The traditional biochemical methods for analyzing cellular composition of oleaginous microorganisms are time-consuming, polluting, and expensive. In the present study, an FT-IR method was used to analyze the cellular composition of the marine oleaginous protistAurantiochytriumsp. during various research processes, such as strains screening, medium optimization, and fermentation, and was evaluated as a green, low-cost, high throughput, and accurate method compared with the traditional methods. A total of 109Aurantiochytriumsp. strains were screened for lipid and carbohydrate production and the best results were found for the strains No. 6 and No. 32. The yields and productivities could reach up to 47.2 g/L and 0.72 g/L/h for lipid, 21.6 g/L and 0.33 g/L/h for docosahexaenoic acid (DHA) in the strain No. 6, and 15.4 g/L and 0.18 g/L/h for carbohydrate in the strain No. 32, under the optimal conditions, respectively. These results confirmed potentials of the twoAurantiochytriumsp. strains for lipid, DHA, and carbohydrate productions at industrial scales. The FT-IR method in this study will facilitate research on the oleaginousAurantiochytriumsp., and the obtained two strains for lipid and carbohydrate productions will provide the foundations for their applications in medical, food, and feed industries.Keywords:Aurantiochytriumsp., carbohydrate;DHA;feed;FT-IR;high-throughput
Dong-Sheng Wang,Xin-Jun Yu,Xiao-Yu Zhu,Zhao Wang,Hui-Juan Li,Zhi-Peng Wang
In the current study, corn steep liquor (CSL) is evaluated as an ideal raw agro-material for efficient lipid and docosahexaenoic acid DHA production byAurantiochytriumsp. Low CSL level in medium (nitrogen deficiency) stimulated the biosynthesis of lipids and DHA while inhibiting cellular growth. The transcriptomic profiles of theAurantiochytriumsp. cells are analyzed and compared when cultured under high (H group), normal (N group), and low (L group) levels of CSL in the medium. The discriminated transcriptomic profiles from the three groups indicates that changes in CSL level in medium result in a global change in transcriptome ofAurantiochytriumsp. The overall de novo assembly of cDNA sequence data generated 61,163 unigenes, and 18,129 of them were annotated in at least one database. A total of 5105 differently expressed (DE) genes were found in the N group versus the H group, with 2218 downregulated and 2887 upregulated. A total of 3625 DE genes were found in the N group versus the L group, with 1904 downregulated and 1721 upregulated. The analysis and categorization of the DE genes indicates that the regulation mechanism of CSL involved in the perception and transduction of the limited nitrogen signal, the interactions between the transcription factors (TFs) and multiple downstream genes, and the variations in downstream genes and metabolites, in sequence, are illuminated for the first time in the current study.Keywords:Aurantiochytriumsp.;nitrogen-deficiency;RNA-seq;corn steep liquor (CSL);signal transduction;DHA
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