Biphasic cellular adaptations and ecological implications of Alteromonas macleodii degrading a mixture of algal polysaccharides
Biphasic cellular adaptations and ecological implications of Alteromonas macleodii degrading a mixture of algal polysaccharides
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DOI：
10.1038/s41396-018-0252-4
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发表时间：
2019-01-01
期刊：
影响因子：
11
通讯作者：
Wietz, Matthias
中科院分区：
文献类型：
--
作者：
Koch, Hanna;Duerwald, Alexandra;Wietz, Matthias
海藻多糖是重要的细菌营养源和海洋食物网的重要组成部分。然而，关于多糖混合物的细菌降解的细胞和生态方面，据推测丰富的自然栖息地，知之甚少。在这里，我们将海洋多糖混合物和它们的细菌利用以几种方式使用模式细菌Alteromonas macleodii 83-1，它可以降解多种藻类多糖，并有助于海洋中的多糖降解。转录组学、蛋白质组学和外切代谢组学分析揭示了A. Macleodii 83-1降解海带多糖、藻酸盐和果胶的混合物。菌株83-1表现出由分解代谢产物阻遏驱动的底物优先化，最初利用海带多糖，然后同时利用藻酸盐/果胶。这种双相表型与基因表达、蛋白质丰度和代谢产物分泌的显著变化相一致，主要涉及CAZymes/多糖利用位点，但也涉及其他功能性状。外泌代谢组组成的明显时间变化，包括藻酸盐/果胶特异性分泌的吡咯喹啉醌，表明底物依赖性适应影响社区内的化学相互作用。细胞适应的生态相关性被强调的分子证据表明，常见的海洋大型藻类，特别是海藻酸钠和墨角藻，释放混合物的藻酸盐和果胶样鼠李半乳糖醛酸聚糖。此外，CAZyme微多样性和对交替单胞菌属之间的多糖混合物的基因组倾向。表明多糖相关性状是一种生态生理因素，可能与具有不同生态策略的不同“碳水化合物利用类型”有关。考虑到藻类在全球范围内的大量初级生产力，这些见解有助于理解细菌-藻类相互作用和化学多样性多糖库的生物化，这是海洋碳循环的关键步骤。
Algal polysaccharides are an important bacterial nutrient source and central component of marine food webs. However, cellular and ecological aspects concerning the bacterial degradation of polysaccharide mixtures, as presumably abundant in natural habitats, are poorly understood. Here, we contextualize marine polysaccharide mixtures and their bacterial utilization in several ways using the model bacterium Alteromonas macleodii 83-1, which can degrade multiple algal polysaccharides and contributes to polysaccharide degradation in the oceans. Transcriptomic, proteomic and exometabolomic profiling revealed cellular adaptations of A. macleodii 83-1 when degrading a mix of laminarin, alginate and pectin. Strain 83-1 exhibited substrate prioritization driven by catabolite repression, with initial laminarin utilization followed by simultaneous alginate/pectin utilization. This biphasic phenotype coincided with pronounced shifts in gene expression, protein abundance and metabolite secretion, mainly involving CAZymes/polysaccharide utilization loci but also other functional traits. Distinct temporal changes in exometabolome composition, including the alginate/pectin-specific secretion of pyrroloquinoline quinone, suggest that substrate-dependent adaptations influence chemical interactions within the community. The ecological relevance of cellular adaptations was underlined by molecular evidence that common marine macroalgae, in particular Saccharin and Fucus, release mixtures of alginate and pectin-like rhamnogalacturonan. Moreover, CAZyme microdiversity and the genomic predisposition towards polysaccharide mixtures among Alteromonas spp. suggest polysaccharide-related traits as an ecophysiological factor, potentially relating to distinct 'carbohydrate utilization types' with different ecological strategies. Considering the substantial primary productivity of algae on global scales, these insights contribute to the understanding of bacteria-algae interactions and the remineralization of chemically diverse polysaccharide pools, a key step in marine carbon cycling.