PDF(Pubmed)
Abstract：
Blooms of gelatinous zooplankton, an important source of protein-rich biomass in coastal waters, often collapse rapidly, releasing large amounts of labile detrital organic matter (OM) into the surrounding water. Although these blooms have the potential to cause major perturbations in the marine ecosystem, their effects on the microbial community and hence on the biogeochemical cycles have yet to be elucidated. We conducted microcosm experiments simulating the scenario experienced by coastal bacterial communities after the decay of a ctenophore (Mnemiopsis leidyi) bloom in the northern Adriatic Sea. Within 24 h, a rapid response of bacterial communities to the M. leidyi OM was observed, characterized by elevated bacterial biomass production and respiration rates. However, compared to our previous microcosm study of jellyfish (Aurelia aurita s.l.), M. leidyi OM degradation was characterized by significantly lower bacterial growth efficiency, meaning that the carbon stored in the OM was mostly respired. Combined metagenomic and metaproteomic analysis indicated that the degradation activity was mainly performed by Pseudoalteromonas, producing a large amount of proteolytic extracellular enzymes and exhibiting high metabolic activity. Interestingly, the reconstructed metagenome-assembled genome (MAG) of Pseudoalteromonas phenolica was almost identical (average nucleotide identity >99%) to the MAG previously reconstructed in our A. aurita microcosm study, despite the fundamental genetic and biochemical differences of the two gelatinous zooplankton species. Taken together, our data suggest that blooms of different gelatinous zooplankton are likely triggering a consistent response from natural bacterial communities, with specific bacterial lineages driving the remineralization of the gelatinous OM.IMPORTANCEJellyfish blooms are increasingly becoming a recurring seasonal event in marine ecosystems, characterized by a rapid build-up of gelatinous biomass that collapses rapidly. Although these blooms have the potential to cause major perturbations, their impact on marine microbial communities is largely unknown. We conducted an incubation experiment simulating a bloom of the ctenophore Mnemiopsis leidyi in the Northern Adriatic, where we investigated the bacterial response to the gelatinous biomass. We found that the bacterial communities actively degraded the gelatinous organic matter, and overall showed a striking similarity to the dynamics previously observed after a simulated bloom of the jellyfish Aurelia aurita s.l. In both cases, we found that a single bacterial species, Pseudoalteromonas phenolica, was responsible for most of the degradation activity. This suggests that blooms of different jellyfish are likely to trigger a consistent response from natural bacterial communities, with specific bacterial species driving the remineralization of gelatinous biomass.
摘要：
大量的凝胶状浮游动物，沿海水域富含蛋白质的生物质的重要来源，经常迅速崩溃，将大量不稳定的碎屑有机物（OM）释放到周围的水中。尽管这些水华有可能对海洋生态系统造成重大扰动，它们对微生物群落以及因此对生物地球化学循环的影响尚未阐明。我们进行了微观实验，模拟了亚得里亚海北部ctenophore（Mnemimopsisleidyi）开花后沿海细菌群落经历的情景。24小时内,观察到细菌群落对M.leidyiOM的快速反应，以细菌生物量产生和呼吸速率升高为特征。然而,与我们之前对水母(Aureliaauritas.l.)的微观世界研究相比，M.leidyiOM降解的特征是细菌生长效率显着降低，这意味着储存在OM中的碳大部分是呼吸的。宏基因组和蛋白质组学联合分析表明，降解活性主要由假交替单胞菌进行，产生大量蛋白水解胞外酶并表现出高代谢活性。有趣的是,重新构建的宏基因组组装基因组(MAG)与先前在我们的A.aurita微观世界研究中重建的MAG几乎相同(平均核苷酸同一性>99%),尽管两种胶状浮游动物物种的基本遗传和生化差异。一起来看,我们的数据表明，不同的凝胶状浮游动物的繁殖可能会引发自然细菌群落的一致反应，特定的细菌谱系驱动凝胶状OM的再矿化。重要的水母水华越来越成为海洋生态系统中反复出现的季节性事件，其特征是凝胶状生物质的快速积累，迅速崩溃。尽管这些水华有可能引起重大扰动，它们对海洋微生物群落的影响在很大程度上是未知的。我们进行了一项孵化实验，模拟了亚得里亚海北部的ctenophoreMnemimopsisleidyi的开花，我们调查了细菌对凝胶状生物质的反应。我们发现细菌群落积极降解凝胶状有机物，总体上与水母Aureliaauritas.l模拟开花后观察到的动力学具有惊人的相似性。在这两种情况下，我们发现一种细菌，假交替单胞菌，是大部分降解活性的原因。这表明，不同水母的开花可能会引发自然细菌群落的一致反应，特定的细菌物种驱动凝胶状生物质的再矿化。
