RESUMO
Five spore-forming bacterial strains were isolated as the most dominant microorganisms from five products of different types of cooked food. Three strains in particular were isolated as spoilage organisms causing acidity. These belonged to the genus Paenibacillus, and one of them was identified as Paenibacillus odorifer. All five strains grew at 10 degrees C in brain heart infusion broth; furthermore, four strains grew at 4 degrees C also. These strains grew optimally at 30 to 35 degrees C. Psychrotrophic Paenibacillus spp. can easily be mistaken for lactic acid bacteria in routine analysis because of their colony characteristics. Because the measures that must be taken for bacterial control are different in the case of contamination by these two bacterial groups, psychrotrophic Paenibacillus spp. contamination must be distinguished from that caused by lactic acid bacteria.
Assuntos
Contaminação de Alimentos/análise , Microbiologia de Alimentos , Bacilos Gram-Positivos Formadores de Endosporo/fisiologia , Contagem de Colônia Microbiana , Qualidade de Produtos para o Consumidor , Bacilos Gram-Positivos Formadores de Endosporo/classificação , Bacilos Gram-Positivos Formadores de Endosporo/isolamento & purificação , Humanos , Filogenia , Especificidade da EspécieRESUMO
Two Paenibacillus macerans strains, JCM 2500T and MCRI 12, exhibited two types of 16S rDNA copies in their genomes, accompanied by a length difference of 12 bp at positions 203 to 214 (Escherichia coli numbering). The long-type sequences were newly identified for P. macerans 16S rDNA, and the copy numbers were different between the two strains. Both types of 16S rRNA were expressed in each strain, and it was predicted that the polymorphism at this position is located in helix H10, based on a comparison with the E. coli 16S rRNA secondary structure model.
Assuntos
Bacillus/genética , DNA Ribossômico/genética , Dosagem de Genes , RNA Ribossômico 16S/genética , Sequência de Bases , Genoma Bacteriano , Polimorfismo GenéticoRESUMO
Three kinds of lactic acid bacteria were isolated from spoiling cooked meat products stored below 10 degrees C. They were identified as Leuconostoc mesenteroides subsp. mesenteroides, Lactococcus lactis subsp. lactis, and Leuconostoc citreum. All three strains grew well in MRS broth at 10 degrees C. In particular, L. mesenteroides subsp. mesenteroides and L. citreum grew even at 4 degrees C, and their doubling times were 23.6 and 51.5 h, respectively. On the other hand, although the bacteria were initially below the detection limit (<10 CFU/g) in model cooked meat products, the bacterial counts increased to 10(8) CFU/g at 10 degrees C after 7 to 12 days.
