Using Grep to change case in 2nd of a two word string

Hello all

I found out after completing my project that I had made a big boo boo.

I have multiple (hundreds) 2 word botanical names of plants which are all located after a certain heading style throughout 400 pages.

The first word in this name is capitalized already. Thats ok. But the second word needs to start with a lower case letter ( Instead of a capital letter like it has now).

All the 2 word names are seperated by commas.

Any ideas?

Thanks in advance

Lauren