Trends in production and fuel properties of biodiesel from heterotrophic microbes (Chapter 16)

Abstract

Biodiesel, a renewable and green energy alternative to the conventional petrodiesel, can be sourced from microbes that have many advantages as compared to plant and animal sources. Heterotrophic microbes like bacteria, microalgae, yeasts, and fungi can be grown on substrates and used for biodiesel production. This chapter emphasizes the various aspects of biodiesel production, namely, growth, screening, harvesting, cell lysis, lipid extraction, transesterification, and evaluation of fuel properties. Screening for oleaginous microbes using recent techniques like Fourier transform infrared spectroscopy to determine lipid content of intact cells are fast emerging as the tools of choice. Different methods for cell lysis-physical, chemical, and biological-have been explored. The conventional two-step process of preparation of fatty acid methyl ester, transesterification, has now been replaced by the in situ reaction, wherein, all reactants are added in a single pot. The determination of fuel properties-cetane number, viscosity, density, and higher heating value for various microbes-is discussed.