The enhanced production and secretion of high-value cajaninstilbene acid and flavonoid aglycones in Cajanus cajan (Linn.) Millsp. cell suspension cultures elicited by Aspergillus oryzae Y-29

Abstract

For the first time, Cajanus cajan cell suspension cultures (CCSCs) were elicited by living GRAS (Generally Recognized as Safe) fungi to enhance the production of bioactive phenolic compounds. Under the inoculum size of mycelia (0.5 %), the optimal fungus Aspergillus oryzae Y-29 (AO Y-29) could achieve the enhanced production of cajaninstilbene acid (5.79-fold increase) in 49-day-old CCSCs at 8 h. Also, AO Y-29 could promote the production of flavonoid aglycones including luteolin (2.25-fold increase), genistein (2.04-fold increase), apigenin (1.96-fold increase), isorhamnetin (1.43-fold increase), and biochanin A (6.48-fold increase) in CCSCs at 12 h. Moreover, the levels of genistein and cajaninstilbene acid in culture media after fungal elicitation increased by 3.58- and 18.02-fold over control, respectively. AO Y-29 mycelia was found to trigger the oxidative stress thus activating the expression of pathogenesis-, biosynthesis-, and ABC transport-related genes, which contributed to the accumulation and secretion of flavonoid aglycones and cajaninstilbene acid in CCSCs. Furthermore, ABCB11 was likely to be correlated with the transport of genistein and cajaninstilbene acid, which was important for systematic metabolic engineering to increase their productivity. Overall, the elicitation of CCSCs with AO Y-29 was attractive for obtaining high yields of valuable flavonoid aglycones and cajaninstilbene acid in pharmaceutical/nutraceutical fields.