循环水系统黏泥细菌群落结构多样性的PCR-DGGE分析

Analysis of Bacterial Community Diversity of Biofouling in Recirculating Cooling Water System by Using PCR-DGGE

以炼油厂循环冷却水作为接种水,考察了水质条件对生物黏泥中活细菌数量的影响,并利用聚合酶链式反应-变性梯度凝胶电泳(PCR-DGGE)技术分析了不同黏泥中的优势菌种组成、多样性及相似性。结果表明,在中营养水平下(COD=50 mg/L)形成的黏泥中含菌量最多,贫营养下的(COD=25 mg/L)最少,但是贫营养下的黏泥中细菌群落多样性最为丰富。3组样品之间,富营养(COD=100 mg/L)与另外2种营养下黏泥中细菌群落结构相似性差别较大。所选19个主要条带与其对应的GenBank中最相近的菌种DNA序列相似度均在97%以上,反映出鉴定结果的准确性。通过16S rDNA序列系统进化树分析发现,有多组菌种在系统发育上具有相近的亲缘关系,但其在不同黏泥中的优势地位由于受到营养水平和生物黏泥空间结构的影响而各不相同。

The recirculating cooling water systems at three different COD values of 25,50 and 100 mg/L were used for vaccination water to investigate the bacterial count variations and microbial community composition of biofouling by polymerase chain reaction-denaturing gradient gel electrophoresis（PCR-DGGE） analysis.The experimental results showed that the maximum bacteria count was found in the biofouling at moderate nutrient level（COD=50 mg/L） rather than abundant nutrient level（COD=100 mg/L）.Both the nutrient level and consequent biofouling structure were the important factors affecting the amount of biofouling bacteria.The diversity of biofouling bacteria community decreased with inoculation COD value of 25,50 and 100 mg/L in turn.Furthermore,the resemblance of bacterial community structure in biofouling at abundant nutrient level was demonstrated to significantly differ from the other two samples by Jaccard coefficient and clustering analysis.In addition,19 main bands in DGGE profile were further selected,cloned and sequenced.Based on similarity matching,all the sequences showed higher than 97% similarity to relative registered DNA sequences of bacteria strains in GenBank.There were two distinct groups of preponderant bacteria strains.Although pair groups of them were closely related to each other,they showed different predominant position in biofouling at different nutrient levels.