(left) Random metagenomic library (E. coli hosts), right arrow: capability test
(upper-right) Pigment production: production of various pigments such as blue, red, yellow, purple, and fluorescent can be confirmed visually.
some of them are luminescent clones that glow at night (they have acquired a luminescent gene)
(middle-right) Siderophore production: We have added a pigment to the medium that turns yellow when siderophores (substances necessary for the
acquisition of iron, an essential nutrient. siderophores' structure varies among bacteria) are present
(lower-right) Production of antibacterial substances: when a metagenomic clone produces an antimicrobial substance, the bacteria around
the clone die and black circles appear.
The obtained fragments of metagenomic DNA are randomly incorporated into a culturable host such as E. coli. Each of the colonies in the lower left photo contains a different metagenomic DNA fragment.
Each colony is called a metagenomic clone, and the aggregate (the entire plate in this example) is called a metagenomic library.
If the metagenome contains a gene that is required to produce some substance (such as a pigment), the clone will produce that substance ( in the case of a pigment, the colony will be colored).