Acrylamidase enzymes are provided which have acrylamidase activity at pH 4.0 which is at least 50 % of their acrylamidase activity at pH 7.0. Such enzymes can be produced by the novel microorganisms Rhodococcus strains NCIMB 40889 and NCIMB 40755. Such enzymes and microorganisms can be used for reducing free acrylamide in polyacrylamides which are produced at low pH and in particular cationic and substantially non-ionic polyacrylamides.