Area de Microbiología, Departamento de Ciencias de la Salud, Facultad de Ciencias Experimentales, Universidad de Jaén, 23071-Jaén, Spain.
Food Microbiol. 2010 Apr;27(2):274-9. doi: 10.1016/j.fm.2009.11.006. Epub 2009 Nov 6.
Cereal doughs are an important part of human diet, but at the same time can act as vehicles for the transmission of human pathogenic bacteria. In the present study, four pathogenic or toxinogenic bacteria (Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Bacillus cereus and Staphylococcus aureus) were inoculated in a dough made from corn flour in combination with the single antimicrobial compounds carvacrol and 2-Nitro-1-propanol (2NPOH). Survival of single and mixed populations in the treated doughs incubated at 37 degrees C was followed by culture-dependent and independent methods (TTGE). All strains were completely inactivated within 24 h by the tested compounds at 5% final concentration, but showed variable inhibition at lower concentrations of 0.5% and 2%. Sensitivity to antimicrobial compounds was in general modified when strains were tested in cocultures compared with single cultures. B. cereus was more sensitive to carvacrol (minimum bactericidal concentration, MBC, 0.5%) in coculture with S. aureus. It was also more sensitive to 2NPOH in cocultures with S. aureus and with S. enterica (MBC, 2% in both cases). S. aureus was more resistant to carvacrol (MBC, 5%) in cocultures with B. cereus, E. coli, as well as S. enterica. However, sensitivity to 2NPOH was not modified in any of the coculture experiments (MBC, 2%). E. coli was more resistant to carvacrol (MBC, 5%) in cocultures with S. aureus and with S. enterica. Resistance of E. coli to 2NPOH also increased in cocultures with B. cereus (MBC, 5%) and with S. aureus (MBC, 2%), but not with S. enterica (MBC, 0.5%). S. enterica was more resistant to carvacrol (MBC, 5%) in cocultures with E. coli, but it was more sensitive to 2NPOH in cocultures with B. cereus as well as with S. aureus (MBC, 2% in both cases). TTGE analysis of survivors from cocultures treated with 2NPOH or carvacrol allowed a good estimation of the identity of survivors according to their DNA band patterns. Results from this study indicate that the efficacy of antimicrobials such as carvacrol and 2NPOH is greatly influenced by the complexity of the microbial populations under target and the relationships between individual populations.
谷物面团是人类饮食的重要组成部分，但同时也可以作为人类病原菌传播的载体。在本研究中，将四种致病性或产毒细菌（大肠杆菌 O157：H7、肠炎沙门氏菌、蜡样芽孢杆菌和金黄色葡萄球菌）接种到玉米粉面团中，并与单一抗菌化合物香芹酚和 2-硝基-1-丙醇（2NPOH）组合使用。在 37°C 下孵育的处理面团中，通过依赖和独立于培养的方法（TTGE）跟踪单种和混合种群的存活情况。在 5%的终浓度下，所有菌株在 24 小时内均被测试化合物完全灭活，但在 0.5%和 2%的较低浓度下表现出不同程度的抑制。与单一培养相比，当在共培养中测试菌株时，对抗菌化合物的敏感性通常会发生变化。在与金黄色葡萄球菌共培养时，蜡样芽孢杆菌对香芹酚（最低杀菌浓度，MBC，0.5%）更敏感。在与金黄色葡萄球菌和肠炎沙门氏菌的共培养中，它对 2NPOH 也更敏感（MBC，两种情况下均为 2%）。金黄色葡萄球菌在与蜡样芽孢杆菌、大肠杆菌以及肠炎沙门氏菌的共培养中对香芹酚的抗性更高（MBC，5%）。然而，在任何共培养实验中，对 2NPOH 的敏感性都没有改变（MBC，2%）。在与金黄色葡萄球菌和肠炎沙门氏菌的共培养中，大肠杆菌对香芹酚（MBC，5%）的抗性更高。在与蜡样芽孢杆菌和金黄色葡萄球菌的共培养中，大肠杆菌对 2NPOH 的抗性也增加（MBC，5%和 2%），但与肠炎沙门氏菌的共培养中则没有（MBC，0.5%）。在与大肠杆菌的共培养中，肠炎沙门氏菌对香芹酚的抗性更高（MBC，5%），但在与蜡样芽孢杆菌和金黄色葡萄球菌的共培养中，它对 2NPOH 更敏感（MBC，两种情况下均为 2%）。用 2NPOH 或香芹酚处理共培养物后的幸存者的 TTGE 分析允许根据其 DNA 条带模式很好地估计幸存者的身份。本研究结果表明，香芹酚和 2NPOH 等抗菌剂的功效受目标微生物种群的复杂性以及种群之间关系的影响。
