Involvement of cell envelope in nisin resistance of Pectinatus frisingensis, a Gram-negative, strictly anaerobic beer-spoilage bacterium naturally sensitive to nisin

Abstract

A nisin-resistant strain of Pectinatus frisingensis (Nis-5000) to high nisin concentration (5000 IU ml −:1) was isolated. The nisin resistance phenotype of strain Nis-5000 was stable after five passages through nisin-free medium. The involvement of the cell envelope in nisin resistance was investigated. EDTA treatment of Nis-5000 strain cells did not render them sensitive to the bacteriocin, suggesting that the lipopolysaccharide layer was not involved in nisin resistance. The Nis-5000 strain shows a significantly different fatty acid composition compared with that of the wild-type strain. The modifications occurred mainly in C17:1 ( P<0.05) and C18:cyclo ( P<0.05), suggesting the involvement of membrane fluidity in preventing nisin’s effect.