What is a bacterial bigwig? What might that person do for a career?

A bacterial bigwig is a person who is a professor of microbiology. This person would be someone who teaches about bacteria and is an expert. They will be considered a "bigwig" at their place of employment or to their peers.

A bigwig refers to a person who is an expert in a particular area of study or field. Thus, a bacterial wig will be someone who is an expert in the area of bacteriology. Such a person will probably have the highest degree that is obtainable in that field and will be an authority to reckon with when it comes to the issue of bacteria.