Isolation and Identification of Algae from Karnataka for Biodiesel Production

Abstract

Energydemands are fast growing due to population expansion, urbanization, and newlineeconomic development. Critical dependence on fossil fuels is unsustainable both newlineeconomically and environmentally. Historically, fossil fuels have been the most newlinesignificant source of environmental pollution and greenhouse gases. Transport sector newlineaccounts for majority of greenhouse gas emissions (GHG) now and has been the major newlinesector causing GHG emissions since 1990. To reduce GHG emissions, replacement of newlinefossil fuels with low emission alternative fuels such as biodiesel from microalgae is most newlinenecessary. newlineThis study involves the isolation of microalgae from some freshwater sources in newlineKarnataka, selecting a strain most suitable for biodiesel production. The growth newlineconditions were optimized for maximum biomass, enhancing the lipid content by various newlinebiochemical strategies and production of biodiesel. newlineC. sorokiniana, a member of the Chlorophyceae, isolated from a freshwater lake newlinein Shivanasamudra, Karnataka was selected based on its rapid growth rate and high lipid newlinecontent. BG-11 medium was optimized for its growth and lipid content using response newlinesurface methodology (RSM). Biochemical strategies including nutrient starvation newline(nitrogen, phosphorous), salt and pH stress showed that nitrogen stress was found to be newlinethe most effective to enhance lipid content. Plant hormone indole acetic acid enhanced newlinebiomass content. To circumvent the biomass loss under nitrogen stress, plant growth newlinepromoting rhizobacteria (PGPR), Pseudomonas aeruginosa (KX010602) was used. newline The mechanism of lipid enhancement under nitrogen stress was studied. The fold newlinechange expression of accD gene under nitrogen stress was studied compared to control. newlineUnder stress conditions, the concentration of reactive oxygen species increased, resulting newlinein an increase in the level of enzymatic antioxidants. Wastewater bioremediation was newlinecoupled with biofuel production. Initial study was promising with reduced chemical newlineoxygen demand (COD), biological oxygen demand (BOD) and total suspended solids newline(TSS) with no loss in biomass and lipid content when compared to the culture in BG-11 newlinemedium. C. sorokiniana was isolated from a freshwater lake in Shivanasamudram, newlineKarnataka under optimized culture conditions maximized lipid yield which can be a newlinepromising source of biofuel. newline