title: Re-cultivation of Neochloris oleoabundans in exhausted autotrophic and mixotrophic media: the potential role of polyamines and free fatty acids.
abstract: Neochloris oleoabundans (Chlorophyta) is widely considered one of the most promising microalgae for biotechnological applications. However, the large-scale production of microalgae requires large amounts of water. In this perspective, the possibility of using exhausted growth media for the re-cultivation of N. oleoabundans was investigated in order to simultaneously make the cultivation more economically feasible and environmentally sustainable. Experiments were performed by testing the following media: autotrophic exhausted medium (E+) and mixotrophic exhausted medium after cultivation with glucose (EG+) of N. oleoabundans cells grown in a 20-L photobioreactor (PBR). Both exhausted media were replenished with the same amounts of nitrate and phosphate as the control brackish medium (C). Growth kinetics, nitrate and phosphate consumption, photosynthetic pigments content, photosynthetic efficiency, cell morphology, and lipid production were evaluated. Moreover, the free fatty acid (FFA) composition of exhausted media and the polyamine (PA) concentrations of both algae and media were analyzed in order to test if some molecules, released into the medium, could influence algal growth and metabolism. Results showed that N. oleoabundans can efficiently grow in both exhausted media, if appropriately replenished with the main nutrients (E+ and EG+), especially in E+ and to the same extent as in C medium. Growth promotion of N. oleoabundans was attributed to PAs and alteration of the photosynthetic apparatus to FFAs. Taken together, results show that recycling growth medium is a suitable solution to obtain good N. oleoabundans biomass concentrations, while providing a more sustainable ecological impact on water resources.
authors: Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
authors: Alessandra
authors: A
authors: Sabia
authors: Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
authors: Costanza
authors: C
authors: Baldisserotto
authors: Department of Biological, Geological and Environmental Sciences, University of Bologna, via Irnerio 42, 40126, Bologna, Italy.
authors: Stefania
authors: S
authors: Biondi
authors: Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
authors: Roberta
authors: R
authors: Marchesini
authors: Department of Chemical and Pharmaceutical Science, University of Ferrara, via Fossato di Mortara 17, 44121, Ferrara, Italy.
authors: Paola
authors: P
authors: Tedeschi
authors: Department of Chemical and Pharmaceutical Science, University of Ferrara, via Fossato di Mortara 17, 44121, Ferrara, Italy.
authors: Annalisa
authors: A
authors: Maietti
authors: Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
authors: Martina
authors: M
authors: Giovanardi
authors: Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy.
authors: Lorenzo
authors: L
authors: Ferroni
authors: Department of Life Sciences and Biotechnology, University of Ferrara, Corso Ercole I d'Este 32, 44121, Ferrara, Italy. simonetta.pancaldi@unife.it.
authors: Simonetta
authors: S
authors: Pancaldi
mesh_terms: D000460:Chlorophyta / Q000254:growth & development* / Q000378:metabolism*; D003470:Culture Media / Q000737:chemistry*; D005230:Fatty Acids, Nonesterified / Q000032:analysis*; D011073:Polyamines / Q000032:analysis*
chemical_list: D003470:Culture Media; D005230:Fatty Acids, Nonesterified; D011073:Polyamines
keywords: Biomass production; Free fatty acids; Neochloris oleoabundans; Photosynthetic apparatus; Polyamines; Recycling culture media