Does anyone know what micrococci is and what it does? American Farmstead Cheese says it is used "to promote surface growth and aroma in washed-rind and natural rind cheese." I am looking for something more specific, Is it a yeast?
No. It is one of several gram+ bacteria belonging to the Micrococcaceae family and either the Micrococcus genus or the Staphylococcus genus. In the Staph genus, it's usually S xylosus, although I've also seen S carnosus.
What does it do chemically?
Noms curd and releases enzymes to break it down, and noms the hydrolyzed proteins. It's a hungry, hungry beast.
What does it do to flavor?
Gives a smelly, pungent sort of aroma and softens paste. You can use S xylosus alone, for example, to create a lovely cheese with a light-red rind resembling a limberger. There are a few smear cheeses with xylosus as the primary rind ripener, don't recall offhand which.
I read somewhere that it degrades caesin, but what does it produce?
Yep, sure does. Broken down as1, as2, b proteins make all sorts of peptide chains (soft cheese paste) with an associated smelliness. Also very strong oligopeptide catabolysis (secondary proteolysis to release more complex, smaller peptide chains). Do you want a list of the peptides or an SDS PAGE? That varies with strain.
They're also used extensively in cured meat production to create characteristic salami flavors, like for the salami made in Naples.
How does it work with b. linens?
As a primary and secondary ripening agent that doesn't consume lactose/lactate. It's like using mycodore and mycoderm together, it adds dimension and aroma because the enzymes target different spots on the milk caseins. One cool application, for example, is to pick a mild b linens that tends to produce a lot of buttery notes, and complement it with a Micrococcus that produces a red rind and complex smelly notes. You'll get lovely soft paste without too much goo, a great color that's appetizing, very layered flavors in the paste, and an aroma that is not unidimensionally "stinky"
Take a look at http://aem.asm.org/cgi/content/short/74/1/172
for some more discussions of the complex interactions possible.