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Canlı fakat kültürü yapılamayan (VBNC) durum henüz moleküler mekanizması çözülememiş bir süreçtir. Bu çalışmada iki bileşikli fosforlama sistemlerinden birisi olan CusS-R’nin alkalin pH (8.5) ortamında VBNC forma geçişte rollerinin olup olmadığı araştırılmıştır. Çalışmada elde edilen sonuçlara göre hem cusS hem de cusR genlerinin nakavt edilmesi pH 7.2 de bir etki göstermezken, E. coli‘nin alkali ortamda yaşamını sınırlamıştır. Yabani tip E. coli W3110’un plak sayımına göre t99 değeri 57 gün iken, bu değer cusS geni nakavt edildiğinde 31, cusR geni nakavt edildiğinde ise 34 gün olduğu tespit edilmiştir. Nakavt edilmiş olan genler plazmit ile tamamlandığında t99 değerinin E. coli cusS mutantı için 62 gün, E. coli cusR mutantı için 61 gün olarak tespit edilmiş olup bu değerler yabani tip E. coli ile benzerdir. Mutantlarda alkali pH’da görülen bu azalmanın VBNC oluşumundan kaynaklanıp kaynaklanmadığını belirlemek için canlı hücre sayımları Live Dead sayımı, CTC sayımı ve DVC sayım metotları ile elde edilmiştir. Bu sayım sonuçlarına göre mutantların plak sayımlarında görülen azalmanın aslında VBNC forma giren bakterilerden kaynaklandığı tespit edilmiştir. Dolayısı ile cusS ve cusR genlerinin VBNC forma geçişte bir rolleri olmadığı tespit edilmiştir.

Microorganisms are exposed to a wide variety of stress factors in their natural environments. Under that stressful conditions, they move into a viable but nonculturable (VBNC) state to survive and maintain the vitality. At VBNC state, microorganisms cannot be detected by traditional laboratory methods, but they can be revived under appropriate conditions. Therefore, VBNC organisms cause serious food safety and public health problems. To date, it has been determined that more than 100 microorganism species have entered the VBNC state through many chemical and physical factors. During the last four decades, dating from the initial detection of the VBNC condition, new approaches have been developed for the induction, detection, molecular mechanisms, and resuscitation of VBNC cells. This review evaluates the current data of recent years on the inducing conditions and detection methods of the VBNC state, including with microorganisms on the VBNC state, their virulence, pathogenicity, and molecular mechanisms.

Free standing artificial lipid bilayers are widely used in the study of biological pores. In these types of studies, the free standing planar lipid bilayer is formed over a micron-sized aperture consisting of either polymer such as Polytetrafluoroethylene (PTFE, Teflon) or glass. Teflon is chemically inert, has a low dielectric constant, and has a high electrical resistance which combined allow for obtaining low noise recordings. This study investigates the reproducible generation of micropores in the range of 50–100 microns in diameter in a Teflon film using a high energy discharge set-up. The discharger set-up consists of a microprocessor, a transformer, a voltage regulator, and is controlled by a computer. We compared two approaches for pore creation: single and multi-pulse methods. The results showed that the multi-pulse method produced narrower aperture size distributions and is more convenient for lipid bilayer formation, and thus would have a higher success rate than the single-pulse method. The bilayer stability experiments showed that the lipid bilayer lasts for more than 33 h. Finally, as a proof-of-concept, we show that the single and multi-channel electrophysiology experiments were successfully performed with the apertures created by using the mentioned discharger. In conclusion, the described discharger provides reproducible Teflon-pores in a cheap and easy-to-operate manner. Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK) – SOBAG – Proje No - 117S114. The Scientific and Technological Research Council of Turkey - (TUBITAK) – SOBAG - 117S114. WOS:000622719400001 PMID: 33638734 Q3

Biosensors are analytical tools used for the analysis of biomaterial samples and provide an understanding about the biocomposition, structure, and function of biomolecules and/or biomechanisms by converting the biological response into an electrical and/or optical signal. In particular, with the rise in antibiotic resistance amongst pathogenic bacteria, the study of antibiotic activity and transport across cell membranes in the field of biosensors has been gaining widespread importance. Herein, for the rapid and label‐free detection of antibiotic permeation across a membrane, a microelectrode integrated microfluidic device is presented. The integrated chip consists of polydimethylsiloxane based microfluidic channels bonded onto microelectrodes on‐glass and enables us to recognize the antibiotic permeation across a membrane into the model membranes based on electrical impedance measurement, while also allowing optical monitoring. Impedance testing is label free and therefore allows the detection of both fluorescent and non‐fluorescent antibiotics. As a model membrane, Giant Unilamellar Vesicles (GUVs) are used and impedance mea- surements were performed by a precision inductance, capacitance, and resistance metre. The measured signal recorded from the device was used to determine the change in concentration inside and outside of the GUVs. We have found that permeation of antibiotic molecules can be easily monitored over time using the proposed integrated device. The results also show a clear difference between bilayer permeation that occurs through the lipidic bilayer and porin‐mediated permeation through the porin channels inserted in the lipid bilayer. Türkiye Bilimsel ve Teknolojik Araştırma Kurumu (TÜBİTAK) - 217M151. The Scientific and Technological Research Council of Turkey - (TUBITAK) - 217M151. WOS:000614875900001 PMID: 34694729 Q4 Q3

Escherichia coli’de alternatif sigma faktörü olarak adlandırılan rpoS (σ38) asit şoku, açlık stresi, ozmotik stres, oksidatif stres, DNA hasarı ve durağan faza geçiş dahil olmak üzere farklı streslere karşı hücresel cevapta görevli olan genlerin ekspresyonunu kontrol etmektedir. Bu çalışmada Escherichia coli W3110’da rpoS geninin metal ve pH stresi altındaki rolü araştırılmıştır. E. coli BW25113 suşunda mutant olan rpoS geni, P1kc fajı ile yabani tip E. coli W3110’a aktarılmıştır. Yabani tip E. coli W3110 ve rpoS mutant E. coli W3110 suşunda yaşam deneyleri pH 5.5, 7.0 ve 8.0 fosfat tamponunda olmak üzere 3 farklı pH’da plak sayım metodu ile yapılmıştır. 6 farklı metal varlığında (Zn, Ni, Co, Cd, Ag ve Cu) metal stresindeki rolü minimal inhibisyon konsantrasyonu ve petri damlatma yöntemi ile belirlenmiştir. Çalışılan tüm pH değerlerinde rpoS mutant suşlarda duyarlılık gözlenmiştir. Cd metaline karşı rpoS mutantının oldukça önemli bir direnç gösterdiği belirlenirken, diğer metallerde herhangi bir rolü olmadığı tespit edilmiştir. rpoS geninin rolü, genin tamamlanması yapılarak doğrulaması sağlanmıştır. Bu sonuçlar RpoS alternatif sigma faktörünün Cd metali ile ilişkili genlerin kontrolünde ve pH stresi ile ilişkili genlerde rolü olduğunu göstermektedir

The nucleophilic substitution reactions of cylochlorotriphosphazene (N3P3Cl6) with N-(1-Naphthyl)ethylenediamine resulted in the following formation of partially and fully substituted cyclotriphosphazene derivatives: 2,4,4,6,6-pentachloro-2-open-chain-N-(1-Naphthyl) ethylendiamino-cyclotriphosphazatriene (3); 4,4,6,6-tetrachloro-2,2-spiro-N-(1-Naphthyl) ethylendiamino-cyclotriphosphazatriene (4); 2,6,6-trichloro-2-open-chain-4,4-spiro-N-(1-Naphthyl)ethylendiamino-cyclotriphosphazatriene (5); 2,4-dichloro-2,4-ansa-6,6-spiro-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (6); and 2,4,6-trichloro-2,4,6-non-gem-open-chain-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (7); 2,2,4,4,6,6-tri-spiro-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (8); 2,4-dichloro-2,4-cis-open-chain-6,6-spiro-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (9); and 2,4,6,6-tetrachloro -2,4-ansa-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (10). The reactions produced the 4,4,6,6-tetrachloro-2,2-spiro-N-(1-Naphthyl) ethylendiamino-cyclotriphosphazatriene (4) and 2,4,6,6-tetrachloro-2,4-ansa-N-(1-Naphthyl)ethylendiamino)-cyclotriphosphazatriene (10) derivatives as the major products in this system. The structures of the compounds were characterized by FT-IR, elemental analysis, TLC-MS, FT-IR, 1H, and 31P NMR spectral data. All the derived compounds (3–10) were screened for antimicrobial activity by using the broth-agar microdilution technique for the determination of MIC and MCC values. In this context, the compounds were examined against three different human pathogens; Escherichia coli W3110, Staphylococcus aureus ATCC 25923 and Candida albicans ATCC 10231. Except compounds 6 and 9, the rest of the compounds exhibited significant antimicrobial activity on E. coli (W3110), S. aureus (ATCC 25923) and C. albicans (ATCC 1023). Among the synthesized derivatives, compound 4 is the most active agent against the referenced bacteria.

WOS: 000373391800007 PubMed ID: 26960359 In this study, the survival time of wild type E. coli W3110 and 11 mutants was analysed with a plate count method in methylene blue added or control groups under daylight fluoroscence illumination (4950 lux) at different pH values (5.0, 6.0, 7.0, and 8.0) in phosphate buffer. As a result, while the number of bacteria did not decrease under photooxidative stress at pH 5.0 and 6.0 during a 6-hour incubation, the wild type and all mutants decreased more than 2 log. at pH 8.0, and approximately one log. at pH 7.0. It was determined that a 2 log decrease in wild type E. coli takes 3.7 h according to t(99) value at pH 8, these values were 2.39 h in the katE mutant, 2.64 h in the soxR mutant, 2.67 h in the oxyR mutant, 2.71 h in the sodB mutant, 3 h in the btuE mutant, 3.38 h in the zwf mutant and 3.40 h in the soxS mutant, respectively (p