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Biofilm Treatment with Polymers

Amelia Hunt a.hunt at lancaster.ac.uk
Fri Jul 2 02:51:09 EST 1999

Hello Mary, 
With regards biofilm quantification. If it is purely a bacterial 
biofilm that you are looking at, then I would recommend removing the 
biofilm by a combination of scraping and sonicating (find the best 
combination for your own work) and then use 4',6 diamidino 2 
phenylindole (DAPI) at a final concentration of 0.1µg/ml or greater to 
stain cells. Then enumerate using epifluorescence microscopy. There are 
lots of papers that describe this method e.g. 
Porter, K.G. & Feig, Y.S. 1980. Limnol. Oceanogr. 25(5) 943-948 (seminal 
and Zweifel & Hagstrom. 1995. Appl. Environ. Microbiol. 61(6) 2180 - 
2185 gives details of methods to exclude non-nucleoid containing 
bacteria - should you be concerned... 
For planktonic studies DAPI and, with reservations, acridine orange (AO) 
provide the best methods to estimate bacterial numbers. Bacteria 
visualised by these methods can also be used to estimate biovolume and 
from this, biomass. Here at Lancaster, we also use direct counts by 
these methods rather than plate counts which have been proven to be 
an underestimate of actual bacterial numbers.
With regards using polymers as biocides (of which I know absolutely 
nothing about) - maybe an examination of some ecology papers examining 
the ability of recalcitrant organic carbon molecules to inhibit 
microbial metabolism could prove interesting with respect to the ability 
of these to move into biofilms.e.g., Freeman C & Lock, MA. 1992. Appl. 
Environ. Microbiol. 58 2030 - 2033.
Hope this is of some help 

Dr Amelia P. Hunt 
Biological Sciences 
Lancaster University 

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