NSF International, 789 Dixboro Road, Ann Arbor, MI 48105, USA.
J Ind Microbiol Biotechnol. 2010 Apr;37(4):407-17. doi: 10.1007/s10295-010-0689-6. Epub 2010 Jan 20.
Brevundimonas diminuta is used as a control organism for validating the efficiency of water filtration systems. Since these protocols use nonselective growth media, heterotrophic plate count bacteria (HPCs) indigenous to the water distribution system may interfere with B. diminuta enumeration, thus leading to inaccurate assessment of the filter's microbial reduction capability. This could negatively impact public health as unsafe drinking water may be produced. This study was conducted to evaluate different potential routes for selective enumeration of B. diminuta in drinking water. B. diminuta's biochemical and molecular relationships to HPCs recovered from a laboratory drinking-water system were investigated. Of the 24 HPC morphotypes recovered, members of the Alpha- and Betaproteobacteria were most commonly identified. Based on comparisons of catabolic profiles (generated by the Biolog system) using principal component analysis, B. diminuta possessed similar metabolic patterns to several of the Alphaproteobacteria (Sphingomonas and Caulobacter), indicating that development of a selective medium based solely on carbon source was not feasible. Antibiotic susceptibility profiles revealed that the HPCs were least resistant to kanamycin, making it a candidate for future selective applications. Sequence comparisons of partial 16S rRNA sequences did not reveal any distinct similarities. However, basic local alignment search tool (BLAST) alignments of the gyrB and rpoD sequences for B. diminuta did show uniqueness, with the next closest match being to Caulobacter (88% and 79% similarity, respectively). Future investigation will focus on applying molecular assays, such as fluorescent in situ hybridization and quantitative real-time polymerase chain reaction (PCR), and incorporating an antibiotic marker or expressed fluorescent protein into the wild-type strain of B. diminuta for selective enumeration of B. diminuta.
小食酸菌被用作验证水过滤系统效率的对照生物。由于这些方案使用非选择性生长培养基，因此水分配系统中原生的异养平板计数细菌 (HPC) 可能会干扰小食酸菌的计数，从而导致对过滤器微生物减少能力的不准确评估。这可能会对公共卫生产生负面影响，因为可能会产生不安全的饮用水。本研究旨在评估饮用水中小食酸菌选择性计数的不同潜在途径。研究了从小型实验室饮用水系统中回收的 HPC 中小食酸菌的生化和分子关系。在所回收的 24 种 HPC 形态中，最常见的是α-和β-变形菌门的成员。基于使用主成分分析生成的代谢谱（通过 Biolog 系统生成）的比较，小食酸菌具有与几种α-变形菌（鞘氨醇单胞菌和胶柄杆菌）相似的代谢模式，表明仅基于碳源开发选择性培养基是不可行的。抗生素敏感性谱表明，HPC 对卡那霉素的抵抗力最低，使其成为未来选择性应用的候选药物。部分 16S rRNA 序列的序列比较没有显示出任何明显的相似性。但是，小食酸菌的 gyrB 和 rpoD 序列的基本局部比对搜索工具 (BLAST) 比对显示出独特性，下一个最接近的匹配是胶柄杆菌（分别为 88%和 79%的相似度）。未来的研究将集中于应用分子测定，例如荧光原位杂交和定量实时聚合酶链反应 (PCR)，并将抗生素标记物或表达荧光蛋白整合到小食酸菌的野生型菌株中，以选择性计数小食酸菌。
