National Centre for Polar and Ocean Research, Ministry of Earth Sciences, Goa, 403804, India.
School of Earth, Ocean and Atmospheric Sciences, Goa University, Goa, 403206, India.
J Microbiol. 2024 Aug;62(8):591-609. doi: 10.1007/s12275-024-00140-1. Epub 2024 May 30.
Microbes residing in cryoconite holes (debris, water, and nutrient-rich ecosystems) on the glacier surface actively participate in carbon and nutrient cycling. Not much is known about how these communities and their functions change during the summer melt-season when intense ablation and runoff alter the influx and outflux of nutrients and microbes. Here, we use high-throughput-amplicon sequencing, predictive metabolic tools and Phenotype MicroArray techniques to track changes in bacterial communities and functions in cryoconite holes in a coastal Antarctic site and the surrounding fjord, during the summer season. The bacterial diversity in cryoconite hole meltwater was predominantly composed of heterotrophs (Proteobacteria) throughout the season. The associated functional potentials were related to heterotrophic-assimilatory and -dissimilatory pathways. Autotrophic Cyanobacterial lineages dominated the debris community at the beginning and end of summer, while heterotrophic Bacteroidota- and Proteobacteria-related phyla increased during the peak melt period. Predictive functional analyses based on taxonomy show a shift from predominantly phototrophy-related functions to heterotrophic assimilatory pathways as the melt-season progressed. This shift from autotrophic to heterotrophic communities within cryoconite holes can affect carbon drawdown and nutrient liberation from the glacier surface during the summer. In addition, the flushing out and export of cryoconite hole communities to the fjord could influence the biogeochemical dynamics of the fjord ecosystem.
微生物生存在冰川表面的冰核孔（由碎屑、水和营养丰富的生态系统组成）中，积极参与碳和养分循环。当强烈的消融和径流改变养分和微生物的流入和流出时，这些群落及其功能如何变化，我们对此知之甚少。在这里，我们使用高通量扩增子测序、预测代谢工具和表型微阵列技术，在夏季融化季节跟踪沿海南极地区和周围峡湾冰核孔中细菌群落和功能的变化。整个季节，冰核孔融水中的细菌多样性主要由异养菌（变形菌门）组成。相关的功能潜力与异养同化和异化途径有关。夏季开始和结束时，碎屑群落中以蓝藻为主导，而在融冰高峰期，异养拟杆菌门和变形菌门相关门增加。基于分类的预测功能分析表明，随着融冰季节的进行，从以光合作用相关功能为主向异养同化途径转变。这种从冰核孔中的自养到异养群落的转变可能会影响夏季从冰川表面吸收碳和释放养分。此外，冰核孔群落被冲出并输出到峡湾，可能会影响峡湾生态系统的生物地球化学动态。
