The idea of new replicators arising in man-made "ecospheres" is not new in science fiction - oftentimes the concept appears in fiction as machines self-assembling out of junk. This is the one interesting idea in John Updike's confused attempt at science fiction Toward the End of Time; there are "metallobioforms" that have appeared out of our waste. In the real world there is already a well-documented and very real machine ecology, albeit a virtual one, that has appeared around the stock market. Look for resources that are important to the tool makers, and there you will find the most advanced tools. The Pacific Garbage Patch is another entity that seems like it was made for speculative fiction, unpleasant though the reality is.
Consequently it's more than interesting that there is now a new micro-ecology detected growing on plastic waste in the ocean. This paper (gated) took waste from the Atlantic, and did some pretty interesting meta-genomics to see what was growing. I'm no microbiologist but I did scan the list for medically significant pathogens; the most concerning one is unidentified Vibrio species, concerning because they cause cholera among other things. But the analysis yielded a long, long list, which also included Moraxella (which causes pneumonia) and Pseudomonas, my personal favorite bacterium, which is kind of a jack-of-all trades in terms of what it can eat and what infections it can cause, and is already used for bio-remediation since many species can eat oil and other hydrocarbons. If you can get to the paper it's especially worth seeing their network analysis of hydrocarbon-metabolizing genes.