Yield enhancement of phytochemicals by Azotobacter chroococcum biotization in hairy roots of Arnebia hispidissima

Abstract

The biological nitrogen fixation is an essential process and occurs in plants by the nitrogenase activity, which exists as a complex metalloenzyme composed of two easily separable components. The hairy roots of Arnebia hispidissima were regenerated by the infection of Agrobacterium rhizogenes (ATCC 15834). These regenerated hairy roots were biotized with selected five strains of Azotobacter chroococcum. The biotization was developed for the enhancement of the yield of medicinally important alkannin and shikonin derivatives. The nitrogenase activity (96±0.381nmol C2H4 hairy root−1), fresh weight (58±0.340mghairyroot−1) and dry matter contents (21±0.349mghairyroot−1)), total nitrogen contents (24±0.635mghairyroot−1)) and concentration of phytochemicals were significantly enhanced 2–3 times more in biotized hairy roots while these contents were lower in the hairy roots of control group. The accumulation of propionylalkannin was reached its maximum peak (86±0.290mg/g fraction) at the cell density of 105CFUml−1 on the 11th day of harvesting of biotized hairy roots of A. hispidissima. The observed results provide novel approach into the application of A. chroococcum for the yield enhancement of alkannin and shikonin derivatives in hairy roots of A. hispidissima.