One step selection strategy for optimization of media to enhance arachidonic acid production under solid state fermentation

An investigation into the effects of various processing methods on the characteristic compounds of highland barley using a widely targeted metabolomics approach

This study explored the influence of diverse processing methods (cooking (CO), extrusion puffing (EX), and steam explosion puffing (SE), stir-frying (SF) and fermentation (FE)) on highland barley (Qingke) chemical composition using UHPLC-MS/MS based widely targeted metabolomics. Overall, 827 metabolites were identified and categorized into 16 classes, encompassing secondary metabolites, amino acids, nucleotides, lipids, etc. There 43, 85, 131, 51 and 98 differential metabolites were respectively selected from five comparative groups (raw materials (RM) vs CO/EX/SE/SF/FE), mainly involved in amino acids, nucleotides, flavonoids, and alkaloids. Compared to other treated groups, FE group possessed the higher content of crude protein (15.12 g/100 g DW), and the relative levels of free amino acids (1.32 %), key polyphenols and arachidonic acid (0.01 %). EX group had the higher content of anthocyanins (4.22 mg/100 g DW), and the relative levels of free amino acids (2.02 %) and key polyphenols. SE group showed the higher relative levels of phenolic acids (0.14 %), flavonoids (0.20 %) and alkaloids (1.17 %), but the lowest free amino acids (0.75 %). Different processing methods all decreased Qingke's antioxidant capacity, with the iron reduction capacity (988.93 μmol/100 g DW) in SE group was the lowest. On the whole, FE and EX were alleged in improving Qingke's nutritional value. CO and SF were also suitable for Qingke processing since fewer differential metabolites were identified in CO vs RM and SF vs RM groups. Differential metabolites were connected to 14 metabolic pathways, with alanine, aspartate, and glutamate metabolism being central. This study contributed theoretical groundwork for the scientific processing and quality control of Qingke products.

Key Enzymes in Fatty Acid Synthesis Pathway for Bioactive Lipids Biosynthesis

Dietary bioactive lipids, one of the three primary nutrients, is not only essential for growth and provides nutrients and energy for life's activities but can also help to guard against disease, such as Alzheimer's and cardiovascular diseases, which further strengthen the immune system and maintain many body functions. Many microorganisms, such as yeast, algae, and marine fungi, have been widely developed for dietary bioactive lipids production. These biosynthetic processes were not limited by the climate and ground, which are also responsible for superiority of shorter periods and high conversion rate. However, the production process was also exposed to the challenges of low stability, concentration, and productivity, which was derived from the limited knowledge about the critical enzyme in the metabolic pathway. Fortunately, the development of enzymatic research methods provides powerful tools to understand the catalytic process, including site-specific mutagenesis, protein dynamic simulation, and metabolic engineering technology. Thus, we review the characteristics of critical desaturase and elongase involved in the fatty acids' synthesis metabolic pathway, which aims to not only provide extensive data for enzyme rational design and modification but also provides a more profound and comprehensive understanding of the dietary bioactive lipids' synthetic process.