Should Strengthen Cognizing and Teaching to the Deceleration Phase of Single Cell Organisms Growth Curve in Batch Cultivation / 微生物学通报

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.

Study on the Optimal Fermentation Process for Production Chitinase of Streptomyces sp. A048 / 微生物学通报

Streptomyces sp. A048 was cultured in a complete medium to the last stage of log phase,the hyphae were washed and collected by centrifugation. Then the hyphae were inoculated in liquid medium for chitinase production using two-step fermentation. Activity of chitinase produced by two-step fermentation was 1.1 times higher than that from one-step fermentation,and ferment cycle was for 54 hours,which was 66 hours shorter than that of one-step fermentation. The hyphae and the powder of chitin were co-immobilizated and cultured in liquid medium for 36 hours,activity of chitinase was 1.8 times higher than that from one-step fermentation,and ferment cycle was 54h shorter than that of one-step fermentation. By adding 0.4% cellulose to two-step fermentation,activity of chitinase was 18.52 U/mL that was 4 times higher than that from the control and 10 times higher than that from one-step fermentation. Two step fermentation with chitin and cellulose may be the optimal fermentation process to produce Chitinase from Streptomyces sp. A048.