Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Av. Antonio Carlos 6627, Belo Horizonte, MG, Brazil.
Antonie Van Leeuwenhoek. 2011 Feb;99(2):355-70. doi: 10.1007/s10482-010-9501-x. Epub 2010 Aug 28.
The genus Chromobacterium encompasses free-living Gram-negative bacteria. Until 2007, the genus consisted of only one species but six species are now recognized. Chromobacterium violaceum is the type species of the genus and is commonly found in soil and water in tropical and sub-tropical regions. We have investigated a collection of 111 isolates displaying violet pigmentation from undisturbed aquatic and soil environments from Brazilian Cerrado ecosystem. The 16S rRNA gene phylogeny revealed that all isolates were allocated in a monophyletic cluster inside the Chromobacterium genus and formed few clusters related most closely with Chromobacterium piscinae. The two sets of isolates from water and soil were analyzed by the repetitive extragenic palindromic (rep)-PCR genomic fingerprinting technique using a BOX-AR1 primer. The antimicrobial susceptibility and the different carbon sources utilized by these isolates were also investigated. Physiological profiles of the isolates generated by BIOLOG GN2 plates showed great versatility in the substrate utilization, much higher than the C. violaceum ATCC 12472. All isolates exhibited a high minimum inhibitory concentration (MIC) to ampicillin (MIC > 512 μg/ml) and were inhibited by ciprofloxacin, tetracycline and mercury at the lowest concentration tested (MIC < 2 μg/ml). Thirteen BOX-PCR band patterns were identified from 33 individual fingerprints. Eleven patterns provided evidence for endemic distributions. Antimicrobial susceptibility and BOX-PCR fingerprint clustering showed a clear distinction between Chromobacterium isolates from the water and soil. The results suggested that microenvironment barriers such as water and soil can play an important role in the periodic selection and diversification of Chromobacterium population ecotypes.
噬色菌属包含自由生活的革兰氏阴性细菌。直到 2007 年,该属仅由一个物种组成,但现在已确认有六个物种。紫色噬色菌是该属的模式种,通常在热带和亚热带地区的土壤和水中发现。我们调查了来自巴西塞拉多生态系统未受干扰的水生和土壤环境的 111 个显示紫色色素的分离株。16S rRNA 基因系统发育树表明,所有分离株都分配在噬色菌属内的一个单系聚类中,并形成了与鱼类噬色菌最密切相关的少数聚类。使用 BOX-AR1 引物的重复外回文(rep)-PCR 基因组指纹分析技术分析了来自水和土壤的两组分离株。还研究了这些分离株的抗菌敏感性和不同碳源的利用情况。通过 BIOLOG GN2 平板生成的分离株的生理图谱显示出对底物利用的极大多功能性,远高于紫色噬色菌 ATCC 12472。所有分离株对氨苄西林(MIC>512μg/ml)的最小抑菌浓度(MIC)均较高,并且对环丙沙星、四环素和汞的抑制作用最低(MIC<2μg/ml)。从 33 个个体指纹中鉴定出 13 个 BOX-PCR 带型。11 种模式为地方性分布提供了证据。抗菌敏感性和 BOX-PCR 指纹聚类显示了来自水和土壤的噬色菌分离株之间的明显区别。结果表明,水和土壤等微环境屏障可以在噬色菌种群生态型的周期性选择和多样化中发挥重要作用。