title: Significance of heme-based respiration in meat spoilage caused by Leuconostoc gasicomitatum.
abstract: Leuconostoc gasicomitatum is a psychrotrophic lactic acid bacterium (LAB) which causes spoilage in cold-stored modified-atmosphere-packaged (MAP) meat products. In addition to the fermentative metabolism, L. gasicomitatum is able to respire when exogenous heme and oxygen are available. In this study, we investigated the respiration effects on growth rate, biomass, gene expression, and volatile organic compound (VOC) production in laboratory media and pork loin. The meat samples were evaluated by a sensory panel every second or third day for 29 days. We observed that functional respiration increased the growth (rate and yield) of L. gasicomitatum in laboratory media with added heme and in situ meat with endogenous heme. Respiration increased enormously (up to 2,600-fold) the accumulation of acetoin and diacetyl, which are buttery off-odor compounds in meat. Our transcriptome analyses showed that the gene expression patterns were quite similar, irrespective of whether respiration was turned off by excluding heme from the medium or mutating the cydB gene, which is essential in the respiratory chain. The respiration-based growth of L. gasicomitatum in meat was obtained in terms of population development and subsequent development of sensory characteristics. Respiration is thus a key factor explaining why L. gasicomitatum is so well adapted in high-oxygen packed meat.
authors.affiliation: Department of Food Hygiene and Environmental Health, University of Helsinki, Helsinki, Finland. Elina.L.Jaaskelainen@helsinki.fi
authors.forename: Elina
authors.initials: E
authors.lastname: Jääskeläinen
authors.forename: Per
authors.initials: P
authors.lastname: Johansson
authors.forename: Olli
authors.initials: O
authors.lastname: Kostiainen
authors.forename: Timo
authors.initials: T
authors.lastname: Nieminen
authors.forename: Georg
authors.initials: G
authors.lastname: Schmidt
authors.forename: Panu
authors.initials: P
authors.lastname: Somervuo
authors.forename: Marzia
authors.initials: M
authors.lastname: Mohsina
authors.forename: Paula
authors.initials: P
authors.lastname: Vanninen
authors.forename: Petri
authors.initials: P
authors.lastname: Auvinen
authors.forename: Johanna
authors.initials: J
authors.lastname: Björkroth
mesh_terms: D018533:Biomass; D020869:Gene Expression Profiling; D006418:Heme / Q000378:metabolism*; D007934:Leuconostoc / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008460:Meat / Q000382:microbiology*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000378:metabolism*; D055549:Volatile Organic Compounds / Q000378:metabolism
chemical_list: D055549:Volatile Organic Compounds; D006418:Heme; D010100:Oxygen