Study of Algal Biofilm to Enhance Biomass and Lipid Accumulation

Abstract

Microalgal biomass for the production of biodiesel is emerging at the forefront in the relevant research realm. They are considered the most versatile biomass due to certain characteristics such as (1) the ability to convert carbondioxide (CO2) into biomass through transesterification, (2) short life-cycle, (3) high growth rate, and (4) microalgae cultivation that does not compete for fertile fields with food crops. Biodiesel production can be improved by increasing biomass and lipid yield (LY), as well as optimizing downstream processing. Studies have shown various approaches to increase microalgae biomass and lipid production. High biomass productivity (BP) and LY depends on the potential of strains and cultivation strategy. The goal of this thesis is to investigate the potential of microalgae species that are native to North-Eastern, India for biodiesel production and to assess their ability to treat wastewater and produce biomass that can be used for animal feed. The freshwater microalga, Scenedesmus sp. DDVG I was selected as a potential strain for biomass production. The freshwater cyanobacterium, Limnothhrix sp. DDVG II was used as an auto-flocculating strain. The Bioenergy Lab isolated both strains from a swampy region of the Indian Institute of Technology Guwahati (IITG), Indai. DDVG I and DDVG II microalgal isolates were molecularly characterized using 18S and 16S rRNA gene sequence analysis. The sequences were submitted to NCBI GenBank as MN630585 and MN630310, respectively. DDDVG I and DDVG II strains grew the fastest in a normal BG11 medium at pH 7 and 27 °C, with specific growth rates of 0.12±0.005 d-1 and 0.11±0.00 d-1, respectively. Further supplementation of the medium with 1.05 g/L urea, 0.04 g/L K2HPO4, and 6 g/L glucose resulted in increased biomass and LY of up to 8.5 g/L & 39.5% for DDDVG I and 3.3 g/L & 19.9% for DDVG II, respectively.