The Growth, Lipid Accumulation and Fatty Acid Profile Analysis by Abscisic Acid and Indol-3-Acetic Acid Induced in Chlorella sp. FACHB-8

Abstract

Microalgae are considered a promising source for biodiesel. The addition of plant hormone can exert a significant impact on the production of microalgae biomass and lipid accumulation. Nevertheless, the response of microalgae cells to hormones is species- or strain-dependent. It remains controversial which genes involved in strong increase of fatty acids production in response to abscisic acid (ABA) in Chlorella sp. FACHB-8 strain. We investigated cell growth, lipid accumulation, and fatty acid composition when ABA and indol-3-acetic acid (IAA) were used in the growth medium of Chlorella sp. FACHB-8. The four treatments, including 5 mg/L IAA (E1), 10 mg/L IAA (E2), 10 mg/L ABA (E3), the combination of 5 mg/L IAA and 5 mg/L ABA (E4), were found to increase cell growth, but only 10 mg/L ABA treatment could enhance the lipid accumulation. The fatty acid profile was changed by the addition of ABA, making fatty acids afflux from polyunsaturated fatty acids to monounsaturated and saturated fatty acids, which were suitable for diesel application. Furthermore, a transcriptome analysis was conducted, unraveling the differentially expressed genes enriched in fatty acid biosynthesis, fatty acid metabolism, and biosynthesis of the unsaturated fatty acid pathway in response to ABA. Our results clarified the correlation of fatty acid synthesis-related genes and fatty acid profiles, helping understand the potential response mechanism of Chlorella sp. FACHB-8 strain respond to ABA treatment.

Effect of Abscisic Acid on Growth, Fatty Acid Profile, and Pigment Composition of the Chlorophyte Chlorella (Chromochloris) zofingiensis and Its Co-Culture Microbiome

“…Fiery et al [ 66 ] examined low ABA concentrations of 0.5 to 5 µM, which are close to the most effective ABA concentration of ABA in our study, and observed a weak induction of ABA on biomass yield of Phaeodactylum tricornutum and no effect on Stauroneis sp and Nitzschia sp. Contrary to some works on different Chlorella species [ 15 , 70 , 74 ], no effect on growth parameters of C. vulgaris was observed [ 75 ] when comparable to our range ABA concentrations were applied. Most likely, this outstanding result occurred because ABA was applied on day 20 of the population growth (early stationary phase), highlighting the importance of the hormone application in the exponential phase of growth or even in the lag phase.…”

“…The effect of ABA on distribution of different FA classes in C. zofingiensis cells appeared to have some discrepancies with the previously reported data. Lin et al [ 74 ] observed a substantial increase in the percentage of MUFA, no effect on SFA, and a clear decline in the percentage of PUFA on the 10th day of their experiment when Chlorella sp. was exposed to an ABA range similar to ours.…”

“…Yet, some discrepancies have been observed in the reports, as well as between the present study and our previous investigation. A recent study [ 74 ] demonstrated statistically significant but weak induction of Chlorella sp. population growth (1.2-fold increase at maximum) when 38 µM ABA was applied to the growth medium.…”

Integrated Omics Approach to Discover Differences in the Metabolism of a New Tibetan Desmodesmus sp. in Two Types of Sewage Treatments

“…In the treatment of heavy metal wastewater, ABA-GE is catalyzed by b-glucosidase to form ABA, counteracting the effects of heavy metal salt stress. The biosynthesis of ABA-GE, amino acids, and 2-OBA are the most significant metabolic paths in microalgae when used to treat heavy metal wastewater under the stress of heavy metals, compared with processing municipal sewage [ 57 , 58 ].…”

Biotechnological Approaches for Biomass and Lipid Production Using Microalgae Chlorella and Its Future Perspectives

“…Abscisic acid (ABA) treatment enhanced the lipid accumulation in Chlorella sp. FACHB-8 strain, changing fatty acids afflux from polyunsaturated fatty acids to monounsaturated and saturated fatty acids, which were suitable for diesel application [ 126 ]. Pyrene (polycyclic aromatic hydrocarbon) is an anthropogenic organic pollutant in various ecological units.…”