Inhibitory effect of NaCl on the production of extracellular proteins by Aeromonas spp.

气单胞菌是成人和儿童腹泻的病原菌，在生理条件下能产生活性金属蛋白酶和脂肪酶，但在含3%氯化钠的条件下不能产生活性金属蛋白酶和脂肪酶。在本研究中，我们构建了编码LysR转录因子基因缺失的突变株，并检测了LysR基因缺失是否影响金属蛋白酶的产生。结果表明，LysR型转录因子不参与金属蛋白酶的产生。此外，我们还发现，脂肪酶基因在含3%氯化钠的培养基中转录，在0。5%的氯化钠，但在盐度条件下脂肪酶产量降低。结果表明，在含3%氯化钠的条件下，脂肪酶稍有变性。

Aeromonas, which is a causative agent of diarrhea of adults and children, could not produce active metalloprotease and lipase in the medium containing 3% NaCl, though it could produce them under physiological condition. In this study, we constructed the mutant strain in which the gene encoding LysR type transcriptional factor is deleted and examined whether the deletion of LysR affects the production of metalloprotease. The results show that LysR type transcriptional factor is not involved in production of metalloprotease. Additionally, we found the lipase gene is transcribed in the medium containing 3% NaCl as well as in the medium 0. 5% NaCl, though production of lipase is reduced under salty condition. And we showed that the lipase produced slightly in the medium containing 3% NaCl is denatured.