Style question: Italicizing prokaryote family names
What's the deal with italicizing bacterial and archaeal taxonomic ranks? I know that for eukaryotes only genus and species names are typically italicized, but the convention seems less firmly established for bacteria and archaea. I'm taking a microbial ecology class this quarter and most of the readings have been papers from the primary literature, with supporting material from two textbooks (Madsen and Osborn). Almost every source seems to be following its own style guide. Madsen goes so far as to italicize the domain names, Eukarya, Archaea and Bacteria. This article italicizes genera and species, writing Microbacterium but leaving Microbacteriaceae unembellished. Wikipedia insists that Alphaproteobacteria "should be styled in italics" because it is recognized as a class, but you don't see people italicizing Mammalia or Saccharomycetes (though one wonders how some mycologists who fancy themselves microbiologists, rather than botanists, might stylize the latter). OK, so Wiki's not a legitimate source, but this illustrates my point.
The main reason I ask is because I'm writing a term paper for said microbial ecology class, and I want to format things correctly. Seeing as a draft is due tomorrow, I'm planning to go with my gut and only italicize the genus and species name, but I'm also interested in what other people have to say about this, or whether other people have noticed this. On the one hand it's just a trivial stylistic problem of little biological significance, but the lack of standardization can be a source of confusion, especially for students. When I encounter an unfamiliar Italicized name I know how to interpret it, but in microbiological contexts it is sometimes less clear.
[EDIT] In no way do I mean to suggest that mycology is properly classified as a subfield of either botany or microbiology. I have nothing but love for fungi, and mad respect for the people who study them—can you say alteration of generations? Egads.