Microbiology and Fermentation Technology Department, CSIR-Central Food Technological Research Institute, Mysore, 570020, India.
Curr Microbiol. 2021 Sep;78(9):3430-3438. doi: 10.1007/s00284-021-02593-8. Epub 2021 Jul 13.
An attempt was made, to characterize natural antibiotics or lantibiotics from unconventional sources and its antibacterial spectrum against food borne pathogens and drug resistant bacteria. Six different traditional fermented foods i.e., fermented fish, fermented soybeans, Soibum (fermented bamboo shoots), milk, idly and dosa batter were used for the isolation of bacteriocin producing Lactic acid bacteria (LAB). Among all bacterial cultures isolated from the various sources, 129 cultures have found to produce antimicrobial compounds. Nisin specific reporter bacteria was utilized as biosensor to identify the Nisin like bacteriocin, where 10 cultures found to be positive Nisin producer. Identified Nisin like bacteriocin was partially concentrated by using ammonium sulphate followed by butanol extraction. Minimum inhibitory concentration (MIC) was analyzed against food borne pathogen and drug resistant bacteria. MIC of partially purified Nisin (pp-Nisin) of all the LAB isolates against food-borne pathogens are ranged between 0.5 and 92 µg/ml respected to various Gram-positive bacteria. Similarly, the drug resistant bacteria were also inhibited by pp-Nisin (MIC ranged between 15 and 175 µg/ml). All samples of ppnisin exhibited auto induction ability. Taxonomic identification of the nisin producers was done by whole genome sequencing which reveals that cultures belongs to Lactococcus lactis ssp. lactis. Also it was found that Lactococcus lactis ssp. lactis C2d and Lactococcus lactis ssp. lactis SP2C4 harbor nisA gene and Lactococcus lactis ssp. lactis FS2 (L. lactis FS2) harbor nisQ gene. The finding of this study highlights the first case of L. lactis FS2 isolated from fermented fish harbor nisQ gene. Antibacterial activity of pp-Nisin against drug resistant LAB is also reported.
本研究旨在从非常规来源中鉴定天然抗生素或类抗生素，并研究其对食源性病原体和耐药菌的抗菌谱。使用六种不同的传统发酵食品，即发酵鱼、发酵大豆、Soibum（发酵竹笋）、牛奶、idly 和 dosa 面糊，来分离产细菌素的乳酸菌（LAB）。从各种来源分离的所有细菌培养物中，发现 129 种培养物可产生抗菌化合物。利用乳链菌肽特异性报告菌作为生物传感器来鉴定类似乳链菌肽的细菌素，发现其中 10 种培养物为阳性乳链菌肽产生菌。通过硫酸铵沉淀和丁醇萃取部分浓缩鉴定出的类似乳链菌肽。采用最低抑菌浓度（MIC）法分析部分纯化的乳链菌肽（pp-Nisin）对食源性病原体和耐药菌的抑制作用。所有 LAB 分离株对食源性病原体的部分纯化乳链菌肽（pp-Nisin）的最低抑菌浓度（MIC）范围为 0.5 至 92μg/ml，与各种革兰氏阳性菌相对应。同样，耐药菌也被 pp-Nisin（MIC 范围为 15 至 175μg/ml）抑制。所有 pp-Nisin 样品均表现出自诱导能力。通过全基因组测序对产乳链菌肽的菌株进行分类鉴定，结果表明这些菌株属于乳球菌乳亚种。还发现乳球菌乳亚种 C2d 和乳球菌乳亚种 SP2C4 携带 nisA 基因，而乳球菌乳亚种 FS2（L. lactis FS2）携带 nisQ 基因。本研究的发现首次报道了从发酵鱼中分离出携带 nisQ 基因的乳球菌乳亚种 FS2。还报道了 pp-Nisin 对耐药 LAB 的抗菌活性。
