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Many different strains of Streptococcus thermophilus are commonly used as starter cultures, and search for new safe strains with desired industrial and probiotic properties is an important issue. In this article, genomes of two new S. thermophilus strains—Str16t and Str159—were sequenced, and the main genome characteristics were determined. In silico analysis of the sequenced genomes revealed the absence of transmissible antibiotic resistance genes, virulence genes associated with pathogenicity, and integrated plasmids; gene clusters encoding class I and class II bacteriocins were found. In vitro tests showed phosphatase, peptidase, β-galactosidase, and esterase activity of both strains. Both strains were capable of fermenting glucose, lactose, sucrose, and ribose; in addition, Str16t fermented mannose. In conclusion, it was demonstrated that both Str16t and Str159 are promising strains for application as starter and probiotic cultures. [ABSTRACT FROM AUTHOR]

In this work, a comparative analysis of the profile of fatty acids (FA) and volatile organic compounds (VOCs) for skimmed cow's milk fermented by four different probiotic strains of Lacticasibacillu paracasei (ABK, KF1, MA2, and MA3) was carried out. Analysis of FA and VOC profiles was performed using gas chromatography with mass spectrometric detection (GC-MS). For additional characterization of odor changes and its intensity in the fermented milk samples, the E-nose "electronic nose" odor analyzer was used. In total, the presence of 42 different FAs was detected in all samples, of which 17 were saturated, 8 monounsaturated, and 5 polyunsaturated. The strain-specific differences between the studied samples were of a complex nature and could not be explained only by the variation in the contribution of several individual FAs. The FA-nutritional indices characterizing the nutritional and biological value of the samples were different for milk fermented by different strains. Analysis of VOCs showed that the main odor-forming compounds in the studied samples were FAs and their reaction products, 2-heptanone, 2-nonanone, and 2-nonanol, which formed as a result of the following chain of transformations: β-oxidation → decarboxylation → reduction. The aroma of L. paracasei fermentation products, predicted on the basis of the odors of individual VOCs, generally coincided with their organoleptic assessment, a flavor typical of fermented milk (yogurt and curdled milk) with floral and fruity notes. [ABSTRACT FROM AUTHOR]

Basidiomycetes are attracting a lot of interest due to their remarkable ability to degrade phthalic acid esters (PAEs). In this article, the degradation process of benzyl butyl phthalate (BBP) and diisobutyl phthalate (DiBP) by the fungus Trametes hirsuta was studied. It was shown that T. hirsuta destroyed >95% of the initial BBP during 24 h, with complete destruction (>99%) occurring by the 3rd day of cultivation. DiBP was destroyed more slowly: 95% of the initial DiBP was destroyed by 10 days. The oxidase activity in the presence of PAEs increased by about 6.0 times, and the esterase activity by 2.0–2.5 times compared to the control. Enzymes involved in the process of PAEs degradation were identified on day 10: manganese peroxidases (MnP2, MnP5, MnP7), versatile peroxidase (VP2), lignin peroxidase (LiP9) and laccase (LacA). For the DiBP, the proportion of MnP5 and LiP9 increased, while the proportion of MnP2 and MnP7 decreased markedly. For the BBP, the proportion of MnP7 increased, while the proportion of VP2 significantly decreased. The GC–MS analysis of PAEs decomposition products were performed. For both PAEs, unique metabolites were found. A toxicity assessment revealed a pronounced toxic effect of metabolites formed during the degradation of BBP. [ABSTRACT FROM AUTHOR]

The ability of white rot fungi from different ecophysiological groups (primary wood-destroying saprotroph Trametes hirsuta, secondary wood-destroying saprotroph Steccherinum ochraceum, litter saprotroph Crucibulum laeve, and humic saprotroph Agrocybe praecox) to degrade phthalic acid esters (PAEs) was studied. It was shown that diethylhexyl phthalate (DEHP) with longer and branched hydrocarbon chains was more rapidly biodegraded by wood-destroying saprotrophs such as T. hirsuta and S. ochraceum, with an efficiency of more than 99%. Dibutyl phthalate (DBP), which is less hydrophobic with shorter hydrocarbon units, was most efficiently transformed by the litter saprotroph C. laeve (up to 96.5%). Diethyl phthalate (DEP) proved to be the most toxic to all fungi. T. hirsuta showed the greatest resistance to elevated DEP concentrations in the medium. It has been shown that fungi destroy PAEs with the formation of various metabolites, depending on the composition of the multienzyme complex of the fungus. Among the secondary metabolites, ionol, an antioxidant formed by fungi when PAEs is added to the medium, was found. [ABSTRACT FROM AUTHOR]

Last year we devoted a number of issues of this journal (Narodnoe obrazovanie, nos. 9, 10, and 12) to a discussion of experiments that are being carried out in our sector today. We began a new column, "Experimental Sites-The Path to New Education," which we consider of paramount interest, for it is at experimental sites (and there are already hundreds of them) that new pedagogical technologies-concepts of democratic administration and extramural upbringing-come into being. The term "experimental sites" itself has become one that is familiar and frequently used. But what lies behind it? What is the meaning of this term? How does the experimental site relate to ordinary research? [ABSTRACT FROM AUTHOR]

As a natural, symbiotic consortium of bacteria and yeasts, kefir grains provide a unique source of new probiotic microorganisms. In this work, three new isolates of lactobacilli, Lactobacillus helveticus and two strains of Lacticaseibacillus paracasei, were isolated from kefir grains originating from the North Caucasus region of Russia, and they were identified with biochemical and genetic methods. The enzyme-activity profiles were described for all strains, and the antimicrobial resistance and genetic determinants of antibiotic resistance were screened. During fermentation of cow's milk, all three strains showed lower acid-forming activity but comparable proteolytic, antioxidant, and hypotensive activities in comparison with kefir starter culture. [ABSTRACT FROM AUTHOR]

The article presents the results of optimization of the culturing conditions to increase the production of bacteriocin-like compounds (presumably including reuterin) by the Lactobacillus reuteri strain LR1. The strain Escherichia coli ATCC 25922, an opportunistic microorganism, the content of which is standardized in foods by the Food Safety Legislation, was selected as an indicator strain of antimicrobial activity. The nutrient medium for L. reuteri LR1 cultivation was optimized to increase the production of bacteriocin-like compounds, and the parameters of two-stage growth of the producer were established: (1) cultivation on the initial medium for biomass accumulation and (2) growth on a water–glycerol medium to convert glycerol to antimicrobial compounds, presumably reuterin. The first stage was carried out as follows: the L. reuteri LR1 culture (5%) was inoculated into a medium with the following composition: hydrolyzed milk—250 mL/L; yeast extract—10 g/L; peptone—5 g/L; glucose—20 g/L; sodium acetate—5.0 g/L; monosubstituted potassium phosphate—2.0 g/L; magnesium sulfate—0.2 g/L, and manganese sulfate—0.5 g/L, pH 6.4–6.6. The cultivation was carried out for 18 h at (37 ± 1)°С. The second stage included the incubation of the obtained biomass in 200 mM of glycerol-containing aqueous solution, pH 6.6, for 2 h at 37°С. The zone of E. coli inhibition caused by the produced bacteriocin-like compounds was 25 mm. [ABSTRACT FROM AUTHOR]

The work presents the results of studies on the creation of a combined starter culture based on lactic and propionic acid bacteria and the functional properties of products based on it. It was shown that the fermented product obtained from a combined starter based on Lactococcus lactis ssp. cremoris CR201, Lactobacillus rhamnosus F and Propionibacterium shermanii E2 strains in a ratio of 2 : 1 : 6 (vol/vol), respectively, had a pronounced antagonistic effect on Escherichia coli and Staphylococcus aureus and causative agents of food spoilage Penicillium brevicompactum and Torulaspora delbrueckii, as well as ACE inhibitory activity in vitro. Bifidogenic and moderate hypotensive effects were demonstrated with in-vivo models. The addition of whey-protein hydrolysates to skimmed milk also leads to an increase in the growth of propionic acid bacteria and an increase in the number of viable cells in the finished fermented beverage, which increased its antimicrobial activity in vitro and bifidogenic effect in vivo. [ABSTRACT FROM AUTHOR]

The laccase from Steccherinum murashkinskyi is a member of the large family of multicopper oxidases that catalyze the oxidation of a wide range of organic and inorganic substrates, accompanied by the reduction of dioxygen to water. The reducing properties of X-ray radiation and the high quality of the laccase crystals allow the study of the catalytic reduction of dioxygen to water directly in a crystal. A series of diffraction data sets with increasing absorbed radiation dose were collected from a single crystal of Steccherinum murashkinskyi laccase at 1.35 Å resolution. Changes in the active-site structure associated with the reduction of molecular oxygen to water on increasing the absorbed dose of ionizing radiation were detected. The structures in the series are mixtures of different states of the enzyme-substrate complex. Nevertheless, it was possible to interpret these structures as complexes of various oxygen ligands with copper ions in different oxidation states. The results allowed the mechanism of oxygen reduction catalyzed by laccases to be refined. [ABSTRACT FROM AUTHOR]

The long-term spontaneous evolution of humans and the human immunodeficiency virus ( HIV) is not well characterized; many vertebrate species, including humans, exhibit remnants of other retroviruses in their genomes that question such possible endogenization of HIV. We investigated two HIV-infected patients with no HIV-related disease and no detection with routine tests of plasma HIV RNA or cell-associated HIV DNA. We used Sanger and deep sequencing to retrieve HIV DNA sequences integrated in the human genome and tested the host humoral and cellular immune responses. We noticed that viruses from both patients were inactivated by the high prevalence of the transformation of tryptophan codons into stop codons (25% overall (3-100% per gene) and 24% overall (0-50% per gene)). In contrast, the humoral and/or cellular responses were strong for one patient and moderate for the other, indicating that a productive infection occurred at one stage of the infection. We speculate that the stimulation of APOBEC, the enzyme group that exchanges G for A in viral nucleic acids and is usually inhibited by the HIV protein Vif, has been amplified and made effective from the initial stage of the infection. Furthermore, we propose that a cure for HIV may occur through HIV endogenization in humans, as observed for many other retroviruses in mammals, rather than clearance of all traces of HIV from human cells, which defines viral eradication. [ABSTRACT FROM AUTHOR]

Screening of the ligninolytic activity of basidiomycetes from the Komarov Botanical Institute Basidiomycetes Culture Collection (LE-BIN), Russian Academy of Sciences, belonging to different taxonomic and ecological groups was performed. The patterns of the position of taxa of active producers of ligninolytic enzymes in the modern system of fungi were identified. Cluster analysis showed that the group of fungi with the greatest ligninolytic and degradation potential includes representatives of the families Pleurotaceae, Polyporaceae, and Phanerochaetaceae, which perform the first stages of wood decomposition. As a result, species of interest for the further study of their oxidative potential and use in biotechnology were selected. [ABSTRACT FROM AUTHOR]