In the cheese-making industry, commonly chymosin is used as the main milk-clotting enzyme. Bactrian camel (Camelus bactrianus) chymosin (BacChym) has a milk-clotting activity higher than that of calf chymosin for cow’s, goat’s, ewes’, mare’s and camel’s milk. A procedure for obtaining milk-clotting reagent based on recombinant camel chymosin is proposed here. Submerged fermentation by a recombinant yeast (Pichia pastoris GS115/pGAPZαA/ProchymCB) was implemented in a 50 L bioreactor, and the recombinant camel chymosin was prepared successfully. The activity of BacChym in yeast culture was 174.5 U/mL. The chymosin was concentrated 5.6-fold by cross-flow ultrafiltration and was purified by ion exchange chromatography. The activity of the purified BacChym was 4700 U/mL. By sublimation-drying with casein peptone, the BacChym powder was obtained with an activity of 36,000 U/g. By means of this chymosin, cheese was prepared from cow’s, goat’s, ewes’, camel’s and mare’s milk with a yield of 18%, 17.3%, 15.9%, 10.4% and 3%, respectively. Thus, the proposed procedure for obtaining a milk-clotting reagent based on BacChym via submerged fermentation by a recombinant yeast has some prospects for biotechnological applications. BacChym could be a prospective milk-clotting enzyme for different types of milk and their mixtures.

Kazakhstan belongs to countries with a high level of brucellosis among humans and farm animals. Although antibiotic therapy is the main way to treat acute brucellosis in humans there is still little information on a circulation of the antibiotic-resistant Brucella strains in the Central Eurasia. In this article we describe an occurrence of the drug resistance of Brucella melitensis isolates in Kazakhstan which is among the largest countries of the region. Susceptibilities to tetracyclin, gentamycin, doxycyclin, streptomycin and rifampicin were investigated in 329 clinical isolates of Brucella melitensis using E-test method. All isolates were susceptible to streptomycin, tetracycline and doxycycline. 97.3% of the Brucella isolates were susceptible to gentamycin, although only 37.4% of isolates were susceptible to rifampicin. 21.9% of isolates had intermediate resistance, and 26.4% of isolates were resistant to this antibacterial drug. Isolates of Brucella melitensis circulating in Kazakhstan are susceptible to streptomycin, doxicyclin, tetracyclin and gentamycin. At the same time the resistance to rifampicin is widespread, almost half of the isolates were rifampicin-resistant (including the intermediate resistance).

Environmental safety and economic factors necessitate a search for new ways of processing poultry farm feathers, which are 90% β-keratin and can be used as a cheap source of amino acids and peptones. In this study, feather-decomposing bacteria were isolated from a site of accumulation of rotten feathers and identified as Bacillus. Among them, the Bacillus sp. A5.3 isolate showed the best keratinolytic properties. Scanning electron microscopy indicated that Bacillus sp. A5.3 cells closely adhere to the feather surface while degrading the feather. It was found that Bacillus sp. A5.3 secretes thermostable alkaline proteolytic and keratinolytic enzymes. Zymographic analysis of the enzymatic extract toward bovine serum albumin, casein, gelatin, and β-keratin revealed the presence of proteases and keratinases with molecular weights 20–250 kDa. The proteolytic and keratinolytic enzymes predominantly belong to the serine protease family. Proteome analysis of the secreted proteins by nano-HPLC coupled with Q-TOF mass spectrometry identified 154 proteins, 13 of which are proteases and peptidases. Thus, strain Bacillus sp. A5.3 holds great promise for use in feather-processing technologies and as a source of proteases and keratinases.

The regeneration of cartilage and osteochondral defects remains one of the most challenging clinical problems in orthopedic surgery. Currently, tissue-engineering techniques based on the delivery of appropriate growth factors and mesenchymal stem cells (MSCs) in hydrogel scaffolds are considered as the most promising therapeutic strategy for osteochondral defects regeneration. In this study, we fabricated a heparin-conjugated fibrin (HCF) hydrogel with synovium-derived mesenchymal stem cells (SDMSCs), transforming growth factor-β1 (TGF-β1) and bone morphogenetic protein-4 (BMP-4) to repair osteochondral defects in a rabbit model. An in vitro study showed that HCF hydrogel exhibited good biocompatibility, a slow degradation rate and sustained release of TGF-β1 and BMP-4 over 4 weeks. Macroscopic and histological evaluations revealed that implantation of HCF hydrogel with SDMSCs, TGF-β1 and BMP-4 significantly enhanced the regeneration of hyaline cartilage and the subchondral bone plate in osteochondral defects within 12 weeks compared to hydrogels with SDMSCs or growth factors alone. Thus, these data suggest that combined delivery of SDMSCs with TGF-β1 and BMP-4 in HCF hydrogel may synergistically enhance the therapeutic efficacy of osteochondral defect repair of the knee joints.

We describe the genetic diversity of 1327 Brucella strains from human patients in Kazakhstan using multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA). All strains were assigned to the Brucella melitensis East Mediterranean group and clustered into 16 MLVA11 genotypes, nine of which are reported for the first time. MLVA11 genotype 116 predominates (86.8%) and is present all over Kazakhstan indicating existence and temporary preservation of a “founder effect” among B. melitensis strains circulating in Central Eurasia. The diversity pattern observed in humans is highly similar to the pattern previously reported in animals. The diversity observed by MLVA suggested that the epidemiological status of brucellosis in Kazakhstan is the result of the introduction of a few lineages, which have subsequently diversified at the most unstable tandem repeat loci. This investigation will allow to select the most relevant strains for testing these hypotheses via whole genome sequencing and to subsequently adjust the genotyping scheme to the Kazakhstan epidemiological situation.