterase activity is decreased with ρ-nitrophenyl ester contains more than 8 carbon chains but lipase activity does not affected with carbon chain length. Optimum temperature of esterase reaction with ρ-nitrophenylbutyrate (pNPC4) was 80°C. When ketoprofen ethyl ester was used as a substrate, activity of Est-AF showed the highest value at 70°C, and 10% of activity still remains after 3 h of incubation at 90°C. This result represents Est-AF has high thermostability with comparison of other esterases that have been reported. However, Est-AF showed low enantioselectivity with ketoprofen ethyl ester. Optimum pH of Est-AF is between pH 7.0 and pH 8.0. Km value of ketoprofen ethyl ester is 1.6 mM and, Vmax is 1.7 μmole/mg protein/min. Est-AF showed similar substrate affinity but slower reaction with ketoprofen ethyl ester compare with esterase from mesophilic strain P. fluorescens.

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