Neochloris oleoabundans was described as a freshwater unicellular green microalga; however, some literature suggested that it was an edaphic and halotolerant alga. Neochloris oleoabundans was studied so far for its high lipid content, especially under nitrogen starvation, for possible industrial applications. Information on the morphophysiological characteristics of the alga and its photosynthetic apparatus in different culture conditions still remained incomplete. In the present work, its growth was compared using low-salinity and brackish media with increasing nitrogen supply. The morphophysiological aspects, with a special attention on its photosynthetic apparatus, were analysed through light and transmission electron microscopy, photosynthetic pigment quantification, PSII maximum quantum yield measurements and evaluations of the chlorophyll-protein assembly state. In contrast to what has been reported in previous work on the positive effect of nitrate on N. oleobundans growth, we found negative or negligible effects in our samples cultivated in low-salinity or brackish media, respectively. Brackish conditions induced a better growth of the alga, which showed some morphological variations (cell volume enlargement, cell wall thickening, increased stromatic starch and polyphosphate grains). Furthermore, brackish cultured algae were characterized by a strong increase in cellular chlorophylls and carotenoids. Fluorimetric analyses pointed to the absence of disturbance to the photosynthetic apparatus and to a higher photosynthetic efficiency in brackish cultured samples with respect to controls in the low-salinity medium, indicating a somehow better photosynthetic performance. Interestingly, the behaviour of the F680/F685+694 ratio pointed to a possible positive correlation between nitrogen supply and PSII core stability. On the whole, morphological, biochemical and biophysical results confirmed the higher acclimatized growth of N. oleoabundans in brackish media, which seem more suitable for algal growth than low-salinity ones.
Salinity promotes growth of freshwater Neochloris oleoabundans UTEX 1185 (Sphaeropleales, Chlorophyta): morphophysiological aspects
BALDISSEROTTO, Costanza;FERRONI, Lorenzo;GIOVANARDI, Martina;BOCCALETTI, Luca;PANTALEONI, Laura;PANCALDI, Simonetta
2012
Abstract
Neochloris oleoabundans was described as a freshwater unicellular green microalga; however, some literature suggested that it was an edaphic and halotolerant alga. Neochloris oleoabundans was studied so far for its high lipid content, especially under nitrogen starvation, for possible industrial applications. Information on the morphophysiological characteristics of the alga and its photosynthetic apparatus in different culture conditions still remained incomplete. In the present work, its growth was compared using low-salinity and brackish media with increasing nitrogen supply. The morphophysiological aspects, with a special attention on its photosynthetic apparatus, were analysed through light and transmission electron microscopy, photosynthetic pigment quantification, PSII maximum quantum yield measurements and evaluations of the chlorophyll-protein assembly state. In contrast to what has been reported in previous work on the positive effect of nitrate on N. oleobundans growth, we found negative or negligible effects in our samples cultivated in low-salinity or brackish media, respectively. Brackish conditions induced a better growth of the alga, which showed some morphological variations (cell volume enlargement, cell wall thickening, increased stromatic starch and polyphosphate grains). Furthermore, brackish cultured algae were characterized by a strong increase in cellular chlorophylls and carotenoids. Fluorimetric analyses pointed to the absence of disturbance to the photosynthetic apparatus and to a higher photosynthetic efficiency in brackish cultured samples with respect to controls in the low-salinity medium, indicating a somehow better photosynthetic performance. Interestingly, the behaviour of the F680/F685+694 ratio pointed to a possible positive correlation between nitrogen supply and PSII core stability. On the whole, morphological, biochemical and biophysical results confirmed the higher acclimatized growth of N. oleoabundans in brackish media, which seem more suitable for algal growth than low-salinity ones.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
