利用DGGE评价不同培养基回收番茄根际细菌类群的能力

用营养肉汤、YG、根系分泌物、土壤浸渍液4种培养基从番茄根际分离培养细菌,并结合变性梯度凝胶电泳(DGGE)技术,对4种培养基回收番茄根际细菌种群的能力进行了比较研究。结果表明,不同培养基和培养温度,回收到的细菌种群有一定差异;低营养浓度的YG培养基在较低的培养温度20℃下进行较长时间的培养,比高营养浓度营养肉汤培养基产生更多、更具代表性的细菌;以根系分泌物为基础的培养基从番茄根际回收到的优势菌群最多。该研究初步建立了用DGGE技术对不同培养基回收分离细菌种群能力进行评价的方法。

Capacity evaluation of different media for isolating bacteria populations from the rhizospere of tomato plants with DGGE

Bacteria from the rhizosphere of tomato plants were cultured on nutrient broth, YG, soil extract and root exudate media. The capabilities of these 4 media for recovering the bacterium communities were evaluated with denaturing gradient gel electrophoresis (DGGE) technique. Results showed that there were certain differences in the obtained bacterial communities when different media and culture tempitures were applied. Numbers of CFU on solid media indicated that the YG agar medium incubated at 20 degrees C could recover more populations than the high-nutrient-concentration Nutrient agar medium; while the root exudate based medium recovered the highest numbers of bacteria from the rhizosphere of tomato plants. 16S rDNA fragments amplified by PCR from different media and rhizosphere soil bacterium DNA were analyzed with DGGE. The DGGE fingerprints showed that there was a discrepancy between bacterial populations observed by cultivation techniques and molecular retrieval. The rhizosphere pattern consisted of more strong bands than the media. The DGGE patterns of the 4 different media incubated at 28 degrees C showed a relatively high level of similarity. In contrast, those of the 4 media incubated at 20 degrees C were significantly different from each other. Shannon-Wiener index (H), species richness (S), Cs values and Cluster dendrogram analysis of different samples revealed that the YG agar medium and the root exudate based medium recovered the highest proportion of predominant populations from the rhizosphere. In the study a new strategy has been proposed for evaluating the capacity of different media in terms of recovering the predominant populations.