Yang En, Fan Lihua, Yan Jinping, Jiang Yueming, Doucette Craig, Fillmore Sherry, Walker Bradley
Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, China.
Agriculture and Agri-Food Canada, Kentville Research and Development Centre, 32 Main Street, Kentville, NS, B4N 1J5, Canada.
AMB Express. 2018 Jan 24;8(1):10. doi: 10.1186/s13568-018-0536-0.
There has been continued interest in bacteriocins research from an applied perspective as bacteriocins have potential to be used as natural preservative. Four bacteriocinogenic lactic acid bacteria (LAB) strains of Lactobacillus curvatus (Arla-10), Enterococcus faecium (JFR-1), Lactobacillus paracasei subsp. paracasei (JFR-5) and Streptococcus thermophilus (TSB-8) were previously isolated and identified in our lab. The objective of this study was to determine the optimal growth conditions for both LAB growth and bacteriocins production. In this study, various growth conditions including culture media (MRS and BHI), initial pH of culture media (4.5, 5.5, 6.2, 7.4 and 8.5), and incubation temperatures (20, 37 and 44 °C) were investigated for LAB growth measured as optical density (OD), bacteriocin activity determined as arbitrary unit and viability of LAB expressed as log CFU ml. Growth curves of the bacteriocinogenic LAB were generated using a Bioscreen C. Our results indicated that Arla-10, JFR-1, and JFR-5 strains grew well on both MRS and BHI media at growth temperature tested whereas TSB-8 strain, unable to grow at 20 °C. LAB growth was significantly affected by the initial pH of culture media (p < 0.001) and the optimal pH was found ranging from 6.2 to 8.5. Bacteriocin activity was significantly different in MRS versus BHI (p < 0.001), and the optimal condition for LAB to produce bacteriocins was determined in MRS broth, pH 6.2 at 37 °C. This study provides useful information on potential application of bacteriocinogenic LAB in food fermentation processes.
从应用角度来看，人们对细菌素的研究一直保持着浓厚兴趣，因为细菌素有潜力用作天然防腐剂。先前在我们实验室中分离并鉴定出了四种产细菌素的乳酸菌（LAB）菌株，分别是弯曲乳杆菌（Arla - 10）、屎肠球菌（JFR - 1）、副干酪乳杆菌副干酪亚种（JFR - 5）和嗜热链球菌（TSB - 8）。本研究的目的是确定乳酸菌生长和细菌素产生的最佳生长条件。在本研究中，研究了各种生长条件，包括培养基（MRS和BHI）、培养基的初始pH值（4.5、5.5、6.2、7.4和8.5）以及培养温度（20、37和44℃），通过光密度（OD）测量乳酸菌的生长情况，以任意单位测定细菌素活性，并以每毫升菌落形成单位（log CFU ml）表示乳酸菌的活力。使用Bioscreen C生成产细菌素乳酸菌的生长曲线。我们的结果表明，在测试的生长温度下，Arla - 10、JFR - 1和JFR - 5菌株在MRS和BHI培养基上均生长良好，而TSB - 8菌株在20℃下无法生长。培养基的初始pH值对乳酸菌生长有显著影响（p < 0.001），最佳pH值范围为6.2至8.5。MRS和BHI培养基中的细菌素活性存在显著差异（p < 0.001），乳酸菌产生细菌素的最佳条件是在MRS肉汤中，pH值为6.2，温度为37℃。本研究为产细菌素乳酸菌在食品发酵过程中的潜在应用提供了有用信息。
