I don't know about bacteria, but a banana variety is all essentially the same plant, propagated from a central stock. Have a look at the controls around planting and growing your own bananas, it's all red tape, permits and extremely fascist:

http://www.backyardbananas.com.au/faq.html

http://www.daff.qld.gov.au/plants/fruit-and-vegetables/fruit...

And for very good reason: every banana of a variety is susceptible to (eg.) a virus outbreak - there won't be any pockets of genetic variability like you would get with potatoes or citrus. If anything that affects bananas becomes widespread - no more bananas.