Research on Injured Microorganisms: Significance, To Date and Into the Future −Special Issues

Abstract

As an introduction for several special issues of this journal regarding research on injured microorganisms (IM), the definition of IM and a brief history, current state and significance, prospects and future problems of IM are overviewed. Although an injured cell is generally considered to be sublethally injured, a model including semilethal injuries is also proposed here. In the fields of microorganism preservation and food processing, the occurrence of IM has been recognized as a key factor, and the presence of IM has been one of the critical problems in the detection and enumeration of microorganisms. Studies on IM have recently been activated by increasing the recognition of their significance in sterilization, disinfection and viability measurements. The execution of the so-called the IM project supported by the Ministry of Agriculture, Forestry and Fisheries, Japan, as well as the establishment of the Japanese Research Society for Injured Microbes may further raise awareness of IM. Nevertheless, there are still unknown and nondescript research areas in the IM world. Eight possible problems in the study of IM are presented and the prospects for resolution of these issues are described.

Effect of High Hydrostatic Pressure Treatment Combined with Alkaline Electrolyzed Water on the Injury and Growth Characteristics of Bacterial Spores

“…Even if the microbial cells are weakened by various stresses, they can recover and proliferate again when they are under the conditions suitable for growth during a certain period of time. These group of weakened but surviving microbial cells is called injured microorganisms , and it has become an extremely important risk to be noted when considering food safety in recent years (Tsuchido, 2018) .…”

Injury modes and physiological characteristics of injured microorganisms with a special reference to heat injury

“…The existence of injured cells has long been recognized and has been considered important not only in terms of methodological aspects related to culture methods for microorganism detection and counting, but also in sterilization, disinfection, and sanitization processes applied to food, medicine, pharmaceuticals, and various environmental applications. Especially in the food industry, there is a trade-off between food quality and sterilization, and there is much interest in injured microorganisms (Hurst 1984;Gould 1989;Wu 2008;Wesche et al 2009;Tsuchido 2018) . In recent years, there has been a renewed interest and attention from the perspective of basic microbiology in relation to culture and counting methods related to survival, development, and culture of microorganisms, as well as the ecological significance of their diverse ways of living and dying, and a better understanding of the mechanisms of cellular responses to various environmental stresses (Li and Gänzle 2016;Cebrián et al 2017;Tsuchido and Sakamoto 2018;Tsuchido and Asada 2020) .…”