Winery Biofilms
Yeast and fungal cells are able to form biofilms in industrial processes. It takes little to
believe that a cleaning-resistant fungal biofilm in a winery could lead to wine spoilage or
off-tasting wine.
We installed fouling cells in two process lines in a large winery, both lines producing the same mix
of product. The fouling cells were installed for 10 weeks, and saw daily hot water flushes and
sanitization with a commercial iodophore.
The biofilms formed in the two process lines were different. Both process lines had mixed species
biofilms (bacteria and fungi), but the biofilm in Line A was thinner and not as uniform as the
biofilm in Line B. Also, the Line A biofilm was primarily proteinaceous, whereas the biofilm in
Line B was primarily polysaccharide and inorganic silicates, with some protein.
These data can be used to develop a more appropriate cleaning method, as sanitization
alone was not effective at controlling biofilm growth.
Winery Line A fouling cell at 10 weeks:
Winery Line A
At 10 weeks of exposure, the fouling cell in Line A of the winery exhibited clear biological structures,
such as the filamentous fungal hyphae show in this image. Infrared data indicated that the biofilm here
was primarily protein, with no indication of polysaccharides or other typical biofilm exopolymers.
Winery Line B fouling cell at 10 weeks:
Winery Line B
The biofilm in Line B of the winery at 10 weeks, however, was very different. Here, fluorescence
microscopy found a much more uniformly coated surface, again with obvious cellular structures of
bacteria and fungi. The infrared spectrum (shown on the same scale as the spectrum from Line A) showed
a very large inorganic silicate peak and possibly polysaccharide, plus a small level of protein.
The silicate in this case came from an upstream filter press charged with diatomaceous earth.
We were not able to determine why these two process lines running such similar product families
generated such different biofilms. Regardless, this process could have benefited from an improved
water flush and the occasional use of surface cleaning chemicals rather than just a sanitizer.
