Artificial symbiosis based bio-process

基于人工共生的生物过程

基本信息

批准号：
09650868
负责人：
SODE Koji
金额：
$ 2.05万
依托单位：
Tokyo University of Agriculture and Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Cyanobacteria play an important role as primary producers in aquatic environment. Carbon dioxide and nitrogen fixed by photosynthetically growing cyanobacteria are further utilized by other heterotrophic organisms. It has been generally accepted that heterotrophic bacteria directly utilize products excreted from algae, including cyanobacteria.Beside, the biological process for the degradation of environmental pollutants, bioremediation, has been paid significant attention. In order to construct an efficient and stable bioremediation system, microbial consortiums are often utilized, which are composed of several strains of microorganisms capable of the degradation and/or mediating the degradation of pollutants. These microbial consortium is composed of heterotrophic bacteria, therefore, is not suitable for the application in the low-nutrient condition, such as marine environment.Here, we focused on the application of the cyanobacteria as the producer and doner of nutrient for heterotrop … More hic bacteria, which are capable for the bioremediaton. We designated such a systematic microbial consortium composed of autotrophic bacteria and heterotrophic bacteria as an "Artificial Symbiosis". We aimed the construction of an artificial symbiosis and its application for the bioremediation of insecticide.First, we have investigated the model artificial symbiosis, which is composed of a nitrogen fixing cyanobacterium, Anabaena sp. PCC7 120 and Escherichia coli as a representative heterotrophic bacterium. E.coli cells were able to grow in the culture supernatant of Anabaena sp., indicating that E.coli cells can metabolite the nutrients excreted by Anabaena sp.. On the basis of this finding, we carried out the pseudo-continuous maintenance of the artificial symbiosis, under both continuous light illumination and light/dark cycle. Both of the system were revealed to be maintained for more than 200 hours without the decrease in both microorganisms, suggesting that our idea of the artificial symbiosis can be constructed and maintained.Then we have constructed an artificial symbiosis for bioremediation of insecticide, As for the cyanobacterium, Anabaena sp. was used. As for the heterotrophic bacterium, Flavobacterium sp. which produces an enzyme, phosphotriesterase (PTE), thereby degradating organophosphorous insecticides, was used. Flavobacterium sp. Was able to grow in the culture supernatant of Anabeana sp., and also express enough level of PTE for the degradation of phenitrothion, a representative organophosphorous insecticide. Pseudo-continuous cultivation of the artificial symbiosis composed of Anabaena sp. and Flavobacterium sp. was carried out under both continuous light illumination and light/dark cyrcle. The ability of the degradation of phenitrothion has been maintained in the both conditions, by expressing PTE activity of growing Flavobacterium sp. cells.We also succeeded in the construction of a recombinant marine cyanobacterial strain, which can grow in the presence of heavy metals, such as Zn, Cu or Cd, by the heterogenic expression of metallothionein gene. Such recombinant marine cyanobacterial strains will be further utilized for the construction of an artificial symbiosis for bioremediation. Less

蓝藻作为水生环境中的初级生产者发挥着重要作用，通过光合生长的蓝藻固定的二氧化碳和氮被其他异养生物进一步利用，人们普遍认为异养细菌直接利用藻类（包括蓝藻）分泌的产物。为了构建高效、稳定的生物修复体系，微生物降解环境污染物的生物修复过程受到了人们的高度重视。经常使用由多种能够降解和/或介导污染物降解的微生物菌株组成的菌群，这些微生物菌群由异养细菌组成，因此不适合在低营养条件下应用。例如海洋环境。在这里，我们重点关注蓝藻作为异养细菌的营养生产者和供体的应用，这些细菌能够进行生物修复，我们指定了这样一个系统。由自养细菌和异养细菌组成的微生物群落作为“人工共生”我们的目标是构建人工共生及其在杀虫剂生物修复中的应用。首先，我们研究了由固氮组成的人工共生模型。蓝藻、鱼腥藻 PCC7 120 和大肠杆菌作为代表性异养细菌能够在其中生长。鱼腥藻的培养上清液，表明大肠杆菌细胞可以代谢鱼腥藻分泌的营养物质。在此发现的基础上，我们在连续光照和光照条件下进行了人工共生的伪连续维持。光/暗循环。这两个系统都被揭示维持超过200小时，而两种微生物都没有减少，这表明我们的人工共生的想法是可以构建和维持的。我们构建了一种用于杀虫剂生物修复的人工共生体，使用了异养细菌黄杆菌，它可以产生磷酸三酯酶（PTE），从而降解有机磷杀虫剂。 sp. 能够在 Anabeana sp. 的培养物上清液中生长，并且还表达足够水平的 PTE研究了鱼腥藻和黄杆菌组成的人工共生体对苯螟硫磷的降解能力。通过表达生长的黄杆菌属细胞的 PTE 活性，在这两种条件下都能维持。我们还成功构建了重组体。海洋蓝藻菌株，通过金属硫蛋白基因的异源表达，可以在重金属（如锌、铜或镉）存在下生长，这种重组海洋蓝藻菌株将进一步用于构建用于生物修复的人工共生体。