（圖:黃色即狩獵者Micavibrio aeruginosavorus,，紫色即獵物Pseudomonas aeruginosa,，周圍灰色則是已經(jīng)死亡的Pseudomonas aeruginosa,；右上角是Micavibrio aeruginosavorus的基因組圖）
近日，一項研究表明,，一種類似“吸血鬼”的細菌（可轉(zhuǎn)移到其它特定細菌上,，包括某些人類病原體）可用作許多感染性疾病的活體抗生素。
該細菌命名為Micavibrio aeruginosavorus,，大約30年前在廢水中被發(fā)現(xiàn),。由于常規(guī)的微生物學(xué)技術(shù)難以對其進行培養(yǎng)和研究，因此一直沒用對其開展廣泛的研究,。盡管如此,，美國維吉尼亞大學(xué)藝術(shù)與科學(xué)學(xué)院的生物學(xué)家Martin Wu和Zhang Wang解碼了該細菌的基因組,，以研究“它們是如何生存的”。
這種細菌的生存方式是通過找到其它種類的細菌作為其獵物,，粘附到它們的細胞壁上并吸取養(yǎng)分,。和其它大部分從周圍環(huán)境汲取養(yǎng)分的細菌不同，M. aeruginosavorus只能通過汲取其它細菌的養(yǎng)分來生存和繁殖,。這會殺死它的宿主細菌,，因此可作為摧毀有害病原體的潛在有效工具。
該細菌的其中一種宿主細菌是Pseudomonas aeruginosavorus,，它是引起囊性纖維化病人嚴重肺部感染的主要病因,。
Wu說道：“因為這種細菌能找出并攻擊特定對人類有害的細菌，病理學(xué)家可以利用這些細菌來“以火滅火”,。”
該研究的論文發(fā)表在最新一期的《BMC Genomics》雜志上,。
Wu說道：“我們實驗室使用了最尖端技術(shù)來解碼該種細菌的基因組。我們對其尋找和攻擊宿主的分子機制相當(dāng)感興趣,。在幾年前,，關(guān)于這方面的研究非常的困難且需要大量的資金。”
傳統(tǒng)抗生素的濫用使得“超級細菌”的出現(xiàn),。目前急需新技術(shù)實現(xiàn)既能殺死病原體,，又不會使它們產(chǎn)生任何抗性。
由于M. aeruginosavorus細菌對宿主非常具有選擇性,，它對人體內(nèi)數(shù)千種有益細菌并無毒害作用,。因此，使用它來做為活體抗生素,，不但能降低我們對傳統(tǒng)抗生素的依賴性,，還可以減緩細菌抗藥性的問題。
該細菌的另一個優(yōu)勢就是它們能在黏性流體中游動,，比如P. aeruginosavorus病菌會在囊性纖維化病人的肺部形成一種跟膠水一樣的生物膜，來增強其對傳統(tǒng)抗生素的抵抗性,。我們注意到M. aeruginosavorus可以在這種黏液中游動,，并攻擊P. aeruginosavorus病菌。
Wu認為,，對于M. aeruginosavorus還需要更進一步的研究以了解它們的基因功能,，才能使其更好的利用在人類疾病治療中。（生物谷 Bioon.com）
doi:10.1186/1471-2164-12-453
PMC:
PMID:
Genomic insights into an obligate epibiotic bacterial predator: Micavibrio aeruginosavorus ARL-13
Zhang Wang , Daniel E Kadouri and Martin Wu
Background
Although bacterial predators play important roles in the dynamics of natural microbial communities, little is known about the molecular mechanism of bacterial predation and the evolution of diverse predatory lifestyles.
Results
We determined the complete genome sequence of Micavibrio aeruginosavorus ARL-13, an obligate bacterial predator that feeds by "leeching" externally to its prey. Despite being an obligate predator depending on prey for replication, M. aeruginosavorus encodes almost all major metabolic pathways. However, our genome analysis suggests that there are multiple amino acids that it can neither make nor import directly from the environment, thus providing a simple explanation for its strict dependence on prey. Remarkably, despite apparent genome reduction, there is a massive expansion of genomic islands of foreign origin. At least nine genomic islands encode many genes that are likely important for Micavibrio-prey interaction such as hemolysin-related proteins. RNA-Seq analysis shows substantial transcriptome differences between the attack phase, when M. aeruginosavorus seeks its prey, and the attachment phase, when it feeds and multiplies. Housekeeping genes as well as genes involved in protein secretion were all dramatically up-regulated in the attachment phase. In contrast, genes involved in chemotaxis and flagellum biosynthesis were highly expressed in the attack phase but were shut down in the attachment phase. Our transcriptomic analysis identified additional genes likely important in Micavibrio predation, including porins, pilins and many hypothetical genes.
Conclusions
The findings from our phylogenomic and transcriptomic analyses shed new light on the biology and evolution of the epibiotic predatory lifestyle of M. aeruginosavorus. The analysis reported here and the availability of the complete genome sequence should catalyze future studies of this organism.
Keywords:
Bacterial predation; Predator-prey interaction; Integrative and conjugative elements (ICEs); Hemolysin-related protein; Quorum sensing, RNA-Seq
