Protein export during growth of Bacillus subtilis: the effect of extracellular protease deficiency

Exponential phase cultures of a protease-deficient and a protease-proficient strain of Bacillus subtilis , growing in minimal medium with a glucose carbon source, were labelled with ¹⁴C-phenylalanine. Subsequent export of labelled protein was detected in trichloroacetic acid-precipitated supernatant fluid samples. During exponential growth the strains exhibited substantially similar protein export kinetics. However, as confirmed by the presence of a cytoplasmic enzyme in the culture supernatant fluid, protease deficiency was associated with an increased tendency of cells to lyse as they approached stationary phase.