  Recent efforts have focused on providing a systematic analysis of syntrophic
microbial growth yields. These biokinetic parameters are key to developing an
accurate mathematical description of the anaerobic digestion process. The
agreement between experimentally determined growth yields and those obtained
from bioenergetic estimations is therefore of great interest. Considering five
important syntrophic groups, including acetoclastic and hydrogenotrophic
methanogens, as well as propionate, butyrate and lactate oxidizers, previous
findings suggest that measured and estimated growth yields were consistent only
for acetoclastic methanogens. A re-analysis revealed that data are also
consistent for lactate oxidizers and hydrogenotrophic methanogens, whereas the
limited data available for propionate and butyrate oxidizers are unsupportive
of firm conclusions. These results highlight pertinent challenges in the
analysis of microbial syntrophy and encourage more accurate measurements of
syntrophic microbial growth yields in the future.
