Yağmur Toptaş

Optimization of hyaluronic acid production and its cytotoxicity and degradability characteristics

Abstract In the present study, culture conditions of Streptococcus equi was optimized through Box–Behnken experimental design for hyaluronic acid production. About 0.87 gL−1 of hyaluronic acid was produced under the determined conditions and optimal conditions were found as 38.42 °C, 24 hr and 250 rpm. The validity and practicability of this statistical optimization strategy were confirmed relation between predicted and experimental values. The hyaluronic acid obtained under optimal conditions was characterized. The effects of different conditions such as ultraviolet light, temperature and enzymatic degradation on hyaluronic acid produced under optimal conditions were determined. 118 °C for 32 min of autoclaved HA sample included 63.09 µg mL−1 of d-glucuronic acid, which is about two-fold of enzymatic effect. Cytotoxicity of hyaluronic acid on human dermal cells (HUVEC, HaCaT), L929 and THP-1 cells was studied. In vitro effect on pro or anti-inflammatory cytokine release of THP-1 cells was determined. Although it varies depending on the concentration, cytotoxicity of hyaluronic acid is between 5 and 30%. However, it varies depending on the concentration of hyaluronic acid, TNF-α release was not much increased compared to control study. Consequently, purification procedure is necessary to develop and it is worth developing the bacterial hyaluronic acid.

Applying on Bacillus cereus of Low-Pressure and Low-Temperature Plasma Jet in a Postdischarge Chamber

A low-temperature flowing postdischarge plasma reactor is first presented. The reactor is a postdischarge chamber coupled to a plasma jet system. The low-pressure flowing postdischarge (jet) in the postdischarge chamber can be generated using direct current (dc) or alternative current (ac) power supplies. A low-pressure plasma jet of Neon using a 25-kHz 25-kV ac voltage and low-pressure plasma jet of ambient air using a 5-kV dc voltage produced in the postdischarge chamber are given. By using sample holders in the postdischarge chamber, early or late flowing postdischarge (jet) can be exposed to the sample surface. In this paper, the low-temperature and low-pressure dc air plasma jet generated using the plasma jet system coupled to a postdischarge chamber is first exposed on to Bacillus cereus, as a model bacterium. The inactivation effect on Bacillus cereus of the low-temperature and low-pressure dc air plasma jet at several exposure times was observed. With treatment of 30 min of exposure times, a value below the decimal value of the used bacterium was obtained of 15 min of exposure times.

Optimization of a biosurfactant production from bacteria isolated from soil and characterization of the surfactant / Topraktan izole edilen bakterilerden biyosurfaktan üretiminin optimizasyonu ve surfaktanın karakterizasyonu

Abstract Objective: Biosurfactants are surface-active substances produced by microorganisms. The growth of microorganism supports biosurfactant production on hydrocarbon polluted environments. In this study, the capacity of biosurfactant production of Georgenia daeguensis (accession number, KP798810) isolated from hydrocarbon- contaminated soil was studied. Methods: The components of biosurfactant production medium were investigated through Plackett-Burman methodology. By using Placket-Burman based on statistical screening, six of the eleven factors of production medium were found to be critically effective on the biosurfactant production. Results: The significant factors were KCl, ZnSO4.7H2O, CaCl2.2H2O, KH2PO4, MgSO4.7H2O and glucose. Among of these, KCl had the highest effect contribution with 55.22%. After the optimization by such design, critical micelle concentration value was reached to 2.2 g L-1. When antibacterial activity of biosurfactant was screened, it showed antibacterial effect against to Klebsiella pneumoniae. Besides, the biosurfactant was characterized by FT-IR, critic micelle concentration and zeta analysis. Conclusion: This study reported that Georgenia daeguensis is able to produce effective biosurfactant exhibiting antibacterial activity against K. pneumoniae. Özet Amaç: Biyosurfaktanlar, mikroorganizmalar tarafından üretilen yüzey aktif bileşiklerdir. Hidrokarbonla kirlenmiş çevrelerde mikroorganizmanın gelişmesi biyosurfaktan üretimini destekler. Bu calışmada hidrokarbonca kirlenmiş topraktan izole edilen Georgenia daeguensis (giriş numarası, KP798810)’nin biyosurfaktan üretme kapasitesi calışılmıştır. Metod: Biyosurfaktan üretim ortamının bileşenleri Plackett- Burman metodolojisi kullanılarak değerlendirilmiştir. Istatistiksel taramaya bağlı Plackett-Burmankullanılarak, üretim ortamının 11 faktorden 6’sının biyosurfaktan üretiminde önemli ölcüde etkili olduğunu ortaya çıkarılmıştır. Bulgular: Önemli faktörler; KCl, ZnSO4.7H2O, CaCl2.2H2O, KH2PO4, MgSO4.7H2O ve glukoz olarak belirlenmiştir. Bunlarına arasından KCl, %55,2 ile en yüksek katkıya sahip olmuştur. Bu şekilde gerçekleştirilen optimizasyon sonrası, kritik misel konsantrasyonu 2,2 g L-1’ye ulaşmıştır. Biyosurfaktanın antibakteriyel aktivitesi değerlendirildiğinde Klebsiella pneumoniae’ye karşı antibakteriyel etkiye sahip olduğu gösterilmiştir. Bunun yanısıra, biyosurfaktan FTIR, kritik misel konsantrasyonu ve zeta analizi açısından da karakterize edilmiştir. Sonuç: Bu çalışma Georgenia daeguensis’in, K. pneumoniae’ye karşı antibakteriyel etki sergileyen etkili bir şekilde biyosurfaktan üretebildiğini bildirmektedir.