[Optimization of the medium and fermentation condition for the Penicillium aurantiocandidum Z12 strain with molluscicidal actions against Oncomelania hupensis].

To optimize the culture and fermentation conditions of the Penicillium aurantiocandidum Z12 strain, a fungal strain with molluscicidal actions against Oncomelania hupensis, so as to provide the basis for the research and development of molluscicidal active substances from the P. aurantiocandidum Z12 strain and its fermentation broth and large-scale fermentation.The carbon source, nitrogen source and mineral salts were identified in the optimal culture medium for the P. aurantiocandidum Z12 strain with a single-factor experiment to determine the best fermentation condition for the P. aurantiocandidum Z12 strain. Factors that significantly affected the growth of the P. aurantiocandidum Z12 strain were identified using the Plackett-Burman design, and the best range of each factor was determined using the steepest climb test. Response surface analyses of temperature, pH value, seeding amount and liquid-filling quantity were performed using the Box-Behnken design to create a regression model for fermentation of the P. aurantiocandidum Z12 strain to identify the optimal culture medium.Single-factor experiment preliminarily identified the best culture medium and conditions for the P. aurantiocandidum Z12 strain as follows: sucrose as the carbon source at approximately 20 g/L, tryptone as the nitrogen source at approximately 5 g/L, K2HPO4 as the mineral salt at approximately 5 g/L, initial pH at approximately 8, temperature at approximately 28 °C, seeding amount at approximately 6%, and liquid-filling quantity at approximately 50 mL/100 mL. Plackett-Burman design showed that factors that significantly affected the growth of the P. aurantiocandidum Z12 strain included temperature (t = -5.28, P < 0.05), seeding amount (t = 5.22, P < 0.05), pH (t = -4.30, P < 0.05) and liquid-filling quantity (t = -4.39, P < 0.05). Steepest climb test showed the highest mycelial growth at pH of 7.5, seeding amount of 8%, and liquid-filling quantity of 40 mL/100 mL, and this condition was selected as the central point of response surface analysis for the subsequent optimization of fermentation conditions. Response surface analyses using the Box-Behnken design showed that the optimal conditions for fermentation of the P. aurantiocandidum Z12 strain included sucrose at 15 g/L, tryptone at 5 g/L, K2HPO4 at 5 g/L, temperature at 28.2 °C, pH at 7.5, seeding amount at 10%, and liquid-filling quantity at 35.8 mL/100.0 mL, resulting in 0.132 g yield of the P. aurantiocandidum Z12 strain.The optimal culture condition for the P. aurantiocandidum Z12 strain has been identified, and the optimized culture medium and fermentation condition may effectively improve the fermentation yield of the P. aurantiocandidum Z12 strain.［摘要］目的 对灭螺真菌橘灰青霉菌Z12株培养及发酵条件进行优化, 为该菌株及其发酵液灭螺活性物质研发和规 模化发酵提供基础。方法 采用单因素试验确定橘灰青霉菌Z12株最佳培养基碳源、氮源、无机盐, 探索该菌最佳发酵 条件; 采用Plackett-Burman试验确定显著影响橘灰青霉菌Z12株生长的因素, 采用最陡爬坡试验确定各因素最佳取值范 围; 采用Box-Behnken设计对温度、pH值、接种量和装液量进行响应面试验, 建立橘灰青霉菌Z12株发酵回归模型, 确定 最优培养条件。结果 单因素试验初步确定橘灰青霉菌Z12株最佳培养基和培养条件：碳源蔗糖20 g/L左右, 氮源胰 蛋白胨5 g/L左右, 无机盐磷酸氢二钾5 g/L左右, 初始pH值8左右, 温度28 °C左右, 接种量6%左右, 装液量50 mL/100 mL左右。Plackett-Burman试验确定对该菌生长有显著影响的因素包括温度 (t = −5.28, P < 0.05) 、接种量 (t = 5.22, P < 0.05) 、pH值 (t = −4.30, P < 0.05) 和装液量 (t = −4.39, P < 0.05) 。最陡爬坡试验结果表明, 当pH值为7.5、接种量为8%、装液量为40 mL/100 mL时, 菌丝干重最高, 以该条件作为响应面试验中心点进行下一步发酵优化。通过Box-Behnken设 计的响应面分析确定发酵最佳条件为蔗糖15 g/L、胰蛋白胨5 g/L、磷酸氢二钾5 g/L、温度28.2 °C、pH值7.5、接种量10% 和装液量35.8 mL/100.0 mL, 验证实验中橘灰青霉菌Z12株产量为0.132 g。结论 本研究确定了橘灰青霉菌Z12株的最 优培养条件, 优化后的培养基和发酵条件能有效提升其发酵产量。.