Abstract
Microbial lipids called a sustainable alternative to traditional vegetable oils invariably capture the attention of researchers. In this study, the effect of limiting inorganic phosphorus (KH2PO4) and nitrogen ((NH4)2SO4) sources in lipid-rich culture medium on the efficiency of cellular lipid biosynthesis by Y. lipolytica yeast has been investigated. In batch cultures, the carbon source was rapeseed waste post-frying oil (50 g/dm3). A significant relationship between the concentration of KH2PO4 and the amount of lipids accumulated has been revealed. In the shake-flask cultures, storage lipid yield was correlated with lower doses of phosphorus source in the medium. In bioreactor culture in mineral medium with (g/dm3) 3.0 KH2PO4 and 3.0 (NH4)2SO4, the cellular lipid yield was 47.5% (w/w). Simultaneous limitation of both phosphorus and nitrogen sources promoted lipid accumulation in cells, but at the same time created unfavorable conditions for biomass growth (0.78 gd.m./dm3). Increased phosphorus availability with limited cellular access to nitrogen resulted in higher biomass yields (7.45 gd.m./dm3) than phosphorus limitation in a nitrogen-rich medium (4.56 gd.m./dm3), with comparable lipid yields (30% and 32%). Regardless of the medium composition, the yeast preferentially accumulated oleic and linoleic acids as well as linolenic acid up to 8.89%. Further, it is crucial to determine the correlation between N/P molar ratios, biomass growth and efficient lipid accumulation. In particular, considering the contribution of phosphorus as a component of coenzymes in many metabolic pathways, including lipid biosynthesis and respiration processes, its importance as a factor in the cultivation of the oleaginous microorganisms was highlighted.
Highlights
Among oleaginous microorganisms capable of accumulating lipids exceeding 20% of cell dry weight, the species Yarrowia lipolytica stands out as a model organism [1]
The results of the current research suggestmay thatfurther nitrogen limitation culture is crucial, but additional phosphorus limitation improve the in culture media is crucial, but additional phosphorus limitation may further improve efficiency of microbial lipid biosynthesis
Knowledge, phosphorus is a component of the culture which to becurrent investigated in relation to the is a component of the culture medium, which still needs to be investigated in relation to the optimal level of its limitation in media stimulating Single cell oil (SCO) biosynthesis
Summary
Among oleaginous microorganisms capable of accumulating lipids exceeding 20% of cell dry weight, the species Yarrowia lipolytica stands out as a model organism [1]. Considering well-studied metabolism, fully sequenced genome and secretion capabilities that provide opportunities to obtain new microbial products previously obtained through other routes, they have become a model for oleaginous species in many basics and applications studies [2,3,4,5,6]. Single cell oil (SCO) extracted from cells of oleaginous microorganisms is promising for food technology and nutrition notably due to its content of polyunsaturated fatty acids. Microbial lipids may increase the nutritional value of the final product enriched with these components, being at the same time a potential substitute for vegetable lipids, e.g., palm oil, cocoa butter and other fatty acids of industrial importance [7,8]
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