In order to address the upcoming crisis in the treatment of Klebsiella pneumoniae infections, caused by an increasing proportion of resistant isolates, new approaches to antimicrobial therapy must be developed. One approach would be to use (bacterio)phages and/or phage derivatives for therapy. In this study, we present a description of the first K. pneumoniae phage from the Zobellviridae family. The vB_KpnP_Klyazma podovirus, which forms translucent halos around the plaques, was isolated from river water. The phage genome is composed of 82 open reading frames, which are divided into two clusters located on opposite strands. Phylogenetic analysis revealed that the phage belongs to the Zobellviridae family, although its identity with the closest member of this family was not higher than 5%. The bacteriophage demonstrated lytic activity against all (n = 11) K. pneumoniae strains with the KL20 capsule type, but only the host strain was lysed effectively. The receptor-binding protein of the phage was identified as a polysaccharide depolymerase with a pectate lyase domain. The recombinant depolymerase protein showed concentration-dependent activity against all strains with the KL20 capsule type. The ability of a recombinant depolymerase to cleave bacterial capsular polysaccharides regardless of a phage’s ability to successfully infect a particular strain holds promise for the possibility of using depolymerases in antimicrobial therapy, even though they only make bacteria sensitive to environmental factors, rather than killing them directly.

CRISPR-Cas systems, widespread in bacteria and archaea, are mainly responsible for adaptive cellular immunity against exogenous DNA (plasmid and phage). However, the latest research shows their involvement in other functions, such as gene expression regulation, DNA repair and virulence. In recent years, they have undergone intensive research as convenient tools for genomic editing, with Cas9 being the most commonly used nuclease. Gene editing may be of interest in biotechnology, medicine (treatment of inherited disorders, cancer, etc.), and in the development of model systems for various genetic diseases. The dCas9 system, based on a modified Cas9 devoid of nuclease activity, called CRISPRi, is widely used to control gene expression in bacteria for new drug biotargets validation and is also promising for therapy of genetic diseases. In addition to direct use for genomic editing in medicine, CRISPR-Cas can also be used in diagnostics, for microorganisms’ genotyping, controlling the spread of drug resistance, or even directly as “smart” antibiotics. This review focuses on the main applications of CRISPR-Cas in medicine, and challenges and perspectives of these approaches.

The results of studies on mce operons of the causative agent Mycobacterium tuberculosis and actinobacteria are summarized. Mce transporters belong to a group of cell-wall proteins. The genome of M. tuberculosis contains four mce operons that encode complexes, each of which consists of two integral membrane proteins (YrbEB) followed by six other Mce proteins (MceA–F). These proteins are functionally similar to ABC transporters. Despite their significant role in the pathogenesis of M. tuberculosis infection, Mce proteins remain poorly studied due to their complex structure and operon regulation. However, a number of their functions have been characterized; they include the penetration of host cells by M. tuberculosis and its survival, as well as the transport of cholesterol and mycolic acids, which are pathogenicity factors of no small importance. The expression of mce operons depends on many factors, such as the growth phase, the culture medium, and the localization of M. tuberculosis infection. Today, strains of M. tuberculosis and M. bovis with deleted mce operons are considered candidates for the development of new attenuated vaccines that might one day replace the M. bovis BCG vaccine, which is no longer deemed strong enough to hold back the tuberculosis epidemic.

A novel aerobic bacterial strain Z-0088 was assigned to the genus Spirosoma on the basis of 16S rRNA analysis; it was isolated from a bacterial community of moderately acidic (pH 5.0) dystrophic, slightly humified water formed by xylotrophic fungi grown on decaying spruce wood. The cells are nonmotile, gramnegative, straight or curved rods, 0.5–1.5 × 1.0–6.0 μm; they may also be toroidal. The cells are usually single but can form spiral filaments containing from 4 to 13 coils; their reproduction is by division. Strain Z-0088 is an organoheterotroph utilizing xylan, inulin, xylose, sucrose, and N-acetylglucosamine as organic growth substrates. The bacterium is oligotrophic (the optimum substrate concentration is 0.5 g/L). It is characterized by high sensitivity to NaCl concentration; growth was completely suppressed at 1% NaCl. The strain grows in a pH range of 3.8–7.5 with the optimum at pH 5.5–6.5. The temperature range for growth was 13–35°C with the optimum at 28°C. The DNA G+C base content was 50.2 mol %. The ecophysiological features of strain Z-0088, such as oligotrophic, mesophilic, moderate acidophilic properties, and sensitivity to NaCl, support its designation as a representative of ombrophilic dissipotrophs. The strain is assigned to a novel species Spirosoma xylofaga sp. nov.