mgr Aksyniia Tsaruk

ORCID: 0000-0002-0902-5103

The topic of my dissertation is: „Metabolic engineering of non-conventional yeast for construction of efficient producers of biofuels (ethanol) and chemicals (lactic acid, antibiotics)”

Lactic acid is considered one of the most commercially valuable compounds with a wide range of applications in the food, chemical and pharmaceutical industries, and is mostly produced by microbiological fermentation. The main challenge is to reduce the costs of raw materials and improve production efficiency by overcoming limiting factors such as poor sugar conversion, and inhibition of the process by the substrate and the final product. The yeast Lachancea thermotolerans has a unique ability to produce lactic acid, but this process has not been studied in them. The yeast Ogataea polymorpha are also promising microorganisms for lactate production: they are thermotolerant, resistant to a number of environmental factors, able to use cheap and renewable substrates, genetic engineering methods are available for them.

Yeast cells also exhibit many advantages as cellular factories for the heterologous production of antibiotics. Due to the growing number of antibiotic-resistant bacteria, the search for new methods of therapy is an important goal of modern biotechnology. The flavin antibiotic roseoflavin and its precursor with antibiotic properties, aminoriboflavin, can be used against Gram-positive and Gram-negative bacteria, while being low-toxic to mammalian cells. These compounds are naturally produced by Streptomyces davaonensis, however, roseoflavin is not biosynthesized in sufficient quantities, and aminoriboflavin is not accumulated by this actinomycete. Metabolic engineering of the riboflavin-overproducing yeast strain Komagatella phaffii and the flavin mononucleotide-overproducing strain Candida famata will lead to obtaining yeast strains for highly sustainable production processes and the development of antibiotic production strategies.

Metabolic engineering has the potential to solve problems of lactic acid, ethanol and antibiotic production related to high production costs, energy consumption, production inhibition, production of undesirable by-products and harsh effects of fermentation conditions, as well as insufficient substrate utilization. Identifying the genetic and biochemical factors that influence the biosynthesis of the previously mentioned compounds in yeast will contribute to understanding the mechanisms of these processes.

Publication:

• Semkiv, M.V., Ruchala, J., Tsaruk, A.Y. et al.The role of hexose transporter-like sensor hxs1 and transcription activator involved in carbohydrate sensing azf1 in xylose and glucose fermentation in the thermotolerant yeast Ogataea polymorpha. Microb Cell Fact 21, 162 (2022). https://doi.org/10.1186/s12934-022-01889-z