RESUMO
Production of extracellular protease by Bacillus subtilis 168 in a medium containing low concentrations of amino acids is essentially linear, whereas in a medium containing high levels of amino acids the time course of production is biphasic. Cells harvested from the growth medium are capable of secreting enzyme for 30 min in the presence of rifampin, but the appearance of the enzyme is sensitive to chloramphenicol and pactamycin. The protease messenger ribonucleic acid (mRNA), nevertheless, appears to have a short half-life typical of bacterial messengers, and this indicates that these cells contain a relatively large pool of protease-specific mRNA. This pattern of results is identical to that observed previously with B. amyloliquefaciens. Because it has now been found in two distinct organisms, it is concluded that the accumulation of mRNA for extracellular protease, supported by rapid transcription, is a biologically meaningful phenomenon related to extracellular enzyme synthesis rather than aberrant behavior due to a transcriptional control mutation.
