Journal of microorganism control最新文献

Clavibacter michiganensis, a gram-positive actinomycete, is a major seed-borne tomato pathogen. We investigated the inactivation efficacy of low-pressure plasma treatment against C. michiganensis inoculated on tomato seeds by placing them on a mesh sheet above the bottom dielectric glass plate. The 2- and 5-minute plasma treatment reduced C. michiganensis populations on the tomato seeds by 0.8 and 1.8 log cfu/seed, respectively. The reduction rates were similar to those of C. michiganensis on shirona (cruciferous) seeds, which have different shapes and surface structures. In contrast, the inactivation of C. michiganensis cells using plasma was more difficult than that of X. campestris cells. Additionally, it was found that placing seeds on a mesh sheet laid on the dielectric glass plate was remarkably effective in inactivating the pathogens on tomato seeds. Since the tomato seeds were susceptible to damage from plasma treatment, methods to reduce its damage need to be investigated.

Norovirus (NoV）is a major causative virus of viral gastroenteritis and requires a general disinfection method because it is resistant to common disinfectants such as ethanol and chlorhexidine. This study aimed to find natural extracts as candidates for versatile disinfectant ingredients. The antiviral effect of natural extracts against NoV can be evaluated using the feline calicivirus (FCV）-inactivation test and NoV virus-like particle (NoV-VLP）-binding inhibition test. In this study, screening of natural extracts with anti- NoV effects was performed using these two methods. Of the 63 natural extracts examined, 14 were found to have high FCV-inactivation and NoV-VLP-binding inhibitory effects. In addition, we evaluated the NoV-VLPbinding inhibitory effect of grape seed extract（GSE）containing proanthocyanidins under multiple concentration conditions and treatment times and determined that the binding inhibitory effect of GSE was concentration- and time-dependent. Electron microscopy showed that GSE-treated NoV-VLPs aggregated, distorted, and swelled, suggesting that GSE directly interacts with NoV particles. The results suggest that some natural extracts containing GSE can be used as components of disinfectants against NoV.

Various sterilization and disinfection processes are used to control harmful microorganisms in food, medicine, and the environment. During killing, microorganisms often remain between life and death, being called injured microorganisms. The degree of injury of the injured microorganisms depends on the load of the disinfection treatment, and the treatment conditions and varies not only quantitatively but also qualitatively. Knowing how they are injured by sublethal and lethal stresses of disinfection, how they repair themselves, what makes the difference between life and death, and their physiological characteristics, will lead to appropriate microbial testing and optimization of disinfection conditions for practical viability and growth potential, and will deepen our understanding of the effectiveness of the treatment. Focusing on mainly heat injury and using Escherichia coli as a model microorganism, in this review, I will discuss the classification of injury modes in injured microorganisms caused by disinfection treatment, including "λ injury" (delayed resumption of growth）," μ injury" (reduced growth rate injury）," β injury" (secondary injury）, and other derivatives.