Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden.
Umeå Marine Sciences Centre, Norrbyn 557, SE-905 71 Hörnefors, Sweden.
FEMS Microbiol Ecol. 2024 Oct 25;100(11). doi: 10.1093/femsec/fiae121.
Prokaryotic maintenance respiration and associated metabolic activities constitute a considerable proportion of the total respiration of carbon to CO2 in the ocean's mixed layer. However, seasonal influences on prokaryotic maintenance activities in terms of morphological and metabolic adaptations at low (winter) and high productivity (summer) are still unclear. To address this, we examined the natural prokaryotic communities at the mesocosm scale to analyse the differences in their morphological features and gene expression at low and high maintenance respiration, experimentally manipulated with the specific growth rate. Here, we showed that morphological features including membrane blebbing, membrane vesicles, and cell‒cell connections occurred under high productivity. Metabolic adaptations associated with maintenance activities were observed under low productivity. Several Kyoto Encyclopedia of Genes and Genomes categories related to signal transduction, energy metabolism, and translational machinery supported maintenance activities under simulated winter conditions. Differential abundances of genes related to transporters, osmoregulation, nitrogen metabolism, ribosome biogenesis, and cold stress were observed. Our results demonstrate how specific growth rate in different seasons can influence resource allocation at the levels of morphological features and metabolic adaptations. This motivates further study of morphological features and their ecological role during high productivity, while investigations of metabolic adaptations during low productivity can advance our knowledge about maintenance activities.
原核生物的维持呼吸及其相关代谢活动构成了海洋混合层中碳向 CO2 总呼吸的相当大的比例。然而，在低生产力（冬季）和高生产力（夏季）条件下，原核生物维持活动在形态和代谢适应方面的季节性影响仍不清楚。为了解决这个问题，我们在中观尺度的现场实验中研究了自然原核生物群落，以分析在维持呼吸高和低时其形态特征和基因表达的差异，通过特定生长率进行实验操作。在这里，我们表明，在高生产力条件下会出现膜泡、膜泡和细胞连接等形态特征。在低生产力条件下观察到与维持活动相关的代谢适应。与信号转导、能量代谢和翻译机制相关的几个京都基因与基因组百科全书类别支持模拟冬季条件下的维持活动。还观察到与转运蛋白、渗透压调节、氮代谢、核糖体生物发生和冷应激相关的基因的差异丰度。我们的结果表明，不同季节的特定生长率如何影响形态特征和代谢适应层面的资源分配。这进一步激发了在高生产力条件下对形态特征及其生态作用的研究，而在低生产力条件下对代谢适应的研究可以增进我们对维持活动的认识。
