Catalyzes the hydrolysis of short-chain aliphatic amides to their corresponding organic acids with release of ammonia. Hydrolyzes propionamide, acetamide and acrylamide. Enables the organism to use such amides as both carbon and nitrogen source. Also exhibits in vitro acyl transferase activity, transferring the acyl moiety of short-chain amides to hydroxylamine or hydrazine to form hydroxamates and acid hydrazides respectively. The highest level of acyl transfer activity is observed with acetamide. a monocarboxylic acid amide + H2O = a monocarboxylate + NH4(+) Homotetramer. Belongs to the carbon-nitrogen hydrolase superfamily. Aliphatic amidase family.