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| Author(s): |
Celina Mara Soares
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Campinas, SP. |
| Institution: | Universidade Estadual de Campinas (UNICAMP). Faculdade de Engenharia de Alimentos |
| Defense date: | 2005-01-31 |
| Examining board members: |
Arnaldo Yoshiteru Kuaye;
Ernani Porto;
Mauro Faber de Freitas Leitão;
Pedro Manuel Leal Germano;
Maria Helena Castro Reis Passos;
Jose Luiz Pereira;
Veleria Christina Amstalden Junqueira
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| Advisor: | Raquel Monteiro Cordeiro de Azevedo; Arnaldo Yoshiteru Kuaye |
| Abstract | |
Environmental and food samples were collected in two food services in the city of Campinas/SP for investigation of Bacillus cereus contamination sources and characterization of strains toxin profiles. The research has been made in three steps: i) analysis of general environmental contamination; ii) diagnosis of contamination during processing cooked meat; and iii) study of microorganism behavior in meat substrate stored at inappropriate temperatures. The results indicated the presence of microorganism in 80 (74.8%) of the 107 environmental air samples (2.0 to 38.4 CFU/m³) and in 58 (46.4%) of the 125 samples of equipments and benches surfaces. The microorganism also was identified in cooked meat samples (10² CFU/g to 2.4x10³ CFU/g) and in spices samples (1.0x10 CFU/g to 5.0x10² CFU/g), collected during the processing. 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 all the 124 strains, 117 (94.3%) were positive for at least one gene; 16 (12.9%) were positive for the three HBL encoding genes; 25 (20.2%) were positive for the three NHE encoding genes; and 7 (5.6%) were positive for all genes. The Bacillus Diarrhoeal Enterotoxin Visual Immunoassay (BDE-VIA; Tecra) also was used for NHE detection. The results obtained with BDE-VIA revealed that 89 (71.8%) from the 124 strains are NHE producers. B. cereus cells showed fast growth in meat substrate stored at 30°C with generation time between 28.8 and 36.0 min, indicating that meat stored at inadequate temperatures is propitious to the microorganism development. At 10°C, the generation time varied between 10.16 and 28.38 h. The presence of potentially enterotoxigenic strains in the environmental samples confirm the importance of environment as a source of microorganism contamination. The results allow to conclude that either the control of microorganism in food services environment either the proper food processing are fundamental to reduce the risks of foodborne diseases associated to B. cereus (AU) | |