Liu Wenli, Zhang Lanwei, Yi Huaxi, Shi John, Xue Chaohui, Li Hongbo, Jiao Yuehua, Shigwedha Nditange, Du Ming, Han Xue
School of Food Science & Technology, Harbin Institute of Technology, 73 HuangHe Avenue, Harbin, Heilongjiang 150090, China.
School of Food Science & Technology, Harbin Institute of Technology, 73 HuangHe Avenue, Harbin, Heilongjiang 150090, China.
J Microbiol Methods. 2014 May;100:121-7. doi: 10.1016/j.mimet.2014.03.006. Epub 2014 Mar 26.
In the present study, a YGNGV-motif-based assay was developed and applied. Given that there is an increasing demand for natural preservatives, we set out to obtain lactic acid bacteria (LAB) that produce bacteriocins against Gram-positive and Gram-negative bacteria. We here isolated 123 LAB strains from 5 types of traditional Chinese fermented food and screened them for the production of bacteriocins using the agar well diffusion assay (AWDA). Then, to acquire LAB producing class IIa bacteriocins, we used a YGNGV-motif-based assay that was based on 14 degenerate primers matching all class IIa bacteriocin-encoding genes currently deposited in NCBI. Eight of the LAB strains identified by AWDA could inhibit Gram-positive and Gram-negative bacteria; 5 of these were YGNGV-amplicon positive. Among these 5 isolates, amplicons from 2 strains (Y31 and Y33) matched class IIa bacteriocin genes. Strain Y31 demonstrated the highest inhibitory activity and the best match to a class IIa bacteriocin gene in NCBI, and was identified as Enterococcus faecium. The bacteriocin from Enterococcus avium Y33 was 100% identical to enterocin P. Both of these strains produced bacteriocins with strong antimicrobial activity against Listeria monocytogenes, Escherichia coli, and Bacillus subtilis, hence these bacteriocins hold promise as potential bio-preservatives in the food industry. These findings also indicated that the YGNGV-motif-based assay used in this study could identify novel class IIa bacteriocinogenic LAB, rapidly and specifically, saving time and labour by by-passing multiple separation and purification steps.
在本研究中,开发并应用了一种基于YGNGV基序的检测方法。鉴于对天然防腐剂的需求不断增加,我们着手获取对革兰氏阳性菌和革兰氏阴性菌具有抗菌活性的乳酸菌(LAB)。我们从5种中国传统发酵食品中分离出123株乳酸菌菌株,并使用琼脂孔扩散法(AWDA)筛选它们是否产生细菌素。然后,为了获得产生IIa类细菌素的乳酸菌,我们使用了一种基于YGNGV基序的检测方法,该方法基于14条简并引物,这些引物与目前保存在NCBI中的所有IIa类细菌素编码基因相匹配。通过AWDA鉴定的8株乳酸菌菌株能够抑制革兰氏阳性菌和革兰氏阴性菌;其中5株YGNGV扩增产物呈阳性。在这5株分离物中,2株(Y31和Y33)的扩增产物与IIa类细菌素基因匹配。菌株Y31表现出最高的抑制活性,并且与NCBI中的IIa类细菌素基因匹配度最佳,被鉴定为粪肠球菌。来自鸟肠球菌Y33的细菌素与肠球菌素P 100%相同。这两株菌产生的细菌素对单核细胞增生李斯特菌、大肠杆菌和枯草芽孢杆菌均具有很强的抗菌活性,因此这些细菌素有望成为食品工业中潜在的生物防腐剂。这些发现还表明,本研究中使用的基于YGNGV基序的检测方法能够快速、特异性地鉴定新型IIa类产细菌素乳酸菌,通过绕过多个分离和纯化步骤节省了时间和人力。