3.3. Distribution of major contaminant species
The most abundant contaminant species, L. plantarum, was
found in all sampling sites throughout the study period, but was
most abundant in the combined liquefaction sample (Fig. 2B).
L. casei and L. fermentum isolates were most abundant in the yeast
propagation tank, where L. plantarum was also abundant. Results
suggest that these two tanks are the major source of these contaminants
going into the fermentation tanks. Total contaminants generally
decreased and were more variable in late fermentations, and
isolates of L. fermentum and L. plantarum decreased in late fermentations.
However, percentages of L. casei and L. mucosae increased
or remained steady throughout the fermentation, suggesting that
these species tolerate conditions in late fermentations.
3.4. Biofilm formation and inhibition of ethanol production by
contaminants