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Sporulation mutants of Bacillus subtilis were developed for overproduction of heterologous proteins. The strains, spoOJ, spoIIG, and spoOJ spoIIG double mutant were constructed from two protease-deleted mutant(DB104 ). The vector containing aprE gene was integrated in the chromosome of each strain, then the morphology of each strain was observed by ´I EM( trasmission electron microscopy). The morphology of spoOJ mutant and spoIIG mutant coincides with the description of the previous reports, respectively. The sporulating cells of spoOJ Spo Il G double mutation resemble spo II G mutant more similarly, but with a little rougher cell wall membrane. The spoOJ mutation in B. subtilis gives negative effect on aprE activity with only a decreased sporulation frequency. On the contrary spoIIG mutation increases the aprE actvity twice with an undetectable sporulation frequency. In the case of spoOJ and spolG, i. e. double mutation, the effect of spoOJ on aprE activity seems to be relieved and the double mutant shows more or less the same aprE activity compared to spoIIG mutant.
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