Characterisation of lactic acid bacteria from spoiled, vacuum-packaged, cold-smoked rainbow trout using ribotyping

A total of 405 lactic acid bacteria (LAB) isolated from spoiled, vacuum-pac kaged, salted, sodium nitrite- or potassium nitrate-treated, cold-smoked ra inbow trout stored at 4 degrees C or 8 degrees C were characterised and ide ntified using a molecular method. The isolates were initially classified ac cording to their restriction endonuclease profiles using HindIII and EcoRI restriction endonucleases and further characterised by rRNA gene restrictio n patterns (ribotypes). Numerical analysis of these ribopatterns was perfor med together with 19 reference LAB strain patterns in order to identify the isolates to species level. The strains were divided with HindIII and EcoRI ribopatterns into ten and nine clusters at the similarity level of 65% and 50%, respectively. The Leuconostoc-clusters and the Lb. sakei/Lb. curvatus -clusters formed the two main groups. Only one isolate was identified as La ctobacillus plantarum and no Carnobacterium strains were discovered. For bo th enzymes, the 35 isolates possessing six individual ribotypes and forming five clusters could not be identified further with the reference strains u sed. The relative proportion of Leuconostoc mesenteroides subsp. mesenteroi des was higher in all samples stored at 4 degrees C. Most of the Leuconosto c citreum were found in the samples stored at 8 degrees C, and particularly in the nitrite-treated samples. (C) 1999 Elsevier Science B.V. All rights reserved.