ATTRIBUTES OF MICROBIAL ASSOCIATIONS OF MEAT GROWING AS XENIC BATCH CULTURES IN A MEAT JUICE AT 4-DEGREES-C

Strains of Gram-positive (Carnobacterium piscicola, Leuconostoc mesent eroides subsp. mesenteroides, Brochothrix thermosphacta) and Gram-nega tive (Pseudomonas fragi and Hafnia alvei) bacteria isolated from mince d lamb packaged under a modified atmosphere were cultivated in a meat (lamb) juice at 4 degrees C. Carbohydrates were catabolised in the ord er glucose > glucose 6-phosphate during the development of the populat ion. Under an atmosphere enriched with carbon dioxide the Gram-negativ e portion of the population was suppressed during the exponential phas e but H. alvei became the dominant organism towards the end of a protr acted stationary phase of growth. With the aerobic atmosphere P. fragi catabolised creatine and became the dominant species in the stationar y phase. The inability of C. piscicola to catabolise glucose 6-phospha te was reflected in its population being smaller than those of the oth er Gram-positive organisms (C. piscicola < L. mesenteroides subsp, mes enteroides < B. thermosphacta). During the stationary phase of growth, indigenous L-lactic acid and the D-isomer produced by leuconostocs we re oxidised to acetic acid by the Gram-positive flora under an atmosph ere enriched with carbon dioxide. These oxidations, which occurred aft er depletion of glucose, were supported by the oxygen in the system. D -Lactic and acetic acid appeared to be possible parameters for the est imation of the microbiological quality of packaged meat.