High Nitrate, Phosphate and Alkaline pH Enhances Total Carotenoids Yield in Leptolyngbya SP. BTA 287

Carotenoids are commercially used as natural colourant, antioxidant and as a vitamin A precursors. In the present investigation, critical factors for high total carotenoid yield from the effect of stress created by high pH, excess NaNO3 and K2HPO4 were investigated by using single factor experiment and later optimization were carried out by using Box-Behnken experimental design from Leptolyngbya sp. BTA 287 belonging to Indo-Burma Biodiversity hot spot. This strain was found to produce maximum total carotenoids at pH 9, NaNO3 concentration of 7.50 mg/ml and K2HPO4 concentration at 0.20 mg ml -1 in BG-11 medium, yielding highest total carotenoids of 40.88 µg/mg dry wt. with 62% more from the control condition, inferring that, carotenogenesis were induced greater than reduced nutrient. The ANOVA showed a significant R 2 value (0.9980), model F-value (380.07) and probability (0.0001), with insignificant lack of fit. The results suggested that there was no significant interactions between pH, nitrates and phosphate at alkaliphilic excess nutrients for the production of high yield of carotenoids and appears more to be additive by each factors. Ability to endure nutrient rich and alkaline medium and produce total carotenoid by Leptolyngbya sp. may be applicable for sewage water carotenoid production.