Release of alkaline phosphatase from cells of Xanthomonas oryzae by manipulation of surface permeability.

Xanthomonas oryzae was shown to contain a constitutive alkaline phosphatase (EC 3.1.3.1.). The enzyme was detectable in intact cells and releasable by osmotic shock or spheroplast formation indicating its periplasmic location in the cell. Sonication released about 85% of the total enzyme, and the releasable amount was increased to 97% when lysozyme was added to the sonicated cells prior to centrifugation. These changes suggest an association of the enzyme with peptidoglycan; the enzyme is not released unless the polymer is digested to small units. Adapted usual method of spheroplast formation released 85%, while modified osmotic shock procedure released about 75% of the enzyme. These procedures released decreased amounts of the enzyme following cell growth reflecting that some changes were taking place toward a tighter association between the enzyme and the cell envelope during aging of the culture. During osmotic shock, the major portion of the released enzyme distributed in supernatant of the first stage (S1) hypertonic solution. The enzyme was inhibited by EDTA, whereas the inhibition was partially removed by dialysis and completely reversed by addition of MgCl2. Data obtained also indicated that X. oryzae seems to have relatively high content of periplasmic protein.