Proteomic Analysis of the Chlorophyta Dunaliella New Strain AL-1 Revealed Global Changes of Metabolism during High Carotenoid Production

Abstract

The green microalgae Dunaliella genus is known for the production of high added value molecules. In this study, strain AL-1 was isolated from the Sebkha of Sidi El Hani (Sousse, Tunisia). This isolate was identified both morphologically and genetically via 18S rRNA gene sequence as a member of the genus Dunaliella. Strain AL-1 was found to be closely related to Dunaliella salina, Dunaliella quartolecta and Dunaliella polymorpha with more than 97% similarity. Response surface methodology was used to maximize carotenoid production by strain AL-1 by optimizing its growth conditions. The highest carotenoid content was obtained at salinity: 51, light intensity: 189.89 μmol photons·m−2·s−1, and nitrogen: 60 mg·L−1. Proteomic profiling, using two-dimensional gel electrophoresis, was performed from standard and optimized cultures. We detected 127 protein spots which were significantly differentially expressed between standard and optimized cultures. Among them 16 protein spots were identified with mass spectrometry and grouped into different functional categories using KEGG (Kyoto Encyclopedia of Genes and Genomes) such as photosynthetic Calvin cycle, regulation/defense, energy metabolism, glycolysis, and cellular processes. The current study could be of great interest in providing information on the effect of stressful conditions in microalgae carotenoid production.

Carotenoids Overproduction in Dunaliella Sp.: Transcriptional Changes and New Insights through Lycopene β Cyclase Regulation

“…Lv et al in 2016 [21] studied the effect of nutrition depletion on carotenoid production that increased from approximately 2 pg/cell in complete medium to 9 pg/cell in nitrogen-depleted medium on day 15. This observation is in agreement with a previous study showing that the limitation of nitrogen availability accompanied by an increase of salinity and light intensity induced carotenoid accumulation [34]. The increase of salinity engenders also an increase in glycerol and polysaccharide synthesis accompanied by starch degradation [57][58][59].…”

“…During these first three days of stress, the level of its mRNA was significantly less expressed in stressed condition than in unstressed one after 72 h of stress. Similarly, but at the proteomic level, the amount of this enzyme was also decreased among Dunaliella under stress [34] and among Nannochloropsis oceanica under nitrogen deprivation [76]. This means that the photosynthetic efficiency is affected by nitrogen amount [76], but, at the same time, the down-regulation of this enzyme allows the accumulation of xylulose-5P, which probably would serve as a substrate for G3P production in the pentose phosphate cycle [34].…”

“…Dunaliella sp. was isolated from the Sebkha of Sidi El Hani (Sousse, Tunisia), having 97% of similarity with D. salina, D. quartolecta, and D. polymorpha [34]. It was cultivated in the F/2 medium [35] based on artificial seawater (ASW).…”

Effect of Microalgae Incorporation on Quality Characteristics and Functional and Antioxidant Capacities of Ready-to-Eat Fish Burgers Made from Common Carp (Cyprinus carpio)

“…Microalgae have been exploited worldwide, with the principal genera used for functional and nutritional food being Arthrospira, Isochrysis, Picochlorum, and Chlorella [6][7][8]. These microalgae are rich in polyunsaturated fatty acids, phytosterols, heat-induced proteins, phenolic compounds, pigments, and sulfated polysaccharides [9,10].…”

Deciphering the Biological Activities of Dunaliella sp. Aqueous Extract from Stressed Conditions on Breast Cancer: from in Vitro to in Vivo Investigations

“…This study was performed with an isolated Dunaliella sp. strain from the Tunisian coast identified to have 97% of similarity with Dunaliella salina [40]. Dunaliella salina is known for its high production of antioxidants, mainly β-carotene, which leads to its anticancer activity [4,5,[12][13][14][15][16][17].…”