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( Ramachandran priyadharshini ),( Ngoc Phuong Thao Nguyen ),( Joon Ho Choi ),( Yun Chan Kang ),( Marimuthu Jeya ),( Jung Kul Lee ) 한국미생물 · 생명공학회 2013 Journal of microbiology and biotechnology Vol.23 No.3
A high β-glucosidase (BGL)-producing strain, Stereum hirsutum, was identified and isolated and showed a maximum BGL activity (10.4 U/ml) when cultured with Avicel and tryptone as the carbon and nitrogen sources, respectively. In comparison with other BGLs, BGL obtained from S. hirsutum showed a higher level of activity to cellobiose (Vmax = 172 U/mg, and kcat = 281/s). Under the optimum conditions (600 rpm, 30oC, and pH 6.0), the maximum BGL activity of 10.4 U/ml with the overall productivity of 74.5 U/l/h was observed. BGL production was scaled up from a laboratory scale (7-L fermenter) to a pilot scale (70-L fermenter). When S. hirsutum was cultured in fed-batch culture with rice straw as the carbon source in a 70-L fermenter, a comparable productivity of 78.6 U/l/h was obtained. Furthermore, S. hirsutum showed high levels of activity of other lignocellulases (cellobiohydrolase, endoglucanase, xylanase, and laccase) that are involved in the saccharification of biomasses. Application of S. hirsutum lignocellulases in the hydrolysis of Pinus densiflora and Catalpa ovata showed saccharification yields of 49.7% and 43.0%, respectively, which were higher than the yield obtained using commercial enzymes.
Repeated Random Mutagenesis of α-Amylase from Bacillus Licheniformis for Improved pH Performance
( Ramachandran Priyadharshini ),( Shankar Manoharan ),( Devaraj Hemalatha ),( Paramasamy Gunasekaran ) 한국미생물 · 생명공학회 2010 Journal of microbiology and biotechnology Vol.20 No.12
The α-amylases activity was improved by random mutagenesis and screening. A region comprising residues from the position 34-281 was randomly mutated in B. licheniformis α-amylase (AmyL), and the library with mutations ranging from low, medium, and high frequencies was generated. The library was screened using an effective liquid-phase screening method to isolate mutants with an altered pH profile. The sequencing of improved variants indicated 2-5 amino acid changes. Among them, mutant TP8H5 showed an altered pH profile as compared with that of wild type. The sequencing of variant TP8H5 indicated 2 amino acid changes, Ile157Ser and Trp193Arg, which were located in the solvent accessible flexible loop region in domain B.
Zhao, Zongpei,Ramachandran, Priyadharshini,Choi, Joon-Ho,Lee, Jung-Kul,Kim, In-Won 한국응용생명화학회 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.3
A highly efficient extracellular ${\beta}$-1,3/1,4-glucanase was purified from the culture broth of Sistotrema brinkmannii HQ717718. The molecular mass of ${\beta}$-1,3/1,4-glucanase was respectively determined to be 83 and 166 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography, indicating that the enzyme is a dimer. The optimum activity of ${\beta}$-1,3/1,4-glucanase against Avicel was observed at pH 4.0 and $65^{\circ}C$. Under the same conditions, $V_{max}$, $K_m$, and $k_{cat}$ values for Avicel were $136.5U{\cdot}mg^{-1}$ of protein, 3.8 mM, and $211s^{-1}$, respectively. Furthermore, the DNA sequence of gene coding the enzyme showed a significant homology with hydrolases from the glycoside hydrolase family 55. Although ${\beta}$-1,3/1,4-glucanases have been purified and characterized from several other sources, S. brinkmannii ${\beta}$-1,3/1,4-glucanase is distinct from other ${\beta}$-1,3/1,4-glucanases due to its high catalytic efficiency toward Avicel and broad substrate specificity.
Zongpei Zhao,이정걸,Priyadharshini Ramachandran,최준호,김인원 한국응용생명화학회 2013 Applied Biological Chemistry (Appl Biol Chem) Vol.56 No.3
A highly efficient extracellular β-1,3/1,4-glucanase was purified from the culture broth of Sistotrema brinkmannii HQ717718. The molecular mass of β-1,3/1,4-glucanase was respectively determined to be 83 and 166 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and gel filtration chromatography, indicating that the enzyme is a dimer. The optimum activity of β-1,3/1,4-glucanase against Avicel was observed at pH 4.0 and 65oC. Under the same conditions, Vmax,Km, and kcat values for Avicel were 136.5 U · mg−1 of protein, 3.8mM, and 211 s−1, respectively. Furthermore, the DNA sequence of gene coding the enzyme showed a significant homology with hydrolases from the glycoside hydrolase family 55. Although β-1,3/1,4-glucanases have been purified and characterized from several other sources, S. brinkmannii β-1,3/1,4-glucanase is distinct from other β-1,3/1,4-glucanases due to its high catalytic efficiency toward Avicel and broad substrate specificity.