title: Unsaturated fatty acids from food and in the growth medium improve growth of Bacillus cereus under cold and anaerobic conditions.
abstract: In a chemically defined medium and in Luria broth, cold strongly reduced maximal population density of Bacillus cereus ATCC 14579 in anaerobiosis and caused formation of filaments. In cooked spinach, maximal population density of B. cereus in anaerobiosis was the same at cold and optimal temperatures, with normal cell divisions. The lipid containing fraction of spinach, but not the hydrophilic fraction, restored growth of B. cereus under cold and anaerobiosis when added to the chemically defined medium. This fraction was rich in unsaturated, low melting point fatty acids. Addition of phosphatidylcholine containing unsaturated, low melting point, fatty acids similarly improved B. cereus anaerobic growth at cold temperature. Addition of hydrogenated phosphatidylcholine containing saturated, high melting point, fatty acids did not modify growth. Fatty acids from phospholipids, from spinach and from hydrogenated phosphatidylcholine, although normally very rare in B. cereus, were inserted in the bacterium membrane. Addition of phospholipids rich in unsaturated fatty acids to cold and anaerobic cultures, increased fluidity of B. cereus membrane lipids, to the same level as those from B. cereus normally cold adapted, i.e. grown aerobically at 15 °C. B. cereus is therefore able to use external fatty acids from foods or from the growth medium to adapt its membrane to cold temperature under anaerobiosis, and to recover the maximal population density achieved at optimal temperature.
authors.affiliation: INRA, UMR408 Sécurité et Qualité des Produits d'Origine Végétale, F-84000 Avignon, France.
authors.forename: Benoît
authors.initials: B
authors.lastname: de Sarrau
authors.forename: Thierry
authors.initials: T
authors.lastname: Clavel
authors.forename: Nicolas
authors.initials: N
authors.lastname: Zwickel
authors.forename: Jordane
authors.initials: J
authors.lastname: Despres
authors.forename: Sébastien
authors.initials: S
authors.lastname: Dupont
authors.forename: Laurent
authors.initials: L
authors.lastname: Beney
authors.forename: Raphaëlle
authors.initials: R
authors.lastname: Tourdot-Maréchal
authors.forename: Christophe
authors.initials: C
authors.lastname: Nguyen-The
mesh_terms: D000693:Anaerobiosis; D001409:Bacillus cereus / Q000254:growth & development* / Q000378:metabolism*; D003080:Cold Temperature; D003470:Culture Media / Q000737:chemistry* / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000032:analysis / Q000378:metabolism*; D005516:Food Microbiology; D018724:Spinacia oleracea / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology*
chemical_list: D003470:Culture Media; D005231:Fatty Acids, Unsaturated
keywords: Anaerobiosis; Bacillus cereus; Cold; Fatty acid; Membrane