Inhibitory effects of nisin and potassium sorbate alone or in combination on vegetative cells growth and spore germination of Bacillus sporothermodurans in milk. (April 2015)

• Record Type: Journal Article
• Authors: Aouadhi, Chedia; Mejri, Slah; Maaroufi, Abderrazak
• Is Part Of: Food microbiology. Volume 46(2015:Apr.)
• Page Start: 40
• Page End: 45
• Publication Date: 2015-04
• Subjects: Reduction -- Antimicrobial agents -- Synergistic effect -- Bacillus sporothermodurans -- Minimum inhibitory concentrations; Food Microbiology -- Periodicals; Aliments -- Microbiologie -- Périodiques; Food -- Microbiology; Periodicals; Food -- Microbiology -- Periodicals; Food contamination -- Periodicals; 664.001579
• DOI: 10.1016/j.fm.2014.07.004
• Languages: English
• ISSNs: 0740-0020

Abstract

Abstract: 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. Highlights: Minimum inhibitory concentrations of nisin and potassium sorbate were 5 × 10 3 IU/ml and 2%. Nisin and potassium sorbate inhibited vegetative cell growth of Bacillus sporothermodurans. Nisin did not affected spore germination. Potassium sorbate perturbed spore germination. Nisin and sorbate potassium results in synergistic inhibition of vegetative cells and spores.