ABSTRACT: Priming effects that stimulate increased degradation of refractory organic matter by microorganisms following fresh organic matter input is a well-known phenomenon in terrestrial environments but remains controversial in marine environments. We used a combination of chemical (gas chromatography-EI quadrupole time of flight mass spectrometry) and molecular biology (DNA stable-isotope probing [DNA-SIP]) methods to trace the fate of terrestrially derived particulate organic matter (TPOM) and the response of the marine microbial community to fresh organic matter inputs. We tested the potential for priming effects among a mixture of marine and terrestrial microbial assemblages, amended either with only ¹³C-labelled TPOM (¹³C-Avena sativa) or with an addition of ¹²C-Skeletonema costatum (a marine diatom) as a labile co-substrate within the range of diatom concentrations found in estuaries. We monitored ¹³C-labelled TPOM lipid tracers (long-chain fatty acids, n-alkan-1-ols, phytol, sitosterol, β-amyrin and components of cutins) throughout a 42 d incubation experiment. Comparisons with controls carried out without diatom addition showed faster decay of phytol, n-alkan-1-ols, and components of cuticular waxes in the presence of diatoms, while fatty acids and sitosterol were unaffected. Bacteria belonging to the Bacteroidota phylum (mainly Flavobacteria and Cytophaga) were the dominant microbes involved in priming-induced TPOM degradation in the incubation treatments. Sphingomonadales and Rhizobiales, capable of lignin and hemicellulose degradation, also contributed to the degradation of TPOM but did not seem to contribute to priming effects related to increased diatom abundance. These lab-based results demonstrate direct evidence that priming of TPOM occurred selectively via a consortium of microbes.

中文翻译：

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硅藻存在下维管植物材料启动的生物学机制

摘要：在陆地环境中，新鲜有机物输入后刺激微生物对难降解有机物进一步降解的启动效应是陆地环境中众所周知的现象，但在海洋环境中仍然存在争议。我们结合使用化学（气相色谱-EI 四极杆飞行时间质谱）和分子生物学（DNA 稳定同位素探测 [DNA-SIP]）方法来追踪陆地来源的颗粒有机物 (TPOM) 的命运和响应海洋微生物群落转化为新鲜有机物质输入。我们测试了海洋和陆地微生物组合混合物中启动效应的潜力，仅用¹³ C 标记的 TPOM（¹³ C- Avena sativa）进行修正）或添加¹² C-中肋骨条藻（一种海洋硅藻）作为河口硅藻浓度范围内的不稳定共基质。我们在整个 42 天的孵化实验中监测了¹³ C 标记的 TPOM 脂质示踪剂（长链脂肪酸、n -alkan-1-ols、植醇、谷甾醇、β-香树脂素和角质成分）。与未添加硅藻的对照进行比较表明，在硅藻存在下，植醇、 n -alkan-1-醇和角质层蜡成分的腐烂速度更快，而脂肪酸和谷甾醇不受影响。属于拟杆菌门的细菌（主要是黄杆菌和噬细胞菌）是在孵化处理中参与引发诱导的 TPOM 降解的主要微生物。鞘氨醇单胞菌目和根瘤菌目能够降解木质素和半纤维素，也促进了 TPOM 的降解，但似乎没有促进与硅藻丰度增加相关的启动效应。这些基于实验室的结果证明了直接证据表明 TPOM 的启动是通过微生物群选择性发生的。