microbial inactivation
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Arcobacter spp. has been isolated from food of animal origin (particularly meats) and from various kind of water. Despite its phylogenetically related neighbor Campylobacter, Arcobacter is regarded as an emerging foodborne pathogen. Since Arcobacter differs in its phenotypic characteristics, the physical and chemical treatments designed for elimination of campylobacters from food and environment needs to be verified. This review focuses on the occurrence, and mainly on susceptibility to various physical and chemical treatments for inactivation of Arcobacter spp. The existing studies have been critically discussed and new challenges were proposed for further studies.
- MeSH
- antibakteriální látky farmakologie MeSH
- Arcobacter fyziologie účinky léků účinky záření MeSH
- financování organizované MeSH
- koncentrace vodíkových iontů MeSH
- mikrobiální viabilita MeSH
- mikrobiologie vody MeSH
- potravinářská mikrobiologie MeSH
- teplota MeSH
- vysoká teplota MeSH
- Publikační typ
- přehledy MeSH
The luxS gene is responsible for the synthesis of AI-2 (autoinducer-2), a signaling molecule that participates in quorum sensing regulation in a large number of bacteria. In this work, we investigated which phenotypes are regulated by luxS gene in Serratia proteamaculans 94, psychrotrophic strain isolated from spoiled refrigerated meat. AI-2 was identified in S. proteamaculans 94, and the luxS gene involved in its synthesis was cloned and sequenced. A mutant with the inactivated luxS gene was constructed. Inactivation of the luxS gene was shown to lead to the absence of AI-2 synthesis, chitinolytic activity, swimming motility, suppression of the growth of fungal plant pathogens Rhizoctonia solani and Helminthosporium sativum by volatile compounds emitted by S. proteamaculans 94 strain, and to a decrease of extracellular proteolytic activity. The knockout of the luxS gene did not affect synthesis of N-acyl-homoserine lactones, lipolytic, and hemolytic activities of S. proteamaculans 94.
- MeSH
- bakteriální proteiny genetika MeSH
- biofilmy růst a vývoj MeSH
- fenotyp MeSH
- homoserin analogy a deriváty metabolismus MeSH
- laktony metabolismus MeSH
- lyasy štěpící vazby C-S genetika MeSH
- maso mikrobiologie MeSH
- mikrobiální interakce MeSH
- quorum sensing genetika MeSH
- regulace genové exprese u bakterií MeSH
- Serratia genetika metabolismus MeSH
- těkavé organické sloučeniny analýza MeSH
- umlčování genů * MeSH
- Publikační typ
- časopisecké články MeSH
Bifidobacterium longum, one of the main microorganisms in the human gut, is used as an adjunct to lactic acid starter cultures or sold as a probiotic product. Therefore, Bifidobacterium longum cell suspensions get freeze-dried with protective additives to prevent activity losses. To date, investigations covering growth and inactivation kinetics of Bifidobacterium longum during the whole process (cultivation, drying, and storage) have been lacking. In this study, the effect of cultivation conditions and shelf temperature as well as the influence of protectants (maltodextrin, glucitol, trehalose) at various concentrations on cell survival during freeze-drying was assessed. Drying was followed by a storage at + 4 °C and + 20 °C for 70 days to evaluate inactivation kinetics. The impact of the different factors was assessed by measuring surival rate and residual moisture content at various points of time over the whole process. In parallel cell membrane integrity and glass transition were determined to reveal inactivation effects. Cultivation strategy had a strong influence on survival with a huge potential for process improvement. A pH of 6.0 at the growth optimum of the strain provides better conditions regarding cell survival after drying than free acidification (non-regulated pH conditions). During the drying step, membrane leakage due to the removal of water is the main reason for the inactivation in this process step. In this study, the highest survival of 49% was obtained with cells dried at + 35 °C shelf temperature with an addition of maltodextrin (75% bacterial dry matter, w/w). The results show that Bifidobacterium longum cells are mostly inactivated during drying, whereas storage conditions at + 4 °C with an addition of 75% BDM maltodextrin relative to bacterial dry mass prevent cell loss completely.
- MeSH
- Bifidobacterium longum růst a vývoj MeSH
- buněčné kultury metody MeSH
- kinetika MeSH
- koncentrace vodíkových iontů MeSH
- kultivační média chemie MeSH
- lidé MeSH
- lyofilizace metody MeSH
- mikrobiální viabilita * MeSH
- polysacharidy MeSH
- probiotika MeSH
- sorbitol MeSH
- teplota MeSH
- trehalosa MeSH
- vysoušení metody MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
Mikrobiální perzistence patří jako jeden ze způsobů odolávání antibiotické léčbě mezi nejaktuálnější témata lékařské mikrobiologie. A to především proto, že ji pozorujeme v jakékoliv mikrobiální populaci, včetně těch, které nebyly žádné antimikrobiální látce vystaveny. Její podstatou je přirozená schopnost bakteriální subpopulace utlumit metabolismus, a tím se vyhnout účinkům léčiv. Ani antibiotická politika v pojetí, které si klade za cíl prevenci rezistence, tedy nemůže jejímu vzniku zabránit. V této práci citujeme účinné metody překonávání perzistence, jejich výběr ale záleží na individuálním zvážení s ohledem na pacienta.
Persistence, as one of the mechanisms of antimicrobial treatment survival, ranks among the hot topics of medical microbiology. We observe it in every microbial population: exposed to antimicrobials or native. It is based on a natural ability to down-regulate metabolic processes and thus avoid the effect of the medications. This is why antibiotic stewardship, in terms of resistance-lowering guidelines, cannot fight persistence. In this paper, we cite other methods of persistence overcoming, but the choice is individual, with regards to the needs of the patient.
The consumption of raw milk is currently increasing due to several beneficial aspects, such as nutritional qualities, taste, and health benefits. However, some authors highlight the potential risk associated with raw milk consumption. In Italy, while the absence of some pathogen microorganisms is set by the regional regulation DGR 381/2007, for other microorganisms, such as Leptospira, no recommendations are provided. Leptospira is not ascribed among classical milk pathogens; however, it can potentially be present in raw milk. The aim of this study was to evaluate the survival in raw milk of six serovars of Leptospira after storage at different temperatures (4 °C ± 2 °C, 20 °C ± 2 °C, and 30 °C ± 2 °C) for different incubation times (20 min, 45 min, 1 h, and 1 h and 30 min), in order to determine the potential risk for consumers. Moreover, the immediate effect of bovine, goat, and donkey raw milk on tested Leptospira serovars was visually evaluated. After incubation, all samples were subcultured in EMJH and incubated aerobically at 30 °C for 3 months. All inoculated media were weekly examined by dark-field microscope in order to assess Leptospira survival. Extemporary observation of strains' behavior in milk allowed to detect an almost immediate motility loss, and no leptospires were detected by microscopic observations carried out weekly during the trial period. According to our results, it could be possible to exclude raw milk as a source of Leptospira infection for consumers.
- MeSH
- aerobióza MeSH
- bakteriologické techniky MeSH
- časové faktory MeSH
- Equidae MeSH
- kozy MeSH
- Leptospira fyziologie MeSH
- mikrobiální viabilita * MeSH
- mléko mikrobiologie MeSH
- skladování potravin MeSH
- skot MeSH
- teplota MeSH
- zvířata MeSH
- Check Tag
- skot MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Itálie MeSH
The surface conditions on the Moon are extremely harsh with high doses of ultraviolet (UV) irradiation (26.8 W · m-2 UVC/UVB), wide temperature extremes (-171°C to 140°C), low pressure (10-10 Pa), and high levels of ionizing radiation. External spacecraft surfaces on the Moon are generally >100°C during daylight hours and can reach as high as 140°C at local noon. A Lunar Microbial Survival (LMS) model was developed that estimated (1) the total viable bioburden of all spacecraft landed on the Moon as ∼4.57 × 1010 microbial cells/spores at contact, (2) the inactivation kinetics of Bacillus subtilis spores to vacuum as approaching -2 logs per 2107 days, (3) the inactivation of spores on external surfaces due to concomitant low-pressure and high-temperature conditions as -6 logs per 8 h for local noon conditions, and (4) the ionizing radiation by solar wind particles as approaching -3 logs per lunation on external surfaces only. When the biocidal factors of solar UV, vacuum, high-temperature, and ionizing radiation were combined into an integrated LMS model, a -231 log reduction in viable bioburden was predicted for external spacecraft surfaces per lunation at the equator. Results indicate that external surfaces of landed or crashed spacecraft are unlikely to harbor viable spores after only one lunation, that shallow internal surfaces will be sterilized due to the interactive effects of vacuum and thermal cycling from solar irradiation, and that deep internal surfaces would be affected only by vacuum with a degradation rate of -0.02 logs per lunation.
- MeSH
- Bacillus subtilis fyziologie účinky záření MeSH
- biologické modely * MeSH
- kosmická loď MeSH
- kosmické záření škodlivé účinky MeSH
- Měsíc * MeSH
- mikrobiální viabilita účinky záření MeSH
- mimozemské prostředí MeSH
- simulace kosmického prostředí metody MeSH
- spory bakteriální fyziologie účinky záření MeSH
- ultrafialové záření škodlivé účinky MeSH
- vakuum MeSH
- vysoká teplota MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
