Re: "one of the 12 cultures evolved the ability to survive by eating citrate..." Is it possible it got this trait from outside contamination, since other strai

Re: "one of the 12 cultures evolved the ability to survive by eating citrate..." Is it possible it got this trait from outside contamination, since other strains can eat citrate? Viruses can snip in foreign DNA, for example. To check, hopefully there's enough generation archives to see exactly how the ability arose. If it were a single gene "flip" rather than a set of changes, then it could be native.