George Jaimee, Halami Prakash Motiram
Department of Microbiology and Fermentation Technology, CSIR - Central Food Technological Research Institute, Mysore 570020, India.
Res Microbiol. 2017 Oct;168(8):722-731. doi: 10.1016/j.resmic.2017.06.002. Epub 2017 Jul 4.
The study aimed to analyze the effects of sub-inhibitory concentrations of gentamicin on the expressions of high level aminoglycoside resistant (HLAR) bifunctional aac(6')Ie-aph(2″)Ia, biofilm and chaperone genes in Lactobacillus plantarum. The analysis of the biofilm formation in five isolates obtained from chicken sausages indicated their role in exhibiting phenotypic resistance based on the varied MIC values despite carrying the bifunctional gene. The biofilm formation significantly increased when L. plantarum MCC 3011 was grown in sub-inhibitory concentrations of gentamicin (4 μg/ml), kanamycin (8 μg/ml) and streptomycin (2 μg/ml). Thirty day gentamicin selection increased minimum inhibitory concentration (MIC) values from 4 to 64 and 2 to 256 fold for gentamicin and kanamycin, respectively when compared to the parental cultures. Expression studies revealed that constant exposure to gentamicin had induced chaperon [groEL] and the bifunctional gene, aac(6')Ie-aph(2″)Ia upto nine fold. Induction of groEL, groES and lamC genes in gentamicin (4 μg/ml) preincubated MCC 3011 indicated their significant role in aminoglycoside mediated response. Our study indicates that constant exposure to sub inhibitory concentrations of gentamicin allows L. plantarum to adapt against higher doses of aminoglycosides. This highlights the risks and food safety issues associated with the use of aminoglycosides in livestock and consumption of farm oriented fermented food products.
该研究旨在分析亚抑菌浓度的庆大霉素对植物乳杆菌中高水平氨基糖苷抗性（HLAR）双功能aac(6')Ie-aph(2″)Ia、生物膜和伴侣蛋白基因表达的影响。对从鸡肉香肠中分离得到的五株菌的生物膜形成情况进行分析，结果表明，尽管这些菌株携带双功能基因，但基于不同的最低抑菌浓度（MIC）值，它们在表现出表型抗性方面发挥了作用。当植物乳杆菌MCC 3011在亚抑菌浓度的庆大霉素（4μg/ml）、卡那霉素（8μg/ml）和链霉素（2μg/ml）中生长时，生物膜形成显著增加。与亲代培养物相比，经过30天的庆大霉素筛选，庆大霉素和卡那霉素的最低抑菌浓度值分别从4倍和2倍增加到64倍和256倍。表达研究表明，持续暴露于庆大霉素会诱导伴侣蛋白[groEL]和双功能基因aac(6')Ie-aph(2″)Ia高达9倍。在预先用庆大霉素（4μg/ml）孵育的MCC 3011中诱导groEL、groES和lamC基因，表明它们在氨基糖苷介导的反应中起重要作用。我们的研究表明，持续暴露于亚抑菌浓度的庆大霉素可使植物乳杆菌适应更高剂量的氨基糖苷。这突出了在牲畜中使用氨基糖苷以及食用以农场为导向的发酵食品所带来的风险和食品安全问题。
