Biology subjects

Illarionov, A.

Publications and source records attributed to Illarionov, A..

3 recordsLinked to original sources

bioRxiv2025

Acidification by nitrogen metabolism triggers extracellular biopolymer production in an oleaginous yeast

The oleaginous yeast Rhodotorula toruloides is a natural producer of lipids and carotenoids. However, its potential as a producer of extracellular biopolymers remains unexplored. Hence, we aimed to evaluate the R. toruloides CCT0783 for extracellular biopolymer production. We found that the carbon-to-nitrogen ratio influenced exopolysaccharide (EPS) production, reaching 5.84 {+/-} 0.45 g/L under glucose-rich conditions. We characterized the crude biopolymer using FTIR and GC-MS, identifying polysaccharide peaks, wherein EPS consisted of (%) glucose (88.83 {+/-} 4.87), galactose (5.50 {+/-} 1.50), mannose (4.80 {+/-} 1.57), and xylose and arabinose (0.87 {+/-} 0.04) monomers. The dried EPS also contained a fractional presence of protein (1.0%). Interestingly, inorganic, but not organic, nitrogen metabolism was associated with the acidification of the culture environment and simultaneous EPS production. A comparison between non-buffered and buffered media indicated that EPS was produced when the final pH was around or below 2, which was observed in the former but not in the latter. Finally, a comparative bioinformatics analysis allowed us to map a putative EPS biosynthesis and transport pathways, as well as regulators of intracellular pH maintenance. In conclusion, our study demonstrates R. toruloides potential as an extracellular microbial biopolymer producer, enabling its development as a cell factory. ImportanceMicrobial biopolymers are extensively investigated for their impact on the environment and health. However, developing a biotechnology process for producing such biopolymers remains challenging despite their potential for valuable applications. Considering this opportunity, we investigated the oleaginous yeast Rhodotorula toruloides as a producer of extracellular biopolymers. Our study describes the conditions of exopolysaccharide (EPS) biosynthesis in R. toruloides. This extracellular biopolymer could have a wide range of applications, from gelling agents in pharmaceuticals to emulsifiers in the food industry. Furthermore, our comparative bioinformatics analysis results could be useful for metabolic engineering and developing Rhodotorula cell factories.

microbiology↗

bioRxiv2020

Characterization of potassium, sodium and their interactions effects in yeasts

Biotechnology requires efficient microbial cell factories. The budding yeast Saccharomyces cerevisiae is an important cell factory but for a sustainable use of natural resources more diverse cellular attributes are essential. Here, we benchmarked non-conventional yeasts Kluyveromyces marxianus (KM) and Rhodotorula toruloides (RT) against the extensively characterized strains of S. cerevisiae, CEN.PK and W303. We developed a computational method for the characterization of cell/vacuole volumes and observed an inverse relationship between the maximal growth rate and the median cell volume that was responsive to monovalent cations. We found that the supplementation of certain K+ concentrations to CEN.PK cultures containing 1.0 M Na+ increased the specific growth rate by four-fold with a parabolic shift in the median cell/vacuole volumes. The impairment of ethanol and acetate utilization in CEN.PK, acetate in W303, at the higher K+/Na+ concentrations implied an interference in the metabolic pathways required for their consumption. In RT cultures, the supplementation of K+/Na+ induced a trade-off in glucose utilization but alleviated cellular aggregates formation where specified cationic concentrations increased the beta-carotene yield by 60% compared with the reference. Our comparative analysis of cell/vacuole volumes using exponential phase cultures showed that the median volumes decreased the most for KM and the least for RT in response to studied cations. Noteworthy for the implication in aging research using yeasts, the vacuole to cell volume ratio increased with the increase in cell volume for W303 and KM, but not for CEN.PK and RT. ImportanceFor designing efficient bioprocesses characterization of microbial cell factories in the relevant culture environment is important. The control of cell volume in response to salt stress is crucial for the productivity of microbial cell factories. We developed an open source computational method for the analysis of optical microscopy images that allowed us to quantify changes in cell/vacuole volumes in response to common salts in yeasts. Our study provides a framework for appreciating the role of cellular/organellar volumes in response to changing physiological environment. Our analysis showed that K+/Na+ interactions could be used for improving the cellular fitness of CEN.PK and increasing the productivity of beta-carotene in R. toruloides, which is a commercially important antioxidant and a valuable additive in foods.

bioengineering↗

bioRxiv2020

Physical confinement impacts cellular phenotype within living materials

Additive manufacturing allows three-dimensional printing of polymeric materials together with cells, creating living materials for applications in biomedical research and biotechnology. However, understanding the cellular phenotype within living materials is lacking and a key limitation for their wider application. Herein, we present an approach to characterize the cellular phenotype within living materials. We immobilized the budding yeast Saccharomyces cerevisiae in three different photocross-linkable triblock polymeric hydrogels containing F127-bis-urethane methacrylate, F127-dimethacrylate, or poly(alkyl glycidyl ether)-dimethacrylate. Using optical and scanning electron microscopy, we showed that hydrogels based on these polymers were stable under physiological conditions, but yeast colonies showed differences in the interaction within the living materials. We found that the physical confinement, imparted by compositional and structural properties of the hydrogels, impacted the cellular phenotype by reducing the size of cells in living materials compared with suspension cells. These properties also contributed to the differences in immobilization patterns, growth of colonies, and colony coatings. We observed that a composition-dependent degradation of polymers was likely possible by cells residing in the living materials. In conclusion, our investigation highlights the need for a holistic understanding of the cellular response within hydrogels to facilitate the synthesis of application-specific polymers and the design of advanced living materials in the future.

bioengineering↗