Abstract
BackgroundThe oleaginous microorganism Schizochytrium sp. is widely used in scientific research and commercial lipid production processes. However, low glucose-to-lipid conversion rate (GLCR) and low lipid productivity of Schizochytrium sp. restrict the feasibility of its use.ResultsOrlistat is a lipase inhibitor, which avoids triacylglycerols (TAGs) from hydrolysis by lipase. TAGs are the main storage forms of fatty acids in Schizochytrium sp. In this study, the usage of orlistat increased the GLCR by 21.88% in the middle stage of fermentation. Whereas the productivity of lipid increased 1.34 times reaching 0.73 g/L/h, the saturated fatty acid and polyunsaturated fatty acid yield increased from 21.2 and 39.1 to 34.9 and 48.5 g/L, respectively, indicating the advantages of using a lipase inhibitor in microbial lipids fermentation. Similarly, the system was also successful in Thraustochytrid Aurantiochytrium. The metabolic regulatory mechanisms stimulated by orlistat in Schizochytrium sp. were further investigated using transcriptomics and metabolomics. The results showed that orlistat redistributed carbon allocation and enhanced the energy supply when inhibiting the TAGs’ degradation pathway. Therefore, lipase in Schizochytrium sp. prefers to hydrolyze saturated fatty acid TAGs into the β-oxidation pathway.ConclusionsThis study provides a simple and effective approach to improve lipid production, and makes us understand the mechanism of lipid accumulation and decomposition in Schizochytrium sp., offering new guidance for the exploitation of oleaginous microorganisms.
Highlights
The oleaginous microorganism Schizochytrium sp. is widely used in scientific research and commercial lipid production processes
A report investigated the impact that adjusting the pH with ammonia and citric acid can increase the lipid production of Schizochytrium sp. by 27.5%, but the lipid productivity and glucose-to-lipid conversion rate (GLCR) did not improve during the middle stage of fermentation (48–96 h), which may be the cause of reaching a peak in production [9]
A recent study showed that the whole polyketide synthase (PKS) pathway from Shewanella japonica was expressed in Aurantiochytrium, resulting in a 26.9% increase in the lipid yield [12]
Summary
The oleaginous microorganism Schizochytrium sp. is widely used in scientific research and commercial lipid production processes. Low glucose-to-lipid conversion rate (GLCR) and low lipid productivity of Schizochytrium sp. Many studies have sought to improve the lipid production of the thraustochytrids through the optimization of fermentation processes. Many studies have only focused on overall lipid production while ignoring the decrease in lipid productivity in the middle and late stages of fermentation, as well as the glucose-to-lipid conversion rate (GLCR). A report investigated the impact that adjusting the pH with ammonia and citric acid can increase the lipid production of Schizochytrium sp. By 27.5%, but the lipid productivity and GLCR did not improve during the middle stage of fermentation (48–96 h), which may be the cause of reaching a peak in production [9]. The search for a simple and effective metabolic flow disturbance strategy has become the recent research priorities
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