Study On The Antibacterial And Anti-Fatigue Effects Of Chitosan

Chitosan is a broad spectra disinfectant, it inhibits the growth of a wide variety of bacteria and fungi. In addition, compared with other preservatives, it possesses a higher antibacterial activity, a broader spectra of activity, a higher killing rate, and lower toxicity toward mammalian cells. Chitosan has a wide range of application as natural preservative. But chitosan is only soluble in acidic solution, and hardly soluble in solution above pH6.5 or most organic reagent because of its poor solubility. This restrains its application in many fields. In order to improve its solubility and broaden its application, N,O-carboxymethylated chitosan was prepared. At the same time, different molecular weight chitosan and N,O-carboxymethylated chitosan were prepared by H₂O₂ and cellulase, respectively.E.coli and St.aureus are both main pathogens in food processing, storage, transportation. The antibacterial effect of chitosan and N,O-carboxymethylated chitosan with different concentration, molecular weight, DDA, DCA, pH, temperature, inorganic elements and medium were determined by spectrophotometry method and Oxford cup-Petri dish method, respectively;and the optimal antibacterial condition was obtained.With further studies of polysaccharide going on, chitosan is drawing more and more attention now. But its anti-fatigue effect is seldom reported at present. The mice were fed with chitosan of different molecular weight (2.4×10³ and 7.6 ×10⁴Da)and the same degree of deacetylation (DDA%=92.8) by oral administration. The swimming time, glucose and lactic acid concentration in blood and glycogen contents in liver and muscle were determined after 18 days and 24 days, respectively.Conclusions:(1) The antibacterial effect of chitosan and N,O-carboxymethylated chitosan on E.coli and St.aureus was distinctly influenced by the concentration, medium, molecular weight, DDA, DCA, pH, temperature and inorganic elements. Chitosan and N,O-carboxymethylated chitosan with molecular weight about 1.0 ×10⁵Da had the best antibacterial effect.(2) Animal experiments showed that chitosan could prolong the swimming time, speed up the recover of blood glucose and elimination of lactic acid;improvethe liver and muscle glycogen content. Results indicated that chitosan had anti-fatigue effect, the effect related to chitosan's dosage and molecular weight. High dosage and low molecular weight chitosan displayed better effect.