Subcellular view of host–microbiome nutrient exchange in sponges: insights into the ecological success of an early metazoan–microbe symbiosis

Background:

Sponges are increasingly recognised as key ecosystem engineers in many aquatic habitats. They play an important role in nutrient cycling due to their unrivalled capacity for processing both dissolved and particulate organic matter (DOM and POM) and the exceptional metabolic repertoire of their diverse and abundant microbial communities. Functional studies determining the role of host and microbiome in organic nutrient uptake and exchange, however, are limited. Therefore, we coupled pulse-chase isotopic tracer techniques with nanoscale secondary ion mass spectrometry (NanoSIMS) to visualise the uptake and translocation of 13C- and 15N-labelled dissolved and particulate organic food at subcellular level in the high microbial abundance sponge Plakortis angulospiculatus and the low microbial abundance sponge Halisarca caerulea.

Results:

The two sponge species showed significant enrichment of DOM- and POM-derived 13C and 15N into their tissue over time. Microbial symbion...

背景：
海绵在诸多水生栖息地中作为关键生态系统工程师的地位日益得到学界认可。其凭借对溶解有机物（dissolved organic matter, DOM）与颗粒有机物（particulate organic matter, POM）的无与伦比的处理能力，以及体内多样且丰富的微生物群落所具备的非凡代谢潜能，在养分循环中发挥着核心作用。然而，针对宿主与微生物组在有机养分摄取与交换过程中所扮演角色的功能研究仍较为有限。因此，本研究将脉冲追踪同位素示踪技术与纳米二次离子质谱（nanoscale secondary ion mass spectrometry, NanoSIMS）相结合，以在亚细胞水平上可视化高微生物丰度海绵Plakortis angulospiculatus与低微生物丰度海绵Halisarca caerulea体内，经13C和15N标记的溶解态与颗粒态有机食物的摄取与转运过程。

结果：
两种海绵均随时间推移，其组织中显著富集了源自DOM与POM的13C和15N。微生物共生体……