Effect Of Aminoalkyl Groups Grafted Bacterial Cellulose On The Activity And Primary Metabolism Of Staphylococcus Aureus

As one of excellent natural polymers,bacterial cellulose has a enormous potential applied in manufacturing industry,food industry and biomedical fields.However,lack of certain properties such as antibacterial.antioxidant and conducting properties has diminished its capabilities in several fields.Functional modification is a considerable strategy to endow BC with new properties and expand its applications.In this study,BC was modified by chemical methods and a series of BC derivation materials were prepared including oxidation bacterial cellulose?OBC?,BC-NH-2 and OBC-NH₂.Scanning Electron Microscope?SEM?,Fourier Transform Infrared Spectra?FT-IR?,13C Nuclear Magnetic Resonance?NMR?and Thermogravimetric Analysis were used to characterize these materials.Staphylococcus aureus was used as the model strain to analysis the antibacterial activity of BC-NH₂ and OBC-NH₂.OBC with high oxidation degree and typical three-dimensional network structure was obtain in TEMPO-NaBr-NaCIO oxidation system.The carboxyl content of the OBC was 1.12mmol/g and the average degree of polymerization was 230.The zeta potential of OBC water dispersion was-42.96±0.46 which indicated that the OBC could be dispersed stably in aqueous solution.BC and OBC were modified by chemical grafting of aminoalkyl groups onto the surface of there nanofibrillar network.The N content of the obtained BC-NH₂ and OBC-NH₂ were 8.28%and 7.39%,respectively.The 1.5 mg/mL of BC-NH₂ and OBC-NH₂ can completely inhibit the growth of S.aureus.The Colony-Forming Units?CFU?of S.aureus treated with 2.0 mg/mL of BC-NH,or OBC-NH₂ was 104 less than control.These results indicated that BC-NH₂ and OBC-NF2 were lethal against gram-positive bacterias?such as S.aureus?.The metabolomics analysis revealed changes of intracellular metabolites in S.aureus based on gas chromatography-mass spectrometer?GC-MS?.In this work,a total of 66 intracellular metabolites were identified and quantified.The results of multivariate statistical analysis revealed the differences among groups in the intracellular metabolite,indicating that BC-NH₂ could interfere the metabolism of S.aureus.On the first principal component,the samples under the role of BC-NH₂ in the same concentration gathered,while the samples in different concentration obviously discreted,indicating that the antibacterial property of BC-NH₂ on S.aureus has a certain concentration dependence.Depending on the carbon metabolism analysis,it was found that glucose metabolism in S.aureus was inhibited under the role of BC-NH₂,decreases in the concentration of glycerate-2P,glycerate-3P and lactic acid,key intermediate metabolites in glycolysis.The accumulation of citric acid increased and the content of fumaric acid reduced,speculating that the TCA cycle was inhibited under the influence of antibacterial material.The content of intracellular ATP declined,which verified that the intracellular capacity pathways of S.aureus was repressed under the BC-NH₂.