Nisin is a gene-encoded short peptide secreted by Lactococcus lactis subsp. lactis and it has wide applications in diverse fields. Foam separation was used for harvesting nisin from fermentation broth in the current work. First, the effects of pH, nisin concentration and gas type on foam property, surface tension and antimicrobial activity of unitary nisin solution were investigated, respectively. At the suitable pH of 5.0, the critical micelle concentration (cmc) of nisin was 2.891 g/L. As nisin concentration exceeded cmc, the foam stability of sample solution gradually decreased. Among four gases, nitrogen (N₂) gas could be selected as the suitable carrier gas for foam formation. Moreover, foam evolution could induce the modification of the nisin secondary structure, resulting in the loss of antimicrobial activity. In batch fermentation, the variations in biomass, nisin concentration and pH over cultivation period were monitored. Experimental results indicated that batch fermentation could be terminated after cultivation for 21 h. The foam property of peptone and yeast extract at different pH conditions was analyzed. The high selectivity of foam separation for harvesting nisin achieved at pH 5.0. Response surface methodology was employed to optimize the operational conditions of foam separation. Finally, the inactivation percentage of nisin in the foamate could be effectively reduced by assembling 300 W ultrasonic treatment into foam separation. The novelty of current work prompts a search for understanding of how operational factors of foam separation affect biochemical property and structural stability of nisin, thereby facilitating the industrial manufacture of nisin.

乳链菌肽是一种基因编码的短肽，由乳酸乳球菌亚种分泌。lactis，它在各个领域都有广泛的应用。在目前的工作中，泡沫分离用于从发酵液中收获乳链菌肽。首先，分别研究了 pH 值、乳链菌肽浓度和气体类型对单一乳链菌肽溶液的泡沫特性、表面张力和抗菌活性的影响。在适宜的pH值5.0下，乳链菌肽的临界胶束浓度（cmc）为2.891 g/L。随着乳链菌肽浓度超过cmc，样品溶液的泡沫稳定性逐渐降低。在四种气体中，氮气（N ₂) 气体可以选择作为泡沫形成的合适载气。此外，泡沫的产生可以诱导乳链菌肽二级结构的改变，从而导致抗菌活性的丧失。在分批发酵中，监测了培养期间生物量、乳链菌肽浓度和 pH 值的变化。实验结果表明分批发酵可在培养21 h后终止。分析了蛋白胨和酵母提取物在不同pH条件下的泡沫特性。在 pH 5.0 下实现了用于收集乳链菌肽的泡沫分离的高选择性。采用响应面方法优化泡沫分离的操作条件。最后，通过将 300 W 超声波处理与泡沫分离相结合，可以有效降低泡沫中乳链菌肽的失活率。