PDF(Pubmed)
Abstract：
Aerobic anoxygenic phototrophic (AAP) bacteria are an important component of freshwater bacterioplankton. They can support their heterotrophic metabolism with energy from light, enhancing their growth efficiency. Based on results from cultures, it was hypothesized that photoheterotrophy provides an advantage under carbon limitation and facilitates access to recalcitrant or low-energy carbon sources. However, verification of these hypotheses for natural AAP communities has been lacking. Here, we conducted whole community manipulation experiments and compared the growth of AAP bacteria under carbon limited and with recalcitrant or low-energy carbon sources under dark and light (near-infrared light, λ > 800 nm) conditions to elucidate how they profit from photoheterotrophy. We found that AAP bacteria induce photoheterotrophic metabolism under carbon limitation, but they overcompete heterotrophic bacteria when carbon is available. This effect seems to be driven by physiological responses rather than changes at the community level. Interestingly, recalcitrant (lignin) or low-energy (acetate) carbon sources inhibited the growth of AAP bacteria, especially in light. This unexpected observation may have ecosystem-level consequences as lake browning continues. In general, our findings contribute to the understanding of the dynamics of AAP bacteria in pelagic environments.
摘要：
有氧缺氧光养(AAP)细菌是淡水浮游细菌的重要组成部分。它们可以用光的能量支持它们的异养代谢，提高增长效率。根据文化的结果，据推测,光异质营养在碳限制下提供了优势,并有助于获得顽固或低能量的碳源.然而,一直缺乏对自然AAP社区的这些假设的验证。这里,我们进行了整个社区操作实验，并比较了AAP细菌在碳限制下的生长以及在黑暗和光（近红外光，λ>800nm）的条件，以阐明它们如何从光异型营养中获利。我们发现AAP细菌在碳限制下诱导光异养代谢，但当碳可用时，它们会过度竞争异养细菌。这种效应似乎是由生理反应驱动的，而不是社区层面的变化。有趣的是,顽固的（木质素）或低能量（乙酸）碳源抑制了AAP细菌的生长，尤其是在光。随着湖泊褐变的继续，这种意外的观察可能会产生生态系统层面的后果。总的来说,我们的发现有助于了解远洋环境中AAP细菌的动态。
