响应面法优化植物乳杆菌LPL-1产细菌素发酵条件及细菌素理化性质分析

为提高新型植物乳杆菌LPL-1所产细菌素（植物乳杆菌素LPL-1）的产量，以单核细胞性李斯特菌为指示菌，相对抑菌效价为响应值，通过响应面法对发酵条件进行优化，确定了最优发酵条件。利用单因素试验与Plackett-Burman试验，确定主要影响因素为温度、发酵时间与初始pH值，通过最陡爬坡试验与Box-Behnken响应面试验，确定最优发酵条件为发酵温度31?℃、培养基初始pH?6.40、发酵时间32?h、接种量0.5%、装液量60%，在此条件下细菌素效价（674.29?AU/mL）比优化前（292.02?AU/mL）提高了1.31倍。通过对细菌素理化性质的分析，证明了细菌素具有热稳定性（100?℃，30?min）、酸碱稳定性（pH?2～10）、蛋白酶敏感性与抑菌性，同时利用二硫键变性剂对细菌素结构中的二硫键进行变性处理，证明二硫键对其抑菌特性的重要性。因此，通过细菌素发酵条件的优化与理化性质的分析，为菌种与细菌素的产业化生产与应用提供了理论支持。

Optimization of Fermentation Conditions for Plantaricin Production by Lactobacillus plantarum LPL-1 by Response Surface Methodology and Its Physicochemical Properties

The present study aimed at improving plantaricin production by Lactobacillus plantarum LPL-1. Fermentation conditions were optimized by response surface methodology (RSM). The inhibitory activity (AU/mL) against Listeria monocytogenes 54002 was used as response variable. Using one-factor-at-a-time method and Plackett-Burman design, temperature, fermentation time and initial medium pH were identified as main factors that influence plantaricin production. The optimal fermentation conditions were determined as 31 ℃, 6.40, 32 h, 0.5% and 60% for temperature, initial medium pH, time, inoculum size and medium volume in flasks, respectively using path of steepest ascent and RSM with Box-Behnken design. The antibacterial activity of plantaricin produced under the optimized conditions was 674.29 AU/mL, which increased by 2.31 times compared with that before optimization. It was also found that the crude plantaricin extracted from the fermentation broth had obvious inhibitory effect on Gram-positive bacteria, and it was stable to heat (100 ℃, 30 min), acid-base conditions (pH 2–10) and sensitive to protease. Meanwhile, the disulfide bonds of bacteriocin were broken by disulfide bond denaturants, which proved the importance of disulfide bonds for bacteriocins. Conclusively, the present study provides insights into the potential use of bacteriocin as a food preservative in the food industry.