Synthetic biology is aimed to design and rewire existing and new biological parts, devices, and systems for useful purposes. The vast majority of microbes (>99%) in natural environment are not yet culturable using traditional approaches. Those unculturable microorganisms in natural environment are an untapped gene
resource which is believed to encode novel industrial catalysts and enzymes, as well as new medical compounds. We developed a novel synthetic biology approach that employs a gene trapping circuit to screen functional genes encoded with special enzymes. Using this approach, we have discovered fi ve new naphthalene and toluene dioxygenases which can be used as industrial biocatalysts such as synthesis of HIV inhibitor. This synthetic biology approach paved the way for mining the gene pool of unculturable microorganisms and searching novel enzymes and antibiotics.