A culture method for microalgal forms using two-tier vessel providing carbon-dioxide environment: studies on growth and carotenoid production

A culture method was developed for photoautotrophic culture of Haematococcu s pluvialis, Chlorella vulgaris, Scenedesmus obliquus, Spirulina platensis, Nostoc and Stigonema in a two-tier flask consisting of nutrient media in t he upper chamber and CO2 generating buffer mixture (KHCO3/K2CO3) in the low er chamber. The concentration of buffer mixture was varied to obtain desire d levels of CO2. CO2 at 2.0% (v/v) level enhanced growth and chlorophyll co ntent over control cultures (without CO2 supplementation) in all microalgal species. Haematococcus pluvialis culture in BBM and KM1 media showed 6.71- and 2.07-fold increase in biomass yields with astaxanthin productivity at 7.26 and 7.48 mg l(-1) level respectively. CO2 supplementation to C. vulgar is and S. obliquus cultures resulted in 5.97- and 7.30-folds increase in bi omass with 2-3 fold increase in chlorophyll and carotenoid contents over th eir respective controls. Similarly 2-3 fold increase in chlorophyll and car otenoid contents were observed in Sp. platensis, Nostoc and Stigonema spp. This culture methodology will provide information on CO2 requirement for gr owth of algae and metabolite production and also facilitates studies on the influence of light and temperature conditions.