Well it all depends on what you want to end up doing. If your ultimate intention is to enter the business world, which your MBA qualification would lead me to suspect, then I'd forget the PhD and start job hunting. A PhD is a lot of work and at the end there's no guarantee that you'll be in a better position for employment than you are already.
If on the other hand you want to start a career in research (microbiology?) then a PhD is almost a necessity. With that in mind, you could either search for current PhD projects with funding attached or approach a university department directly, if you have a clear research proposal. You will probably have more success applying for an existing project as forming a research proposal is tough and requires a leap of faith from the point of view of your supervisor, that he/she may not be willing to take.