Extracellular polymers are susceptible to oxidativereductive
depolymerization (ORD) which results in cleavage
of linkages in the polymeric backbone (Herp [50]; Christensen
et al. [51]; Wingender et al. [10]). The degradation
of alginate by ORD has been studied in detail (Smidsrod
et al. [52–54]). ORD involves a series of free radical reactions
which ultimately lead to chain scission. Molecular
oxygen and transition metal ions (e.g. Fe
2+
/Fe
) are efficient
catalysts. The Fenton reagent effectively degrades
polymers (Christensen et al. [55]). ORD has the advantage
that relatively high depolymerization rates may be obtained
at ambient temperature due to the low activation energies,
whereas acid or alkaline hydrolysis require high temperatures.
Acids or alkalis can be employed, but the degradative
effects are non-specific and may severely affect the cells.
Most cells have an intracellular defense system against toxic
radicals. This means that peroxides may operate within a
biofilm, but that they degrade only extracellular material
such as the matrix (Christensen et al. [55]).
3+