Proteome Dynamics during Antibiotic Persistence and Resuscitation

While bactericidal antibiotics typically require actively growing cells to exploit their function, persister cells are slowly replicating which makes them tolerant to the lethal action of antimicrobials. Here, we used an established in vitro model of bacterial persistence based on overexpression of the paradigm toxin-antitoxin (TA) system hipA / hipB to devise a generic method for temporal analysis of protein synthesis during toxin-induced persistence and antitoxin-mediated resuscitation.

The identification of critical lethal action in antimicrobial mechanism of glycerol monomyristate against foodborne pathogens

Glycerol monomyristate (GMM) is a promising antimicrobial substance due to its broad antibacterial spectrum: however, the critical lethal action in its antimicrobial mechanism for foodborne pathogens remains unclear. In the present study, the inhibitory activities of GMM on Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Candida albicans (C. albicans) were compared, and its membrane and intracellular action mechanism was investigated. The results showed that the susceptibility of E. coli to GMM was the highest, followed by S. aureus, and C. albicans being the poorest. Using flow cytometry, the GMM dose causing above 50% permeability ratio on E. coli was lower than that on S. aureus. The images from scanning electron microscope revealed no doses difference existed between the two strains when the obvious cell damage occurred. Furthermore, cell cycle and multiple fluorescent staining assays showed only the cell division of E. coli and S. aureus, excluding that of C. albicans, was obviously affected at 1/4 MIC and 1/2 MIC, indicating that the DNA interfere and subsequent cell division inhibition was likely to be the critical lethal action with doses near MIC, which can also explain the poor sensitivity of C. albicans.ImportanceFoodborne pathogens, as a common source of biological pollution in the food industry, can cause millions of food poisoning incidents each year, which poses great risks to consumers’ health and safety. The use of monoglyceride as an edible surfactant to inhibit the growth of food-borne microorganisms has been a long time, but the relevant antibacterial mechanism is too broad to accurately grasp its key lethal effect and its action doses, which not only affects the antibacterial efficiency, but also may result in the abnormalities of food flavor when adding at overdoses. The significance of the study is to identify the key lethal effect and its action doses, which will greatly enhance the understanding of the response mechanism of different types of foodborne pathogens to monoglycerides, and provide a more reasonable reference for differential control and treatment of different gastrointestinal infections when combined with antibiotics in clinical.

Influence of some physical factors on the growth and sporulation of entomopathogenic fungi

The objective of the study was to examine, how some physical factors and inoculation techniques affect the growth and sporulation of three insecticidal fungal strains, <em>Hirsutella tompsonii, Paecilomyces</em> sp., and <em>Pandora</em> sp. Although the methods of inoculation, as well as such physical parameters as temperature, the osmotic value of the habitat and UV radiation, exerted an influence on the above-mentioned features of the fungi, their contribution varied from one strain to another. Some of the effects, however (e.g., the production of filamentous structures by <em>Pandora</em>, or the lethal action of glycerol on <em>Pandora</em>), require a close examination.