Péter Sátorhelyi

The vaginal microbiota plays a crucial role in bovine reproductive health in the periparturient period. This study aimed to characterize the naturally occurring bacterial species in the vaginal microbiome of healthy Holstein Frisian cows and evaluate their antibiotic sensitivity. Vaginal samples were collected from 44 healthy cows on three dairy farms. A total of 54 bacterial species were detected, with Gram-positive bacteria comprising 87% of the isolates. The most prevalent genera were Bacillus, Streptococcus, and Staphylococcus. Antibiotic susceptibility tests indicated that some isolates carried resistance genes, but most remained sensitive to commonly used antibiotics. The average vaginal mucosa pH was 7.2. These findings provide valuable insights into the diversity of vaginal microbiota of healthy dairy cows. Understanding the bacterial composition and antibiotic susceptibility can support reproductive health management and prudent use of antibiotics in dairy herds.

A number of class I lyase‐like enzymes, including aromatic ammonia‐lyases and aromatic 2,3‐aminomutases, contain the electrophilic 3,5‐dihydro‐5‐methylidene‐4H‐imidazol‐4‐one (MIO) catalytic moiety. This study reveals thatPseudomonas fluorescensR124 strain isolated from a nutrient‐limited cave encodes a histidine ammonia‐lyase, a tyrosine/phenylalanine/histidine ammonia‐lyase (XAL), and a phenylalanine 2,3‐aminomutase (PAM), and demonstrates that an organism under nitrogen‐limited conditions can develop novel nitrogen fixation and transformation pathways to enrich the possibility of nitrogen metabolism by gaining a PAM through horizontal gene transfer. The novel MIO enzymes are potential biocatalysts in the synthesis of enantiopure unnatural amino acids. The broad substrate acceptance and high thermal stability ofPfXAL indicate that this enzyme is highly suitable for biocatalysis.

The activity of SynBiocat Ltd, a small spin-off company, is related to various areas of synthetic chemistry, biotechnology and enzymology. This chapter gives an overview of the knowledge and technologies of the company covering the development of suitable biocatalysts and bioreactor solutions for synthetic biotransformations. In co-operation with Bioorganic Chemistry Group (BCG) at Budapest University of Technology and Economics and Fermentia Ltd, SynBiocat can offer a wide selection of enzyme immobilization methods for known or novel enzymes to select the most suitable variant for a desired technology. Our company also offers custom immobilization development as a service to develop the optimal immobilized form of the biocatalyst of customers. For immediate screening, kits of immobilization supports or immobilized enzymes such as lipases, proteases, ketoreductases (as whole-cell biocatalysts), phenylalanine ammonia-lyases, phenylalanine 2,3-aminomutases are accessible. To enable screening of continuous-flow biotransformations, a selection of immobilized biocatalyst-filled minireactors are available off-the-shelf.

Background: The saprophytic pathogen Listeria monocytogenes has to cope with a variety of acidic habitats during its life cycle. The impact of low-temperature coupled with pH decrease for global gene expression and subsequent virulence properties, however, has not been elucidated. Results: qRT-PCR revealed for the first time a transient, acid triggered prfA induction of approximately 4-fold, 5.7-fold, 7-fold and 9.3-fold 60 to 90 min after acid shock of L. monocytogenes at 37°C, 25°C, 18°C, and 10°C, respectively. Comparable data were obtained for seven different L. monocytogenes strains, demonstrating that prfA induction under these conditions is a general response of L. monocytogenes. Transcriptome analysis revealed that the in vivo-relevant genes bsh, clpP, glpD, hfq, inlA, inlB, inlE, lisR, and lplA1 as well as many other genes with a putative role during infection are transiently induced upon acid shock conducted at 25°C and 37°C. Twenty-five genes repressed upon acid shock are known to be down regulated during intracellular growth or by virulence regulators. These data were confirmed by qRT-PCR of twelve differentially regulated genes and by the identification of acid shock-induced genes influenced by σ^B. To test if up regulation of virulence genes at temperatures below 37°C correlates with pathogenicity, the capacity of L. monocytogenes to invade epithelial cells after acid shock at 25°C was measured. A 12-fold increased number of intracellular bacteria was observed (acid shock, t = 60 min) that was reduced after adaptation to the level of the unshocked control. This increased invasiveness was shown to be in line with the induction of inlAB. Using a nematode infection assay, we demonstrated that Caenorhabditis elegans fed with acid-shocked L. monocytogenes exhibits a shorter time to death of 50% (TD₅₀) of the worms (6.4 days) compared to infection with unshocked bacteria (TD₅₀ = 10.2 days). Conclusions: PrfA and other listerial virulence genes are induced by an inorganic acid in a temperature-dependent manner. The data presented here suggest that low pH serves as a trigger for listerial pathogenicity at environmental temperatures.