土壤食细菌线虫对细菌的取食偏好及生理生化机制的初步研究

发布时间：2018-05-25 23:03

本文选题：灰潮土 + 食细菌线虫　；参考：《南京农业大学》2015年硕士论文

【摘要】：土壤线虫是土壤生态系统中极为丰富的后生动物,也是土壤动物中重要的功能类群,它们在各种生境的土壤中分布都很广泛,数量多达7.6×105-9.2×106条/m2。因农田食物环境更有利于食细菌线虫的生长发育,食细菌线虫在农田土壤中的重要性显得更为突出。选择性取食是动物普遍存在的现象,食细菌线虫选择性取食土壤细菌不但会改变土壤微生物数量、活性和群落结构,还会直接影响线虫的生存适应性及健康。本研究以模式线虫秀丽隐杆线虫(Caenorhabditis elegans)、两株土著优势食细菌线虫拟丽突属线虫(Acrobeloidessp.)及中杆属线虫(Mesorhabditissp.)和五株细菌(解淀粉芽抱杆菌(S.amyloliquefaciens)、贪噬菌(Variovorax sp.)、巨大芽抱杆菌(B.megaterium)、荧光假单胞菌(P.fluorescens)和大肠杆菌OP50(E.coli))为材料,研究了食细菌线虫对五株细菌的活菌体、灭活菌体及细菌分泌物的取食行为,同时还研究了食细菌线虫对不同浓度细菌的取食行为。取食偏好试验在线虫培养基上进行,并于接种线虫后的1、2、4、8、12、24h后观察记录线虫的迁移数量,研究食细菌线虫对土壤中不同细菌的取食行为。本试验从细菌的总糖、蛋白质、体积大小、挥发性代谢产物等方面出发,对食细菌线虫对不同细菌取食偏好性的机制进行了初步研究,主要研究结果如下:本试验从南京市长江南岸的灰潮土中筛选出两株土著优势食细菌线虫和一株优势细菌,经过初步鉴定两株食细菌线虫分别是拟丽突属线虫和中杆属线虫,一株优势细菌为荧光假单胞菌。食细菌线虫对不同的细菌具有取食偏好性,三种食细菌线虫均偏好取食P.fluorescens细菌,不偏好S.amyloliquefaciens和S.megaterium这两株细菌。相对于革兰氏阳性细菌,食细菌线虫更加偏好取食革兰氏阴性细菌。通过食细菌线虫对活菌体、灭活菌体以及菌体分泌物的取食比较,试验发现秀丽隐杆线虫对活菌体和灭活菌体的取食偏好不完全一致,对细菌分泌物的取食没有偏好性;拟丽突属线虫对活菌体和灭活菌体具有相似的取食偏好性,而对细菌分泌物的取食没有偏好性;中杆属线虫对活菌体和灭活菌体的取食偏好不完全一致,中杆属线虫对细菌分泌物的取食有偏好性,并且取食偏好顺序和对活菌的偏好顺序一致。细菌分泌物对秀丽隐杆线虫和拟丽突属线虫的取食偏好没有影响,而对中杆属线虫的取食偏好有影响。通过研究食细菌线虫对不同浓度的细菌的取食偏好,我们发现食细菌线虫偏好取食高浓度的细菌,并且喜欢聚集在高浓度的细菌上。通过对五株细菌的大小、含水量、总糖以及总蛋白质的测定,试验结果表明食细菌线虫对不同细菌的取食偏好与细菌的总糖和总蛋白质没有相关性,而与细菌的大小和细菌的含水量有一定的相关性,食细菌线虫偏好取食体积比较小及含水量比较高的细菌。通过对细菌的脂肪酸和挥发性代谢产物的测定,发现食细菌线虫偏好取食的P fluorescens和E.coli在组成上比较接近,食细菌线虫不偏好的Variovorax sp.、B.megateriu、B.amyloliquefaciens在组成比较接近。食细菌线虫对取食细菌的偏好性的机制还需进一步深入的研究。
[Abstract]:Soil nematode, a very rich metazoan in the soil ecosystem, is also an important functional group in soil animals. They are widely distributed in various habitats, with a number of as many as 7.6 x 105-9.2 x 106 /m2., which are more conducive to the growth of bacteria eating nematodes, and the weight of bacteria eating nematodes in farmland soil. The selective feeding is a common phenomenon in animals. The selective feeding of bacteria by bacteria eating nematodes will not only change the number of soil microorganisms, the activity and community structure, but also directly affect the survival adaptability and health of the nematodes. This study is based on the Caenorhabditis elegans of model nematode, two strains of nematode nematode The indigenous predominance of Acrobeloidessp. and Mesorhabditissp. and five strains of bacteria (S.amyloliquefaciens, Variovorax sp., B.megaterium), Pseudomonas aeruginosa (P.fluorescens) and Escherichia coli (E.coli) were used as materials. The feeding behavior of the living bacteria, inactivating mycelia and bacterial secretions of five strains of bacteria, and the feeding behavior of bacterial nematodes to bacteria of different concentrations was also studied. The feeding preference test was carried out on the online insect medium, and the number of nematode migration was observed after 1,2,4,8,12,24h after inoculation, and the nematode eating nematodes was studied. The feeding behavior of different bacteria in the soil was studied in this experiment. From the total sugar, protein, volume and volatile metabolites of bacteria, the mechanism of the feeding deviation of bacterial nematodes for different bacteria was preliminarily studied. The main results were as follows: two strains of soil were screened from the soot soil in the South Bank of the Yangtze River in Nanjing. The dominant bacteria eating nematodes and one of the dominant bacteria were preliminarily identified as two bacterial nematodes, Pseudomonas nematodes and middle genus nematode, and one of the dominant bacteria was Pseudomonas fluorescens. Bacteria eating nematodes were feeding preference to different bacteria. Three species of bacterial nematodes preferred to eat P.fluorescens bacteria and did not prefer S.amylol Iquefaciens and S.megaterium were two bacteria. Compared with Gram-positive bacteria, bacterial nematode was more preferred to eat Gram-negative bacteria. The feeding preference of Caenorhabditis elegans to living and inactivated bacteria was not completely consistent by comparing the feeding of living bacteria, inactivated mycelia and mycelium secretion by the bacterial nematode. There is no preference for the feeding of bacterial secretions; the nematode has a similar feeding preference to living and inactivated bacteria, but no preference for the feeding of bacterial secretions; the feeding preference of the nematode to the living and inactivated mycelia is not exactly the same, and the nematode of the genus nematode has a preference for the feeding of bacterial secretions. The order of feeding preference and the order of preference for living bacteria are consistent. Bacterial secretions have no effect on the feeding preference of Caenorhabditis elegans and P. elegans, but have an influence on the feeding preference of the nematode. By studying the feeding preference of bacterial nematode to different concentrations of bacteria, we found that the high concentration of the bacteria eating nematodes preference is high. The test results showed that the feeding preference of bacterial nematodes to different bacteria was not related to the total sugar and total protein of bacteria, but with the size of bacteria and the water content of bacteria in a certain phase, by measuring the size, water content, total sugar and total protein of five strains of bacteria. By the determination of the fatty acid and volatile metabolites of bacteria, it was found that the composition of P fluorescens and E.coli for eating bacterial nematode preference was close to that of Variovorax sp., B.megateriu, B.amyloliquefaciens, which were not preferred by bacterial nematodes. The mechanism of bacterial preference for bacterial feeding needs further study.
【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S154.386

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