OBJECTIVETo study the inducible antibacterial activity of the hemolymph from housefly larva and analyze the antibacterial molecules.

METHODSThe hemolymph was collected from the third instar housefly larvae 48 h after pricking treatment. Nine standard bacterial strains were used for determination of the antibaterial activity of the collected hemolymph and its combination with ampicillin. The anti-yeast activity of the hemolymph and its mixture with fluconazol was also assayed. The antibacterial molecules in the hemolymph was analyzed by SDS-PAGE.

RESULTSThe growth of E.coli, Staphylococcus aureus, Staphylococcus albus, subserotypes of Shigeila flexneri, Bacillus proteus, Bacillus subtilis, Bacillus typhi, Bacillus paratyphosus, and Micrococcus lysodeikticus could be inhibited by the hemolymph collected from housefly larva, and the effect differed significantly between the groups (Plt;0.001). The hemolymph produced the strongest antibacterial activity against Micrococcus lysodeikticus, and the combination of the hemolymph with ampicillin most conspicuously inhibited the growth of Staphylococcus albus. The hemolyph and fluconazol exhibited obvious synergistic effect against yeast. SDS-PAGE identified some specific antibacterial molecules in the hemolymph.

CONCLUSIONThe induced hemolymph from housefly larva possesses strong antibacterial and antifungal activities especially against Micrococcus lysodeikticus. The hemolymph in combination with ampicillin produces the strongest effect against Staphylococcus albus, and fluconazol can significantly enhance the anti-yeast activity of the hemolymph through a synergistic mechanism.