Occurrence and antigenic heterogeneity of L-2,4-diaminobutyrate decarboxylase in Acinetobacter species.

We have previously reported that a novel enzyme, L-2,4-diaminobutyrate decarboxylase (DABA DC), which is responsible for the formation of 1,3-diaminopropane, occurs in two Acinetobacter species. The present study extends this observation to additional Acinetobacter species and strains (6 reference strains and 30 clinical isolates). Furthermore, the DABA DC protein was detected in every strain by Western blot analysis with the antiserum against the enzyme purified from A. baumannii ATCC 19606. However, only the DABA DCs in the A. calcoaceticus and Acinetobacter genospecies 3 in addition to A. baumannii strains strongly cross-reacted with the antiserum, suggesting antigenic heterogeneity among the DABA DC proteins in Acinetobacter species. Therefore, immunological testing of the DABA DC protein may provide an additional method for differentiating and identifying Acinetobacter strains.