Acipenser baerii (Siberian sturgeon) is native to Kazakhstan and is currently endangered and is listed within the first class of protected animals. Sturgeon aquaculture is becoming an important tool for the recovery of this endangered species. Nonetheless, diseases involving typical symptoms of skin ulceration and systemic bacterial hemorrhagic septicemia have occurred in cultured A. baerii on a fish farm located in Western Kazakhstan. In this study, an infectious strain of bacteria isolated from an ulcer of diseased A. baerii was identified as Aeromonas salmonicida (strain AB001). This identification involved analyses of 16S rRNA, gyrB, rpoD, and flaA genes’ sequences. Even though strain AB001 belongs to A. salmonicida, it exhibited noticeable mobility and growth at temperatures of ≥37 °C. Profiling of virulence genes uncovered the presence of seven such genes related to pathogenicity. Antibiotic sensitivity testing showed that the strain is sensitive to aminoglycosides, amphenicols, nitrofurans, quinolones, and tetracyclines. Half-lethal doses (LD₅₀) of strain AB001 for Oreochromis mossambicus and A. baerii were determined: respectively 1.7 × 10⁸ and 7.2 × 10⁷ colony-forming units per mL. The experimentally induced infection revealed that strain AB001 causes considerable histological lesions in O. mossambicus, including tissue degeneration, necrosis, and hemorrhages of varied severity.

Aeromonas spp. are opportunistic pathogens that are widely distributed in water sources, with several species being associated with fish and human diseases. We have previously identified an Aeromonas AB005 isolate from diseased Acipencer baerii. This isolate was identified as A. hydrophila based on the 16S rRNA and gyrB gene sequences. However, this novel strain does not produce indole and tested negative for ornithine decarboxylase and d-xylose fermentation—differences that set it apart from typical A. hydrophila strains. In the present study, this strain was subjected to whole-genome sequencing and compared with the genomes of the type strain (Aeromonas hydrophila ATCC 7966^T) and other Aeromonas spp. Comprehensive genome analysis suggests that AB005 represents a distinct species within the genus. The draft genome of the AB005 strain comprises 4,780,815 base pairs with a GC content of 61.2% and contains 6104 predicted protein-coding sequences along with numerous genes implicated in antibiotic resistance. The core/pan-genome analysis reveals extensive genetic diversity, indicative of a dynamic genomic structure. These findings collectively underscore the taxonomic distinction of the AB005 strain as a novel species and highlight its potential pathogenic implications in aquaculture and public health settings.

The Coronaviridae family represents a broad group of RNA-containing viruses that infect humans and animals. This family belongs to the order Nidovirales and is divided into four main genera: α-CoV, β-CoV, γ-CoV and δ-CoV. It is particularly noteworthy that representatives of β-CoV have caused serious epidemics in humans, such as the outbreaks of SARS-CoV, MERS-CoV, and COVID-19 caused by SARS-CoV-2. Although the clinical manifestations of CoVs can range from mild cold-like symptoms to severe respiratory diseases, they share common features in their structure, modes of transmission, and natural reservoirs. Identifying natural reservoirs, as well as establishing intermediate hosts, is crucial for understanding the mechanisms of interspecies transmission of CoVs. These processes are often mediated by molecular interactions between viral spike (S) proteins and cellular receptors of different species, which contribute to zoonotic outbreaks. Thus, the interaction of various species and the study of these processes of viral spread, cross-species transmission, and pathogen evolution play a key role in ensuring global biological safety. Therefore, we conducted this review to summarize the data from existing studies focused on the taxonomy of CoVs, their main types, natural reservoirs, intermediate hosts, pathways of interspecies transmission, and the significance of the One Health concept as an interdisciplinary approach to monitoring, prevention and control of CoV infections at the intersection of human, animal, and environmental health. We examined databases such as PubMed, Science Direct, Web of Science, and Google Scholar to identify relevant scientific articles in English available for such a review. The aim of this work is to study the taxonomy and classification of coronaviruses, as well as to identify their natural reservoirs, intermediate hosts, and applicable control measures. A review of human and animal coronaviruses has revealed their evolutionary diversity, their main natural reservoirs, their intermediate hosts, and their interactions with cellular receptors. This information allows for a better understanding of the mechanisms by which the viruses are transmitted from animals to humans. The concept of One Health demonstrated the interconnections between human, animal and environmental factors.

Heterologous expression of Aspergillus niger endo-1,4-beta- glucanase (ENG1) in Saccharomyces cerevisiae was tested both with an episomal plasmid vector (YEGAp/eng1) and a yeast vector capable of integration into the HO locus of the S. cerevisiae chromosome (pHO-GAPDH-eng1-KanMX4-HO). In both cases, eng1 gene expression in yeast, with its native signal sequence for secretion, was under the control of the strong glyceraldehyde 3-phosphate dehydrogenase (GAPDH) promoter. We aimed to verify how each expression system affects protein expression, posttranslational modification, and biochemical properties. Expression of eng1 from the episomal plasmid vector YEGAp/eng1 significantly slowed the growth of a yeast cell culture. However, expression of eng1 from the vector integrated into the HO locus of the chromosome did not cause growth suppression, and the enzyme activity in a culture supernatant was maintained throughout the incubation time. ENG1 has optimum catalytic activity at pH 6.0, and is stable in the pH range 5.0-9.0. The enzyme's optimum temperature for catalytic activity at pH 6.0 is 70 degrees C; importantly, more than 95% of the enzyme's initial activity remained after a 2-h incubation at 60 degrees C. The biochemical characterization of ENG1 confirmed the correct expression of the protein and showed that ENG1 expressed by the pHO-GAPDH-eng1-KanMX4-HO vector, in addition to its N-linked sites, is overglycosylated at its O-glycosylation sites compared with ENG1 expressed by the YEGAp/eng1 vector. It is likely that the O-glycosylated form of the A. niger ENG1 retains more stable activity during continuous cultivation of recombinant yeasts than the form that is only N-glycosylated.