Genetic analysis of bacterial functions involved in biofilm formation

1.细菌生物膜（Bf）的耐药性一直被认为是由于胞外多糖（EPS）可能阻碍药物的扩散。在寻找其他耐药原因的过程中，我们分离了粘质沙雷氏菌突变株，它们能够构建厚的Bf，但所形成的Bf在产生耐药性方面是有缺陷的。由于这些突变体的增殖细胞表现出正常的药物敏感性，这些突变体似乎是缺陷的Bf特异性耐药机制。测序和同源性分析表明，功能相关的LPS和EPS的生物合成，铁载体的摄取可能参与耐药的BF。2。在Bf中，局部微环境如pH、营养盐浓度或O_2是不均匀的。因此，构成Bf的细菌是异质的。因此，如果某些细菌处于耐药状态，则很难根除Bf。我们发现铜绿假单胞菌和其他细菌 关于我们 在贫磷条件下，材料物种的细胞膜由富含磷脂的组成变为富含鸟磷脂的组成。细菌膜的这种剧烈变化可能会引起对化学物质和物理化学因素的敏感性变化。因此，对在贫磷条件下生长的细菌进行了敏感性检查。对抗菌药物的耐药性没有明显增加，但具有富鸟苷脂膜的细菌表现出较强的耐酸性.浮游细菌与Bf共存表现出增加的耐药性。从Bf释放的未知物质似乎有助于增加耐药性。在面对MF膜的腔室中用嗜热菌检查来自Bf的膜渗透性物质的作用，MF膜在另一面上携带铜绿假单胞菌的Bf。嗜酸菌确实表现出抗药性增强。此外，在MF膜分隔的腔室中，我们发现了应包含在Bf腔室中的细菌。发现了一种新的细菌活性，“膜过滤器（孔径，0.22 mm）通过活性”。少

1. Drug resistance of bacterial biofims (Bf) has been considered to be due to extracellular polysaccharide (EPS) which may hinder diffusion of drugs. In searching for other reasons of drug resistance, we isolated Serratia marcescens mutants which are able to construct thick Bf, but the formed Bf are defective in developing drug resistane. Since planktonic cells of these mutants showed normal drug susceptibility, these mutants seemed to be defective in Bf specific resistance mechanisms. Sequencing and homology analyses with three identified genes indicated that functions related to biosynthesis of LPS and EPS, and siderophore uptake may be involved in drug resistance at the population level of Bf.2. In Bf, local micro-conditions such as pH, concentration of nutrients or O_2 are heterogeneous. Consequently, bacteria composing Bf are heterogenous. So, if some bacteria are in drug resistant status, it will be difficult to eradicate Bf. We found that Pseudomonas aeruginosa and some other ba … More cterial species change their cellular membrane from phospholipid-rich to ornithinelipid-rich composition under phosphorus-poor condition. Such drastic changes in bacterial membranes may induce susceptibility changes to chemicals and physicochemical factors. So, bacteria growing under phosphorus-poor condition was examined for susceptibility. There were no remarkable resistance increase to antibacterial drugs, but bacteria having ornithinelipid-rich membrane showed strong acid resistance.3. Planktonic bacteria coexisting with Bf demonstrated increased drug resistance. Unknown substances released from Bf seemed to contribute to the increased drug resistance. Effects of membrane permeable substances from Bf were examined with planktonic bacteria in the chamber facing the MF membrane which carried Bf of P. aeruginosa on the another face. The planktonic bacteria certainly showed increased drug resistance. In addition, in the chamber separated by MF membrane we found bacteria which should be contained in the chamber with Bf. A novel bacterial activity, "membrane filter (pore size, 0.22 mm) passing-through activity" was discovered. Less