Insights into the rapid metabolism of Geobacillus sp. LC300: unraveling metabolic requirements and optimal growth conditions.

This study investigated the metabolism of Geobacillus sp. LC300, a promising biorefinery host organism with high substrate utilization rates. A new defined medium was designed and tested that allows for exponential growth to elevated cell densities suitable for quantitative physiological studies. Screening of the metabolic requirements of G. sp. LC300 revealed prototrophy for all essential amino acids and most vitamins and only showed auxotrophy for vitamin B12 and biotin. The effect of temperature and pH on growth rate was investigated, adjusting the optimal growth temperature to several degrees lower than previously reported. Lastly, studies on carbon source utilization revealed a capability for fast growth on several common carbon sources, including monosaccharides, oligosaccharides, and polysaccharides, and the highest ever reported growth rate in defined medium on glucose (2.20 h^-1) or glycerol (1.95 h^-1). These findings provide a foundation for further exploration of G. sp. LC300's physiology and metabolic regulation, and its potential use in bioproduction processes.