Kawarai Taketo, Furukawa Soichi, Narisawa Naoki, Hagiwara Chisato, Ogihara Hirokazu, Yamasaki Makari
Department of Food Science and Technology, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-8510, Japan.
J Biosci Bioeng. 2009 Jun;107(6):630-5. doi: 10.1016/j.jbiosc.2009.01.018.
High osmotic environments produced by NaCl or sucrose have been used as reliable and traditional methods of food preservation. We tested, Escherichia coli as an indicator of food-contaminating bacterium, to determine if it can form biofilm in a hyperosmotic environment. E. coli K-12 IAM1264 did not form biofilm in LB broth that contained 1 M NaCl. However, the bacterium formed biofilm in LB broth that contained 1 M sucrose, although the planktonic growth was greatly suppressed. The biofilm, formed on solid surfaces, such as titer-plate well walls and glass slides, solely around the air-liquid interface. Both biofilm forming cells and planktonic cells in the hypertonic medium adopted a characteristic, fat and filamentous morphology with no FtsZ rings, which are a prerequisite for septum formation. Biofilm forming cells were found to be alive based on propidium iodide staining. The presence of 1 M sucrose in the food environment is not sufficient to prevent biofilm formation by E. coli.
氯化钠或蔗糖产生的高渗环境一直被用作可靠且传统的食品保存方法。我们以大肠杆菌作为食品污染细菌的指示菌进行测试，以确定其是否能在高渗环境中形成生物膜。大肠杆菌K-12 IAM1264在含有1 M氯化钠的LB肉汤中未形成生物膜。然而，该细菌在含有1 M蔗糖的LB肉汤中形成了生物膜，尽管浮游生长受到了极大抑制。生物膜仅在气液界面周围的固体表面形成，如滴定板孔壁和载玻片。高渗培养基中的生物膜形成细胞和浮游细胞均呈现出特征性的、肥大且丝状的形态，没有FtsZ环，而FtsZ环是隔膜形成的先决条件。基于碘化丙啶染色发现生物膜形成细胞是活的。食品环境中1 M蔗糖的存在不足以阻止大肠杆菌形成生物膜。
