Fermentation and recovery processes are used to make and purify biological products:
proteins, pharmaceuticals, vaccines, etc. In bioproducts, the purity of the product is critical,
and places a heavy burden on the CIP process to completely eliminate residual biofilms.
In this study, fouling cells were placed in a bioproducts facility in two locations. The first location
was at the outlet of the fermentation vessel, a location rich with microbial cells and nutrient media.
The second location was at the end of the recovery process, where the microbes had been physically removed
and the desired biomolecule isolated and enriched.
Both locations were cleaned after each batch, with high-temperature caustic. Results clearly showed
a cleaning-resistant biofilm in both locations, but also showed that the biofilms were different from each
other in these two locations.
Two-day fermentation fouling cell, before chemical cleaning.
Two-day fermentation fouling cell, after chemical cleaning. Note the presence of residual
biofilm cells and the formation of early exopolymer.
Four-week fermentation fouling cell, after chemical cleaning. The biofilm has become very
thick and very resistant to chemical cleaning. The orange filaments are organisms on the
surface of the stainless steel. The green patches are inorganic crystals, perhaps precipitated
by the biofilm organisms.
Two-day recovery fouling cell, before chemical cleaning. Note the presence of two species of
bacteria, in a portion of the process where there are supposed to be no microbial cells.
Two-day recovery fouling cell, after chemical cleaning. The surface is uniformly coated with a thin
layer of organic material, which is apparent in an area where the organic layer has been scraped away
(the black streak through the image). A cleaning-resistant biofilm has begun, as apparent by the clump
of exopolymer in the upper portion of the image.
Four-week recovery fouling cell, after chemical cleaning. The well-developed biofilm is thick and
porous, drastically altering the internal surface of the transfer line.