蓝藻神经毒素β-甲氨基-L-丙氨酸（BMAA）在农田土壤生态系统中的迁移与累积

β-methylamino-L-alanine (BMAA) is a neurotoxic non-protein amino acid, which may be produced by all known groups of cyanobacteria, including cyanobacterial symbionts and free-living cyanobacteria. Ecology provides an important line of evidence supporting the occurrence of BMAA in the Western Pacific Guam ecosystem and many aquatic ecosystems combined with its possible transfer and bioaccumulation within the major food webs, some ending in human consumption, suggesting a potential for human health and ecological safety risks. In the previous study, we found that BMAA also present in cyanobacterial organic fertilizer and may be transferred into the farmland soil ecosystems by using cyanobacterial organic fertilizer. Following up the clue, we designed and proposed this application. In this application, we are going to first research whether the cyanobacterial organic fertilizer processing technology is able to result in the degradation of BMAA or not. And then, two different types of farmland soil ecosystems will be selected as our research objects, to which cyanobacterial organic fertilizer has been applied for several years. Revealing the possible transfer and bioaccumulation pathways of BMAA within the major food webs in the two farmland soil ecosystems will be performed by analysis of BMAA amount within the soil, soil organisms, and crops/plants in the three ecosystems, respectively. Finally, the transfer and bioaccumulation of BMAA in various organs of 1-2 crops/plants will be carried out by detection of the BMAA amount in these organs of the crops/plants continuously within the whole crops/plants growing process. Our results will provide important scientific evidence for BMAA environmental health and soil ecological risk assessment.

β-甲氨基-L-丙氨酸（BMAA），是蓝藻普遍产生的一种具有神经毒性的非蛋白质氨基酸。研究已经发现，BMAA能够通过食物链进入西太平洋关岛生态系统和水生态系统，并沿食物链进行迁移放大，引发人类健康与生态安全风险。我们在前期研究中发现，BMAA还存在于蓝藻有机肥中，可以通过施用蓝藻有机肥的方式进入农田土壤生态系统。本申请以此为切入点，首先通过实验阐明蓝藻有机肥加工工艺对其中BMAA含量的影响；而后选择反复多次施用蓝藻有机肥的两种不同类型农田土壤生态系统作为研究对象，通过测定BMAA在土壤、土壤生物、作物/植物体内的含量，解析出BMAA在两种不同类型农田土壤生态系统中可能的迁移累积途径；最后在1～2种作物/植物的整个生长过程中，连续监测BMAA在其不同部位的含量变化，揭示出BMAA在作物/植物体内的迁移规律。本申请研究结果将为BMAA环境健康预警与土壤生态风险评价提供重要的科学依据。

β-甲氨基-L-丙氨酸（β-N-methylamino-L-alanine, BMAA）是蓝藻普遍产生的一种具有神经毒性的非蛋白质氨基酸，在自然界中存在游离态和蛋白结合态两种形式。研究发现，BMAA 能够通过食物链进入西太平洋关岛生态系统和水生态系统，并沿食物链进行迁移放大，引发人类健康与生态安全风险。我国多个大型淡水湖泊（滇池、太湖、巢湖）已发生严重蓝藻水华污染，在这些地区藻华会被打捞起来做成蓝藻有机肥。施用蓝藻有机肥可能导致BMAA进入农田并在土壤与作物间进行迁移累积，从而威胁到人类健康，因此开展农田土壤环境中BMAA毒素的调研工作迫在眉睫。本文通过HPLC-MS/MS技术，首先在蓝藻有机肥中检测到了高含量的BMAA（1.8-16.3 μg/g），随后研究了两种形态BMAA在土壤和作物（小白菜）间的迁移累积过程。此外，研究报道BMAA会导致果蝇、蜜蜂和恒河猴出现运动神经功能紊乱和寿命缩短的症状。我们猜测BMAA可能会对土壤动物造成损伤，导致土壤动物的行为紊乱和寿命缩短，进而影响其生态功能，最终破坏土壤生态系统。以模式生物秀丽隐杆线虫（Caenorhabditis elegans）作为试验对象，通过使线虫暴露在不同浓度BMAA下，证明了BMAA对线虫的寿命、繁殖、发育均产生了不利影响。线虫平均寿命和最长寿命均随着添加BMAA浓度的提高而缩短，并且产生了体长变短、繁殖提前、繁殖量减少的现象。我们通过转录组测序和qRT-PCR实验，发现线虫的基因表达发生了较大变化。本研究内容可以为农田土壤环境中BMAA 对人类健康风险评价与预警以及其对农田土壤生态系统的危害提供重要的科学依据。