Isolation and application of new microorganisms from soil Samples

为了增加从微生物中发现有用的新生物活性化合物的可能性，我们试图通过在分离琼脂中添加各种物质来分离新的微生物菌株。在寻找细菌菌落生长所必需的因素的过程中，我们发现优势细菌菌株向培养液中释放蛋白质，从而增加土壤样品中的细菌菌落数量。令人惊讶的是，从活性培养基中分离出的常见蛋白质是超氧化物歧化酶(SOD)。此外，商业用SOD增加了菌落数量，过氧化氢酶的加入进一步增强了这种反应。分离琼脂上清液中可定量检测到超氧阴离子自由基(O2)，加入超氧化物歧化酶或加过氧化氢酶可抑制超氧阴离子自由基的产生。我们的结果有力地表明，一些细菌细胞可以通过抑制琼脂基培养基上的氧化应激来恢复。

To increase the possibility of discovering useful new bioactive compounds from microorganisms, we have attempted to isolate new microbial strains by adding various substances to the isolation agar media. In the course of searching for factors necessary for bacterial colony growth, we have found that the predominant bacterial strains release proteins into the culture broths that increase the number of bacterial colonies from a soil sample. Surprisingly, the common protein isolated from the active culture troths was superoxide dismutase (SOD). Moreover, commercial SODs increased the number of colonies, a response further enhanced by the addition of catalase. Superoxide (O_2) was quantitatively detected in the isolation agar medium and the level was suppressed by adding SOD or SOD plus catalase. Our results strongly suggest that some of the bacterial cells may be recovered by suppressing oxidative stress on the agar-based medium.