The State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China.
School of Municipal and Environmental Engineering, Shandong Jianzhu University, Jinan, China.
Microbiol Spectr. 2024 Oct 3;12(10):e0119524. doi: 10.1128/spectrum.01195-24. Epub 2024 Aug 21.
Microorganisms can produce a vast diversity of volatile organic compounds of different chemical classes that are capable of mediating intra- and inter-kingdom interactions. In this study, we showed that the soil-dwelling bacterium can produce alkaline volatiles under multiple growth conditions, which we discovered through investigation of the mutant strain MU-1. Strain MU-1 has a defective morphology and exhibits a bald phenotype due to the lack of aerial mycelia and spores, as confirmed by scanning electron microscopy. Using physical barriers to separate the strains on culture plates, we determined that volatile compounds produced by wild-type could rescue the phenotype of strain MU-1, and pH analysis of the growth medium indicated that these volatile compounds were alkaline. Ultra-high-performance liquid chromatography, combined with mass spectrometry analysis, showed that wild-type produced abundant levels of the alkaline volatile trimethylamine (TMA) and the oxide form TMAO; however, the levels of these compounds were much lower in strain MU-1. Notably, exposure to TMA alone could rescue the phenotype of this mutant strain, restoring the production of aerial mycelia and spores. We also showed that the rescue effect by alkaline volatiles is mostly species-specific, suggesting that the volatiles may aid particular mutants or other less-fit variants of closely related species to resume normal physiological status and to compete more effectively in complex communities such as soil. Our study reveals a new and intriguing role for bacterial volatiles, including volatiles that may have toxic effects on other species.
Bacterial volatiles have a wide range of biological roles at intra- or inter-kingdom levels. The impact of volatiles has mainly been observed between producing bacteria and recipient bacteria, mostly of different species. In this study, we report that the wild-type, soil-dwelling bacterium , which forms aerial hypha and spores as part of its normal developmental cycle, also produces the alkaline volatile compound trimethylamine (TMA) under multiple growth conditions. We showed that the environmental dispersion of TMA produced by promotes the growth and differentiation of growth-deficient mutants of the same species or other slowly growing bacteria, and thus aids in their survival and their ability to compete in complex environmental communities such as soil. Our novel findings suggest a potentially profound biological role for volatile compounds in the growth and survival of communities of volatile-producing species.
微生物能够产生大量不同化学类别的挥发性有机化合物，这些化合物能够介导种内和种间相互作用。在这项研究中，我们表明，土壤栖息细菌 在多种生长条件下都能产生碱性挥发物，这是通过对突变株 MU-1 的研究发现的。菌株 MU-1 形态缺陷，由于缺乏气生菌丝和孢子，表现出光秃表型，这一点通过扫描电子显微镜得到了证实。我们使用物理屏障将菌株在培养板上分隔开来，确定野生型 产生的挥发性化合物可以拯救菌株 MU-1 的表型，并且培养基的 pH 分析表明这些挥发性化合物是碱性的。超高效液相色谱法结合质谱分析表明，野生型 产生丰富的碱性挥发性三甲胺（TMA）和氧化物形式 TMAO；然而，在菌株 MU-1 中这些化合物的水平要低得多。值得注意的是，单独暴露于 TMA 即可拯救该突变株的表型，恢复气生菌丝和孢子的产生。我们还表明，碱性挥发物的拯救效应主要是种间特异性的，这表明这些挥发物可能有助于特定的突变体或其他亲缘关系密切的物种中不太适应的变体恢复正常的生理状态，并在土壤等复杂群落中更有效地竞争。我们的研究揭示了细菌挥发物的一个新的、有趣的作用，包括可能对其他物种有毒的挥发物。
细菌挥发物在种内或种间水平上具有广泛的生物学作用。挥发物的影响主要在产生细菌和受体细菌之间观察到，这些细菌大多属于不同的物种。在这项研究中，我们报告说，土壤栖息细菌 ，在其正常发育周期中形成气生菌丝和孢子，在多种生长条件下也能产生碱性挥发性化合物三甲胺（TMA）。我们表明， 在环境中扩散产生的 TMA 促进了相同物种或其他生长缓慢的 生长缺陷突变体的生长和分化，从而有助于它们在土壤等复杂环境群落中的生存和竞争能力。我们的新发现表明，挥发性化合物在产生挥发性化合物的 物种群落的生长和存活中可能具有潜在的深远生物学作用。
