Rapid cooling, moderate heat treatment and nisin addition influence cell homeostasis of Clostridium perfringens type A.
Vegetative cells of Clostridium perfringens type A were exposed to heat shock (50 degrees C), cold shock (4 degrees C) and nisin, respectively. In all cases, pronounced leaks of cellular K+ were observed. These losses were not systematically related to cell death, as demonstrated by cell viability measurement by the most probably number method. During heat shock treatment, a 90% decrease of initial population was measured within 15 min, and K+ leaks were mainly associated to cell death. A cold shock induced a rapid and large K+ efflux from the cells, at least 50% of the total potassium content. Potassium movements were not associated with internal pH changes, or with cell death during cooling at 4 degrees C. After nisin addition up to 70% of the cellular potassium was lost within 5 min. These potassium losses led to a transmembrane pH gradient decrease, but not to cell death at 50 IU ml-1 of nisin. Increasing the nisin concentration to 200 IU ml-1 resulted in a decimal reduction of 2.62.
Guerlava
P
P
Laboratoire de Génie des Procédés et de Technologie Alimentaire, Institut National de la Recherche Agronomique, Villeneuve d'Ascq, France.
Nolf
S
S
Tholozan
J L
JL
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003016:Clostridium perfringens / Q000187:drug effects / Q000502:physiology*; D003080:Cold Temperature; D015169:Colony Count, Microbial; D005520:Food Preservatives / Q000494:pharmacology*; D005525:Food-Processing Industry / Q000592:standards / Q000639:trends; D006706:Homeostasis / Q000187:drug effects / Q000502:physiology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D009561:Nisin / Q000494:pharmacology*; D011188:Potassium / Q000032:analysis / Q000378:metabolism; D012588:Scintillation Counting; D013054:Spectrophotometry, Atomic
D000900:Anti-Bacterial Agents; D005520:Food Preservatives; D009561:Nisin; D011188:Potassium