Hydrolysis rates under potentially inhibitory concentrations of ammonia and salinity were investigated for two model feedstocks (manure and food waste). Rates were determined under a range of ammonia and salinity concentrations (1.0-10.0 g TAN [total ammonia nitrogen] L-1 and 3.9-20.0 g sodium L-1) with unacclimated and acclimated microbial inocula. Microbial community changes as a function of acclimation and feedstock were also investigated. Using unacclimated inocula, hydrolysis was found to be severely inhibited for elevated ammonia and salinity (similar to 4 to 10-fold, respectively) or hydrolysis was not detected. However, for inocula acclimated over 2-4 months, statistically significant inhibition generally was not detectable. Molecular analyses demonstrated that microbial community composition changed during acclimation, and bacterial communities under elevated ammonia were distinct from communities under elevated salinity. Feedstock source also had a major influence on bacterial community structure. (c) 2013 Elsevier Ltd. All rights reserved.