The effect of nisin‐sodium chloride interactions on the outgrowth of Bacillus licheniformis spores

Abstract

The effect of salt (NaCl) on the efficacy of nisin in preventing outgrowth of Bacillus licheniformis spores was determined in Plate Count Agar (PCA). An equivalent liquid medium was used for heat activation. Nisin and salt were added to the heat‐activation medium, the PCA, or both. The spores were extremely sensitive to nisin; outgrowth were completely inhibited in salt‐free media when 10 iu/ml of nisin was present in both the heat‐activation and the growth media or when 100 iu/ml nisin was present in either the heat‐activation and the growth medium. In media supplemented with 1% salt, outgrowth occurred from 1% of spores exposed to 100 iu/ml nisin in either the heat‐activation or the growth medium. A 3% salt supplement was necessary before detectable outgrowth occurred when both the heat‐activation and the growth media contained 100 iu/ml nisin. Salt appears to antagonize the sporicidal action of nisin by interfering with nisin adsorption onto the spore.

Combined effect of reuterin and lactic acid bacteria bacteriocins on the inactivation of food-borne pathogens in milk

“…However, variations in pH (4.5e6.5) and salt content (0.5e3%) did not influence the inhibitory activity of reuterin on E. coli K12 (Rasch, 2002). It has also been reported that presence of NaCl could enhance the antimicrobial effect of bacteriocins (Ananou, Valdivia, Martínez Bueno, Gálvez, & Maqueda, 2004;Parente, Giglio, Riccardi, & Clementi, 1998), or oppositely be antagonistic with them (Bell & de Lacy, 1985;Bouttefroy, Mansour, Linder, & Milliere, 2000). Moreover, the increase in net charge of bacteriocins at low pH could facilitate translocation of the bacteriocins through the cell wall and enhance their antibacterial activity.…”

Bacteriocins: Biological tools for bio-preservation and shelf-life extension

“…The end product (consisting of nisin ð1 Â 10 6 IU g À1 Þ, 74.4% NaCl, 23.8% denatured milk solids and 1.7% moisture) has found many applications in food processing and a large body of data on the use of nisin in food systems has been generated over the past 50 years. While nisin has been found to be extremely effective as an additive to prevent spoilage and increase shelf-life in a number of foods (Chen & Hoover, 2003;Choi & Park, 2000;Cutter & Siragusa, 1995;Davies et al, 1999) its effectiveness has been more variable with respect to other applications (Bell & De Lacy, 1985;Jones, 1974;Jung, Bodyfelt, & Daeschel, 1992;Scott & Taylor, 1981a,b). The fact that situations have been described where nisin is…”

Inhibition of Listeria monocytogenes in Camembert cheese made with a nisin-producing starter

“…lt could be due to the combined effect of salt and low temperature on Listeria previously impaired by the acidic conditions. The absence of an extra inhibitory effect of nisin may be due to two factors: firstly, salt was shown to antagonize the action of nisin by interfering with nisin adsorption to bacteria cells (Bell and De Lacy, 1985); moreover, Mohamed et al (1984) showed that sensitivity of bacteria to nisin diminished when the temperature of incubation decreased. Nevertheless, an overail decrease of Listeria count of ca 1.0 log CFU/g in the control and 3.3 log CFUlg in the Nis+ cheese was obtained from milk to cheese aged 1 week (table Il).…”