香蒲浮床有机物去除能力及根表微生物群落结构

COD_(Cr) Removal and Rhizoplane Bacterial Diversity in the Cattail Aquaculture Systems

为探讨植物浮床有机物去除能力和根表细菌群落组成特点,选择香蒲为研究对象,通过对根系诱导扩增,构建根系覆盖度(遮光率)分别为50%、70%和90%的香蒲浮床系统,并对其COD_(Cr)去除能力及根系微生物群落结构开展系统研究.结果表明,3个覆盖度系统的根系体积分别达到1.74、3.48、4.30 L/m^2.经过适应驯化,3个系统都可以有效地对人工模拟生活污水有机物进行去除,COD_(Cr)的单位面积负荷平均去除速率分别为8.28、8.78、13.46 g/(m^2·d);系统根系体积增加或加入一定体积的软性纤维填料都可以提高有机物去除能力.基于各系统根系和填料表面微生物样品高通量测序结果显示,根系与填料表面细菌多样性及组成都有较大差异,根系细菌丰度及多样性均小于填料.但在门水平上,根系和填料表面细菌优势类群相同,前2个优势菌门为变形菌门(Proteobacteria)和厚壁菌门(Firmicutes).根系表面细菌群落优势菌种类(OTUs)较单一,各系统根表微生物仅由1~3个相对丰度在10%以上种类构成了优势种群,并且根系和填料优势种类具有较大的不同.根系优势种类为Enterobacter、Acinetobacter、Clostridium属,代表序列OTUs2、OTUs4、和OTUs8,分别与Enterobacter ludwigii、Acinetobacter soli、Clostridium diolis有着100%的匹配度;填料优势种为Bacillus、Pseudomonas属,代表序列OTUs3和OTUs11分别与Bacillus funiculus NAF001、Pseudomonas argentinensis具有非常高的相似度.研究显示,根系经过诱导扩增的植物浮床系统对有机物具有较高的去除能力,与常规颗粒填料人工湿地相当,但根表微生物群落多样性较低,优势菌较单一,抗冲击负荷潜在能力较低.

Cattail aquaculture systems with three different root coverages （shading rates） of 50% , 70% and 90% were constructed by root induced amplification, and the COD_cr removal capacity and bacteria diversity on root surface of the cattail roots were investigated. The results showed that the root volumes were 1.74, 3.48 and 4.30 L/m2 , which corresponded to the 50% , 70% and 90% root coverage systems, respectively. Moreover, the three systems all performed effectively in removing organic compounds in artificial sewage, with COD_cr removal rates of 8.28, 8.78 and 13.46 g/（ m2 .d） in the 50% , 70% and 90% root coverage systems, respectively. This indicated that organic removal capacity could be enhanced by increasing the root volume or adding fiber packing. In addition, the analysis of IIluminaMiseq PE sequencing data found that the diversity and composition of bacteria on the root surface and packing surface significantly differed among the three different systems. Though the dominated bacteria in phylum level were similar, among which Proteobacteria and Firmicutes were the most abundant phylum, the richness of bacteria in the root samples was lower than that in the packing samples. The constitution of dominate bacteria （OTUs） on the root surface was quite simple, which was composed by 1-3 top abundant OTUs with relative abundance over 10%. Furthermore, the types of dominate species differed between samples from root and parking. Enterobacter, Acinetobacter and Clostridium were dominate genera in root samples, in which OTUs2, OTUs4 and OTUs8 were representative sequencing with 100% similarity to Enterobacter ludwigii, Acinetobacter soli and Clostridium diolis, respectively. By contrast, Bacillus and Pseudomonas were dominant genera in packing samples, in which OTUs3 and OTUs11 were representative sequencing with fairly high similarity to Bacillus funiculus NAF001 and Pseudomonas argentinensis.