番茄青枯病植物疫苗菌株FJAT-1458的培养条件优化及发酵过程状态参数研究

对番茄青枯病植物疫苗菌株FJAT-1458进行培养条件优化和发酵过程状态参数研究。采用摇瓶培养和单因素试验研究菌株FJAT-1458的培养条件,确定最适培养基为SPA(蛋白胨5g·L~(-1),蔗糖20g·L~(-1),KH2PO40.5g·L~(-1),MgSO40.25g·L~(-1)),最适培养温度为30℃,250 mL三角瓶最适装液量为35 mL。用50L发酵罐发酵FJAT-1458,发酵过程中菌体数量呈现先升后降的变化趋势,FJAT-1458的生长可分为4个时期:0~6h为发酵适应期、6~36h为对数生长期、36~60h为稳定生长期,72h后为消亡期。发酵过程中,菌体的致病性指标-弱化指数变化小,介于0.832~0.855,方差分析表明其差异不显著,P0.05;发酵液pH值从7.23上升至8.78;菌体细胞为短杆状,大小为(1.0~1.5)μm×(0.5~0.8)μm,随着发酵进程,细胞颜色变深,发酵后期细胞开始变形、裂解。

Optimization of Culture Conditionsand Analysis of Fermentation Process for Plant Vaccine-producing Bacterium,FJAT-1 4 5 8

Conditions to culture FJAT-1458,a bacterium that produces plant vaccine against the tomato bacterial wilt caused by Ralstonia solanacearum,were optimized by asingle factor experiment.They were determined to be the use of an SPA medium containing peptone 5 g·L-1 ,sugar 20 g·L-1 ,KH2 PO4 0.5 g·L-1 ,and MgSO4 0.25 g·L-1 at 30℃ with 35 mL of broth in a 250 mL shaking flask.Subsequently,in a 50 L fermentation tank,the fermentation was carried out and the process monitored.During the fermentation,the cell count on FJAT-1458 increased initially and followed by a gradual decline with a 4-stage growth period that included the adaptive (0-6 h),logarithmic (6-36 h),stationary (36-60 h),and decline phases (after 72 h).In addition,it was observed that (a)the pathogenicity indicator,attenuation index,of FJAT-1458 ranged from 0.832 to 0.855 showing no significant difference (P>0.05)throughout the entire process;(b)the pH of the fermentation broth increased from 7.23 to 8.78;(c)morphologically,the bacteria appeared to be (1.0-1.5)μm× (0.5-0.8)μm rods with a darkening color as the process proceeded;(d)the cellular secretion from the bacteria increased with time;and,(e) some of the bacterial cells deformed and lysed near the end of fermentation.