Catalyzes the conversion of L-asparagine to L-aspartate and ammonium. H2O + L-asparagine = L-aspartate + NH4(+) Homotetramer. Expression is induced during limiting-nitrogen conditions by the nitrogen regulatory factor TnrA. B.subtilis contains two L-asparaginase isoenzymes: L-asparaginase I, a low-affinity enzyme located in the cytoplasm, and L-asparaginase II, a high-affinity secreted enzyme. Belongs to the asparaginase 1 family.