AZOSPIRILLUM BALDANIORIUM SP245 IMPROVES MICROALGAL ACCLIMATION, LIPID PRODUCTIVITY AND OXIDATIVE RESPONSE UNDER SALT STRESS.

PAGNUSSAT, L.A.; DO NASCIMIETO M; MARONICHE G ; GONORAZKY GABRIELA; SANCHEZ RIZZA L; CREUS CECILIA; CURATTI LEONARDO

Los Cocos

Congreso; SAMIGE 2022; 2022

There is a growing interest in using microalgae for several purposes, as pharmaceutical applications, wastewater treatment and biomass as a feedstock for biofuels and feed/food supplements. With the exception of a few continental regions of the world around the Tropics, algal biomass productivity is usually constrained by seasonal environmental conditions from sub-optimal to adverse in most of the world. Although under nutritional or salt stress, most microalgae tend to accumulate lipids and/or carbohydrates in their biomass, this effect does not compensate for the decrease in cell proliferation, and the productivity of these macromolecules remains diminished. Salt acclimation is common in plant cells, where previous salinity exposure induces protective mechanisms and confers tolerance against future salinity exposure. Here we show that the plant growth-promoting bacterium Azospirillum baldaniorum Sp245 ammeliorates the sharp salinity-induced inhibition of algal growth This Azospirillum-dependent early acclimation enabled an increase in both final biomass and lipid yields. Accordingly, stress responsive parameters as SH groups, chlorophyll and carotenoids levels in salt-treated microalgae are also augmented, while microalgae inoculated with Azospirillum did not accumulate this stress related molecules. Inoculation with Azospirillum strains genetically modified to produce contrasting levels of IAA, suggested that although under non-stress conditions most of the algal growth promotion appears to be AIA-dependent, under salt stress other still-unidentified factor(s) may play a more prominent role. The existing understanding of the mechanisms underpinning bacterial-microalgal consortia is deepened by this study, improving our awareness of these ecological connections in the environment and broadening their biotechnological applications.