Expression, antibacterial and anti-inflammatory activity of secretory lysozyme from maggots of Musca domestic

  Objective  To investigate antibacterial and anti-inflammatory activities of secretory lysozyme from larvae of Musca domestic.

  Methods  Secretions from the third instar larva of Musca domestic were collected; then the expression of lysozyme in the secretions was detected with sodium dodecyl-polyacryl gradient gel electrophoresis (SDS-PAGE) assay and the content of the lysozyme was measured with turbidimetry. The chemical components with the molecular weight (MW) of 10 – 30 kDa were purified from the secretion with millipore filter. The purifications' bacteriostasis against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was determined with bacteriostatic curve method and the anti-inflammatory activity was detected with RAW264.7 cells.

  Results  The concentration of lysozyme in the secretions was 0.432 ± 0.01 μg/mg. Bacteriostatic curves of the secretions' components with MW of 10 – 30 kDa showed an inhibitory effect on the proliferation of both E. coli and S. aureus. Compared to that (0.42 ± 0.02 μmol/L) in the blank control, the concentration of nitric oxide (NO) in RAW264.7 cell culture fluid significantly increased to 15.34 ± 2.05 μmol/L in the lipopolysaccharide (LPS) group; while, the cell culture fluid NO concentration (7.32 ± 0.62 μmol/L) of the Musca domestic larvae secretion group was significantly decreased in comparison with that of LPS group, indicating the anti-inflammatory activity of secretion components with the MW of 10 – 30 kDa.

  Conclusion  There is lysozyme in the secretory components with the MW of 10 – 30 kDa from larvae of Musca domestic and the components have antibacterial and anti-inflammatory activities.