Induction to the synthesis of secondary carotenoids and qualitative analysis of pigments in the microchlotophyta
Castillo Flores, Antonio de Padua
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The induction to the synthesis of secondaty carotenoids (SC) in the green microalga Chlorella zofingiensis (Ch. zofingiensis) by stressant conditions of high irradiance (range 345- 645 µmol m·²·s·¹ limited potassium nitrate concentration (8.1 mg-¹) in the culture medium, and the addition of cupper ion (0.002 mg -¹) was studied. A marked accumulation of SC were detectable by Thin Layer ehromatography (TLC) in cells growing under high irradiance as well as in nitrogent deficiency conditions. 1t is suggested that se synthesis on Ch. zofingiensis involves the degradation of chlorophylls and primary carotenoids, and the esterification of astaxanthin. lt was not clear if the addition of cupper ion induce the synthesis of se in the cells. Ch. zofingiensis growing in optimal conditions (temperature: 24 ± 1 °C; light intensity: 175-230 µmol m·² s-¹ ; day length: 12 h: 12 h; airation : ca. 2500 cm3/min) synthetized astaxanthin in less than four days (rninimum time). The ketocarotenoid astaxanthin was isolated, purified and characterized by chromatography and spectrophotometry with a R f value of 28.28 and a maximum absorption (A max ) of 472 mm. A qualitative analysis of pigments displayed by TLC and UV -visible absorption spectrophotometry shows that Ch. zofinginesis synthesized the following pigments: • Ch. zofingiensis vegetative cells; Astaxanthin ester n° 1, carotene, chlorophyll subproduct, astaxanthin ester n° 5, chlorophyll b, astaxanthin ester n° 8, violaxanthin, neoxanthin, plus two unidentified xantophylls. • Ch. zofingiensis vegetative cells growing under high irradiace stress; Astaxanthin ester n° 1, ~- carotene, astaxanthin ester n° 3, chlorophyll subproduct, astaxanthin esters n° 4, 5, chlorophyll b, astaxanthin ester n° 8, astaxanthin, neoxanthin, plus three xantophylls and one ketocarotenoid unidentified. • Ch. zofingiensis akinete stage; Astaxanthin esters no 1, 3, 4, 5, 6, 8, and neoxanthin, plus three xantophylls and one ketocarotenoid unidentified. Nota: resumen extraído de un programa de reconocimiento de texto, fórmulas pueden contener inexactitudes, consulte el texto original.