Studies Of The Degradation Of Chitosan By Irradiated And Effects Of Decomposed Gradients Of Chitosan On The Promoting Growth Of Maize And The Inhibition Of Bacteria

Chitosan is a kind of cationic polymer glycosaminoglycans which is taken from acetyl-off Chitin.Chitin mainly consists in the shell of Arthropod,whose output is after cellulose in the natural world.Chitosan has good compatibility with organisms,so it has been widely used in industry,agriculture,medicine,cosmetics,film and other fields.In this experiment,chitosan was degraded through radiated by ⁶⁰Co-γ-ray at different doses. The different molecular weight oligosaccharides were separated and the physicochemical properties of the degradation production were studied.The effect of the irradiation product of chitosan on the germination,growth,physiological and biochemical characteristics of maize were studied and the effects of chitosan of different molecular weights on Bacillus subtilis and Escherichia coli were also studied.The results are presented as follows:1.Radiated by ⁶⁰Co-γ-ray,the chitosan will degrade,accompanying by the change of its physical and chemical properties.Its pH and solubility monotonously increase with the radiation dose increasing.When the radiation dose reached 600 kGy,its solubility and pH reached maximum,were 0.204g(g·100 mL)and 8.18 respectively.In the soluble products after radiation,three kinds of degradation products,whose molecular weight were 0～1000Da,1000～3000Da and over 3000Da,increased with the radiation dose increasing.When the radiation dose was 600 kGy,the content of each component within the scope of the experiment was the biggest,0.04271 g(g·100mL)^-1,0.03897 g(g·100mL)^-1,0.12232 g(g·100mL)^-1respectively,and the ratio of soluble degradation products reached 20.4%2.Chitosan degradations can enhance seed germination rate,raise corn resilience and resistance.When the irradiation dose was 200 kGy and the solution concentration was 0.3%,the seed germination rate and the sprouts length were significantly higher than the comparison;when the irradiation dose was 200 kGy and the solution concentration was 0.4%,the length of taproot was significantly higher than the comparison.When the radiation doses were 200～400 kGy and solution concentrations were 0.2%～0.3%the a-amylase activity and the chlorophyll were significantly higher than the comparison. When the radiation doses were 200～400 kGy and solution concentration is 0.2%～0.3%, the peroxidase(POD)activity of maize seed was significantly higher than the comparison. When the radiation dose was 200kGy and solution concentration is 0.2%～0.3%,the peroxidase(PAL)activity of maize seed was significantly higher than the comparison. Considering these results and cost of production,to exploder resistance reagent on maize, the appropriate ⁶⁰Co-γ-ray irradiation doses are 200～400kGy,and the concentrations is 0.2%～0.4%3.The results of the inhibition of Escherichia coli and Bacillus subtilis by irradiated chitosan mixed product,water-soluble components and non-water-soluble component, showed that the irradiation product can significantly inhibit the growth of two types of bacteria in the volume and concentration of reagent.When the irradiation dose was 400 kGy and the concentration was 0.8%,the diameter of antibacterial circle of B.sub and E. coli reached maximum,(14.5±0.7)and(15.8±0.8)mm,respectively.The antibacterial properties of three types of separated water-soluble chitosan oligosaccharide of 0～1000 Da,1000～3000 Da and over 3000 Da were weaker than un-water-soluble chitosan, showed that inhibition of the growth of Escherichia coli and Bacillus subtilis need larger molecular chitosan.In summary,for developing chitosan antibacterial reagent by ⁶⁰Co-γ-ray irradiation,the appropriate ⁶⁰Co-γ-ray radiation dose is 400 kGy and the irradiation product concentration range is 0.6%～0.8%.