镉（Cd2+）胁迫对地木耳生长和生理特性的影响
毕业论文关键词：地木耳；镉胁迫；生长；生理特性；
Effects of cadmium (Cd2+) stress on growth and physiological characteristics of Nostoc commune
Student majoring in life science and technology baseGaoShuyuan
Tutor Luwei
Abstract：Nostoc commune is a kind of blue-green algae, which belonged to Cyanophta, Cyanophyceae, Nostocates, and a type of Nostoc in cluster. It is edible and medicinal, abundant in polysaccharides, proteins, amino acids and other nutritional ingredients. The usage of N. commune is wide and the history is long in China. In order to study the effect of Cadmium stress on Nostoc commune growth and physiological characteristics, the Nostoc commune were treated with BG11 nutrient solution supplemented with cadmium. Growth indexes of Nostoc commune were also recorded during growth. After two weeks of culture, cadmium treatment was carried out, and the growth indexes such as color change and mass growth were recorded on day 14, day 28 and day 42 after cultured, and the content of MAD and proline were determined after culture for 42 days. The value of Fv/Fm and Fv/Fo were also recorded. The results showed that the growth index of Nostoc commune under the treatment of cadmium was significantly lower than that of the control group, while MAD and Pro increased with the increase of cadmium concentration.
Keywords:Nostoc commune；Cadmium stress；Biological characteristic
引言 地木耳（Nostoc commune）是一种有一定食用价值与医疗保健价值的天然食品。在我国许多省市，地木耳都作为野菜资源而被记载。地木耳含有丰富的多糖、蛋白质、氨基酸等，可以食用也可以作为药材，我国人民对其利用广泛且历史久远。地木耳含水量高，且可以进行固氮作用，在农业、食品业、环境保护业以及医药业等方面发挥作用，有实验表明，地木耳中的胞外二萜类物质具有抗菌作用[1]。随着科技的发展，地木耳的应用范围逐渐扩大。
地木耳中矿质元素含量丰富，其含有的许多微量元素是人体必需的元素成分，但是如果重金属元素过高，会对人体健康造成严重影响。Katoh报道[3]，地木耳容易从土壤中吸收Cs等放射性元素，使土壤中元素含量降低，但地木耳中元素含量增加。某些地区由于污染等影响，可能会导致地木耳中重金属元素超标，危害人们的健康[2,3,4,5，6]，某些需要经过检测后再谨慎食用。如盛家荣等报道的采自于大学校园的地木耳，铜含量高达10. 46mg/100g , 锌含量高达36 . 86mg/ 100g。这就要受到人们的重视，谨慎采食。
地木耳的食用安全性值得深度研究，地木耳是一种野生资源，而土壤镉富集现象多见，故镉对其的影响值得研究。
镉（Cd）作为一种重金属，本身是具有金属光泽的，并且是一种非典型过渡性元素。它在元素周期表中的位置是第五周期第ⅡB族。镉元素的毒性非常强，对生物的毒性几乎仅次于汞，并且由于它有特殊的聚集性，容易累积在植物或环境中，同时又具有 “三致”效果，所以是非常强烈的剧毒元素。如果生物摄入过量的镉，产生的危害极其严重，甚至会伤害到生物体的许多重要器官，例如肾脏、肝脏、肺部、骨骼、生殖器官等，生物体最重要的免疫系统和心血管系统也会受到镉的毒害，严重的话会引其多种疾病。当下研究情况来说，镉作为对环境、医学等领域有严重危害和强烈毒性的重金属元素，已经受到了广泛的关注和深入的针对性研究。