Vol 53, No 8 (2017)

Resistance to fusidic acid in Corynebacterium glutamicum and Brevibacterium flavum is associated with mutations in the fusA gene, which encodes the elongation factor G (EF-G). Two to ten percent of fusidic acid-resistant clones were shown to produce more lysine than parent strains. Sequencing of the fusA gene in clones with a high level of lysine production made it possible to find two mutations in the gene at position 1383—С1383G and С1383А. These mutations cause amino acid replacement at position 461 in the protein EF-G, namely, histidine is substituted by glutamine (H461Q). The mutation С1383G was introduced in the chromosomal copy of the fusA gene in C. glutamicum and B. flavum strains by homologous recombination. All clones containing the mutant variant of the fusA gene produced 10% more lysine than the parent strains.

A multistep random UV mutagenesis of an eremomycin-producing strain Amycolatopsis orientalis VKPM Ac-1125 with rather low productivity (0.5 g/L) and the further selection of the most high-yield mutant strains have resulted in a highly productive E 13-26 strain. After optimization of the fermentation medium by multifactor analysis, the most efficient composition for the fermentation medium was established, %: glycerol, 8; soybean meals, 2.0; MgCl₂, 0.02; KH₂PO₄, 0.02; KNO₃, 0.6; CaCl₂, 0.3; skim milk powder, 0.46; and glucose, 0.8. The maximum productivity of this strain on the optimized medium reached 3.42 ± 0.17 g/L. Therefore, the obtained strain is considered to be very promising for further use in the selection and development of technology for the large-scale eremomycin production.

The interdependences between the structure of fatty acid and biofuel characteristics obtained from these fatty acids were briefly reviewed. The fatty acid compositions of the lipids of yeasts and phototrophic microorganisms were analyzed. The main parameters of the biodiesel (iodine value, cetane number, and kinematic viscosity) that can be made from the lipids of these microorganisms were calculated based on the data and compared to the current standards. The lipids of the yeast Rhodosporidium toruloides VKPM Y-3349 were shown to be the most suitable for biofuel production due to the composition and content of fatty acid. The possibilities of a decrease in the prime cost of microbial lipids (along with plant oils) that would make them competitive raw material for biofuel production were considered.

Gel-forming starch phosphates with a content of acidic phosphate groups ranging from 2.1 to 3.8 mmol/g were obtained in a phosphoric acid-urea system. The rates of starch phosphate degradation in buffer solution in the absence of amylase and in the presence of this enzyme were investigated in vitro. Starch phosphate gels were shown to be prone to enzymatic degradation. However, the rate of biodegradation decreased gradually as the content of phosphate groups increased. The use of microgels with average particle sizes in the range of 7.8–60.1 μm for the production of controlled-release preparations of interferon-alpha 2b has been demonstrated to be possible in principle.