Simultaneous production of high-value lipids in Schizochytrium sp. by synergism of chemical modulators

The study focuses on the simultaneous improvement of biomass, lipid, and docosahexaenoic acid (DHA) productivities in a single reactor using modulator control strategies. The efficacy of three different biochemical modulators, sesamol (Ses), 6-benzylaminopurine (6-BAP), and ethylenediaminetetraacetic acid (EDTA), as potential stimulants in augmenting the biomass, lipid, and DHA production of Schizochytrium sp. MTCC 5890 was elucidated. After 48 h of cultivation, among tested modulators, the individual supplementation of 6-BAP and Ses showed improvement in biomass, lipid, and DHA accumulation by 28.2%, 56.1%, and 87.2% and 21.7%, 47.9%, and 91%, respectively, over the non-supplemented group. In addition, the cooperative effect of selected concentrations, i.e., 10 mgL −1 6-BAP and 200 mgL −1 Ses, further increased the productivities of biomass of 13.5 gL −1 d −1 ± 0.66, lipid of 7.4 gL −1 d −1 ± 0.69, and DHA of 3.2 gL −1 d −1 ± 1.09 representing 8%, 39%, and 69% increase over the individual addition of 6-BAP or Ses, respectively, in batch culture. Supplementation with 6-BAP + Ses at 12 h of time point eventually increased the lipid yield to 15.6 ± 0.42 gL −1 from 7.88 ± 0.31 gL −1 (control) and DHA yield to 6.4 ± 0.11 gL −1 from 2.23 ± 0.09 gL −1 (control), respectively. Furthermore, the process was optimized in continuous culture supplemented with 6-BAP + Ses for enhanced productivities. Continuous culture resulted in maximum biomass (2.04 ± 1.12 gL −1 day −1 ), lipid (1.0 ± 0.73 gL −1 day −1 ), and DHA (0.386 ± 0.22 gL −1 day −1 ) productivities, which were higher as compared with the batch and fed-batch processes by 26 ± 1.21%, 22 ± 1.01%, and 21 ± 0.98% and 24 ± 0.45%, 16 ± 0.38%, and 14 ± 0.12%, respectively. This work represents the potential application of the combined effect of modulators for the simultaneous enhancement of biomass production and lipid and DHA productivities. Key points • The cumulative study of 6-BAP and sesamol proved to be more efficient in the simultaneous production of biomass, lipid, and DHA in a single reactor. • Addition of a combination of 6-BAP + Ses remarkably increased the biomass, lipid, and DHA productivities in tandem in continuous culture. Graphical abstract