Blastocladia and aqualinderella: fermentative water molds with high carbon dioxide optima. 
The uniflagellate aquatic phycomycete Blastocladia ramosa appears to be a facultative anaerobe.  Blastocladia pringsheimii requires traces of oxygen.  Growth of both species is no greater or only slightly greater at normal atmospheric oxygen pressure than under 0.2 percent oxygen pressure, but their growth is enhanced by the addition of 5 or 20 percent carbon dioxide.  The cells of both species lack typical cristate mitochondria and contain only traces of cytochrome.  Blastocladia resembles the biflagellate Aqualinderella fermentans in adaptation to an environment poor in oxygen and rich in carbon dioxide.