Abstract:The in vitro inhibitory activities of microbial lysozyme against 14 microbial species and lipopolysaccharide（LPS）-induced inflammation in RAW264.7 macrophages were determined. The minimum inhibitory concentration（MIC）of the microbial lysozyme against the microbial species were determined by double dilution method，on the basis of which the in vitro antimicrobial activity of the lysozyme was measured.RAW264.7 macrophages were used to establish he LPS-induced inflammation model，and the anti-inflammatory activity of microbial lysozyme was evaluated based on the secretion of nitric oxide（NO）and tumor necrosis factor-alpha（TNF-α）in cells.The results showed that the microbial lysozyme exerted inhibitory effects against Escherichia coli，Bacillus subtilis，Staphylococcus aureus，Salmonella sp.，Listeria monocytogenes，Bacillus thermophilus，Saccharomyces cerevisiae，Clostridium butyricum，Penicillium flavum，Aspergillus niger，and Rhizopu sp.，demonstrating strong broad-spectrum antimicrobial activities.Within the tested concentration range，the microbial lysozyme had no inhibitory effect against Lactobacillus bulgaricus，Streptococcus thermophilus or Lactococcus lactis lactis，but promoted their growth. The microbial lysozyme showed significant inhibitory effect on LPSinduced inflammation of RAW264.7 macrophages，which significantly reduced the secretion of NO and TNF-α in a concentration-dependent manner.Compared with the model group，the microbial lysozyme reduced the secretion of NO and TNF-α by 57.92% and 36.75%，respectively.Microbial lysozyme has good antimicrobial and anti-inflammatory activities，which provides a theoretical basis for its application as a food additive in inhibiting the growth of spoilage microorganisms and promoting the proliferation of probiotics.