Azospirillum brasilense Increases CO2 Fixation on Microalgae Scenedesmus obliquus, Chlorella vulgaris, and Chlamydomonas reinhardtii Cultured on High CO2 Concentrations

Abstract

Mutualism interactions of microalgae with other microorganisms are widely used in several biotechnological processes since symbiotic interaction improves biotechnological capabilities of the microorganisms involved. The interaction of the bacterium Azospirillum brasilense was assessed with three microalgae genus, Scenedesmus, Chlorella, and Chlamydomonas, during CO fixation under high CO concentrations. The results in this study have demonstrated that A. brasilense maintained a mutualistic interaction with the three microalgae assessed, supported by the metabolic exchange of indole-3-acetic acid (IAA) and tryptophan (Trp), respectively. Besides, CO fixation increased, as well as growth and cell compound accumulation, mainly carbohydrates, in each microalgae evaluated, interacting with the bacterium. Overall, these results propose the mutualism interaction of A. brasilense with microalgae for improving biotechnological processes based on microalgae as CO capture and their bio-refinery capacity.

Impact of thiamine metabolites and spent medium from Chlorella sorokiniana on metabolism in the green algae Auxenochlorella prototheciodes

“…The use of mixed cultures to promote algae growth through mutualistic interaction is an emerging research frontier in algal biotechnology [17]. Emulating natural symbioses, engineers can design processes that utilize mutually beneficial organisms with biotechnological applications.…”

Toward the Enhancement of Microalgal Metabolite Production through Microalgae–Bacteria Consortia

“…Nutritional conditions seem to modulate the interaction between these two microorganisms; in experiments when the interaction was supported by a nutrient-rich medium, production of both the signal molecules IAA and tryptophan was detected but not when this interaction began with nitrogen-free (N-free) or carbon-free (C-free) media [62]. The exchange of IAA and tryptophan between A. brasilense and the microalgae Chlorella vulgaris, Scenedesmus obliquus, and C. reinhardtii was corroborated by Choix et al [63] in experiments under different concentrations (15%, 25%, and 35%) of CO 2 . In all concentrations, the bacterium and the microalga, respectively, produced AIA and tryptophan during all the experimental time, indicating that the synthesis of this compound is not affected by high CO 2 concentrations.…”

“…For instance, the cultivation of A. brasilense with the microalgae S. obliquus, C. vulgaris, and C. reinhardtii under high CO 2 concentrations, as discussed earlier, significantly enhanced microalgal growth as well as metabolite accumulation on each microalga. The authors reported an increase of carbohydrates, proteins, and lipids under all gas mixtures evaluated [63]. Higher levels of microalgal carbohydrates have also been reported as a result of co-cultivation with bacteria.…”

“…Although high CO 2 concentrations can be detrimental to microalgal physiological activity and hence CO 2 sequestration [141], growth-promoting bacteria can play a key role in improving CO 2 capture by microalgae. As presented elsewhere, Choix et al [63] evaluated the CO 2 fixation rate of three microalgae species in co-culture with A. brasilense under different CO 2 concentrations. The results revealed that A. brasilense has the ability to mitigate the stress caused by CO 2 levels of up to 35%, improving the CO 2 fixation rate by 25-50% in S. obliquus, 46-87% in C. vulgaris, and 41-53% in C. reinhardtii.…”

Discoloration in the marine red algae Pyropia: causative factors and exploiting the biotechnological potential of a waste resource

“…and Scenedesmus sp. have attracted considerable attention recently, diverse macro-algae, commonly referred to as seaweed, can also be a useful industrial resource due to their continuously growing productivity, the increasing demand for seafood and their well-established mass cultivation and harvesting technologies in the nonarable coastal ocean over the past hundred years (Chennubhotla et al 1987;Buchholz et al 2012;Leupold et al 2013;Angus 2017;Buschmann et al 2017;Choix et al 2018).…”