MORPHOLOGICAL CHARACTERIZATION OF LACTIC-ACID BACTERIA FROM SPOILED, VACUUM-PACKAGED VIENNA SAUSAGES

The morphology of 61 lactic acid bacteria from spoiled vacuum-packaged vienna sausages and 10 reference strains were compared as an initial characterization step. Twenty-four-hour de Man, Rogosa and Sharpe (MRS ) agar and broth cultures of all strains were then examined using phas e contrast microscopy and scanning electron microscopy, respectively. Phase contrast microscopy proved useful in determining the basic morph ology of strains. Scanning electron microscopy revealed detailed morph ological features, such as the production of extracellular polysacchar ides, and proved useful in characterizing individual isolates. The mor phology ranged from cocci to long rods. Morphologies were more diverse among isolates than reference strains. The morphology of reference st rains allowed the differentiation of specific strains with highly dist inguishing features. Reference strains such as members of the genus Le uconostoc shared many morphological features, such as cell shape and p airing, with other members of the same genus and some members of the g enus Lactobacillus. Morphology was used to place the isolates in broad groups, namely cocci, cocco-bacilli, short rods and long rods. Compar ison of these groups with reference strains did not allow definite ass ociation of any group with any particular genus or species. The morpho logy of lactic acid bacteria isolates and reference strains was useful for the initial characterization of isolates, although other means ar e required for the confirmation of identity.