International Journal of Food Microbiology, 9 (1989) 33-43 33 Elsevier JFM 00275 Characterization of lactic acid bacteria isolated from vacuum-packed cooked ring sausages H. Korkeala and P. M~ikel~i Department of Food and Environmental Hygiene, College of Veterina~ Medicine, Helsinki, Finland (Received 12 November 1988; accepted 21 March 1989) The bacterial populations of the surface layer and the centre of 15 spoiled vacuum-packed cooked ring sausages were characterized. About 95% of the total bacterial population in the surface layer and 55% at the centre were lactic acid bacteria. Another large bacterial group at the centre consisted of Bacillus spp. The lactic acid bacteria on the surface and at the centre were quite similar. Atypical streptobacteria, i.e. homofermentative psychrotrophic lactobacilli, were a major group of lactic acid bacteria in the surface layer of the spoiled sausages. Three main homofermentative groups could be observed on the basis of different carbohydrate patterns. Heterofermentative lactic acid bacteria belonged mainly to genus Leuconostoc. The proportion of leuconostocs in the spoiled sausages was also quite large. They could be divided into three main groups on the basis of different carbohydrate fermentation patterns. The lactic acid bacteria population of spoiled cooked ring sausages thus seemed to be heterogeneous. The strains isolated resembled strains observed by other workers in meat and meat products. Key words: Sausage, cooked; Lactic acid bacteria; Lactobacillus; Leuconostoc; Taxonomy Introduction Lactic acid bacteria are the major component of the microbial population developing on various types of vacuum-packed meat and meat products (Alien and Foster, 1960; Reuter, 1970b; Mol et al., 1971; Hitchener et al., 1982; Blickstad and Molin, 1983; Shaw and Harding, 1984). Reuter (1970a) characterized lactobacilli isolated from meat products and grouped some of them as atypical streptobacteria. These bacteria had a tendency towards coccoid cell shapes, a lower acid tolerance and lower growth temperature minima than typical lactobacilli. Atypical streptobacteria have been shown to be the most important component of vacuum-packed cooked meat products (Mol et al., 1971; Reuter, 1975; Holzapfel and Gerber, 1986). A number of other reports have been published dealing with classification of lactic acid bacteria isolated from meat and meat products (Hitchener et al., 1982; Shaw and Harding, 1984; Morishita and Correspondence address: Dr. Hannu Korkeala, Department of Food and Environmental Hygiene, College of Veterinary Medicine, P.O. Box 6, SF-00551 Helsinki, Finland. 0168-1605/89/$03.50 © 1989 Elsevier Science Publishers B.V.