PHYLOGENY OF ANAEROBIC RUMEN CHYTRIDIOMYCETES INFERRED FROM SMALL SUBUNIT RIBOSOMAL-RNA SEQUENCE COMPARISONS

The 18S-like rRNA sequences of four recently isolated strains of rumen anaerobic phycomycetes (Neocallimastix frontalis MCH3, Piromonas communis FL, Sphaeromonas communis FG, and Neocallimastix joyonii NJ1) were analyzed and compared to examine the phylogenetic relatedness of the four isolates to each other and to other eukaryotes. The rumen chytrids characterized demonstrated very high 18S-like rRNA sequence similarities (97-99%). They are more closely related to the true fungi than to any other eukaryotes.