Specificity in the settlement -: modifying response of bacterial biofilms towards zoospores of the marine alga Enteromorpha
Specificity in the settlement -: modifying response of bacterial biofilms towards zoospores of the marine alga Enteromorpha
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DOI：
10.1046/j.1462-2920.2003.00407.x
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发表时间：
2003-05-01
影响因子：
5.1
通讯作者：
Callow, JA
中科院分区：
文献类型：
--
作者：
Patel, P;Callow, ME;Callow, JA
先前的研究表明，混合微生物生物膜刺激了绿色浒苔游动孢子的沉降速率，并且游动孢子沉降的数量与生物膜中的细菌数量呈正相关。在本研究中，这种关系的特异性进行了研究。从天然岩石生物膜和浒苔属植物表面分离到99株海洋细菌。通过变性梯度凝胶电泳（DGGE）筛选分离株，以消除重复和16 S rDNA测序确定了共37个独特的菌株。系统发育分析表明，所分离的细菌属于γ-变形菌门（28株）、噬细胞-黄菌门-拟杆菌门（CFB）（6株）和α-变形菌门（1株）3个类群。两个菌株未分配，显示与CFB组的序列相似性< 93%。γ-变形菌主要属为假交替单胞菌属（14株）、弧菌属（5株）、希瓦氏菌属（5株）、盐单胞菌属（3株）和假单胞菌属（1株）。孢子沉降实验进行了单种生物膜，发展为不同的时间在载玻片上。评价了校正孢子沉降值对生物膜密度的影响。结果表明，细菌菌株对孢子沉降的影响是菌株特异性的，而不是分类特异性的，并且活性随生物膜的年龄而变化。然而，大多数属于弧菌属和希瓦氏菌属的菌株显示出刺激性。假交替单胞菌菌株表现出一系列的影响，包括沉降抑制，麻痹和裂解活动。在孢子存在和不存在的细菌密度的空间分析揭示了一系列不同类型的孢子和细菌之间的关联。总体而言，孢子和细菌之间的空间关联似乎是独立的细菌细胞对孢子沉降的整体定量影响。
Previous studies have shown that the rate of settlement of zoospores of the green alga Enteromorpha is stimulated by mixed microbial biofilms and that the number of zoospores settling is positively correlated with the number of bacteria in the biofilm. In the present study the specificity of this relationship has been investigated. Ninety-nine strains of marine bacteria were isolated from natural biofilms on rocks and the surface of Enteromorpha plants. Isolates were screened by denaturing gradient gel electrophoresis (DGGE) to eliminate replicates and 16S rDNA sequencing identified a total of 37 unique strains. Phylogenetic analysis revealed that the isolated bacterial strains belonged to three groups gamma-Proteobacteria (28 strains), Cytophaga-Flavobacteria-Bacteroid (CFB) group (six strains) and alpha-Proteobacteria (one strain). Two strains were unassigned, showing < 93% sequence similarity with the CFB group. The main genera of gamma-Proteobacteria were Pseudoalteromonas (14 strains), Vibrio (five strains), Shewanella (five strains), Halomonas (three strains) and Pseudomonas (one strain). Spore settlement experiments were conducted on single-species biofilms, developed for different times on glass slides. The effect of correcting spore settlement values for biofilm density was evaluated. Results showed that the effect of bacterial strains on spore settlement was strain- but not taxon-specific and activity varied with the age of the biofilm. However, most of the strains belonging to genera Vibrio and Shewanella showed stimulation. Pseudoalteromonas strains showed a range of effects including settlement-inhibiting, paralysing and lysing activities. Spatial analysis of bacterial density in the presence and absence of spores revealed a range of different types of association between spores and bacteria. Overall, the spatial association between spores and bacteria appears to be independent of the overall quantitative influence of bacterial cells on spore settlement.