Medical Definition of Prototheca
: a genus of unicellular algae that resemble algae of the genus Chlorella but lack chlorophyll and that include two (P. zopfii and P. wickerhamii) that cause mastitis in cows and sometimes localized infection (as of the skin) in humans
Seen and Heard
What made you want to look up Prototheca? Please tell us where you read or heard it (including the quote, if possible).