Method 2) full sequencing

The sequenced metagenomic information is subjected to a database search.

If the sequence is similar to that of a gene related to the intended function, then a similar function is expected.

In addition, by searching for homology, you can obtain various information other than the intended function, such as what kind of organism the metagenomic DNA was derived from and what kind of compound it can produce.

Advantages and disadvantages of method 2)

Advantages

It requires little time and effort, and can process a huge amount of genetic information in a short period of time.
Genes that do not function in E. coli can be found.

Disadvantages

Only genes that are similar to already identified genes can be found (completely new genes cannot be found).
Since we only have data, we need to artificially synthesize the genes.