Low-Cost Feedstocks for Biofuels and High Value Added Products Production: Using Multi- Parameter Flow Cytometry as a Tool to Enhance the Process Efficiency

Currently there is an increase search for microorganisms as a potential source of biofuels and other bioproducts with commercial interest. A way to reduce microbial cultivation costs consists of using low-cost feedstocks, such as lignocellulosic materials, industrial by-products, effluents and wastewaters to cultivate microbes which, in some cases, allow the simultaneous effluent biological treatment and the production of high value-added products. However, such feedstocks may contain, or their pre-treatment may release inhibitory compounds that affect microbial metabolism, thus the process efficiency. Multi-parameter flow cytometry (FC) is an advanced and powerful technique that has been used for bioprocess monitoring, showing many advantages over the conventional microbiological/analytical techniques that are still currently used in most laboratories for process control. This chapter will describe the cell stress response to the most known inhibitors present in low-cost feedstocks, emphasizing the advantages of using the at-line FC technique in these process monitoring.

Keywords: Crude Glycerol, Cell Membrane Damage, Enzymatic Activity, Flow Cytometry, Hydrophobic Wastes, Inhibitors, Intracellular pH, Intracellular Products, Low-Cost Feedstocks, Lignocellulosic Materials, Microorganisms, Reactive Oxygen Species, Wastewaters.