[Breeding, optimized fermentation and enzymatic properties of a Bacillus licheniformis mutant producing cyclomaltodextrin glucanotransferase].
A bacterial strain 403 selected from various soil was found to produce cyclomaltodextrin glucanotransferase (CGTase) with an activity of 0.95 U/mL after 96 h submerged incubation. A mutant, Bacillus licheniformis CLS403, obtained by means of ultraviolet radiation and diethyl sulfate, enhanced CGTase production by 43% (1.36 U/mL). The optimized conditions for CGTase production of mutant were soluble starch as carbon source, ammonium nitrate as nitrogen source, 35 degrees C and pH 6.5 for incubation. Under these conditions, the production of CGTase by the mutant in submerged peaked at the period of 96 h incubation, two days later than bacterial biomass peak. The resultant CGTase reacted best at 55 degrees C and pH 6.0, and had activities > 90% after 1 h maintenance at 50 degrees C with pH 6.0-7.5. Addition of Ca2+ in the reaction largely enhanced stability of the CGTase activity at 55 degrees C. Based on HPLC analysis, the products of starch hydrolyzed by the CGTase of B. licheniformis CLS403 included much more alpha-cyclodextrin than beta-cyclodextrin but no gamma-cyclodextrin. The total yield of cyclodextrin from starch reached 29.8% with the ratio of the two cyclodextrins 2.47:1.
Chen
Long-ran
LR
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou 310029, China. chenlongran@zju.edu.cn
Yuan
Kang-pei
KP
Feng
Ming-guang
MG
Wang
Ya-fen
YF
D001407:Bacillus / Q000201:enzymology* / Q000254:growth & development / Q000302:isolation & purification; D018533:Biomass; D003470:Culture Media; D005964:Glucosyltransferases / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D016296:Mutagenesis; D012988:Soil Microbiology; D013696:Temperature
D003470:Culture Media; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase