Taksonomie van melksuurbakteriee geassosieer met vakuumverpakte vleisprodukte

Abstract

Several workers have indicated the importance of lactic acid bacteria in the spoilage of vacuumpacked meatproducts. Research on the systematics of these lactic acid bacteria in the past have been sporadic and uncoordinated, which resulted in an unreliable and arbitrary classification system for these organisms. The general occurrence of the unclassifiable "atypical streptobacteria" as the dominant group in vacuum-packaged meatproducts shows the necessity of thorough taxonomic investigation of these lactic acid bacteria. Altogether 27 meatsamples and 22 exudatesamples (Vienna sausages, Frankfurters, cold meats, smoked and country sausages and Russians) were analysed microbiologically. The total microorganism-count of each sample was determined as well as the numbers of lactic acid bacteria, Brochothrix thermosphacta, enterobacteria, enterococci, staphylococci, yeasts and fungi. The lactic acid bacteria were the largest group (more than 99%), with yeasts and fungi, and B. thermosphacta in percentages of ca. 0,013 and 0,002 respectively. Enterobacteria, enterococci and typical as well as atypical staphylococci were found, sometimes in larger numbers than permitted by regulations and directives. The 538 isolates from LactobaciUus -selective media were divided by their catalase-reaction; 63 isolates were catalasepositive and not investigated further. The other 475 isolates were investigated taxonomically using a number of morphological and physiological criteria, of which the lactic acid-isomer, gas formed from glucose and the presence of meso-diaminopimelic-acid (~ - A2 pm) in the cellwall were used for dividing the isolates into main groups. The morphology of each isolate was investigated with a phase contrast microscope and a representative of each of the six main groups was investigated with a scanning electronmicroscope. The morphology of the colonies was also described.