Biofilm growth of individual and dual strains of <Emphasis Type="Italic">Klebsiella oxytoca</Emphasis> from the dairy industry on ultrafiltration membranes |
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Authors: | Xuemei Tang Steve H Flint Rod J Bennett John D Brooks R Hugh Morton |
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Institution: | (1) Institute of Food, Nutrition and Human Health, Massey University, Palmerston North, New Zealand;(2) School of Applied Sciences, Auckland University of Technology, Auckland, New Zealand |
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Abstract: | Formation of biofilms in dairy membrane plants causes membrane pore blocking, product contamination and subsequent economic
loss. To investigate the biofilm growth, two Klebsiella
oxytoca strains, K. B006 and TR002, previously isolated from New Zealand dairy membrane plants, were grown both individually and combined on
three types of ultrafiltration (UF) membranes in different concentrations of whey medium in biofilm reactors (CBR 90, BioSurface
Technologies, Bozeman, USA). Biofilms of both the individual and combined strains grew on the membrane surfaces to levels
of 4.9–7.99 log colony-forming units (CFU) cm−2 measured by standard plate counting after removing the cells by sonication. More biofilm grew on used polyethersulfone (PES)
membranes than on new PES and polyvinylidene fluoride (PVDF) membranes. Both strains formed good biofilms, although K. B006 formed a denser biofilm than TR002. This corresponded to our previous study on the attachment of these organisms, where
K. B006 attached in greater numbers than K. TR002. The dual strains produced a higher biofilm density than single strains on the new membranes. Biofilm density tended
to increase with increased whey concentration. The saturated biofilm was approximately 108 CFU cm−2. PES membranes appeared to support biofilm growth less readily than did PVDF membranes and therefore may be the preferred
material for UF membranes to reduce problems with microbial colonisation. Used membranes were more readily colonised with
biofilm than were new membranes. Therefore, selecting a membrane type and monitoring membrane age will help manage biofilm
development during UF. |
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