Joaquin Jonathan C, Kwan Calvin, Abramzon Nina, Vandervoort Kurt, Brelles-Mariño Graciela
Biological Sciences Department, California State Polytechnic University, 3801 W. Temple Avenue, Pomona, CA 91768, USA.
Center for Macromolecular Modeling and Materials Design (CM3D), California State Polytechnic University, 3801 W. Temple Avenue, Pomona, CA 91768, USA.
Microbiology (Reading). 2009 Mar;155(Pt 3):724-732. doi: 10.1099/mic.0.021501-0.
Conventional disinfection and sterilization methods are often ineffective with biofilms, which are ubiquitous, hard-to-destroy microbial communities embedded in a matrix mostly composed of exopolysaccharides. The use of gas-discharge plasmas represents an alternative method, since plasmas contain a mixture of charged particles, chemically reactive species and UV radiation, whose decontamination potential for free-living, planktonic micro-organisms is well established. In this study, biofilms were produced using Chromobacterium violaceum, a Gram-negative bacterium present in soil and water and used in this study as a model organism. Biofilms were subjected to an atmospheric pressure plasma jet for different exposure times. Our results show that 99.6 % of culturable cells are inactivated after a 5 min treatment. The survivor curve shows double-slope kinetics with a rapid initial decline in c.f.u. ml(-1) followed by a much slower decline with D values that are longer than those for the inactivation of planktonic organisms, suggesting a more complex inactivation mechanism for biofilms. DNA and ATP determinations together with atomic force microscopy and fluorescence microscopy show that non-culturable cells are still alive after short plasma exposure times. These results indicate the potential of plasma for biofilm inactivation and suggest that cells go through a sequential set of physiological and morphological changes before inactivation.
传统的消毒和灭菌方法对生物膜往往无效，生物膜无处不在，是嵌入主要由胞外多糖组成的基质中的难以破坏的微生物群落。气体放电等离子体的使用代表了一种替代方法，因为等离子体包含带电粒子、化学反应物种和紫外线辐射的混合物，其对自由生活的浮游微生物的去污潜力已得到充分证实。在本研究中，使用紫色色杆菌形成生物膜，该菌是一种存在于土壤和水中的革兰氏阴性细菌，在本研究中用作模式生物。生物膜在不同暴露时间下接受大气压等离子体射流处理。我们的结果表明，处理5分钟后，99.6%的可培养细胞被灭活。存活曲线显示出双斜率动力学，即cfu ml(-1)最初迅速下降，随后下降速度慢得多，其D值比浮游生物灭活的D值更长，这表明生物膜的灭活机制更为复杂。DNA和ATP测定以及原子力显微镜和荧光显微镜显示，在短时间等离子体暴露后，不可培养的细胞仍然存活。这些结果表明了等离子体对生物膜灭活的潜力，并表明细胞在灭活前会经历一系列生理和形态变化。
