青年说 ‖ 李依静：自然知道答案

由于一直对生物学科感兴趣，我从一开始就选择了环境微生物学作为自己的科研方向。下至的海底热液喷口，上至常年冰冻的高原冰川，微生物几乎无处不在。微生物具有及其多样的遗传信息，进行成千上万种代谢生长方式，组成结构功能各异的微生物群落，进而在不同的生态位发挥其独特的功能。即使是培养鉴定技术已经取得极大进步的今天，目前我们能够进行实验室培养的微生物也仅占到了全部微生物的1~10%左右，无数角落潜藏的微生物资源仍等待我们去进行更深入的探索。

Because I’ve been always interested in biology, so I chose environmental microbiology as my study interest at the beginning. From marine hydrothermal whose temperature can be as high as 400℃, to the whole year frozen plateau glacier, microorganism are ubiquitous in environment. Microbes are highly diverse in phylogeny with various genetic information, they perform a wide range of metabolism and growth patterns, and form microbial communities with distinct compositions and structures, and play unique roles in different niches in consequence. Even nowadays, when the microbial cultivation and identification technology has developed into a new stage, the microbes we can cultivate in the labs only accounts for 1~10% of the total microorganisms in nature, the hidden resources of microorganisms are still there for further explorations.

本科时期，我主要进行氮素厌氧氨氧化过程的研究。厌氧氨氧化菌是一种非常神奇的细菌，它们选择了一种十分困难的生活方式——在厌氧的条件下利用亚硝酸盐/硝酸盐氧化铵盐获取能量，以无机的碳酸盐作为碳源生长，因此这种细菌的倍增代时可长达两周以上。然而就是这样一种以艰难方式努力生长的细菌，却贡献了海洋中50%的氮素去除，同时为污水的厌氧脱氮打开了高效节能工艺的大门，是环境微生物学中一个里程碑式的发现。

In my bachelor period, I mainly studied on anaerobic ammonium oxidation. The bacteria (anaerobic ammonium oxidation bacteria, AAOB) proceeding this process is magical, they choose a harsh way to make livings, namely, using nitrate/nitrite to oxidize ammonium under anoxic condition, and grow on inorganic carbonate as carbon source, thus the doubling time of AAOB can be as long as two weeks. However, living such a struggling life, AAOB contribute to half nitrogen removal in marine environment, as well as shed the light on the energy-efficient technology of anaerobic wastewater denitrogenation, which is a milestone discovery in the field of environmental microbiology.

硕士阶段，我主要关注环境有机污染物的厌氧微生物降解。随着科技发展，无数有机化合物被排放到了环境中去，如多环芳烃、农药、抗生素等等，这些有机污染物的毒性效应对人类健康和生态环境安全造成重大威胁。许多报道表明，新兴合成的污染物在进入环境之初总能“大杀四方”，由于其复杂特殊的分子结构，环境中往往缺乏能够实现对其降解的微生物。但经过一定时间的适应演化过程，少则几周、多则百年，这种污染物的“天敌”就会出现，它可能是单独的某一种能够实现对其特异性降解的细菌，也可能是一个群落中多个物种协同作用的结果。工业化进程至今，由于环境问题的滞后性，人类已经制造了无数自己都不知如何处理的化合物，但幸运的是，似乎自然总是会默默准备一个解决答案等待我们去发现，而环境微生物科研工作者的一项使命便是——努力找出那些潜藏的答案。

In my master period, I mainly focus on anaerobic biodegradation of environmental organic pollutants. With the development of technology, various organic compounds have been released into environment, such as polycyclic aromatic hydrocarbon, herbicides, antibiotics, which results in risks to human health and eco-environment safety, due to their toxicity. It has been widely reported that, the newly synthesized compounds could cause severe inhibition on local bacteria when they enter certain environment at the beginning, because there may be lack of relevant degraders due to their complicated and specific molecular structure. However, through the natural evolution of indigenous microbes, several weeks or thousand years, the “enemy” of this pollutant would appear, maybe a certain species who evolved and harbor the specific degrading genes targeted on this certain compound, may be multiple populations working in synergistic pattern as well. In the process of industrialization, due to the delay characteristic of environment problem, human beings have created countless compounds that even ourselves have no idea about how to deal with, but luckily, it seems that nature always prepare an answer for that, in silence, waiting for the discovery of human beings. That is the mission for environmental microbiologist, in my mind, to find out those hidden answers.