Costa-Ribeiro Ana, Lamas Alexandre, Prado Marta, Garrido-Maestu Alejandro
International Iberian Nanotechnology Laboratory, Av. Mestre José Veiga s/n, 4715-330 Braga, Portugal.
Department of Biochemistry, Genetics and Immunology, University of Vigo, 36310 Vigo, Spain.
Foods. 2023 Dec 23;13(1):63. doi: 10.3390/foods13010063.
Multiplex assays implementing DNA-based methods have been demonstrated as suitable alternatives to culture-based microbiological methods; however, in most cases, they still require a suitable enrichment step. Finding suitable enrichment conditions for different bacteria may result in challenges. In the present study, a novel selective broth named MSB (mTA10 selective broth) was formulated for the simultaneous recovery of spp., O157:H7 and . Attention was paid to ensure the optimal enrichment of as its enrichment is more challenging. To this end, cellobiose was added to increase the growth of , and sodium pyruvate was also added to improve the recovery of stressed bacteria. Four selective agents were added, namely nalidixic acid, sodium cholate, lithium chloride and potassium tellurite, to control the growth of interfering microorganisms. It was concluded that the novel broth was suitable for the simultaneous enrichment of the target pathogens, allowing them to reach concentrations higher than 7 log CFU/mL for each bacterium in pure culture. Furthermore, all heavily contaminated ready-to-eat salad samples reached concentrations higher than 5 log CFU/g. Finally, after 24 h of enrichment of spiked salad, it was possible to detect concentrations below 10 CFU/25 g.
实施基于DNA方法的多重检测已被证明是基于培养的微生物学方法的合适替代方法；然而，在大多数情况下，它们仍需要合适的富集步骤。为不同细菌寻找合适的富集条件可能会带来挑战。在本研究中，配制了一种名为MSB（mTA10选择性肉汤）的新型选择性肉汤，用于同时回收 spp.、O157:H7和 。由于 的富集更具挑战性，因此注意确保其最佳富集。为此，添加纤维二糖以促进 的生长，还添加丙酮酸钠以提高应激细菌的回收率。添加了四种选择性试剂，即萘啶酸、胆酸钠、氯化锂和亚碲酸钾，以控制干扰微生物的生长。得出的结论是，这种新型肉汤适用于同时富集目标病原体，在纯培养中每种细菌的浓度可高于7 log CFU/mL。此外，所有严重污染的即食沙拉样品的浓度均高于5 log CFU/g。最后，在加标沙拉富集24小时后，可以检测到浓度低于10 CFU/25 g。
