Clostridium gasigenes sp nov., a psychrophile causing spoilage of vacuumpacked meat

Two psychrophilic Clostridium strains, DB1A(T) and R26, were isolated from incidences of 'blown-pack' spoilage of vacuum-packed chilled lamb. Vacuum p acks of meat inoculated with these strains developed gas bubbles and pack d istension within 14 d storage at 2 degrees C. The two main gases responsibl e for pack distension were carbon dioxide and; hydrogen. l-Butanol, butyric and acetic acid and butyl esters were the major volatile compounds produce d by the strains in the artificially inoculated packs. The unknown strains were Gram-stains In me artificially inoculated packs. The unknown strains w ere Gram-positive motile rods producing elliptical subterminal spores durin g the late-stationary growth phase. At pH 7.0, they grew from -1.5 to 26 de grees C, and their optimum growth temperature was 20-22 degrees C. At 20 de grees C, the ph range for growth was 5.4-8.9 and the optimum pH for growth was 6.2-8.6. In peptone/yeast extract broth, the organisms grew little or n ot at all in the absence of fermentable carbohydrates. Both strains hydroly sed gelatin, aesculin and starch. The fermentation products formed in pepto ne yeast extract glucose starch broth were ethanol, acetate, butyrate, lact ate, butanol, carbon dioxide and hydrogen. The G+C: contents of the DNA of strains DB1A(T) and R26 were 29.4 and 28.3 mol%, respectively. Phylogenetic analyses indicated that the strains belong to cluster I of the genus Clost ridium (sensu Collins et al. 1994). The new strains differed from the phylo genetically related clostridia in cellular fatty acid composition, soluble protein profiles and phenotypic properties. On the basis of rDNA analysis a nd phenotypic and phylogenetic characterization, the strains were assigned to a new species for which the name Clostridium gasigenes is proposed. Stra in DB1A(T) (= DSM 12272(T)) is designated as the type strain.