ABSTRACT
A.niger M1, the initial strain, was treated by UV and a mutant with 30% higher xylanase activity was obtained. Zymogram for detecting xylanase showed there are three different xylanases in the mutant mature culture, while two xylanases in initial strain. After orthogonal experiment, the optimum fermentation conditions of the mutant were obtained as follows: concentration of the major carbon resource 4 %, ratio between bran and corncob 5:5, concentration of glucose 0.1%, concentration of ammonium oxalate as supplemental nitrogen resource 2.0%, the initial pH of liquid medium 5.0, 100mL/250mL flask.
ABSTRACT
Saccharmyces cerevisiae 220 has certain resistance to Pb2+ was found through the test of it's cultured on media containing lead cation. Sacchannyces cerevisiae 220 cultured was put into the media cotaining lead cation and it's biosorp-tion to lead cation was studied. The results show this strain has maximum biosorption ratio (96.6%) to 6mg/L lead cation, biosorption-equilibrilium period is 25-30min, biosorption kinitics equation is q-26.318C/ (1 + 0.437C) . Acetic acid is benefit to de-biosorption, glucose and KH2PO4 can improve biosorption ratio to lead cation.
ABSTRACT
The growth curve of single cell organisms in batch cultivation could divide into 6 phases, lag phase, acceleration phase, log phase, deceleration phase, stationary phase, and death phase, based on specific growth rate during cultivation process. There were significantly differences between deceleration phase and the other phases in cell growth, substrate consumption, product formation, and genes express profile. The deceleration phase was highly important to fermentation process. However, cognizing and teaching to the deceleration phase had been considerably weakened since a long period. So it should be strengthened.