Isolation, identification, and analysis of growth influencing factors of a Dunaliella pseudosalina strain from Zabuye Salt Lake

Abstract:

[Background] With rich metabolites and unique physiological properties, Dunaliella has wide applications in the pharmaceutical, food, aquaculture, chemical, and light industries. [Objective] To analyze the factors affecting the biomass of Dunaliella and the optimal culture conditions with a view to increasing the biomass of Dunaliella and identify the secondary metabolites of Dunaliella under the optimal culture conditions. [Methods] D. pseudosalina ZBY-1 was isolated by the culture method and identified by 18S rRNA gene sequencing. The growth conditions (nutrients and concentrations) were optimized by single factor and orthogonal experiments. The secondary metabolites of strain ZBY-1 cultured under the optimal conditions were then analyzed by LC-MS. [Results] The strain ZBY-1 showcased the best growth performance at 10% NaCl, pH 8.5, and 25 ℃. The optimal carbon, nitrogen, and phosphorus sources and their concentrations for this strain were NaHCO₃ 1.26 g/L, CO(NH₂)₂ 0.84 g/L, and NaH₂PO₄ 0.06 g/L, respectively. The cell density of strain ZBY-1 cultured under the optimal conditions reached (2.57±0.12)×10⁷ cells/mL, which increased by 1.25 times compared with that before optimization. LC-MS results showed that secondary metabolites were mainly terpenoids, alkaloids, phenylpropanoids, and amino acid-related compounds. The enriched metabolite pathways were the cofactor biosynthesis pathway, plant-derived metabolite biosynthesis pathway, and the ABC transport pathway. [Conclusion] Zabuye Salt Lake has a special geographical location, whereas the algal resources remain to be exploited. The isolated strain ZBY-1 can adapt to the high saline-alkali environments, which provide a basis for subsequent development and application of the metabolites of this strain.