Department of Agricultural, Environmental and Food Sciences, University of Molise, Via De Sanctis, 86100 Campobasso, Italy.
Biomed Res Int. 2018 Nov 27;2018:8490614. doi: 10.1155/2018/8490614. eCollection 2018.
Coliform bacteria consist of both nonpathogen commensal and human opportunistic pathogen species isolated from different habitats like animals, man, vegetables, and water. Olives normally carry natural nonpathogenic epiphytic bacteria, but during growth, harvest, and processing, one of the final products, represented by virgin olive oil, can be contaminated with coliform. Present study showed that coliform bacteria can survive and reproduce in virgin olive oil containing low level of phenolic compounds. The laboratory inoculation trials demonstrated that when the bacterium isolated from the olives carposphere, was transferred in olive oil containing high polar phenols content, equal to 372 mg caffeic acid equivalent per kg, the survival was completely inhibited after 15 days of storage. On the contrary, the bacterium reproduced quickly when it was inoculated in virgin olive oil samples containing lower concentration of polar phenols. The SDS-PAGE analysis of the proteins showed different electrophoretic patterns when the bacterium was inoculated in the virgin olive oil with high phenolic compounds content, confirming the strong interaction between the olive oil phenols content and the bacterial wall proteins. The SEM ultrastructural observations confirmed the presence of a more higher number of damaged microbial cells in virgin olive oil rich of polar phenols. This finding needs further studies since, in an era of antibiotic resistance, the development of new strategies to fight unwanted food bacteria is promising way for the future.
大肠菌群包括非病原菌共生菌和从不同生境（如动物、人类、蔬菜和水）中分离出来的人类机会致病菌。橄榄通常携带天然的非病原菌附生菌，但在生长、收获和加工过程中，最终产品之一，即特级初榨橄榄油，可能会受到大肠菌群的污染。本研究表明，大肠菌群可以在含有低水平酚类化合物的特级初榨橄榄油中存活和繁殖。实验室接种试验表明，当从橄榄果皮中分离出的细菌转移到含有高极性酚类化合物含量（相当于每公斤 372 毫克咖啡酸当量）的橄榄油中时，在储存 15 天后，其存活率会完全被抑制。相反，当将细菌接种到含有较低极性酚类化合物浓度的特级初榨橄榄油样品中时，细菌会迅速繁殖。当细菌接种到含有高酚类化合物含量的特级初榨橄榄油中时，对蛋白质的 SDS-PAGE 分析显示出不同的电泳模式，证实了橄榄油中酚类化合物含量与细菌细胞壁蛋白之间的强烈相互作用。SEM 超微结构观察证实了在富含极性酚类化合物的特级初榨橄榄油中存在更多受损的微生物细胞。由于在抗生素耐药性的时代，开发新的策略来对抗不受欢迎的食源性病原体是未来有希望的方法，因此需要进一步研究这一发现。
