Department of Microbial and Molecular Systems, Laboratory for Process Microbial Ecology and Bioinspirational Management (PME&BIM), KU Leuven, B-3001, Leuven, Belgium.
Department of Animal Health, Complutense University of Madrid, 28040, Madrid, Spain.
Microb Ecol. 2021 May;81(4):990-1003. doi: 10.1007/s00248-020-01671-x. Epub 2021 Jan 6.
Floral nectar is commonly colonized by yeasts and bacteria, whose growth largely depends on their capacity to assimilate nutrient resources, withstand high osmotic pressures, and cope with unbalanced carbon-to-nitrogen ratios. Although the basis of the ecological success of these microbes in the harsh environment of nectar is still poorly understood, it is reasonable to assume that they are efficient nitrogen scavengers that can consume a wide range of nitrogen sources in nectar. Furthermore, it can be hypothesized that phylogenetically closely related strains have more similar phenotypic characteristics than distant relatives. We tested these hypotheses by investigating the growth performance on different nitrogen-rich substrates of a collection of 82 acinetobacters isolated from nectar and honeybees, representing members of five species (Acinetobacter nectaris, A. boissieri, A. apis, and the recently described taxa A. bareti and A. pollinis). We also analyzed possible links between growth performance and phylogenetic affiliation of the isolates, while taking into account their geographical origin. Results demonstrated that the studied isolates could utilize a wide variety of nitrogen sources, including common metabolic by-products of yeasts (e.g., ammonium and urea), and that phylogenetic relatedness was associated with the variation in nitrogen assimilation among the studied acinetobacters. Finally, nutrient source and the origin (sample type and country) of isolates also predicted the ability of the acinetobacters to assimilate nitrogen-rich compounds. Overall, these results demonstrate inter-clade variation in the potential of the acinetobacters as nitrogen scavengers and suggest that nutritional dependences might influence interactions between bacteria and yeasts in floral nectar.
花的蜜腺通常被酵母菌和细菌定植，其生长在很大程度上取决于它们同化营养物质的能力、耐受高渗透压的能力以及应对不平衡碳氮比的能力。尽管这些微生物在花蜜这种恶劣环境中具有生态成功的基础仍未得到充分理解，但可以合理地假设它们是高效的氮素掠食者，可以消耗花蜜中广泛的氮源。此外，可以假设亲缘关系密切的菌株比远缘菌株具有更相似的表型特征。为了检验这些假设，我们研究了从花蜜和蜜蜂中分离出的 82 株不动杆菌的集落，这些菌株代表了五个物种（嗜麦芽寡养单胞菌、鲍氏不动杆菌、蜜蜂不动杆菌和最近描述的 Bareti 不动杆菌和 Pollinis 不动杆菌）的成员，考察了它们在不同富氮基质上的生长性能。我们还分析了生长性能与分离株的系统发育关系之间的可能联系，同时考虑到它们的地理起源。结果表明，研究的分离株可以利用各种氮源，包括酵母菌的常见代谢副产物（如铵和尿素），并且系统发育关系与研究的不动杆菌中氮同化的变化有关。最后，营养源和分离株的起源（样本类型和国家）也预测了不动杆菌同化富氮化合物的能力。总的来说，这些结果表明了不动杆菌作为氮素掠食者的潜在能力存在种间差异，并表明营养依赖性可能影响细菌和酵母菌在花卉花蜜中的相互作用。
