Wang Mei-Zhen, Lai Bai-Min, Dandekar Ajai A, Yang Yu-Sheng, Li Na, Yin Jun, Shen Dong-Sheng
School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, People's Republic of China.
Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, People's Republic of China.
Appl Environ Microbiol. 2017 Aug 1;83(16). doi: 10.1128/AEM.00870-17. Print 2017 Aug 15.
SD-1 is efficient at degrading aromatic compounds and can therefore contribute to the bioremediation of wastewater. uses quorum sensing (QS) to regulate the production of numerous secreted "public goods." In wastewater bioaugmentation applications, there are myriad nitrogen sources, and we queried whether various nitrogen sources impact the stabilities of both QS and the bacterial populations. In a laboratory strain of , PAO1, the absence of a nitrogen source has been shown to destabilize these populations through the emergence of QS mutant "cheaters." We tested the ability of SD-1 to grow in casein broth, a condition that requires QS for growth, when the nitrogen source with either NHCl, NaNO, or NaNO or with no added nitrogen source. There was great variability in susceptibility to invasion by QS mutant cheaters and, by extension, the stability of the SD-1 population. When grown with NHCl as an extra nitrogen source, no population collapse was observed; by contrast, two-thirds of cultures grown in the presence of NaNO collapsed. In the populations that collapsed, the frequency of social cheaters exceeded 40%. NaNO and NaNO directly favor QS mutants of SD-1. Although the mechanism by which these nitrogen sources act is not clear, these data indicate that the metabolism of nitrogen can affect the stability of bacterial populations, an important observation for continuing industrial applications with this species. Bioaugmentation as a method to help remediate wastewater pollutant streams holds significant potential to enhance traditional methods of treatment. Addition of microbes that can catabolize organic pollutants can be an effective method to remove several toxic compounds. Such bioaugmented strains of bacteria have been shown to be susceptible to competition from the microbiota that are present in wastewater streams, limiting their potential effectiveness. Here, we show that bioaugmentation strains of bacteria might also be susceptible to invasion by social cheaters and that the nitrogen sources available in the wastewater might influence the ability of cheaters to overtake the bioaugmentation strains. Our results imply that control over the nitrogen sources in a wastewater stream or selective addition of certain nitrogen sources could help stabilize bioaugmentation strains of bacteria.
SD-1在降解芳香族化合物方面效率很高，因此有助于废水的生物修复。它利用群体感应（QS）来调节多种分泌的“公共物品”的产生。在废水生物强化应用中，有无数种氮源，我们研究了各种氮源是否会影响QS和细菌群体的稳定性。在实验室菌株PAO1中，已表明缺乏氮源会通过QS突变体“骗子”的出现使这些群体不稳定。我们测试了SD-1在酪蛋白肉汤中生长的能力，酪蛋白肉汤是一种生长需要QS的条件，此时氮源分别为NH₄Cl、NaNO₂、NaNO₃或不添加氮源。QS突变体骗子入侵的易感性以及由此延伸的SD-1群体的稳定性存在很大差异。当以NH₄Cl作为额外氮源生长时，未观察到群体崩溃；相比之下，在NaNO₂存在下生长的培养物中有三分之二崩溃了。在崩溃的群体中，社会骗子的频率超过了40%。NaNO₂和NaNO₃直接有利于SD-1的QS突变体。尽管这些氮源起作用的机制尚不清楚，但这些数据表明氮的代谢可以影响细菌群体的稳定性，这对于该物种在持续的工业应用中是一个重要的观察结果。生物强化作为一种帮助修复废水污染流的方法，在增强传统处理方法方面具有巨大潜力。添加能够分解有机污染物的微生物可以是去除几种有毒化合物的有效方法。这种生物强化的细菌菌株已被证明易受废水流中存在的微生物群竞争的影响，限制了它们的潜在有效性。在这里，我们表明生物强化的细菌菌株也可能易受社会骗子的入侵，并且废水中可用的氮源可能会影响骗子取代生物强化菌株的能力。我们的结果表明，控制废水流中的氮源或选择性添加某些氮源可能有助于稳定生物强化的细菌菌株。
