【作者】 王丽莉；

【导师】 朱苏文；

【作者基本信息】 安徽农业大学 ， 生物物理学， 2007， 硕士

【摘要】 壳聚糖是甲壳素脱去部分乙酰基后得到的一种高分子阳离子多聚氨基多糖,主要存在于节肢动物的外壳中,在自然界产量仅次于纤维素。壳聚糖与生物体具有良好的相容性,被广泛应用于工业、农业、医药、化妆品、膜材料等领域。本文采用不同剂量的⁶⁰Co-γ射线辐照壳聚糖,研究其辐照降解效应,进行降解物的理化性质分析和不同分子量低聚糖分离,研究不同剂量辐照产物的壳聚糖溶液对玉米种子发芽、幼苗生长及相关生理生化特性的影响,同时研究壳聚糖辐照产物及不同分子量范围的壳聚糖对枯草杆菌和大肠杆菌的抑生效果。结果表明:1、壳聚糖经⁶⁰Co-γ射线辐照后,可引起壳聚糖降解,导致其理化性质发生了改变。pH值、溶解度均随着辐照剂量的增大而增大,当辐照剂量为600 kGy时,其溶解度和pH值分别为0.204 g（g·100 mL）^-1和8.18,在供试范围内达最大值。在辐射降解后的可溶产物中,0～1000 Da、1000～3000 Da、3000 Da以上的3个分子量范围的降解产物含量也随着辐照剂量的增大而增加。当辐照剂量为600 kGy时,各组分含量在实验范围内达最大,分别为0.04271 g（g·100 mL）^-1、0.03897 g（g·100 mL）^-1、0.12232 g（g·100 mL）^-1,其可溶性降解物比例达20.4%。2、壳聚糖的辐照产物可提高玉米种子发芽率、促进玉米幼苗生长,提高玉米抗逆相关生理生化指标。当辐照剂量为200 kGy时,壳聚糖辐照产物溶液浓度为0.3%时,可显著提高玉米种子萌发率和促进芽长;浓度为0.4%时,显著促进主根长度。当辐照剂量为200～400 kGy时,产物溶液浓度为0.2%～0.4%时,可显著提高胚乳中a-淀粉酶活性和幼苗中叶绿素含量。当辐照剂量为200～400 kGy时,其辐照产物浓度为0.2%～0.3%时,可显著提高幼苗过氧化物酶（POD）的活性;当辐照剂量200kGy,浓度在0.2%～0.3%时,苯丙氨酸解氨酶（PAL）活性显著高于对照。综合上述实验结果及成本等因素,利用壳聚糖辐照产物开发玉米促生抗逆剂的适宜⁶⁰Co-γ射线辐照剂量为200～300 kGy,浓度为0.2%～0.3%。3、利用壳聚糖辐照产物、水溶性组份和非水溶性组份对大肠杆菌和枯草杆菌抑生效果研究表明,在供试剂量和浓度范围内辐照产物能显著地抑制两种细菌的生长。在400 kGy,浓度为0.8%时,对枯草杆菌和大肠杆菌抑菌圈直径达最大,分别为（14.5±0.7）mm和（15.8±0.8）mm。分离得到的0～1000 Da、1000～3000 Da、3000Da以上的3种水溶性低聚壳聚糖的抑菌效果不明显,但非水溶性的辐照降解产物浓度在0.3%～0.5%有较明显的抑制效果,这表明抑制枯草杆菌和大肠杆菌的生长需要较高分子量的壳聚糖（＞10000Da）。综合研究结果表明:利用⁶⁰Co-γ射线辐照壳聚糖开发抑菌剂其辐照剂量为400 KGy左右,辐照产物浓度为0.6%～0.8%为宜。更多还原

【Abstract】 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%.更多还原