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Rapid Methods in Cosmetic Microbiology
Published in Philip A. Geis, Cosmetic Microbiology, 2020
Viability-based technologies differentiate viable cells from dead cells and can target specific microorganisms using nucleic acid, enzymatic or monoclonal antibody probes. In many cases, direct labeling of single cells is possible with no cell growth requirement, facilitating time-to-result in hours or even minutes. And because these methods do not require growth, the enumeration of stressed, fastidious, dormant or viable, but non-culturable organisms may be higher than that obtained using conventional, growth-based methods. Applications are fairly broad-based, including quantitative in-process and finished product bioburden testing, water analysis, environmental monitoring and even sterility testing.
Silver as an Antimicrobial Agent: The Resistance Issue
Published in Huiliang Cao, Silver Nanoparticles for Antibacterial Devices, 2017
Kristel Mijnendonckx, Rob Van Houdt
The antimicrobial activity of Ag NPs is mostly assessed via culture-dependent methods. However, it has been observed that Ag NPs (and Ag+ as well) can induce a viable but nonculturable state in P. aeruginosa AdS. More specifically, exposure to Ag NPs and AgNO3 drastically decreased colony-forming units of planktonic cells and decreased the cellular ATP concentration, whereas the total cell count, membrane integrity and rRNA content were unaffected (Koenigs et al. 2015). This observation should be taken into account by other antimicrobial assessments of Ag NPs.
Probiotics of Diverse Origin and Their Therapeutic Applications: A Review
Published in Journal of the American College of Nutrition, 2020
Monika Yadav, Pratyoosh Shukla
Probiotics and prebiotics present in food products result in the enhancement of the gut microbiota, which stimulates the overall gut health of an individual. Postbiotics are generated by probiotic microorganisms that influence the biological functions and functional foods are modified food products which provide health benefits to the host (17). Immunologically active microbial cells are non-viable and non-culturable microorganisms, but they are responsible for health benefits to hosts (18). According to the literature, paraprobiotics are referred as inactivated probiotics, ghost probiotics or postbiotics. These are the metabolic byproducts of probiotic microorganisms, which are dead bacterial structures having biological activity in the host. All these terms are directly or indirectly related to probiotics (19). The different effects of probiotics in the normal microbiota, immunomodulation and metabolic effects are briefly described in Figure 1.
Detection of microbial colonization of the urinary tract of patients prior to secondary ureterorenoscopy is highly variable between different types of assessment: results of a prospective observational study
Published in Biofouling, 2019
Valentin Zumstein, Patrick Betschart, Matthias T. Buhmann, Werner C. Albrich, Oliver Nolte, Sabine Güsewell, Daniel S. Engeler, Hans-Peter Schmid, Qun Ren, Dominik Abt
In addition, this study found a poor correlation for stent cultures and sensitive 16S qPCR examination of stent biofilms. As gene expression analyses by qPCR are known to represent a highly sensitive and reproducible state-of-the art method to detect bacterial DNA (VanGuilder et al. 2008), this finding may be explained by the presence of varying amounts of extracellular DNA, non-viable, or viable but not cultivable bacteria in the biofilms. It is well known that viable but non-culturable bacteria are present in human urine (Anderson et al. 2004; Barer, Bogosian, and Steck 2004). The authors’ group was recently able to show using the same sensitive methods that there are in general surprisingly low bacterial loads in encrustations of ureteral stents (Buhmann et al. 2019).
Antimicrobial mechanism and the effect of atmospheric pressure N2 plasma jet on the regeneration capacity of Staphylococcus aureus biofilm
Published in Biofouling, 2018
Jiaquan Wang, Zhiyuan Yu, Zimu Xu, Shuheng Hu, Yunxia Li, Xiaojuan Xue, Qiuchen Cai, Xiaoxia Zhou, Jie Shen, Yan Lan, Cheng Cheng
The ability of resazurin to be reduced to resorufin is proportional to the population of biofilm cells possessing metabolic capacity, and the semi-quantitative data on the bacterial metabolic capacity can be obtained by mixing the bacterial suspension with the specific fluorescence probes for detection. Figure 2 shows that 21.463 ± 1.646% of the cells in the total bacterial population finally retained their metabolic capacity after N2 APPJ treatment measured immediately after exposure, but were not able to grow and reproduce normally. The bacterial living status lacking culturability could be considered a sub-lethal, viable but non-culturable state (VBNC) (Chang et al. 2006; Marchal et al. 2012) if these viable cells could regain their cultivability through reverse transition in the re-culture processes. Therefore, more tests were carried out to verify whether these approximately 21% of cells had entered the VBNC state using the bacteriostatic antibiotic, chloramphenicol. The experimental results clearly show that a small portion (∼5%) of the plasma-triggered non-cultivable and metabolically active S. aureus cells had reversed into the cultivable state, and could be considered as VBNC cells. However, the other 95% might not reach the VBNC state (see supplemental materials). Further studies are still needed on this interesting finding. The VBNC state occurs when bacteria face environmental stress such as oxidative stress, desiccation, starvation, osmotic stress, and other adverse conditions. It has been reported that non-thermal plasmas also convert microorganisms into the VBNC state as one of the environmental stresses (Xu et al. 2015, 2017). Since the RS in the liquid inhibit bacterial growth, RS such as H2O2, NO3−, and O3 can be classified as an environmental stress.