Conjugative Selectivity of Plasmids Is Affected by Coexisting Recipient Candidates
Conjugative Selectivity of Plasmids Is Affected by Coexisting Recipient Candidates
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DOI：
10.1128/msphere.00490-18
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发表时间：
2018-12
期刊：
影响因子：
4.8
通讯作者：
Ayako Sakuda;C. Suzuki-Minakuchi;K. Okada;H. Nojiri
中科院分区：
文献类型：
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作者：
Ayako Sakuda;C. Suzuki-Minakuchi;K. Okada;H. Nojiri
大多数以前的质粒接合转移研究采用两种菌株的实验装置：一种作为供体，另一种作为受体。然而，所获得的结果有时与在自然环境条件下或在使用自然土壤和水样本的模型微观世界中获得的观察结果不一致。因此，我们认为，有一个“差距”，在我们的质粒行为的背景下存在的细菌聚生体的实际环境条件下的理解。在这项研究中，我们清楚地表明，一个质粒的接合选择性可以通过使用一个简化的实验设置与一个菌株作为供体和两个菌株作为受体周围存在的受体候选人的影响。这些现象不能解释的因素，已知的影响质粒转移的建议，由以前的研究。因此，我们建议存在新的元件调节质粒转移聚生体内。摘要了解质粒在不同环境条件下的行为机制对于预测质粒在自然界中的命运具有重要意义。大多数以前的质粒转移研究采用两种菌株：一种作为供体，另一种作为受体。然而，在自然环境中，通常有不同的受体细胞可供质粒转移。在这项研究中，为了揭示潜在的机制，我们评估了质粒从一个供体菌株转移到两个受体候选人中的任何一个作为最简化的模型。我们使用恶臭假单胞菌KT 2440和食脂假单胞菌CA 10 dm 4作为模型宿主，pCAR 1（IncP-7）、NAH 7（IncP-9）、pB 10（IncP-1β）和R388（IncW）作为模型质粒。正如预期的那样，在大多数情况下，在液体和过滤器交配的条件下，这些质粒通常更频繁地转移到相同物种的受体，而不是不同物种的受体，尽管在过滤器交配期间，NAH 7从P. resinovorans转移到P. putida比转移到P. resinovorans更频繁。除pCAR 1受影响较小外，其他受体的共存增强了向同一物种接合转移的偏好。特别地，在液体中的NAH 7转移和过滤器配对中的R388转移期间，通过共存的相同受体（P. putida）的存在，减少了对应于从P. putida转移到不同受体（P. resinovorans）的偏好。我们确定大细胞聚集体和分泌到培养上清液中的物质不是造成这种现象的原因。总体而言，本研究的结果表明，存在未知因素决定最佳质粒转移到本地受体。以前大多数关于质粒接合转移的研究采用两种菌株的实验装置：一种作为供体，另一种作为受体。然而，所获得的结果有时与在自然环境条件下或在使用自然土壤和水样本的模型微观世界中获得的观察结果不一致。因此，我们认为，有一个“差距”，在我们的质粒行为的背景下存在的细菌聚生体的实际环境条件下的理解。在这项研究中，我们清楚地表明，一个质粒的接合选择性可以通过使用一个简化的实验设置与一个菌株作为供体和两个菌株作为受体周围存在的受体候选人的影响。这些现象不能解释的因素，已知的影响质粒转移的建议，由以前的研究。因此，我们建议存在新的元件调节质粒转移聚生体内。
Most previous studies on plasmid conjugal transfer employed experimental setups with two strains: one as a donor and the other as a recipient. However, the results obtained sometimes failed to agree with observations obtained under natural environmental conditions or in a model microcosm using natural soil and water samples. Therefore, we consider that there is a “gap” in our understanding of plasmid behavior in the context of bacterial consortia that exist under the actual environmental conditions. In this study, we clearly showed that the conjugation selectivity of a plasmid can be affected by the recipient candidates existing around the donor strain by the use of a simplified experimental setup with one strain as the donor and two strains as recipients. These phenomena could not be explained by factors known to affect plasmid transfer as suggested by previous studies. Therefore, we suggest the presence of novel elements regulating plasmid transfer within consortia. ABSTRACT Understanding the mechanisms underlying plasmid behavior under conditions of various environments is important to predict the fate of plasmids in nature. Most previous studies on plasmid transfer employed two strains: one as a donor and the other as a recipient. However, in natural environments, there are usually different recipient cells available to which plasmid can be transferred. In this study, to reveal the underlying mechanisms, we assessed the transferability of plasmids from one donor strain to either of two recipient candidates as the most simplified model. We used Pseudomonas putida KT2440 and Pseudomonas resinovorans CA10dm4 as model hosts and pCAR1 (IncP-7), NAH7 (IncP-9), pB10 (IncP-1β), and R388 (IncW) as model plasmids. As expected, in most cases these plasmids were generally transferred more frequently to a recipient of the same species than to a recipient of a different one under conditions of liquid and filter mating, although NAH7 was transferred from P. resinovorans more frequently to P. putida than to P. resinovorans during filter mating. With the exception of pCAR1, which was less affected, the coexistence of other recipients enhanced the preferences of conjugative transfer to the same species. In particular, preferences corresponding to transfer from P. putida to a different recipient (P. resinovorans) were reduced by the presence of a coexisting same recipient (P. putida) during transfer of NAH7 in liquid and transfer of R388 in filter mating. We determined that large cell aggregates and substances secreted into culture supernatant were not responsible for this phenomenon. Overall, the results of this study suggest the existence of unknown factors determining optimal plasmid transfer to native recipients. IMPORTANCE Most previous studies on plasmid conjugal transfer employed experimental setups with two strains: one as a donor and the other as a recipient. However, the results obtained sometimes failed to agree with observations obtained under natural environmental conditions or in a model microcosm using natural soil and water samples. Therefore, we consider that there is a “gap” in our understanding of plasmid behavior in the context of bacterial consortia that exist under the actual environmental conditions. In this study, we clearly showed that the conjugation selectivity of a plasmid can be affected by the recipient candidates existing around the donor strain by the use of a simplified experimental setup with one strain as the donor and two strains as recipients. These phenomena could not be explained by factors known to affect plasmid transfer as suggested by previous studies. Therefore, we suggest the presence of novel elements regulating plasmid transfer within consortia.