Fungal endophytes enhanced the growth and production kinetics of Vinca minor hairy roots and cell suspensions grown in bioreactor

A vincamine positive hairy root clone of Vinca minor with integration of all the three- rolA, rolB and rolC genes and its subsequently raised cell suspensions were treated with culture filtrate of four endophytic fungi namely Chaetomium globosum; Aspergillus niveoglaucus; Paecilomyces lilacinus and Trichoderma harzianum. Addition of 10 % v/v T. harzianum culture filtrate boosted maximum biomass accumulation and highest total alkaloid content (TAC) both in the hairy roots and in the cell suspensions. Treated (10 % v/v T. harzianum) hairy roots registered growth index (GI) of 640 ± 28.3 and TAC of 3.6 ± 0.1 dry wt% in comparison to non-treated roots (GI = 420 ± 14.2; TAC = 3.1 ± 0.3 dry wt%). Treated cell suspensions showed GI of 600 ± 19.1 and TAC of 1.67 ± 0.03 dry wt% in comparison to non-treated cell suspensions (GI = 250 ± 12.6; TAC = 1.15 ± 0.02 dry wt%). The hairy roots and the cell suspensions were successfully up-scaled in the 5 l stirred tank bioreactor with respective GI of 850.0 and 654.0 under optimized conditions. On Real time (qPCR) analysis, treated hairy roots showed fourfold to sixfold enhanced tryptophan decarboxylase (TDC) transcript level [relative quantity value (RQ) = 4.64 ± 0.30 (shake flask); RQ = 5.95 ± 0.31 (bioreactor)] while treated cell suspensions showed only two fold increase in TDC transcript [RQ = 2.1 ± 0.26 (shake flask); RQ = 2.5 ± 0.21 (bioreactor)]. Similarly, fivefold to sixfold [RQ = 5.6 ± 0.20 (shake flask); RQ = 6.7 ± 0.49 (bioreactor)] and threefold to fourfold [RQ = 3.5 ± 0.18 (shake flask); RQ = 3.8 ± 0.68 (bioreactor)] increased transcript of strictosidine synthase (STR) in treated hairy roots and cell suspensions, respectively was observed. Treated shake flask roots showed 0.002 dry wt% vincamine that was further enhanced in the bioreactor grown treated roots (0.015 dry wt%). No vincamine was detected in the shake flask culture or in the bioreactor grown cell suspensions.