Antibacterial activity of xanthan-oligosaccharide against Staphylococcus aureus via targeting biofilm and cell membrane

Previously, an antioxidant xanthan-oligosaccharide (LW-XG) was successfully produced via bio-degradation of commercial xanthan. In present work, the antibacterial activity and mechanism action of LW-XG against Staphylococcus aureus were studied. Inhibition zone of LW-XG in agar diffusion test was evident and its minimal inhibitory concentration (MIC) against S. aureus was 0.63 mg/mL. Inhibitory mechanism investigation showed that LW-XG increased the cell membrane permeability of S. aureus. Meanwhile, we found that LW-XG could retard the formation of S. aureus biofilm and lower the transcriptional levels of genes (fnbA,fnbB and clfB) related to biofilm formation. Furthermore, LW-XG decreased the Ca2+-Mg2+ -ATPase activity on S. aureus cell membrane and promoted the accumulation of calcium ions in cytoplasm. Overall, LW-XG could inhibit the growth of S. aureus and be regarded as a promising antibacterial substitute in food and pharmaceutical industries. (C) 2020 Elsevier B.V. All rights reserved.