Does the Mass Balance of the Reactive Tracers Resazurin and Resorufin Close at the Microbial Scale?
Does the Mass Balance of the Reactive Tracers Resazurin and Resorufin Close at the Microbial Scale?
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DOI：
10.1029/2019jg005435
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发表时间：
2020-02-01
影响因子：
3.7
通讯作者：
Gonzalez-Pinzon, Ricardo
中科院分区：
文献类型：
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作者：
Dallan, Eleonora;Regier, Peter;Gonzalez-Pinzon, Ricardo
刃天青（Raz）是一种吩恶嗪染料，可通过有氧呼吸不可逆地还原为子化合物试卤灵（Rru）。以前的水文研究，使用Raz-Rru反应示踪剂系统，以量化水-沉积物的相互作用和代谢活动的报告，稀释校正质量的拉兹和Rru回收小于质量的拉兹注入。这种缺乏质量平衡关闭已被报告为这种示踪剂系统的非理想性，迄今为止，仍然不清楚是什么驱动不完全恢复。我们使用受控实验室实验改变Raz的初始浓度、实验持续时间和存在的微生物群落的类型，以在去除田间实验中不完全恢复的其他可疑原因的条件下量化Raz和Rru的质量平衡，即，吸附沉积物和光衰变。我们使用Raz和Rru浓度随时间的总和来评估质量回收率和变异性，发现质量回收率在85.6- 110.4%的范围内，最大标准偏差为7.5%。在四个实验中的三个实验中，质量恢复没有强烈的时间趋势。在使用枯草芽孢杆菌细菌的实验中，较低的回收率和回收率的时间趋势的证据仅在Raz完全转化后13小时后发生（即，超过大多数田间实验的持续时间）。这些结果表明，在现场研究中缺乏质量回收可能与物理或化学机制，而不是生物相互作用与Raz-Rru示踪system.Plain语言摘要刃天青（拉兹）是一种荧光染料，可以转化为试卤灵（RRU）的微生物。十年来，它一直被用来研究水如何与沉积物和微生物群落相互作用。然而，这些研究中的大多数回收的Raz和Rru少于添加的Raz，这引发了一个问题：Raz和Rru的质量平衡在微生物规模上是否接近？我们用不同的微生物进行了多次实验来回答这个问题。我们的结果通常显示完全质量恢复，这意味着现场研究中报告的不完全回收受物理或化学因素的影响。关键点质量平衡用于评估微生物转化是否可以解释刃天青的不完全回收。试卤灵的现场研究用不同微生物进行的实验表明，在所有转化阶段，质量完全恢复。在围隔生态系统和实地实验中不完全恢复
Resazurin (Raz) is a phenoxazine dye that can be reduced irreversibly to the daughter compound resorufin (Rru) by aerobic respiration. Previous hydrologic studies using the Raz-Rru reactive tracer system to quantify water-sediment interactions and metabolic activity have reported that dilution-corrected masses of Raz and Rru recovered are smaller than the mass of Raz injected. This lack of mass balance closure has been reported as a nonideality of this tracer system and, to date, it is still unclear what drives incomplete recovery. We used controlled laboratory experiments varying the initial concentrations of Raz, the duration of the experiments, and the type of microbial communities present to quantify mass balances of Raz and Rru under conditions that removed other suspected causes of incomplete recovery in field experiments, i.e., sorption to sediments and photodecay. We used the summation of Raz and Rru concentrations over time to assess mass recovery and variability and found mass recoveries in the range of 85.6-110.4%, with a maximum standard deviation of 7.5%. In three of the four experiments, no strong temporal trend in mass recovery is present. In an experiment with Bacillus subtilis bacteria, lower recovery and evidence of a temporal trend in recovery only occurred after 13 hr past the complete transformation of Raz (i.e., beyond the duration of most field experiments). These results suggest that the lack of mass recovery in field studies is likely associated with physical or chemical mechanisms rather than biological interactions with the Raz-Rru tracer system.Plain Language Summary Resazurin (Raz) is a fluorescent dye that can be transformed into resorufin (Rru) by microorganisms. It has been used for a decade to study how water interacts with sediments and microbial communities. However, most of these studies recover less Raz and Rru than the Raz that was added, prompting the question: Does the mass balance of Raz and Rru close at the microbial scale? We conducted multiple experiments with different microbes to answer this question. Our results generally show full mass recovery, meaning that the incomplete recovery reported in field studies is governed by physical or chemical factors.Key PointsMass balances were used to assess if microbial transformation explains incomplete recovery of resazurin-resorufin in field studies Experiments conducted with different microorganisms indicate complete mass recovery during all conversion stages Complete mass recovery at the microbial scale suggests sorption is responsible for incomplete recovery in mesocosm and field experiments