Applied Biochemistry and Microbiology最新文献

The resistance of rice plants to deep-water flooding in Rostov oblast can be used as a “natural herbicide” to control weeds that reduce the yield of rice varieties up to 50%. A study of rice genotypes with different levels of resistance to deep-water flooding was carried out. Using molecular markers, we identified new genetic resources of tolerance to anaerobic stress factors in hybrid rice samples. Hybrid lines were analyzed for the most important breeding traits, and after crossing resistant donors with domestic high-yielding varieties, the SNORKEL1 (SK1) gene allele was detected in selected rice samples. The resistance of hybrids and parental varieties to flooding was tested by germination under hypoxic conditions. Promising genotypes of special interest for breeding, which can be used in programs for the introduction of herbicide-free farming technologies, were identified.

Based on acidophilic strain Schizosaccharomyces pombe, L-lactic acid producing strains with deletion of the NDE1 gene encoding NADH dehydrogenase, presumably regulating the cytosolic NADH/NAD+ balance in yeast, were constructed. When the genome of previously obtained producer strains is saturated with heterologous L-LDH genes encoding L-lactate dehydrogenase, culture growth worsens and glucose consumption slows down. An increase in the dose of L-LDH genes does not always lead to an increase in biosynthesis of the target product. Perhaps the limiting factor in the biosynthesis of lactic acid is the lack of cytosolic NADH oxidized to NAD+ by NADH dehydrogenase encoded by the NDE1 gene. The S. pombe strain with deletion of the NDE1 gene and an additional copy of the L-LDH gene surpasses the parent strain in growth, glucose consumption, and lactic acid biosynthesis (139 g/L, which is 28% more, final pH 3.2). This study will provide a better understanding of the underlying cellular processes in the yeast S. pombe and use the results obtained for the design of highly productive strains producing lactic acid.

Rhamnolipids are highly effective microbial surfactants that can be used as a component of cosmetics and detergents. Heterologous expression of rhamnolipid genes is a way to avoid complex regulation of rhamnolipid biosynthesis. The composition of the medium and cultivation conditions for rhamnolipid producers were optimized. For heterologous Pseudomonas viridiflava AlC1223: P5, P6, P8, when using soybean and tall oil as a carbon source, the maximum yield of the product was obtained, which amounted to: 120.3 ± 0.6, 210.1 ± 1.7, 172 ± 0.3 mg/mL, respectively; in heterologous Escherichia coli BLWT: E14, the highest product yield (43.2 ± 0.4 mg/mL) was observed with glycerol. In all cases, peptone as a nitrogen source had a positive effect on the yield of rhamnolipids. The best source of trace elements is yeast extract for E14 and a mixture of salts (magnesium sulfate and potassium monohydrophosphate) for P5, P6, P8. The increase in temperature and pH has a positive effect on productivity when hydrophobic substrates are used.

A comparative in vivo analysis was conducted to evaluate the biodistribution efficiency of cells and microvesicles labeled with fluorescent proteins. Mesenchymal stem cells (MSCs) were genetically modified using a recombinant lentivirus carrying the gene for the fluorescent protein Katushka2S, with the goal of labeling both the cells and their derived microvesicles (MVs). The selection of genetically modified MSCs was performed through cell sorting using a FACS Aria III flow cytometer–sorter. The biodistribution of the cells was assessed by detecting the fluorescent signal using the IVIS Spectrum system. Intravenous administration of 5 × 10⁵ MSC-Katushka2S in mice was insufficient for in vivo detection of cell biodistribution. Ex vivo analysis revealed that immediately after intravenous administration, the MSCs accumulated in the lungs and liver. The intensity of Katushka2S protein fluorescence and the sensitivity of the IVIS Spectrum system were sufficient for ex vivo visualization of MSC-Katushka2S cell clusters. However, the quantity of MVs-Katushka2S isolated from 1.5 × 10⁶ MSC-Katushka2S was insufficient for the detection of MV biodistribution both in vivo and ex vivo. Therefore, the application of this method for evaluating the biodistribution of individual cells and microvesicles in vivo is ineffective.

The intrinsic antimicrobial activity of personal care products against the sweat odor is a necessary element of their functional properties. To estimate this characteristic, two bacterial strains typical for the armpit zone were selected as test organisms: Corynebacterium stationis VKPM-V-10645 and Micrococcus luteus VKPM-V-7845 that demonstrated a sensitivity to all tested commercial deodorant/antiperspirant samples. An express method (a method of “rapid” microbiology) using a 0.03% water solution of 2,3,5-triphenyltetrazolium chloride (TTC) was suggested. The testing conditions were selected: the amount of test strain inoculum introduced into the reaction medium, as well as the amount and method of introducing a cosmetic product for significant accounting of the results after 3 h of incubation of the samples. This express method can be used for rapid estimation of antimicrobial activity and recommended for the analysis of large volume of objects, particularly, when searching or synthesizing new active biocidal ingredients and in large-scale testing of cosmetics against the sweat odor.

Polylactide/starch/polycaprolactone compositions have been created that are promising for the production of biodegradable packaging materials. The influence of the composition of the proposed mixtures on their mechanical properties and ability to decompose both under in vitro conditions in an accelerated mode in water and in the soil of central Russia was studied. It has been shown that a small addition of polycaprolactone improves the polylactide processing and also reduces the fragility of these compositions at starch concentrations of up to 30 wt %.

This study describes the generation of monoclonal producer clones using the ClonePix™ FL robotic system. CHO cells producing the enzyme arylsulfatase B (ASB) were used as an example. As a result, 20 leading clones producing the recombinant lysosomal enzyme ASB were selected. The probability of monoclonality calculated using the formula provided by the developers of the ClonePix™ FL system was 99.94%. However, the probability of monoclonality calculated by the Monte Carlo method was 97.79%. The Monte Carlo method provided a more accurate estimate of the probability of monoclonality, allowing us to make adjustments in the process of clone production and optimize cell seeding in a semi-solid medium by taking into account additional parameters. The probability of monoclonality of producer clones is a necessary parameter for drug registration.