近日,，來自諾丁漢大學(xué)的研究者對(duì)細(xì)菌的感染以及細(xì)菌間信號(hào)交流進(jìn)行了深入的研究,，研究者首次提出了降低細(xì)菌間信號(hào)傳遞交流的方法,，細(xì)菌間的信號(hào)交流主要依賴于群體感性系統(tǒng)（quorum-sensing,，QS）,，群體感性系統(tǒng)是一種依賴于細(xì)菌細(xì)胞數(shù)量的信號(hào)交流系統(tǒng),，研究者揭示了如何停止細(xì)菌間的交流來達(dá)到關(guān)閉細(xì)菌毒力產(chǎn)生的目的,。
近年來,，致病菌不斷增加對(duì)傳統(tǒng)抗生素的耐藥性，包括諾丁漢大學(xué)的研究者在內(nèi)的全世界的醫(yī)藥科學(xué)家正在奮起研究,，試圖去尋找到一種抵御致病菌感染的方法,，本項(xiàng)研究中，研究者使用了一種群體感應(yīng)淬滅的化合物來感染細(xì)菌間進(jìn)行信號(hào)傳遞,，從而感染細(xì)菌的生長(zhǎng),，最終使得細(xì)菌致死。
細(xì)菌（銅綠假單胞菌）可以利用群體感應(yīng)系統(tǒng)（QS）中的信號(hào)分子來進(jìn)行相互交流以及基因表達(dá)的控制,，同時(shí)銅綠假單胞菌也可以利用QS系統(tǒng)來引發(fā)一系列的感染,，耐甲氧西林金黃色葡萄球菌也是如此，可以引發(fā)嚴(yán)重的感染性疾病,。研究者Stephen Diggle表示,，QS系統(tǒng)控制的因子只有在細(xì)胞密度達(dá)到一定程度時(shí)才會(huì)發(fā)揮出作用，而且QS系統(tǒng)也只有在細(xì)胞數(shù)量一定的時(shí)候才能夠刺激細(xì)菌的某些行為，尤其是致病性,。
這項(xiàng)研究刊登在了近日的國(guó)際雜志PNAS上,，文章中，研究者提出,，在銅綠假單胞菌中,，細(xì)胞的密度是調(diào)節(jié)QS系統(tǒng)的關(guān)鍵因子，運(yùn)用特殊的培養(yǎng)基以及分子操作技術(shù),，研究小組揭示了QS信號(hào)通路只是在低細(xì)胞密度的時(shí)候發(fā)生,，但是對(duì)細(xì)菌并沒有帶來好處，然而在細(xì)胞密度高的時(shí)候,，QS才會(huì)發(fā)揮巨大作用,，對(duì)于細(xì)菌的感染非常有利。
未來,，研究者的研究將致力于在感染者身上進(jìn)行相關(guān)的實(shí)驗(yàn)研究,，細(xì)菌可以利用QS系統(tǒng)來控制毒力基因的表達(dá)，進(jìn)而控制毒力蛋白的產(chǎn)生,，研究者將會(huì)解釋,，什么時(shí)候細(xì)菌會(huì)釋放大量的毒素來引起人類的嚴(yán)重感染。這項(xiàng)研究同時(shí)也揭示了,，控制感染性細(xì)菌的細(xì)胞密度（bacterial population density）對(duì)于避免毒性感染的重要性,。（生物谷：T.Shen編譯）
doi:10.1073/pnas.1118131109
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Density-dependent fitness benefits in quorum-sensing bacterial populations
Sophie E. Darcha, Stuart A. Westb, Klaus Winzera, and Stephen P. Digglea,1
It has been argued that bacteria communicate using small diffusible signal molecules to coordinate, among other things, the production of factors that are secreted outside of the cells in a process known as quorum sensing (QS). The underlying assumption made to explain QS is that the secretion of these extracellular factors is more beneficial at higher cell densities. However, this fundamental assumption has never been tested experimentally. Here, we directly test this by independently manipulating population density and the induction and response to the QS signal, using the opportunistic pathogen Pseudomonas aeruginosa as a model organism. We found that the benefit of QS was relatively greater at higher population densities, and that this was because of more efficient use of QS-dependent extracellular “public goods.” In contrast, the benefit of producing “private goods,” which are retained within the cell, does not vary with cell density. Overall, these results support the idea that QS is used to coordinate the switching on of social behaviors at high densities when such behaviors are more efficient and will provide the greatest benefit.
