Phytohormone Supplementation Significantly Increases Growth of Chlamydomonas reinhardtii Cultivated for Biodiesel Production

Abstract

Cultivation is the most expensive step in the production of biodiesel from microalgae, and substantial research has been devoted to developing more cost-effective cultivation methods. Plant hormones (phytohormones) are chemical messengers that regulate various aspects of growth and development and are typically active at very low concentrations. In this study, we investigated the effect of different phytohormones on microalgal growth and biodiesel production in Chlamydomonas reinhardtii and their potential to lower the overall cost of commercial biofuel production. The results indicated that all five of the tested phytohormones (indole-3-acetic acid, gibberellic acid, kinetin, 1-triacontanol, and abscisic acid) promoted microalgal growth. In particular, hormone treatment increased biomass production by 54 to 69 % relative to the control growth medium (Tris-acetate-phosphate, TAP). Phytohormone treatments also affected microalgal cell morphology but had no effect on the yields of fatty acid methyl esters (FAMEs) as a percent of biomass. We also tested the effect of these phytohormones on microalgal growth in nitrogen-limited media by supplementation in the early stationary phase. Maximum cell densities after addition of phytohormones were higher than in TAP medium, even when the nitrogen source was reduced to 40 % of that in TAP medium. Taken together, our results indicate that phytohormones significantly increased microalgal growth, particularly in nitrogen-limited media, and have potential for use in the development of efficient microalgal cultivation for biofuel production.

The Effects of Plant Growth Regulators on Cell Growth, Protein, Carotenoid, PUFAs and Lipid Production of Chlorella pyrenoidosa ZF Strain

“…Earlier study reported ABA functioned as a stress molecule in cyanobacteria under salt stress [53] and under salt, osmotic, oxidative, drought and nutrient stresses in unicellular eukaryotic algae [54][55][56][57][58]. The superiority of ABA in promoting lipid biosynthesis was also reported by Park et al [27], where ABA-treatment favored energy storage in the form of either starch or lipid. However, ABA had little effect on algal growth in our results.…”

Stimulatory effect of indole-3-acetic acid and continuous illumination on the growth of Parachlorella kessleri

“…The biomass productivity of P. kessleri obtained for the concentration of 10 -5 M IAA was 0.83 and 0.63 g l -1 , respectively, for the photoperiod and continuous illumination. Park et al (2014) examined the effect of various concentrations of IAA on biomass production in Chlamydomonas reinhardtii. They reported that the ca.…”

“…Exogenous auxin increases the growth rate of algae such as Chlorella vulgaris, Chlorella sorokiniana, Chlamydomonas reinhardtii, Haematococcus pluvialis, Pleurochrysis carterae, and Phaeodactylum tricornutum (Lu and Xu, 2015;Park et al, 2014;Piotrowska-Niczyporuk and Bajguz, 2014).…”

Seaweed reproductive biology: environmental and genetic controls

“…Many of the signaling pathway components are not present in basal early-diverging lineages of the Streptophyta and/or other algal lineages (De Smet et al 2010, Lu andMori et al 2017) making it less likely that a phytohormone function could have been inherited from a common unicellular ancestor. Nonetheless, evidence for phytohormone function in unicellular algae is beginning to accumulate, such as the role of abscisic acid and auxins in regulation of growth in unicellular green algae and diatoms ( Kobayashi et al 1997, Yoshida et al 2004, Park et al 2013, Lu et al 2014, Amin et al 2015. This is consistent with the hypothesis that hormones such as auxin might have served initially as growth-regulating hormones or pheromones in unicellular ancestors predating the advent of multicellularity (Cooke et al 2002, Bogaert et al 2013).…”