Potential transformation of organic matter by microbes in cryoconite,Tibetan Plateau

Microorganisms play an essential role in the glacier carbon cycle;how they transform organic matter in mountain glacial cryoconite remains to be studied.Here,we applied ultra-high resolution Fourier transform ion cyclotron resonance mass spectrometry(FT-ICR MS)and deep sequencing of 16S rRNA gene,to investigate the temporal microbial transformation of dissolved organic matter(DOM)of the Tibetan Plateau cryoconite.During the 60-day incubation,we found that DOM in cryoconite underwent a three-stage transformation,with decreasing bioavailability over time.The microbial community did not change much in the first week while degrading DOM molecules that were associated with higher H/C_(wa)and lower O/C_(wa).During days 15-30,DOM composition remained stable while microbial diversity increased.By day 60,the DOM was microbially converted into a higher state of recalcitrance,with higher values of aromatic index,O/C_(wa),and lower H/C_(wa),which contained molecules containing more heteroatoms.Cooperation among various microbial taxa,like Cyanobacteria,Bacteroidota,Gammaproteobacteria,Firmicutes,and Actinobacteriota,drove the DOM transformation in cryoconite.This study sheds light on the in-situ transformation of DOM composition meditated by microbial populations in cryoconite at a temporal scale,providing new insights into understanding the microbial roles in the glacier organic carbon transformation.

山地与极地冰川表面生态系统DNA病毒的多样性与功能

冰川覆盖了地球表面的10%,是典型的极端环境.病毒在冰川表面生态系统中丰富且活跃,在控制微生物群落中发挥关键作用.然而,我们对冰川表面生态系统病毒及其对下游生态系统的潜在影响了解非常有限.本研究构建了冰川表面生态系统DNA病毒基因组数据集(SgVG),将已有冰川DNA病毒基因组数量扩展了15倍.数据集包含了来自全球38个山地和极地冰川,涵盖雪、冰、融水和冰尘的10,840个DNA病毒物种.冰川表面DNA病毒特异性高,但对公众健康的潜在风险极低.冰川表面病毒群落结构主要受生境影响,且冰尘病毒最为活跃.裂解性病毒在所有生境中普遍存在,而雪和冰中溶源性病毒的相对比例较高.此外,冰川表面病毒可侵染冰川中83%的门或纲的原核微生物,并且能够编码具有促进宿主代谢和协助宿主适应寒冷环境等功能的多种辅助代谢基因.本研究系统地描述了山地和极地冰川表面生态系统DNA病毒的多样性和功能,为评估冰川DNA病毒的生态功能、安全风险及构建区域生态模型提供了重要科学依据.