Thank you for sharing the information. It appears slanted toward those using and storing large amounts of fuel but most of us buy our fuel from exactly those types of places. Fuel treatment appears to be the answer but one must find a treatment which deals with all the various types of growths and the different organisms are handled differently.
The principles of maintaining good fuel quality are the same if you are storing 5 gallons or 5000 gallons, i.e. minimize condensation and treat your fuel in storage. It's only a matter of scale. Most of us are only familiar with dealing with gasoline fuel in our cars where we don't have many problems with fuel storage.
Our tractors, in most cases, don't get used daily, we store fuel for relatively long periods of time because of low usage and we don't pay much attention to draining fuel filters, keeping our tractor tanks full, between uses to minimize condensation and treating our stored fuel. It has been my experience on these forums that during cold weather, a lot of these fuel problems show up with "won't start", "run downs", lack of power, etc. posts. In the summer, when users are actively using their machines, bacterial contaminations issue can halt their hay harvest or mowing, etc. Paying attention to your fuel management can go a long way toward avoiding a panic "HELP" post because a major storm is coming or you have 10 acres of hay down and it's supposed to rain tomorrow and your tractor is having some of these aforementioned problems. As far as the species of bacteria are concerned, they are all around and you don't have to worry about what specific bug you may have because you probably have a little bit of all and commercial biocide treatments will treat them all.
My pupose for this post was to educate the users of this forum on this issue in hopes that they can take the simple steps to manage their fuel quality and avoid these problems.
To re-iterate : Drain the water from your filters and separators, change your filters regularly, keep your tractor fuel tanks and storage tanks full especially between uses, treat your fuel, both stored and in the tractor, with good fuel treatments and biocides.