红壤产多糖细菌的筛选及其生物多样性

发布时间：2018-06-07 00:21

  本文选题：细菌 + 胞外多糖　； 参考：《南京农业大学》2015年硕士论文

【摘要】：多糖是一种重要的生物大分子,它拥有各种各样的特异性的结构,具有多种生理生态功能,在工农业生产及医疗、制药等领域具有非常广泛的应用。微生物来源的多糖具有潜在的应用价值和发展前景,其研究越来越受到人们的重视。因此,研究土壤产胞外多糖细菌有着重要的理论和现实意义。鉴于此,本课题拟从红壤中筛选高效产胞外多糖细菌,并研究细菌的遗传多样性和功能多样性,探索产多糖细菌的培养基营养和条件;并通过产多糖细菌对环境条件抗性的研究,来寻找能不受外部条件太多限制的产多糖菌株,使产多糖细菌在土壤改良中发挥作用。研究结果不仅有助于对产多糖细菌生物多样性的深入认识,丰富产多糖细菌资源库、基因库,还能够为该类菌种代谢机制及在各领域的应用提供试验依据。也可为后续试验研究提供菌种资源。本文以来源于红壤的207株产多糖细菌为材料,采用苯酚-硫酸法测定发酵液中可溶性多糖,筛选获得30株多糖高产菌株,对高产菌株进行了细菌菌落形态及其对环境适应性的研究,分析了碳氮源对高产菌株多糖产量的影响,并对其中26株高产胞外多糖细菌进行了 16SrDNA序列测定及系统发育关系的研究。研究结果如下:1、菌落形态学的研究表明,菌落呈白色或微黄色,有粘性,透明或半透明,形状圆形突起,大小在2.0-5.2 mm之间;2、大部分菌株正常生长的pH范围在6-8之间,温度在20℃-30℃之间,渗透压范围在1%—2%,大部分菌株对氨苄青霉素有抗性,对四环素和利福平无抗性;同时还发现,菌株2-7、菌株2-34、菌株3-3和菌株1-22在酸性、碱性、低温和高盐溶液的环境中都具有很强的抗性。可作为后续试验土壤改良的菌种资源。3、碳氮源对菌株多糖产量影响的研究结果表明,菌株4-27-1、菌株5-3、菌株4-8、菌株4-30和菌株4-27-2生长的最佳碳源和氮源分别为蔗糖和硫酸铵;糖蜜是菌株4-8和菌株4-27-2的次选碳源;菌株5-3和菌株4-27-2也可选择硝酸铵作为氮源;菌株6-20可选择大豆粉作为氮源。4、16S rDNA序列分析结果表明,26株细菌分别隶属于7个属,菌株1-1和菌株1-3属于芽孢杆菌属(Bacillus);菌株1-22、菌株2-7和菌株3-3属于沙雷氏菌属(Serratia);菌株1-35、菌株5-12和菌株6-22属于伯克霍尔德氏菌属(Burkholderia);菌株2-22属于中慢生根瘤菌属(Mesorhizobium);菌株6-34属于根瘤菌属(Rhizobium);菌株3-15、菌株4-27-1、菌株4-27-2、菌株4-30、菌株5-3、菌株5-19、菌株5-25、菌株5-33共8株属于类芽孢杆菌属(Paenibacillus);菌株2-26、菌株2-34、菌株3-25、菌株4-5、菌株4-6、菌株4-8、菌株4-9、菌株4-39共8株属于剑菌属(Ensifer)。初步确定产胞外多糖能力最强且菌株来源最多的是类芽抱杆菌属(Paenibacillus),其中菌株4-27-1的多糖浓度最高为3.21 mg/ml;产胞外多糖能力相对较弱的是根瘤菌属(Rhizobium),其多糖浓度为0.70mg/ml。
[Abstract]:Polysaccharide is an important biological macromolecule, it has a variety of specific structures, has a variety of physiological and ecological functions, and has a wide range of applications in industrial and agricultural production, medical treatment, pharmaceutical and other fields. Polysaccharide from microbial sources has potential application value and development prospect, and its research has been paid more and more attention. Therefore, the study of soil extracellular polysaccharide bacteria has important theoretical and practical significance. In view of this, the aim of this study was to screen the highly efficient extracellular polysaccharide producing bacteria from red soil, to study the genetic diversity and functional diversity of the bacteria, and to explore the nutrition and conditions of the culture medium for the polysaccharide producing bacteria. By studying the resistance of polysaccharide-producing bacteria to environmental conditions, we can find out the polysaccharide producing strains which can not be restricted by external conditions, so that the polysaccharide-producing bacteria can play an important role in soil improvement. The results can not only help to understand the biological diversity of polysaccharide producing bacteria, enrich the resource bank and gene pool of polysaccharide producing bacteria, but also provide experimental basis for the metabolic mechanism of this kind of bacteria and its application in various fields. It can also provide strain resources for further experimental research. In this paper, 207 strains of polysaccharide producing bacteria from red soil were used as materials to determine soluble polysaccharides in fermentation broth by phenol-sulfuric acid method. The morphology of bacterial colony and its adaptability to environment were studied, and the effects of carbon and nitrogen sources on polysaccharide yield of high-yielding strains were analyzed. The 16SrDNA sequence and phylogenetic relationship of 26 strains of high-yielding extracellular polysaccharide bacteria were studied. The results were as follows: 1. The colony morphology showed that the colony was white or yellowish, sticky, transparent or translucent, with a circular protuberance, ranging in size from 2.0 to 5.2 mm, and the pH range of normal growth of most strains ranged from 6 to 8. The temperature ranged from 20 鈩，

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