Isolation, cultivation of freshwater chlorophyta and screening of the synthesized bioactive compounds and phytohormone

Microalgae are aquatic biochemically diverse assemblage of microorganisms found in both fresh and marine systems, are capable of photosynthesis, and grow as individual cells, chains, or colonies. The scientific research community is concentrating on isolating and extracting primary and secondary metabolites produced by these organisms. The current study aimed to isolate freshwater microalgal strains, determine their growth rates and screen their bioactive compounds to assess their suitability for different applications especially biofertilizer. By applying this methodology, freshwater microalga Chlorella vulgaris, Tetradesmus dimorphus, and Kirchneriella aparta were isolated and cultivated on Bold Basal Media (BBM). Isolated microalgae exhibited different growth rates, recording 0.45, 0.53, and 0.26, respectively. They have also produced some significant bioactive molecules such as lipids, forming 4.87, 4.71, and 6.59 % from their dry weight, respectively, while carbohydrates content per dry weight percentages equal 14.75, 45.80, and 25.46 %, respectively, and proteins 43.73, 31.26, and 26.52 %, respectively. Additionally, pigments have been identified, such as chlorophyll a, which has been recorded at 13.94, 23.42, and 14.96 mg/g D.w., respectively; chlorophyll b, at 17.43 ±0.21, 18.60 ±3.80, and 20.18 ±3.16 mg/g D.w.; and carotenoid, at 12.18, 12.32, and 7.40 mg/g D.w. Antioxidant compounds are also produced, including flavonoids (12.77, 19.99, and 26.88 mg/g F.w., respectively) and phenols (8.76, 18.79, and 16.38 mg/g F.w., respectively). Furthermore, biostimulants, including kinetin, ziaten, gibrillic acid (GA3), indole acetic acid (IAA), and abscisic acid (ABA) have been estimated, with values varying depending on the species of microalgae. C. vulgaris yielded 0.24, 3.28, 308.40, 13.88, and 3.94 µg/100 mL, whereas T. dimorphus recorded 0.936, 4.36, 812.2, 4.14, and 3.32 µg/100 mL, and K. aparta recorded 0.487, 4.74, 182.6, 9.54, and 10.49 µg/100 mL, respectively and this creates opportunities for its application as a biostimulant.. These findings conclude that these microalgae may be potential candidates for many uses in different sectors and open new horizons in the pharmaceutical and cosmetic industries as ingredients in functional foods and biofertilizers.