Trade-off between oxygen and iron acquisition in bacterial cells at the air-liquid interface
Trade-off between oxygen and iron acquisition in bacterial cells at the air-liquid interface
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DOI：
10.1111/j.1574-6941.2011.01087.x
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发表时间：
2011-07-01
影响因子：
4.2
通讯作者：
Igarashi, Yasuo
中科院分区：
文献类型：
--
作者：
Yamamoto, Kyosuke;Arai, Hiroyuki;Igarashi, Yasuo
由于氧气的可获得性，气液界面对好氧菌来说是一个选择性有利的生态位。各种类型的需氧菌在气液界面形成一种类似生物膜的结构，称为膜。尽管膜是微生物的主要生长方式之一，但膜细胞的代谢特征和膜形成的决定因素在很大程度上还不清楚。在本研究中，我们调查了兼性好氧菌铜绿假单胞菌影响膜细胞生长的因素，并检测了膜细胞的基因表达谱，以表征膜生活方式的特征。与野生型菌株相比，缺乏胞外多糖的突变菌株在静态条件下膜形成能力较差，生长不利。值得注意的是，添加另一种电子受体硝酸盐的培养基会减少细胞膜的形成。硝酸盐促进了厌氧浮游细胞亚群的生长，该亚群与需氧细胞亚群竞争铁，导致观察到的膜层减少。转录组分析表明，膜细胞处于有氧和缺铁状态。因此，尽管膜的形成在静态条件下肯定是一种生长优势，但膜细胞面临着氧和铁获取之间的营养权衡。
The air-liquid interface is a selectively advantageous niche for aerobes due to the accessibility to oxygen. Various species of aerobes form a biofilm-like structure at air-liquid interfaces, known as a pellicle. Although the pellicle is one of the major growth modes of microorganisms, the metabolic features of pellicle cells and the determinative factors for pellicle formation are largely unknown. In this study, we investigated the factors affecting pellicle growth by the facultative aerobe Pseudomonas aeruginosa, and also examined the gene expression profiles of pellicle cells in order to characterize features of the pellicle lifestyle. A mutant strain deficient in the production of exopolysaccharides displayed poor pellicle-forming ability and a growth disadvantage under static conditions compared with the wild-type strain. Notably, supplementation of culture medium with an alternative electron acceptor, nitrate, led to diminished pellicle formation. Nitrate facilitated the growth of an anaerobic planktonic cell subpopulation that acted as a competitor for iron with the aerobic subpopulation, resulting in the observed pellicle reduction. Transcriptome analysis revealed that pellicle cells were under aerobic and iron-depleted states. Thus, although pellicle formation certainly confers a growth advantage under static conditions, pellicle cells face a nutritional trade-off between oxygen and iron acquisition.