The DNA Bank is a machine developed by the Visitors and installed onboard their Motherships. The machine is flower-design in appearence and is very tall. The device spins at very high speeds, for the preservation of the DNA which has been abstracted by all the Live Aboard's. It's purpose is to extract the DNA from the Live Aboard's, and later when the DNA Bank is complete, then it will be later injected into the selected male who will mate with Lisa. The device is accompanied by a robotic arm which takes the DNA sample and place it into the DNA bank. When this happens the DNA bank stops spinning and later spins. The device is hold into the restricted rooms where the Live Aboard's are taken.
This growth culture served as a respository of genetic information they had collected from the best specimens on a target planet. This was part of the goal of the Visitors to bypass thousands of years of evolution by incorporating the best traits of other races into their own thus circumventing natural evolution in favor of an artificial process. After arriving on Earth, the Visitors secretly began their plans to gather the best specimens for their plan and thus created the Live Aboard Program. Whilst seen as an inter-species exchange, the subjects were secretly harvested by way of a special harvesting machine. Once the sample was produced, the genetic material was taken to the DNA Bank for storage.
After learning of the true nature of the Visitors goals, Erica Evans of the Fifth Column decided to conduct an aggressive campaign against Visitor High Commander Anna. This involved infecting the last of the Live Aboard's with a virus that would corrupt their genetic code thus, in essence, creating DNA bombs that would have corrupted the DNA Bank. However, Joshua learnt of the goal after one of the infectees collapsed onboard the New York Mothership leading to the subjects being terminated after their genetic material was harvested. This combined genetic material was later injected into Tyler Evans to prevent him from dying as he was deemed a suitable breeding candidate for Lisa. ("Uneasy Lies the Head")