Growth of enterotoxin producing Bacillus cereus in meat substrate at 10ºC and 30ºC

The behaviour of enterotoxin-producing Bacillus cereus in meat was investigated by inoculating spore suspensions of five cultures into meat substrate (pH 5.8) and incubating at 10ºC and 30ºC. The bacterial populations were evaluated after different times by plate counts in nutrient agar. All the cultures presented growth at 30ºC with the generation time varying from 28.8 to 36.0 minutes. Three cultures also presented growth at 10ºC with generation times between 10.16 and 28.38 h. Considering the results, it was concluded that meat kept at abusive temperatures would be subject to development of this microorganism.(AU)

Contaminação ambiental e perfil toxigênico de Bacillus cereus isolados em serviços de alimentação / Environmental contamination and enterotoxigenic profile of Bacillus cereus isolated in food services

A avaliação da contaminação ambiental por Bacillus cereus foi realizada em 90 amostras de ar ambiente e em 96 amostras de superfícies de bancadas e de equipamentos, de dois restaurantes institucionais. O microrganismo foi detectado em 84,4% e 44,8% das amostras de ar ambiente e de superfícies, respectivamente. O potencial enterotoxigênico dos isolados foi investigado através da reação da polimerase em cadeia (PCR) para os genes hblA, hblD e hblC (que codificam a hemolisina BL) e para os genes nheA, nheB e nheC (que codificam a enterotoxina não hemolítica - NHE). De um total de 70 isolados investigados, 14,3% foram positivos para os três genes da HBL e 12,8% foram positivos para os três genes da NHE. A produção de NHE também foi verificada através do Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (kit BDE-VIA; Tecra). Os resultados obtidos com o kit revelaram que 61,4% dos 70 isolados são produtores de NHE(AU)

Ninety air samples and ninety six samples from benches and equipments surfaces were collected in two food services for investigation of Bacillus cereus contamination sources and characterization of strains toxin profiles. B. cereus was detected in 84.4% and 44.8% from air samples and samples from benches and equipments surfaces, respectively. The potential of enterotoxin production was investigated using polymerase chain reaction (PCR) methods for genes hblA, hblD e hblC (encoding hemolysin BL) and for genes nheA, nheB and nheC (encoding non-hemolytic enterotoxin - NHE). From 70 isolates investigated 14.3% were positive for the three HBL encoding genes and 12.8% were positive for the three NHE encoding genes. The Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (BDE-VIA; Tecra) also was used for NHE detection. The results obtained with BDE-VIA revealed that 61.4% from the 70 strains are NHE producers(AU)

Características microbiológicas e físico-químicas do salmão (Salmo salar) utilizado em sashimis / Microbiological characteristics and physicochemical of the salmon (Salmo salar) used in sashimis

Amostras de salmão in natura (Salmo salar), provenientes de sashimis comercializados em estabelecimentos de shopping centers da cidade de São Paulo/SP, foram analisadas quanto às características físico-químicas e microbiológicas. Os valores das contagens bacterianas variaram de 1,00x10³ a 1,90x10 UFC/g; 1,45x10² a 1,10x10 UFC/g. e 3,50x10 a 1,10x10 UFC/g para os grupos de bactérias aeróbias mesófilas, enterobactérias e coliformes totais, respectivamente. A temperatura das amostras foi observada no momento da colheita e os valores encontrados variaram entre 5,7ºC e 22,0ºC. Com relação ao pH, observaram-se valores entre 5,74 e 6,39. Para a atividade de água, os valores obtidos oscilaram entre 0,98 e 0,99. As análises, também, foram efetuadas com amostras de salmão in natura antes e após o emprego de shoyu (molho de soja) e wasabi condimentos que tradicionalmente acompanham este prato. A adição dos condimentos às amostras, nas proporções adotadas nesta pesquisa, não interferiu de forma significativa nos valores observados nas contagens bacterianas e nas contagens bacterianas e nas análises do pH e atividade de água. De modo geral, observou-se que quanto menor a temperatura das amostras, menores os valores de contagens bacterianas (p<0,05). (AU)

Samples of in nature salmon (Salmo salar) from sashimis commercialized in establishments in shopping centers inthe city of São Paulo/SP /Brazil were analyzed for their physicochemical and microbiological characteristics. The bacterial counts varied from 1.00xl03 to 1.90xl06 CFU/g; 1.45x102 to 1.10xl06 CFU/g and 3.50xlO to 1.lOx106 CFU/g for aerobic mesophyllic bacteria, enterobacteria and total coliforms respectively. The temperature of the samples was measured at the moment of collection and varied between 5.7" C and 22.0° C. The pH values observed varied between 5.74 and 6.39 and the values for water activity oscillated between 0.98 and 0.99. The analyses were carried out on the in nature salmon both before and after the application of shoyu (soy sauce) and wasabi - condiments traditionally accompanying this dish. The addition of the condiments to the samples in the proportions adopted in this study did not significantly affect the bacterial counts or the pH and water activity values. In general the lower the sample temperature the lower the bacterial count (p<0.05). (AU)