Squalene production under oxygen limitation by Schizochytrium sp. S31 in different cultivation systems

authored by
Lina Schütte, Patrick G. Hanisch, Nina Scheler, Katharina C. Haböck, Robert Huber, Franziska Ersoy, Ralf G. Berger
Abstract

Abstract: The triterpene squalene is widely used in the food, cosmetics and pharmaceutical industries due to its antioxidant, antistatic and anti-carcinogenic properties. It is usually obtained from the liver of deep sea sharks, which are facing extinction. Alternative production organisms are marine protists from the family Thraustochytriaceae, which produce and store large quantities of various lipids. Squalene accumulation in thraustochytrids is complex, as it is an intermediate in sterol biosynthesis. Its conversion to squalene 2,3-epoxide is the first step in sterol synthesis and is heavily oxygen dependent. Hence, the oxygen supply during cultivation was investigated in our study. In shake flask cultivations, a reduced oxygen supply led to increased squalene and decreased sterol contents and yields. Oxygen-limited conditions were applied to bioreactor scale, where squalene accumulation and growth of Schizochytrium sp. S31 was determined in batch, fed-batch and continuous cultivation. The highest dry matter (32.03 g/L) was obtained during fed-batch cultivation, whereas batch cultivation yielded the highest biomass productivity (0.2 g/L*h−1). Squalene accumulation benefited from keeping the microorganisms in the growth phase. Therefore, the highest squalene content of 39.67 ± 1.34 mg/g was achieved by continuous cultivation (D = 0.025 h−1) and the highest squalene yield of 1131 mg/L during fed-batch cultivation. Volumetric and specific squalene productivity both reached maxima in the continuous cultivation at D = 0.025 h−1 (6.94 ± 0.27 mg/L*h−1 and 1.00 ± 0.03 mg/g*h−1, respectively). Thus, the choice of a suitable cultivation method under oxygen-limiting conditions depends heavily on the process requirements. Key points: • Measurements of respiratory activity and backscatter light of thraustochytrids • Oxygen limitation increased squalene accumulation in Schizochytrium sp. S31 • Comparison of different cultivation methods under oxygen-limiting conditions.

Organisation(s)
Institute of Food Chemistry
External Organisation(s)
University of Applied Sciences München
Type
Article
Journal
Applied Microbiology and Biotechnology
Volume
108
No. of pages
12
ISSN
0175-7598
Publication date
13.02.2024
Publication status
Published
Peer reviewed
Yes
ASJC Scopus subject areas
Biotechnology, Applied Microbiology and Biotechnology
Sustainable Development Goals
SDG 14 - Life Below Water
Electronic version(s)
https://doi.org/10.1007/s00253-024-13051-3 (Access: Open)