东湖生物膜的建群过程及其生理特性研究

Colonization Process and Physiological Characteristics of Biofilms in East Lake,Wuhan

为探讨天然水体中生物膜的建群过程及生理特性,本研究将人工基质大理石投放到东湖沿岸带浅水区域,分析了生物膜在人工基质上从开始建群直至发育为成熟群落,并最终衰退的整个过程。结果表明,建群过程中,生物膜的生物量(叶绿素a、蛋白质、干重、无灰干重)、营养物质含量(总氮、总磷)均呈现先上升后下降的趋势,各指标之间具有显著相关性。低温会减缓生物膜的生长,弱光会加剧生物膜的衰退,生物膜的生长发育会影响周围水体氮、磷元素浓度。生物膜中碱性磷酸酶活性与自身生物量呈显著正相关性。水体中氮/磷的比值决定生物膜中氮/磷的比值。刚毛藻属是东湖生物膜的优势物种。对生物膜建群过程及生理特性的研究,有助于更好地将生物膜应用于污染水体的净化和修复。

Biofilms play important roles in nutrient dynamics and energy cycling in aquatic ecosystems,and significantly affect the migration and transformation of pollutants.In order to explore the colonization process and physiological properties of biofilms in a natural water body,the process of biofilm formation on an artificial substratum of marbles was studied,from initial colonization through biofilm maturation and decline.Beginning in February 2013,a 14-week biofilm colonization test was carried out in the shallow,near-shore waters of East Lake.Changes in biofilm morphology,biomass,nutrient content,alkaline phosphatase activity(APA)and dominant species were analyzed during the colonization period.As colonization proceeded,changes in the physicochemical parameters of surrounding lake water were monitored,including water temperature(WT),pH,electrical conductivity(EC),total nitrogen(TN),total phosphorus(TP),chlorophyll a(Chl-a)and APA.Both biomass(Chl-a,protein,dry weight(DW),ash-free dry weight(AFDW))and nutrient content(TN,TP)of biofilms initially increased and then decreased,and correlations between biomass and nutrient content were significant.The biofilm colonization period on the artificial matrix accorded with the natural process of biofilm formation and,as in nature,the process was significantly affected by environmental conditions.Low temperature decreased the biofilm growth rate,and low light intensity aggravated biofilm decline.Biofilm growth affected concentrations of N and P in the surrounding water,as indicated by the significant negative correlations of biofilm concentration of TN and TP with the corresponding TN and TP concentrations in surrounding water.The APA of biofilms was determined primarily by the biomass of biofilms rather than phosphorus availability in the surrounding water.The N∶P ratio in the surrounding water determined the N∶P ratio in biofilms.Affected by the surrounding water environment,Cladophora was the dominant biofilm species in East Lake.The growth of Cladophorain biofilms and the surrounding water effectively removed nitrogen and phosphorus from water.This study on the colonization process and physiological characteristics of biofilms will contribute to improved biofilm applications for purifying and remediating polluted water.