Simultaneous Saccharification and Fermentation (SSF) of lignocellulosic biomass to fuels and chemicals requires a microbial biocatalyst that functions optimally at pH 5.0 and at temperatures ≥50°C, conditions that are also optimal for fungal cellulase activity. We have previously reported that a facultative anaerobe, Bacillus coagulans, requires less cellulase compared to yeast or lactic acid bacteria for optimum SSF of crystalline cellulose to products due to its ability to grow and ferment at pH 5.0 and 50-55 °C. However, this sporogenic lactic acid bacterium is recalcitrant to genetic modification although one strain, P4-102B, has been reported to be transformable by plasmids. Using a plasmid that is thermosensitive for replication, we have developed a method for deleting specific genes in B. coagulans strain P4-102B. An ldh deletion mutant lacking L-lactate dehydrogenase activity constructed using this method produced ethanol as the major fermentation product at pH 7.0 with 2,3-butanediol, acetate and formate as minor products. At pH 5.0, the Δldh strain fermented glucose to primarily 2,3-butanediol. Although aerobic growth of this mutant is comparable to the wild type, anaerobic growth was significantly impaired irrespective of the culture pH. Based on the fermentation profiles, PDH is apparently contributing to ethanol production at pH 7.0 and not at pH 5.0. This is the first published report of targeted genetic modification of B. coagulans and opens a way to metabolically engineer this thermotolerant bacterium for cost-effective production of various chemicals and fuels from biomass.