Linda Bergaust says “Microbes (bacteria, fungi and algae) can be used to produce pharmaceuticals, bioplastics, nutritional supplements, feed or food. For these purposes, they are grown to very high density in a process termed high cell density cultivation (HCDC). They can utilize resources that are not directly usable to us and would otherwise be lost; they can even grow on “air and water”. A range of aerobic cultivation strategies, dependent on costly oxygen provision, are already in use, but no HCDC method using anaerobic (oxygen free) respiration has been developed. This is somewhat surprising because a wide range of bacteria can respire anaerobically, with high biomass yields. We have invented a method for HCDC by anaerobic respiration and will explore the imperatives for maximal growth, the boundaries in terms of biomass yield, and range of growth substrates and energy sources. A likely outcome is up-scalable ideas for industrial application.”