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根据2018年《中国生态环境状况公报》,我国111个重要湖泊(水库)中,富营养化湖泊占23.4%,富营养化造成的有害水藻水华(HABs),严重影响人民的饮用水安全、工业用水效率[1-3]。近年来,HABs的治理方案层出不穷,物理法、化学法在短时间内能够有效去藻,但不利于长足治理,微生物(溶藻细菌、噬藻体)作为控藻的有效手段具有标本兼治、容易从湖泊水体中分离、生态安全性好的优点,引起国内外研究者的关注[4-7]。生态学控藻是被国家列入生态环保领域的技术需求,如《太湖流域管理条例》(国务院令第604号)第37条“国家鼓励运用技术成熟、安全可靠的方法对蓝藻等有害藻类进行生态防治”。
随着微生物控藻研究的深入,国内外研究者在溶藻细菌筛选鉴定的基础上,将光谱分析技术应用于藻类有机物AOM(包括EOM和IOM)分析[8-9]。Wang 等[10]发现三维荧光光谱可用来区分自然水体中不同类型和来源的可溶性有机物DOM。Henderson等[11]研究了四种藻类分泌藻类有机物的光谱特征,发现生长期的藻类AOM中含有较少亲水性多糖物质和疏水性蛋白物质。但溶藻细菌溶藻过程中DOM的组成和特性不明确,溶藻机制尚不清晰。
本课题组发现太湖水系HABs爆发时期,当地农民用含HABs的藻水灌溉水稻田,而水稻田中并未出现大量蓝藻。由此引起本课题组关注,进而从稻田水稻根部土壤中筛选分离出一株高效溶藻菌Paenibacillus sp. XXG,为探究XXG菌溶藻机制,本研究通过对溶藻前后的铜绿微囊藻液进行紫外-可见光光谱、三维荧光光谱、红外光谱和倒置显微镜回放,系统分析溶藻产物并据此推测溶藻机制,以期为生态学控藻研究提供参考。
Spectral analysis of cyanobacterium- lysing product of Paenibacillus sp. XXG
- Received Date: 04/03/2020
- Available Online: 27/07/2021
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Key words:
- cyanobacterium-lysing bacterium /
- spectrum /
- cyanobacterium-lysing product /
- cyanobacterium-lysing mechanism
Abstract: Paenibacillus sp. XXG was screened from the soil irrigated with HABs algae water by our group in previous study, which was determined as the tested strain. UV, 3-dEEMs and IR were used to characterize and analyze cyanobacterium−lysing product during the processes of cyanobacterium−lysing. The inverted microscope video was used to record the processes of cyanobacterium−lysing and infer the cyanobacterium−lysing mechanism based on the spectral characteristics. UV spectrum characteristics showed that the peak area of B at 630—750 nm of cyanobacterium decreased gradually during the processes of cyanobacterium−lysing. 3-dEEMs spectra showed that the fluorescence peaks were formed in three regions of soluble microbial by-product, humic acid and fulvic acid, and the fluorescence peak strength of each and total gradually increased. IR spectra showed that cyanobacterium produced three peaks at 1600—1300 cm−1, 1690—1640 cm−1, and 3500—3100 cm−1/3550—2500 cm−1, respectively. The area of the three peaks increases first, then decreases, and further increases. The video playback of the inverted microscope showed that the processes of cyanobacterium−lysing was as follows: XXG bacteria infected cyanobacterium cells → cyanobacterium cell membrane contraction and sag → cyanobacterium cell wall damage, intracellular material outflow → cyanobacterium cell death. Spectral characteristic analysis showed that the content of Chl-a in cyanobacterium decreased gradually, the amide bond of proteins was destroyed gradually, the cell wall of the alga was broken, the cyanobacterium−lysing product was mainly composed of protein-like proteins and amino acids, including Chl-a, humic acid and fulic acid. The mechanism of cyanobacterium−lysing was speculated to be as follows: XXG infecting cyanobacterium cells, causing the cyanobacterium cell membrane to contract and sagging until the cyanobacterium cell wall broken, and the osmotic pressure inside and outside the cyanobacterium fine bubble was unbalanced, resulting in the rupture of cyanobacterium cell membrane. The intracellular substances of cyanobacterium cells, the destruction of Chl-a in vitro, the decomposition of proteins and other organic substances came out, the content of humic acid and fulic acid then increased significantly, and cyanobacterium cells dissolved, and died.