Characterization of Enterococcus faecium mutants resistant to mundticin KS, a class IIa bacteriocin.
The emergence and spread of mutants resistant to bacteriocins would threaten the safety of using bacteriocins as food preservatives. To determine the physiological characteristics of resistant mutants, mutants of Enterococcus faecium resistant to mundticin KS, a class IIa bacteriocin, were isolated. Two types of mutant were found that had different sensitivities to other antimicrobial agents such as nisin (class I) and kanamycin. Both mutants were resistant to mundticin KS even in the absence of Mg(2+) ions. The composition of unsaturated fatty acids in the resistant mutants was significantly increased in the presence of mundticin KS. The composition of the phospholipids in the two resistant mutants also differed from those in the wild-type strain. The putative zwitterionic amino-containing phospholipid in both mutants significantly increased, whereas amounts of phosphatidylglycerol and cardiolipin decreased. These changes in membrane structure may influence resistance of enterococci to class IIa and class I bacteriocins.
Sakayori
Youko
Y
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
Muramatsu
Mizuho
M
Research Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan.
Hanada
Satoshi
S
Research Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan.
Kamagata
Yoichi
Y
Research Institute for Biological Resources and Functions, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba, Ibaraki, 305-8566, Japan.
Kawamoto
Shinichi
S
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
Shima
Jun
J
National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
D001430:Bacteriocins / Q000494:pharmacology*; D024881:Drug Resistance, Bacterial; D016984:Enterococcus faecium / Q000187:drug effects*; D005227:Fatty Acids / Q000032:analysis; D008274:Magnesium / Q000494:pharmacology; D008563:Membrane Lipids / Q000032:analysis; D009154:Mutation; D010743:Phospholipids / Q000032:analysis
D001430:Bacteriocins; D005227:Fatty Acids; D008563:Membrane Lipids; D010743:Phospholipids; C114588:mundticin; D008274:Magnesium