ANTIMICROBIAL COMPOUNDS FROM NOVEL MICROBIAL SOURCES

研究人员提出了一种发现具有生物活性的天然物质的新途径 化合物。利用这样一个事实，即存在于 自然环境，大多数是不能在实验室培养的，她说 将从DNA中制作细菌人工染色体(BAC)文库 与土壤隔离，也可能与其他环境隔离。当前估计数 每克土壤中细菌数量的约为10(11)。如果有 代表大约10(4)个物种，每个物种将有大约10(7)个细胞 善良。这接近于菌落中的细胞数量，应该可以提供 有足够的DNA进行克隆。该文库将被引入到大肠杆菌中，并 在其将表达的基因中相对杂乱的有机体； 因此，基因表达的障碍应该相对较少 这个图书馆。图书馆的多样性将通过审查 克隆的表型及通过聚合酶链式反应筛选独特的rDNA 特定细菌门的特征。 将对产生的转化子进行筛选，以生产 具有抗菌活性的化合物。汉德尔斯曼教授估计， 500,000个克隆的库很容易获得，如果只有0.1%显示了一些 活动，搜索将提供丰厚的收益。克隆人将是 在48个培养皿和每个培养皿的培养上清液中生长 群将被发现在播撒了检测细菌的培养皿上； 首先将对葡萄球菌和肠球菌进行检测， 因为这些生物对现有抗生素的抗药性已经成为一种 严重的临床问题。任何能引起环状生长的化合物 抑制作用将得到进一步测试。

The investigator proposes a novel route to discover bioactive natural compounds. Taking advantage of the fact that of the bacteria present in natural environments, most are not cultivatable in the laboratory, she will make a Bacterial Artificial Chromosome (BAC) library from DNA isolated from soil and possibly from other environments. Current estimates of the number of bacteria per gram of soil are about 10(11). If there are about 10(4) species represented, there will be about 10(7) cells of each kind. This is close to the number of cells in a colony and should provide enough DNA for cloning. The library will be introduced into E. coli, an organism which is relatively promiscuous in the genes it will express; thus there should be relatively few barriers to the expression of genes in this library. The diversity of the library will be tested by examining the phenotypes of the clones in it and by screening by PCR for the unique rDNA signatures of particular phyla of bacteria. The resulting transformants will be screened for the production of compounds with antimicrobial activity. Prof. Handelsman estimates that a library of 500,000 clones is easily obtainable, and if only 0.1% show some activity, the search will have provided a rich yield. The clones will be grown in 48 well microtiter dishes and the culture supernatants in each group will be spotted onto petri plates sown with tester bacteria; the first tests will be carried out against Staphylococcus and Enterococcus, since resistance of these organisms to existing antibiotics has become a significantly clinical problem. Any compounds that cause a ring of growth inhibition will be tested further.