Agglutination of Bacteria by a Lectin in the Hemolymph of the Pacific Oyster Crassostrea gigas

摘要

Cell-free hemolymph (plasma) from the Pacific oyster, Crassostrea gigas, contains two lectins with the ability to agglutinate ERBC (Gigalin E) and human RBC (Gigalin H). We investigated whether C. gigas plasma can agglutinate nine bacterial species, including five marine bacteria. All vertebrate erythrocytes (RBCs) tested (ERBC, GRBC and SRBC) were agglutinated by C. gigas plasma. Only Gigalin E required calcium ions for hemagglutinating activity (HA). A. globiformis, B. subtilis, D. aquamarina, E. coli, S. putrefaciens and S. aureus were agglutinated by C. gigas plasma, whereas M. halophilus, V. alginolyticus and V. tubiashii were not. Pre-incubation of C. gigas plasma with GRBC resulted in strongly reduced titers when the adsorbed plasma was titrated for agglutinating activity toward live cells of the three bacterial species. In contrast, pre-incubation with ERBC had no effect on subsequent agglutination of bacteria. The agglutinating activity of fixed cells of S. aureus did not change due to pre-adsorption with either ERBC or GRBC. These results indicate that the hemolymph component(s) responsible for erythrocyte agglutination also appear to be involved in bacterial agglutination. One component is probably Gigalin H, as indicated by the adsorption of hemagglutinating activity by GRBC.