Department of Entomology and Nematology, University of California, Davis, Davis, California, USA.
Department of Entomology, Cornell University, Ithaca, New York, USA.
Environ Microbiol Rep. 2023 Jun;15(3):170-180. doi: 10.1111/1758-2229.13139. Epub 2023 Feb 13.
Floral nectar is frequently colonised by microbes. However, nectar microbial communities are typically species-poor and dominated by few cosmopolitan genera. One hypothesis is that nectar constituents may act as environmental filters. We tested how five non-sugar nectar compounds as well as elevated sugar impacted the growth of 12 fungal and bacterial species isolated from nectar, pollinators, and the environment. We hypothesised that nectar isolated microbes would have the least growth suppression. Additionally, to test if nectar compounds could affect the outcome of competition between microbes, we grew a subset of microbes in co-culture across a subset of treatments. We found that some compounds such as H O suppressed microbial growth across many but not all microbes tested. Other compounds were more specialised in the microbes they impacted. As hypothesised, the nectar specialist yeast Metschnikowia reukaufii was unaffected by most nectar compounds assayed. However, many non-nectar specialist microbes remained unaffected by nectar compounds thought to reduce microbial growth. Our results show that nectar chemistry can influence microbial communities but that microbe-specific responses to nectar compounds are common. Nectar chemistry also affected the outcome of species interactions among microbial taxa, suggesting that non-sugar compounds can affect microbial community assembly in flowers.
花的蜜腺经常被微生物定植。然而，花蜜微生物群落通常物种较少，以少数世界性属为主。一种假设是花蜜成分可能充当环境过滤器。我们测试了五种非糖花蜜化合物以及升高的糖如何影响从花蜜、传粉者和环境中分离的 12 种真菌和细菌的生长。我们假设花蜜分离的微生物受到的生长抑制最小。此外，为了测试花蜜化合物是否会影响微生物之间竞争的结果，我们在部分处理中进行了微生物共培养。我们发现，一些化合物，如 H2O，抑制了许多但不是所有测试微生物的生长。其他化合物对它们影响的微生物更具特异性。如假设的那样，花蜜专性酵母 Metschnikowia reukaufii 不受大多数测试的花蜜化合物的影响。然而，许多非花蜜专性微生物仍然不受被认为可以减少微生物生长的花蜜化合物的影响。我们的结果表明，花蜜化学可以影响微生物群落，但微生物对花蜜化合物的特定反应很常见。花蜜化学还影响了微生物分类群之间物种相互作用的结果，这表明非糖化合物可以影响花朵中微生物群落的组装。
