Enhancing Red Yeast Biomass Yield and Lipid Biosynthesis by Using Waste Nitrogen Source by Glucose Fed-Batch at Low Temperature

Abstract

This work reports the effect of simple feeding strategies and temperature to obtain high-cell-density cultures of Rhodotorula glutinis var. rubescens LOCKR13 maximizing the de novo lipid productivity using deproteinated potato wastewater (DPW) as a basic medium. Feeding DPW with glucose enables a high yield of Rhodotorula glutinis var. rubescens LOCKR13 biomass (52 g d.w. L−1) to be obtained. The highest values of lipid accumulation (34.15%, w/w), production (14.68 g L−1) and yield coefficients (YL/S: 0.242 g g−1), and volumetric productivity (PL: 0.1 g L−1 h−1) were reached by the strain in the two-stage fed-batch process at 20 °C. The lipid of yeast biomass was rich in oleic acid (Δ9C18:1) and palmitic acid (C16:0), and the lower temperature of incubation significantly increased the MUFA (especially oleic acid) content. For the first time, a unique set of thermal analyses of the microbial oil was performed. The isotherms of the oxidation kinetics (PDSC) showed that lipids extracted from the biomass of red yeast had high oxidative stability. This feature of the yeast oil can be useful for long-shelf-life food products and can be promising for the production of biodiesel.

The Thermal Properties and Nutritional Value of Biomass of Oleaginous Yeast Rhodotorula sp. during Glucose Fed-Batch Cultivation in Medium with Waste Nitrogen

“…The parameters of cultivation in the BioFlo 3000 bioreactor (New Brunswick Scientific Co., Edison, NJ, USA) were as follows: working volume; 3 L; temperature, 20 • C; stirring, 200 rpm; and air rate, 2 v/v/min. As previously described, a medium with deproteinated potato wastewater and glucose was prepared [10]. As antifoaming agent silicone (Antifoam 204, Sigma-Aldrich, Burlington, MA, USA) was used after 72 h of daily operation, and a sterile glucose solution (1:1) was added to the total concentration of glucose, which was 50 g L −1 .…”

“…Previous research showed that strain Rhodotorula glutinis var. rubescens can grow efficiently (biomass yield 39.52 g L −1 ) in deproteinated potato wastewater and glucose medium [8], and after fed-batch cultivation, the content of lipids in biomass exceed >34% d.w. [10]. Except for accumulated fat in intracellular lipid droplets, the cells are also rich in proteins, carbohydrates, and carotenoids [11].…”

“…The temperature influences the phase transitions and chemical reactions, so the thermal properties of biomass are valuable for processing. Differential scanning calorimetry (DSC) can be used to determine qualitative parameters, as well as the parameters of certain types of phase transitions (e.g., melting and crystallization) and oxidative stability of lipid-rich samples [10,12]. Regardless of the next technological steps after the cultivation of red yeast, the quantitative and qualitative characteristics of biomass components are necessary for the prediction of the nutritional properties.…”