Figure 3. Genetic tool and fermentation condition discovery for use in alkaline biorefining with B. marmarensis.

(a) Promoters were cloned from the genomes of B. marmarensis, B. subtilis, and E. coli and tested for their expression of native beta-galactosidase in B. marmarensis. B. subtilis/E. coli promoters are given by common names. B. marmarensis promoters are given annotation numbers (Further detail in Supplementary Table 1). (b) Fermentative production of lactate, succinate, and acetate from 4%w/v glucose in 48 hours. Providing 1.7 vol headspace air optimized organic acid production. (c) Increasing cell mass loading of cells greatly boosted organic acid yields. Productivity more than doubled-reaching maximum values at 14 hours instead of 48 hours. (d) Optimization of pH, buffer strength, and peptone concentration led to 94% conversion of glucose with high selectivity for lactate without acetate.