Abstract
Exopolysaccharides (EPS) are high molecular weight biomaterials of industrial interest due to their variety of applications in the pharmaceutical, cosmetic, environmental, and food industries. EPS produced by Rhodotorula mucilaginosa UANL-001 L has sparked interest due to its bio-adsorbent and wide spectrum antimicrobial properties. However, full exploitation and commercial application of EPS has been restrained due to low yields and high production costs. In the present work, the production and separation of EPS from Rhodotorula mucilaginosa UANL-001L was attempted through extractive fermentation in order to increase EPS production while simplifying the recovery process. Extractive fermentation was implemented with a thermoseparating polymer for phase formation (EOPO 970 and EOPO 12,000); culture viability, biomass generation, EPS production, rheological system properties, and phase formation time and temperature were monitored throughout the process. Extractive fermentation of Rhodotorula mucilaginosa UANL-001L with EOPO 970 resulted in a 42% EPS and 7% biomass recovery on the top phase after 5 to 13-min phase formation time and temperatures between 30 and 40 °C. This is the first report of extractive fermentation application for EPS production by yeast of the genera Rhodotorula, resulting in an interesting strategy for EPS production and recovery, although further optimization is needed.
Highlights
Exopolysaccharides (EPS) is a high molecular weight biomaterial excreted by various microorganisms [1], especially by the yeast of the following genus: Aureobasidium, Bullera, Candida, Cryptococcus, Pichia, Phomopsis, Exophiala, Lipomyces, Rhodotorula, Sporobolomyces, Tremella, and Trichosporon [2].Various EPS are of industrial interest due to its variety of applications in pharmaceutical, cosmetic, environmental, and food industries [3], where some EPS, including xanthan, dextran, and hyaluronate, Fermentation 2020, 6, 108; doi:10.3390/fermentation6040108 www.mdpi.com/journal/fermentationFermentation 2020, 6, 108 are commercially produced [2]
It is important to note that EPS production is very low at the first 72 h of cultivation, resulting in a higher production after 120 h of culture in both media, being the highest EPS concentration obtained from Yeast Malt Broth (YM) medium
EPS production has been previously reported in other Rhodotorula strains, such as Rhodotorula mucilaginosa YR-2, where EPS production was observed after 120 h culture [20], which coincides with our results
Summary
Exopolysaccharides (EPS) is a high molecular weight biomaterial excreted by various microorganisms [1], especially by the yeast of the following genus: Aureobasidium, Bullera, Candida, Cryptococcus, Pichia, Phomopsis, Exophiala, Lipomyces, Rhodotorula, Sporobolomyces, Tremella, and Trichosporon [2].Various EPS are of industrial interest due to its variety of applications in pharmaceutical, cosmetic, environmental, and food industries [3], where some EPS, including xanthan, dextran, and hyaluronate, Fermentation 2020, 6, 108; doi:10.3390/fermentation6040108 www.mdpi.com/journal/fermentationFermentation 2020, 6, 108 are commercially produced [2]. EPS produced by Rhodotorula mucilaginosa UANL-001L has sparked interest due to its bioadsorbent [4] and wide spectrum antimicrobial [5] properties. Full exploitation and commercial application of EPS has been restrained due to low yields and high production costs. The recovery and purification of EPS starts with cell removal by centrifugation or filtration, followed by precipitation with solvents (ethanol, acetone, or isopropanol) and contaminants are removed by enzymatic or physical deproteinization [7]. Recuperation and purification of EPS has become an economical and technical challenge due to the application of unit operations such as centrifugation, sedimentation, and solvent extraction, where recoveries are reported to be not optimal [8]
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