Although Space colonization and genetic engineering are separate concepts and the creation of space habitats is perfectly possible without the use genetic engineering, we believe that genetic engineering is a key technology for the success of Space colonization.
Cells can make complex molecules at relatively modest cost, whilst humans need large factories to produce even simple molecules. In our daily life we need all kind of chemicals, by modifying plants we can produce all chemicals we need without having to resort to large and environment-unfriendly factories. And by choosing the right crops, we can replace labour intensive factories with a few acres of farmland.
Unlike chemical factories, plants have no risk catastrophic collapse. Plants, unlike machines, do not human supervision at every second of process. Once a plant has been genetically engineered, natural reproduction will ensure the continuation of production. This means that the production of almost every chemical will be cheaper if the are produced through the use genetic engineering.
Another useful is to increase the yield of food crops, since agricultural land will be limited in the early days of Space settlement. Plants has an efficiency of approximately four percent, genetic modification might increase to ten percent. This will also increase the yield per square meter.
We can conclude that genetic engineering will help Space settlements to achieve economic self-sufficiency much sooner than would be possible without.