Aouadhi Chedia, Mejri Slah, Maaroufi Abderrazak
Laboratory of Epidemiology and Veterinary Microbiology, Bacteriology and Biotechnology Development Groups, Institute Pasteur of Tunisia (IPT), University Manar, BP 74, 13 place Pasteur, Tunis-Belvédère 1002, Tunisia; Laboratory of Animal Resources and Food Technology, National Institute of Agronomy of Tunisia (INAT), University of Carthage 43, Rue Charles Nicole, Cité Mahrajène, Belvédère, 1082 Tunis, Tunisia.
Laboratory of Animal Resources and Food Technology, National Institute of Agronomy of Tunisia (INAT), University of Carthage 43, Rue Charles Nicole, Cité Mahrajène, Belvédère, 1082 Tunis, Tunisia.
Food Microbiol. 2015 Apr;46:40-45. doi: 10.1016/j.fm.2014.07.004. Epub 2014 Jul 15.
The inhibitory activities of nisin or/and potassium sorbate on spores and vegetative cells of Bacillus sporothermodurans LTIS27, which are known to be a contaminant of dairy products and to be extremely heat-resistant, were investigated. First, the tested concentrations of nisin or potassium sorbate inhibited vegetative cell growth; with the minimum inhibitory concentrations were 5 × 10(3) IU/ml and 2% (w/v), respectively. Then, the behaviour of vegetative cells and spores in presence of sub-lethal concentrations of nisin (50 UI/ml) or/and potassium sorbate (0.2%), in milk at 37 °C for 5 days, were evaluated. In the absence of inhibitors, strain grew and sporulated at the end of the exponential phase. Nisin (50 UI/ml) was able to inhibit spore outgrowth but didn't affect their germination. It induced an immediate and transitory reduction (1.6log(10) after 1 h and 2.8log(10) after 6 h of incubation) of vegetative cell growth which reappeared between 10 h and 24 h. Potassium sorbate (0.2%) had a durable bacteriostatic effect (1.1log(10) after 6 h), on vegetative cells, followed by a slower regrowth. It was able to inhibit both germination and outgrowth of spores. Association of nisin and potassium sorbate, at sub-lethal concentrations, showed a synergistic effect and resulted in a total inhibition of cells growth after 5 days. The results illustrate the efficacy of nisin and potassium sorbate in combination, and the commercial potential of applying such treatment to decontaminate any product that has a problem with persistence of bacterial spores.
乳酸链球菌素或/和山梨酸钾对嗜热栖热芽孢杆菌LTIS27的孢子和营养细胞的抑制活性进行了研究，该菌是乳制品中的一种污染物，具有极强的耐热性。首先，测试浓度的乳酸链球菌素或山梨酸钾抑制了营养细胞的生长；最低抑菌浓度分别为5×10(3) IU/ml和2%（w/v）。然后，评估了在亚致死浓度的乳酸链球菌素（50 UI/ml）或/和山梨酸钾（0.2%）存在下，37℃牛奶中营养细胞和孢子5天的行为。在没有抑制剂的情况下，菌株在指数期末生长并形成孢子。乳酸链球菌素（50 UI/ml）能够抑制孢子萌发但不影响其发芽。它使营养细胞生长立即出现短暂减少（培养1小时后减少1.6log(10)，6小时后减少2.8log(10)），并在10小时至24小时之间再次出现。山梨酸钾（0.2%）对营养细胞有持久的抑菌作用（6小时后减少1.1log(10)），随后生长较慢。它能够抑制孢子的发芽和萌发。亚致死浓度的乳酸链球菌素和山梨酸钾联合使用具有协同作用，5天后导致细胞生长完全受到抑制。结果说明了乳酸链球菌素和山梨酸钾联合使用的有效性，以及应用这种处理方法对任何存在细菌孢子持久性问题的产品进行去污的商业潜力。
