ANTIMICROBIAL COMPOUNDS FROM NOVEL MICROBIAL SOURCES

研究人员提出了一种新的途径，发现生物活性的天然 化合物.利用细菌存在于 自然环境，大多数是不能在实验室培养，她 将从DNA中构建细菌人工染色体（BAC）文库 与土壤隔离，也可能与其他环境隔离。目前的估计 每克土壤中细菌的数量约为10（11）。如果有 代表约10（4）个物种，每个物种约有10（7）个细胞 kind.这接近于一个集落中的细胞数量， 足够的DNA进行克隆。该文库将被引入E.大肠杆菌 基因表达相对混杂的生物体; 因此，对于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检查 表型的克隆，并通过PCR筛选独特的rDNA 特定细菌门的特征。 将筛选得到的转化体以产生 具有抗菌活性的化合物。汉德尔斯曼教授估计， 500，000个克隆的文库很容易获得，如果只有0.1%的克隆显示出一些 活动，搜索将提供丰富的收益。克隆人将会 在48孔微量滴定皿中生长，并在每个培养皿中培养上清液 组将被点样到播种有测试细菌的培养皿上; 首先将对葡萄球菌和肠球菌进行测试， 由于这些生物体对现有抗生素的耐药性已经成为 严重的临床问题。任何能引起年轮生长的化合物 将进一步测试抑制。

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.