Sürdürülebilir Kalkınma Amaçları
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- MakaleAçık Erişim2026Scopus SJRQ4Cloning and biochemical characterization of a novel GH1 β-glucosidase from thermophilic bacterium, Anoxybacillus flavithermus DSM 2641T
Akgeyik, Aytul Uzun; Akyildiz, Esma; Karaoglu, Hakan; Beris, Fatih Saban
β-glucosidases belong to the class of glycoside hydrolases (GHs) and can mediate the cleavage of β-1-4 glycosidic bonds in alkyl or aryl-β-D-glucosides, amino, cyanogenic glucosides, and oligo-or disaccharides. The gene encoding β-glucosidase of Anoxybacillus flavithermus DSM2641T was subcloned and expressed in E. coli BL21 Star(DE3) cells with pET100 Directional TOPO Expression Kit. The recombinant AFBGL was purified by a Ni-NTA affinity chromatography. The enzyme was 53 kDa and had 5.13 × 105 µmol/min/mg protein of Vmax and 422.3 µM of Km towards p-nitrophenyl β-D-glucoside as a main substrate. The optimum temperature and pH of the purified enzyme were 65°C and 6.8, respectively. We also determined kinetic parameters of AFBGL against the other artificial substrats, pNPC, pNPX, and oNPG. The enzyme had the Vmax and Km for 5.13 × 105 µmol/min/mg protein and 0.42 mM for pNPG, 0.007 µmol/min/mg protein and 0.19 mM for pNPC, 0.01 µmol/min/mg protein and 11.97 mM for pNPX, 0.06 µmol/min/mg protein and 0.134 mM for oNPG, respectively. AFBGL's substrate affinity was found to be more directed towards oNPG. Although 0.5 mM Mg2+ increases the enzyme's activity 1.6-fold, higher concentrations of Mg2+ and the presence of K+, Fe2+, Mn2+, Zn2+, Cu2+, and Al3+ decreases its activity. AFBGL retained 50% of the initial activity towards pNPG for 25 min and the activity was not detected after 225 min. According to amino acid motifs, AFBGL belongs to family 1 of glycosylhydrolase and 4/7 super family. So, AFBGL is a member of GH1, as the amino acid sequence contained a GH1 specific domain.
- MakaleAçık Erişim2023Trabzon Fatih Devlet Hastanesinden İzole Edilen Klinik Acinetobacter baumannii ve Pseudomonas aeruginosa Suşlarında Antibiyotik Direnç Genlerinin Araştırılması
Sarıyer, Aysegül Saral; Düzgün, Azer Özad; Akyildiz, Esma; Köse, Tuba; Beris, Fatih Saban
Bu çalışmanın amacı Acinetobacter baumannii ve Pseudomonas aeruginosa izolatlarının antibiyotik duyarlılık profilini araştırmak ve bu izolatlarda direnç genlerinin varlığını belirlemektir. Direnç genlerinin tespiti PCR yöntemi ile değerlendirildi. Acinetobacter baumannii izolatlarında imipenem ve meropenem direnci sırasıyla %93,2 ve %91 olduğu görüldü. P. aeruginosa izolatlarında imipenem direnç oranı %53,9 ve meropenem direnç oranı %38,5 olarak belirlendi. Pseudomonas aeruginosa izolatları arasında aranan genlerden bir izolatta sadece OXA-23 tespit edildi. Acinetobacter baumannii izolatlarından bir izolatta OXA-24, 40 izolatta OXA-23 saptandı. Bu çalışma, CRPA (Karbapenem dirençli Pseudomonas aeruginosa) ve CRAB (Karbapenem dirençli Acinetobacter baumannii) izolatlarında karbapenem direncinden OXA-23'ün sorumlu olduğunu göstermektedir.
- MakaleAçık Erişim2015Scopus SJRQ2Distribution of β-Lactamase Genes Among Carbapenem-Resistant Klebsiella pneumoniae Strains Isolated From Patients in Turkey
Iraz, Meryem; Düzgün, Azer Ozad; Sandalli, Cemal; Doymaz, Mehmet Ziya; Akkoyunlu, Yasemin; Saral, Aysegul; Peleg, Anton Y.; Özgümüs, Osman Birol; Beris, Fatih Saban; Karaoglu, Hakan
Background: The emergence of carbapenem-resistant Klebsiella pneumoniae poses a serious problem to antibiotic management. We investigated the beta-lactamases in a group of carbapenem-resistant K. pneumoniae clinical isolates from Turkey. Methods: Thirty-seven strains of K. pneumoniae isolated from various clinical specimens were analyzed by antimicrobial susceptibility testing, PCR for the detection of p-lactamase genes, DNA sequencing, and repetitive extragenic palindronic (REP)- FOR analysis. Results: All 37 isolates were resistant to ampicillin, ampicillin/sulbactam, piperacillin, piperacillin/tazobactam, ceftazidime, cefoperazone/sulbactam, cefepime, imipenem, and meropenem. The lowest resistance rates were observed for colistin (2.7%), tigecycline (11%), and amikacin (19%). According to FOR and sequencing results, 98% (36/37) of strains carried at least one carbapenemase gene, with 32 (86%) carrying OXA-48 and 7 (19%) carrying NDM-1. No other carbapenemase genes were identified. All strains carried a CTX-M-2-like beta-lactamase, and some carried SHV- (97%), TEM- (9%), and CTX-M-1-like (62%) beta-lactamases. Sequence analysis of bla(TEM) genes identified a bla(TEM-166) with an amino acid change at position 53 (Arg53Gly) from bla(TEM-1b), the first report of a mutation in this region. REP-FOR analysis revealed that there were seven different clonal groups, and temporo-spatial links were identified within these groups. Conclusions: Combinations of beta-lactamases were found in all strains, with the most common being OXA-48, SHV, TEM, and CTX-M-type (76% of strains). We have reported, for the first time, a high prevalence of the NDM-1 (19%) carbapenemase in carbapenem-resistant K. pneumoniae from Turkey. These enzymes often co-exist with other beta-lactamases, such as TEM, SHV, and CTX-M beta-lactamases.
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