摘要

由乳酸菌（LAB）生产的细菌素有可能作为食品工业中的天然防腐剂。为了开发大量生产这些肽的策略，在大肠杆菌BL21（DE3）中成功异源表达了由两种肽PLNC8α和PLNC8β组成的IIb类LAB细菌素植物油NC8。 PLNC8α和PLNC8β肽表达为His6-标签融合蛋白，并通过Ni2 +螯合亲和层析分离。为了获得N端没有额外氨基酸的PLNC8α和PLNC8β肽，将融合蛋白用肠激酶切割并使用Ni-NTA Sefinose TM树脂试剂盒进一步纯化。使用Tricine-SDS-PAGE和MALDI-TOF-MS检查肽的分子量。纯化的PLNC8α的产量在2-2.5mg / L左右，PLNC8β的产量在1.5-2mg / L左右。初步证实了切割肽的抗菌谱，初步证实了PLNC8α和PLNC8β的协同作用。发现大肠杆菌是用于以显着产量异源表达植物甾醇NC8的合适宿主。重要的是，细菌素似乎对控制和抑制食源性致病性革兰氏阴性菌沙门氏菌属物种非常活跃，并且可能用作天然防腐剂候选物。

Bacteriocin, which is produced by lactic acid bacteria (LAB), has the potential to act as natural preservatives in the food industry. To develop strategies to overproduce suchpeptides, plantaricin NC8, a class IIb LAB bacteriocin that consists of two peptides, PLNC8α and PLNC8β, was successfully heterologously expressed in Escherichia coli BL21 (DE3). PLNC8α and PLNC8β peptides were expressed as His6-tag fusion proteins and were separated by Ni2+ chelating affinity chromatography. To get the PLNC8α and PLNC8β peptides without extra amino acids in the N-terminus, the fusion proteins were cleaved byenterokinase and further purified using the Ni-NTA Sefinose™ Resin Kit. The molecular masses of peptides were checked using Tricine-SDS-PAGE and MALDI-TOF-MS. The yield of purified PLNC8α was around 2–2.5 mg/L, and the yield of PLNC8β was around 1.5–2 mg/L. The antimicrobial spectrum of cleaved peptides was detected and the synergistic action of PLNC8α and PLNC8β was preliminarily confirmed. It was found that E. coli was a suitable host for heterologous expression of plantaricin NC8 with a significant yield. Importantly, the bacteriocin appeared to be very active for controlling and inhibiting the food-borne pathogenic Gram-negative bacteria Salmonella spp., and might be useful as a natural preservative candidate.

https://www.sciencedirect.com/science/article/pii/S1046592816301139