Effects of moisture and sorption on bioavailability of p-hydroxybenzoic acid to Arthrobacter sp. in soil

Effects of bioavailability on degradation of C-14-p-hydroxybenzoate were ex amined using sterile soil inoculated with Arthrobacter sp. Physical accessi bility of p-hydroxybenzoate was controlled by varying pore continuity with a range of moisture regimes (-33 to -420 kPa), whereas sorption was control led via addition of an exchange resin. Arthrobacter sp. accessed 94% of p-h ydroxybenzoate in soil at -33 kPa, owing to continuity of soil pores and su fficient cells to exploit available space. A deviation in degradation kinet ics at -420 kPa soil was attributed to inaccessible p-hydroxybenzoate in so lution. Addition of resin decreased extent of degradation, though the effec t diminished as pore continuity decreased. Subtle differences in effects of these processes on degradation kinetics may facilitate their separate trea tment in environmental fate models.