With the discovery of interspecies hydrogen transfer in the late 1960s (Bryant et al. in Arch Microbiol 59:20–31, 1967), it was shown that reducing the partial pressure of hydrogen could cause mixed acid fermenting organisms to produce acetate at the expense of ethanol. Hydrogen and ethanol are both more reduced than glucose. Thus there is a tradeoff between production of these compounds imposed by electron balancing requirements; however, the mechanism is not fully known. Deletion of the hfsA or B subunits resulted in a roughly 1.8-fold increase in ethanol yield. The increase in ethanol production appears to be associated with an increase in alcohol dehydrogenase activity, which appears to be due, at least in part, to increased expression of the adhE gene, and may suggest a regulatory linkage between hfsB and adhE. We studied this system most intensively in the organism Thermoanaerobacterium saccharolyticum; however, deletion of hfsB also increases ethanol production in other thermophilic bacteria suggesting that this could be used as a general technique for engineering thermophilic bacteria for improved ethanol production in organisms with hfs-type hydrogenases. Since its discovery by Shaw et al. (JAMA 191:6457–64, 2009), the hfs hydrogenase has been suspected to act as a regulator due to the presence of a PAS domain. We provide additional support for the presence of a regulatory phenomenon. In addition, we find a practical application for this scientific insight, namely increasing ethanol yield in strains that are of interest for ethanol production from cellulose or hemicellulose. In two of these organisms (T. xylanolyticum and T. thermosaccharolyticum), the ethanol yields are the highest reported to date.

A recombinant carbonic anhydrase (CA, EC 4.2.1.1) from the soil-dwelling bacterium Enterobacter sp. B13 was cloned and purified by Co²⁺ affinity chromatography. Bioinformatic analysis showed that the new enzyme (denominated here B13-CA) belongs to the β-class CAs and to possess 95% homology with the ortholog enzyme from Escherichia coli encoded by the can gene, whereas its sequence homology with the other such enzyme from E. coli (encoded by the cynT gene) was of 33%. B13-CA was characterized kinetically as a catalyst for carbon dioxide hydration to bicarbonate and protons. The enzyme shows a significant catalytic activity, with the following kinetic parameters at 20 °C and pH of 8.3: k_cat of 4.8 × 10⁵ s⁻¹ and k_cat/K_m of 5.6 × 10⁷ M⁻¹ × s⁻¹. This activity was potently inhibited by acetazolamide which showed a K_I of 78.9 nM. Although only this compound was investigated for the moment as B13-CA inhibitor, further studies may reveal new classes of inhibitors/activators of this enzyme which may show biomedical or environmental applications, considering the posssible role of this enzyme in CaCO₃ biomineralization processes.

One of the mechanisms responsible for antibiotic resistance in Klebsiella pneumoniae is the enzymes produced by the bacteria; another important mechanism is the ability to form biofilm. In this study, antibiotic resistance, genes associated with virulence, and biofilm-forming properties of K. pneumoniae strains were investigated. A total of 100 K. pneumoniae isolates were obtained from different clinical samples identified by Matrix-Assisted Laser Desorption/Ionization time-of-flight Mass Spectrometry. Antimicrobial susceptibility testing was performed with the Phoenix 100 apparatus. The biofilm forming properties of strains were determined by the microtiter plate method. For molecular analysis, genes encoding the carbapenemase enzyme (bla_OXA-48, bla_NDM-1, bla_IMP, and bla_VIM) and biofilm-related genes (treC, luxS, mrkA, and wza) were investigated by polymerase chain reaction (PCR). While 76% of clinical isolates were resistant to three or more antimicrobials, 24% were classified as non-multidrug resistant (non-MDR). When biofilm-forming capacities of clinical isolates were tested, it was determined that the resistant-isolates produced 59.2% strong biofilm, and susceptible-isolates produced 12.5% strong biofilm. According to PCR results, carbapenemase genes were determined as follows: bla_OXA-48-70%, bla_NDM-49%, and bla_KPC-19%, bla_OXA-48/bla_NDM/bla_KPC-12%, bla_OXA-48/bla_NDM-26%, and bla_OXA-48/bla_KPC-4%. The biofilm-associated genes in bacterial isolates were determined as follows: luxS-98%, treC-94%, mrkA-88%, and wza-15%. In addition, Hierarchical Clustering Tree and Heatmap analysis revealed an association between isolates that lacks resistance genes and isolates lacks biofilm-formation related genes that were included in MDR or non-MDR classes. As a result, biofilm should be considered in the treatment of MDR infections, and therapy should be planned accordingly. In addition, pursuing the data and genes of antibiotic resistance is significant for combating resistance.

Genotype and cultivar identification is essential for conserving tea genetic diversity within plantation ecosystems and ensuring the sustainability of high-quality tea production. This study represents the first large-scale genetic characterization of 200 elite varietal candidate tea (Camellia sinensis) clones, which were pre-selected from 2,034 genotypes originating from the Eastern and Western Black Sea regions of Türkiye. Eight polymorphic simple sequence repeat (SSR) markers located near loci associated with catechin content, including epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin gallate (EGCG), were employed. SSR profiles were generated for all 200 tea clones cultivated in control plots at the National Tea Gene Bank, and the resulting data were additionally used for DNA barcoding of 12 varietal candidate tea clones currently under registration. Among the evaluated markers, TM412 (EGC) exhibited the highest polymorphism information content (PIC = 0.8816), whereas TM376 (EC) showed the lowest (0.4321). Notably, TM412 (EGC) and TM399 (ECG) displayed high PIC values, indicating their strong discriminatory potential for Turkish tea genotypes. The findings indicate that Turkish tea germplasm possesses substantial genetic diversity, and some markers may be effectively utilized in variety registration and breeding efforts. This study presents the first comprehensive molecular characterization of tea genetic resources in Türkiye. It contributes to the long-term conservation of selected clones and supports the variety registration process through DNA barcoding and a QR code-based traceability system. The genetic dataset generated in this work contributed directly to the establishment of Türkiye’s first and the world’s fifth-largest tea gene pool in Rize Province, providing a valuable reference for strengthening tea genetic resource conservation and breeding programs at both national and global scales.