Simões Lúcia Chaves, Simões Manuel, Vieira Maria João
Centro de Engenharia Biológica, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal.
Appl Environ Microbiol. 2007 Oct;73(19):6192-200. doi: 10.1128/AEM.00837-07. Epub 2007 Aug 3.
In the environment, multiple microorganisms coexist as communities, competing for resources and often associated as biofilms. In this study, single- and dual-species biofilm formation by, and specific activities of, six heterotrophic intergeneric bacteria were determined using 96-well polystyrene plates over a 72-h period. These bacteria were isolated from drinking water and identified by partial 16S rRNA gene sequencing. A series of planktonic studies was also performed, assessing the bacterial growth rate, motility, and production of quorum-sensing inhibitors (QSI). This constituted an attempt to identify key attributes allowing bacteria to effectively interact and coexist in a drinking-water environment. We observed that in both pure and dual cultures, all of the isolates formed stable biofilms within 72 h, with specific metabolic activity decreasing, in most cases, with an increase in biofilm mass. The largest single- and dual-biofilm amounts were found for Methylobacterium sp. and the combination of Methylobacterium sp. and Mycobacterium mucogenicum, respectively. Evidences of microbial interactions in dual-biofilm formation, associated with appreciable biomass variation in comparison with single biofilms, were found for the following cases: synergy/cooperation between Sphingomonas capsulata and Burkholderia cepacia, S. capsulata and Staphylococcus sp., and B. cepacia and Acinetobacter calcoaceticus and antagonism between S. capsulata and M. mucogenicum, S. capsulata and A. calcoaceticus, and M. mucogenicum and Staphylococcus sp. A neutral interaction was found for Methylobacterium sp.-M. mucogenicum, S. capsulata-Staphylococcus sp., M. mucogenicum-A. calcoaceticus, and Methylobacterium sp.-A. calcoaceticus biofilms, since the resultant dual biofilms had a mass and specific metabolic activity similar to the average for each single biofilm. B. cepacia had the highest growth rate and motility and produced QSI. Other bacteria producing QSI were Methylobacterium sp., S. capsulata, and Staphylococcus sp. However, only for S. capsulata-M. mucogenicum, S. capsulata-A. calcoaceticus, and M. mucogenicum-Staphylococcus sp., dual-biofilm formation seems to be regulated by the QSI produced by S. capsulata and Staphylococcus sp. and by the increased growth rate of S. capsulata. The parameters assessed by planktonic studies did not allow prediction and generalization of the exact mechanism regulating dual-species biofilm formation between the drinking-water bacteria.
在环境中，多种微生物作为群落共存，争夺资源，且常形成生物膜。在本研究中，使用96孔聚苯乙烯板在72小时内测定了六种异养属间细菌的单物种和双物种生物膜形成情况及其比活性。这些细菌从饮用水中分离出来，并通过16S rRNA基因部分测序进行鉴定。还进行了一系列浮游生物研究，评估细菌的生长速率、运动性和群体感应抑制剂（QSI）的产生。这旨在确定使细菌能够在饮用水环境中有效相互作用和共存的关键特性。我们观察到，在纯培养和混合培养中，所有分离菌株均在72小时内形成稳定的生物膜，在大多数情况下，随着生物膜质量的增加，比代谢活性降低。单物种和双物种生物膜量最大的分别是甲基杆菌属和甲基杆菌属与产黏液分枝杆菌的组合。在以下情况下发现了双物种生物膜形成中微生物相互作用的证据，与单物种生物膜相比，其生物量有明显变化：荚膜鞘氨醇单胞菌与洋葱伯克霍尔德菌、荚膜鞘氨醇单胞菌与葡萄球菌属之间的协同/合作，以及洋葱伯克霍尔德菌与醋酸钙不动杆菌之间的协同/合作；荚膜鞘氨醇单胞菌与产黏液分枝杆菌、荚膜鞘氨醇单胞菌与醋酸钙不动杆菌以及产黏液分枝杆菌与葡萄球菌属之间存在拮抗作用。对于甲基杆菌属-产黏液分枝杆菌、荚膜鞘氨醇单胞菌-葡萄球菌属、产黏液分枝杆菌-醋酸钙不动杆菌以及甲基杆菌属-醋酸钙不动杆菌生物膜，发现它们之间存在中性相互作用，因为形成的双物种生物膜的质量和比代谢活性与每个单物种生物膜的平均值相似。洋葱伯克霍尔德菌具有最高的生长速率和运动性，并产生QSI。其他产生QSI的细菌有甲基杆菌属、荚膜鞘氨醇单胞菌和葡萄球菌属。然而，仅对于荚膜鞘氨醇单胞菌-产黏液分枝杆菌、荚膜鞘氨醇单胞菌-醋酸钙不动杆菌以及产黏液分枝杆菌-葡萄球菌属，双物种生物膜的形成似乎受荚膜鞘氨醇单胞菌和葡萄球菌属产生的QSI以及荚膜鞘氨醇单胞菌生长速率增加的调节。浮游生物研究评估的参数无法预测和概括饮用水细菌之间双物种生物膜形成的确切调节机制。
