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Master's Dissertation
DOI
10.11606/D.74.2011.tde-11082011-085506
Document
Author
Full name
Fernanda Bovo
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
Pirassununga, 2011
Supervisor
Committee
Oliveira, Carlos Augusto Fernandes de (President)
Sabino, Myrna
Trindade, Carmen Sílvia Fávaro
Title in Portuguese
Avaliação da eficiência de bactérias ácido-láticas para descontaminação de aflotoxina M1
Keywords in Portuguese
Aflatoxina M1
Bactérias ácido-láticas
Descontaminação
Leite
Abstract in Portuguese
O objetivo do trabalho foi avaliar a capacidade de cepas de bactérias ácido-láticas (BAL) em remover a aflatoxina M1 (AFM1) em solução tampão fosfato salina (TFS) e em amostras de leite. Nos ensaios com TFS, verificou-se a influência do tempo de contato (15 min. ou 24 horas) entre as células de sete cepas de BAL e AFM1, as diferenças entre a eficiência de remoção das bactérias viáveis e inviabilizadas termicamente, e a estabilidade do complexo BAL/AFM1 formado. As três cepas de BAL com maior percentual (> 33%) de remoção da AFM1 nos ensaios com TFS foram re-avaliadas utilizando-se leite UHT (ultra-high-temperature) desnatado artificialmente contaminado com AFM1. Para isso, foram utilizadas somente células inviabilizadas termicamente, verificando-se o efeito da temperatura (4ºC ou 37ºC) sobre a capacidade de remoção da toxina por 15 minutos. A remoção média da AFM1 pelas cepas de BAL em TFS variou entre 5,60±0,45 e 45,67±1,65% (n=3), sendo que as células inviáveis obtiveram percentuais de remoção de AFM1 significativamente maiores que as células viáveis, em ambos os tempos de contato analisados (15 min. ou 24 horas), não havendo diferença significativa entre os tempos. Observou-se que o complexo BAL/AFM1 obtido nos ensaios com TFS é instável, pois 40,57±4,66 a 87,37±1,82% da AFM1 retida pela bactéria foram recuperados em solução após a lavagem do complexo com TFS. As três cepas de BAL com maior percentual de remoção da AFM1 em TFS (Lactobacillus rhamnosus, Lactobacillus delbrueckii spp. bulgaricus e Bifidobacterium lactis) não apresentaram diferenças significativas nos ensaios com leite UHT a 37ºC. Somente B. lactis apresentou maior capacidade de remover a AFM1 do leite UHT a 4ºC. Os resultados demonstraram que a remoção de AFM1 empregando-se as BAL em alimentos é viável para reduzir as concentrações da toxina a níveis seguros. Entretanto, estudos adicionais são necessários a fim de investigar os mecanismos envolvidos na remoção da toxina pelas BAL com vistas à aplicação em indústrias de alimentos.
Title in English
Evaluation of the efficiency of lactic acid bacteria for the decontamination of aflatoxin M1
Keywords in English
Aflatoxin M1
Decontamination
Lactic acid bacteria
Milk
Abstract in English
The purpose of this study was to evaluate the ability of strains of lactic acid bacteria (LAB) to remove aflatoxin M1 (AFM1) in phosphate buffer saline (PBS) and in milk samples. In the assays with PBS, the influence of contact time (15 min. or 24 hours) between the cells of seven LAB strains and AFM1 was evaluated, as well as the differences between the removal efficiency of viable and non-viable (heat-killed) bacteria, and the stability of AFM1/LAB complex produced. The three LAB strains with the highest percentage (> 33%) of AFM1 removal in the tests with PBS were reevaluated using UHT (ultra-high-temperature) skimmed milk spiked with AFM1. For these assays, only non-viable bacterial cells were used for checking the effect of temperature (4ºC or 37ºC) on the toxin removal capacity during 15 min. The mean AFM1 removal by LAB strains in PBS ranged from 5.60±0.45 and 45.67±1.65% (n=3). Non-viable cells showed AFM1 removal percentages significantly higher than viable cells in both contact times (15 min. or 24 hours), although there were not significant differences between these contact times. The AFM1/LAB complex resulted from the tests with PBS was unstable, as 40.57±4.66 to 87.37±1.82% of AFM1 retained by the bacteria were recovered in solution after washing the complex with PBS. The three LAB strains with the highest percentage of AFM1 removal in the PBS assays (Lactobacillus rhamnosus, Lactobacillus delbrueckii spp. bulgaricus and Bifidobacterium lactis) showed no significant differences in the UHT skimmed milk assays at 37ºC. Only B. lactis had greater ability to remove AFM1 in UHT milk at 4ºC. The results demonstrated that the removal of AFM1 by using LAB in foods is viable to reduce the toxin concentrations until safe levels. However, additional studies are needed to investigate the mechanisms involved in the toxin removal by LAB aiming its application in food industries.
 
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ME4962460.pdf (1.26 Mbytes)
Publishing Date
2011-08-12
 
WARNING: The material described below relates to works resulting from this thesis or dissertation. The contents of these works are the author's responsibility.
  • BOVO, Fernanda, et al. Efficiency of lactic acid bacteria strains for decontamination of aflatoxin M1 in phosphate buffer saline solution and in skimmed milk. Food and Bioprocess Technology, 2012, vol. 5, p. 1-5.
  • BOVO, Fernanda, et al. Eficiência de bactérias ácido-láticas para descontaminação de aflatoxina M1 em solução tampão fosfato. UNOPAR Científica: Ciências Biológicas e da Saúde, 2011, vol. 13, p. 151-156.
  • BOVO, Fernanda, CORASSIN, Carlos Humberto, e OLIVEIRA, Carlos Augusto Fernandes de. Descontaminação de aflatoxinas em alimentos por bactérias ácido-láticas. UNOPAR Científica: Ciências Biológicas e da Saúde, 2010, vol. 12, p. 15-21.
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