Study On Antimicrobial Effect Of Ferrous And Preservation Of Tilapia

7food deterioration bacteria of Staphylococcus aureus, Salmonella paratyphi, Escherichia coli and so on was used as the tested strains to study on the antibacterial activity of ferrous and the effect of pH on antibacterial activity. In addition, to investigate the antibacterial effect of ferrous and the application on Tilapia fish, the results are shown as follows:(1)In order to study the antibacterial effect of iron lactate, ferrous gluconate and ferrous citrate on food deterioration bacteria. The antimicrobial effect of organic acid ferrite was examined in vitro against Staphylococcus aureus, Escherichia coli, etc. And diameters of inhibition zone, MIC and MBC were used as the target. The results showed that the antimicrobial diameters of14.00mg/mL ferrite samples were all above12mm, iron lactate had best antibacterial activity, ferrous citrate was followed, ferrous gluconate was worest among them. The MIC was3.75mg/mL～10mg/mL, and the MBC was3.75mg/mL～20mg/mL. In the acid condition, antibacterial activity was better, as the pH rising, antibacterial activity receded.(2) The effect of ferrous lactate on growth inhibition and cell membrane damage of Staphylococcus aureus (G+) and Pseudomonas aeruginosa (G-) were investigated, through the determination of growth curve and its leakage of intracellular substances. As the results showed, the growth of bacteria was inhibited after treated by ferrous lactate; the conductivity value of treatment group had an increase of14%; the260nm absorbing material increased>42%, reducing sugar increased40%and increased concentrations of soluble protein>6.87%. The facts indicated that ferrous lactate solutions could damage the cell membrane, which resulted in the increase of permeability of cell membrane and release of cell components, and finally inhibit the growth of bacteria.(3) In order to study the antibacterial mechanism, select common Gram-positive pathogen Staphylococcus aureus and aquatic products typical of gram-negative bacteria Pseudomonas aeruginosa for detection, the OH·,the cell membrane oxidation, the change of cell lysis rate and the effect of DNA.(4) Ferrous lactate with0.5%citric acid were used for Tilapia preservation at8℃, the distilled water as control. The experiment result showed that, the sensory changes, the total count of bacteria colonies, pH, volatile basic nitrogen (TVB-N value), thiobarbituric acid (TBA value) were lower in these samples than the blank test group, which indicated the preservative term of Tilapia could be prolonged remarkably by using ferrous lactate.