Growth and biochemical response of an indigenous oleaginous microalga Scenedesmus obtusus cultivated in outdoor open ponds

Understanding the response of microalgae to outdoor culture conditions is necessary for the development of large open pond cultivation system for various value added applications. In this context, we evaluated the response of an indigenous oleaginous green microalga Scenedesmus obtusus CFR 1-09/FW to outdoor culture conditions. The microalga was cultivated in open ponds at various culture depths under nutrient replete condition. The pond with 3 cm culture depth showed highest biomass productivity (49.05±11.74 mg L-1 day-1). The high surface solar irradiance (1831 µmol m-2 s-1) led to a decrease in chlorophyll content (from 12.21 to 4 µg mg-1). The long duration exposure to lower temperatures (≤20°C) during night led to an increase in poly unsaturated fatty acids (PUFAs) content (47.21±2.83% w/w mass fraction of FAME). The omega-3 alpha linolenic acid (ALA) content rose significantly reaching 31.01±3.79% (w/w) mass fraction of FAME. The high content of carbohydrate (23.4±0.64% w/w), protein (37.62 ± 2.15% w/w), lipid (21.55±1.43% w/w), palmitic acid (30.97±4.02% w/w mass fraction of FAME) and ALA in outdoor cultures makes this microalga a potential candidate for outdoor cultivation for food and feed applications. The study provides valuable insights for developing outdoor open pond cultivation protocol.

Capsaicin formation in p-fluorophenylalanine resistant and normal cell cultures of Capsicum frutescens and activity of phenylalanine ammonia lyase.

Callus cultures of Capsicum frutescens capable of producing a maximum of 53 ~g capsaicin/g FW were exposed to various levels of p-fluorophenyialanine (PFP) at 100, 400, 1000 and 2000 ~M to develop a resistant cell line that over produces capsaicin. After 15 days of culturing on media lacking PFP, cell lines resistant to 100, 400 and 1000 ~M registered 18%, 34.5% and 45% increase in capsaicin content over normal cell line (cells not exposed to PFP). Capsaicin accumulation was inhibited in 2000 ~M PFP resistant cell line. The profile of phenylalanine ammonia lyase (PAL), the key enzyme in pheny1propanoid pathway in resistant cell cultures was studied and compared with normal cell cultures to understand its role in capsaicin formation. Importantly increased production of capsaicin was obtained using PFP resistant cell lines. The activity profile of PAL had no correlation with capsaicin content in both control and PFP resistant cells.