Revisiting the concept of ‘enzymic latch’ on carbon in peatlands

Urbanová, Zuzana; Hájek, Tomáš

doi:10.1016/j.scitotenv.2021.146384

Cited by 26 publications

(30 citation statements)

References 63 publications

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“…Oxidative enzyme activity has previously been shown to release hydrolytic enzyme activity from constraints by reducing phenolic concentrations in peat (Freeman et al, 2002, 2004; Saraswati et al, 2016). Similar to previous studies (Romanowicz et al, 2015; Strickland et al, 2009; Urbanová & Hájek, 2021), we find no evidence of constraints on oxidative and hydrolytic enzyme activity due to low oxygen availability or phenolic concentrations. The inundated and low oxygen conditions found in the young bog shallow layer may have led to enhance iron reduction, which has been shown to promote oxidative enzyme activity (Wen et al, 2019).…”

Section: Discussionsupporting

confidence: 92%

“…Oxidative enzyme activity has previously been shown to release hydrolytic enzyme activity from constraints by reducing phenolic concentrations in peat (Freeman et al, 2002(Freeman et al, , 2004Saraswati et al, 2016). Similar to previous studies (Romanowicz et al, 2015;Strickland et al, 2009;Urbanová & Hájek, 2021), we find no evidence of constraints on oxidative and hydrolytic enzyme activity due F I G U R E 5 (a) Boxplots of enzyme multifunctionality estimate (MultEnzMeso) in young bog and mature bog peat mesocosms under both oxic (blue) and anoxic (red) conditions. No difference in MultEnzMeso between oxic and anoxic in the young bog (p = 0.99) and MB (p = 0.94) mesocosms.…”

Section: Constraints On Potential Enzyme Activity Along a Thermokarst Bog Transectsupporting

confidence: 80%

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Constraints on potential enzyme activities in thermokarst bogs: Implications for the carbon balance of peatlands following thaw

Heffernan

Jassey

Frederickson

et al. 2021

Global Change Biology

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Section: Discussionsupporting

confidence: 92%

“…Oxidative enzyme activity has previously been shown to release hydrolytic enzyme activity from constraints by reducing phenolic concentrations in peat (Freeman et al, 2002(Freeman et al, , 2004Saraswati et al, 2016). Similar to previous studies (Romanowicz et al, 2015;Strickland et al, 2009;Urbanová & Hájek, 2021), we find no evidence of constraints on oxidative and hydrolytic enzyme activity due F I G U R E 5 (a) Boxplots of enzyme multifunctionality estimate (MultEnzMeso) in young bog and mature bog peat mesocosms under both oxic (blue) and anoxic (red) conditions. No difference in MultEnzMeso between oxic and anoxic in the young bog (p = 0.99) and MB (p = 0.94) mesocosms.…”

Section: Constraints On Potential Enzyme Activity Along a Thermokarst Bog Transectsupporting

confidence: 80%

Constraints on potential enzyme activities in thermokarst bogs: Implications for the carbon balance of peatlands following thaw

Heffernan

Jassey

Frederickson

et al. 2021

Global Change Biology

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“…However, inconsequential effects of oxygen introduction on phenolic abundance have been observed in some peatland sites [36,[52][53][54]. It has been suggested that peat bogs are .…”

Section: Prod Sat )mentioning

confidence: 99%

“…Though the inhibitory effects of soluble phenolics are generally accepted, the extent to which they inhibit C mineralization in Sphagnum-rich peatlands ("bogs") remains unclear [9,20,21,36,37]. Studies to date have focused heavily on the potential for soluble phenolics to inhibit enzymatic hydrolysis.…”

Section: Introductionmentioning

confidence: 99%

“…Studies to date have focused heavily on the potential for soluble phenolics to inhibit enzymatic hydrolysis. These studies have yielded conflicting assessments of this role, ranging from significant [9,20,21] to inconsequential [36,37]. To clarify the impacts of soluble phenolics on bog C mineralization, it is necessary to incorporate all three stages of bog decomposition (hydrolysis, fermentation, and methanogenesis) into this assessment.…”

Section: Introductionmentioning

confidence: 99%

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Quantifying the Inhibitory Impact of Soluble Phenolics on Carbon Mineralization fromSphagnum-rich Peatlands

Cory

Chanton

Spencer

et al. 2021

Preprint

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The mechanisms controlling the extraordinarily slow carbon (C) mineralization rates characteristic of Sphagnum -rich peatlands (“bogs”) remain somewhat elusive, despite decades of research on this topic. Soluble phenolic compounds have been invoked as potentially significant contributors to bog peat recalcitrance due to their affinity to slow microbial metabolism and cell growth. Despite this potentially significant role, the effects of soluble phenolic compounds on bog peat C mineralization remain unclear. We analyzed this effect by manipulating the concentration of free soluble phenolics in anaerobic bog peat incubations using water-soluble polyvinylpyrrolidone (PVP), a compound that binds with and inactivates phenolics, preventing phenolic-enzyme interactions. CO 2 and CH 4 production rates (end-products of C mineralization) correlated positively with PVP concentration following Michaelis-Menten (M.M.) saturation functions. Using M.M. parameters, we determined that soluble phenolics inhibit, at minimum, 57 ± 16% of total C (CO 2 +CH 4 ) mineralization in the anaerobic incubation conditions studied. These findings are consistent with other studies that have indicated that soluble phenolics play a significant role in regulating bog peat stability in the face of decomposition.

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From Sphagnum to shrub: Increased acidity reduces peat bacterial diversity and keystone microbial taxa imply peatland degradation

Xue

Xiang

et al. 2023

Land Degrad Dev

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Peatlands store one‐third of the Earth's carbon. Human activities and climate change‐induced peatland vegetation shift from Sphagnum to shrub may lead to peatland degradation. To understand the ecology and functions of these peatlands, we collected samples from 10 peatland mosaics dominated by Sphagnums, mixed plant communities of Sphagnums, and shrubs across south China. Through sequencing the plant rhizosphere microbiome and measuring peat properties, we explored the plant–soil interactions and identified the keystone microbial taxa in peatlands of three vegetation types. Results showed that peat pH decreased along with the plant community shift from Sphagnum to shrub, which may be due to the accumulation of sulfur and phenolics. Lower pH further reduced bacterial diversity in shrub peatlands as Acidobacteriota became predominant in the keystone taxa. Overall, microbiomes in shrub peatlands showed degraded properties, such as a less stable microbial community dominated by few keystone taxa and the loss of methane‐mitigating microbes. The keystone microbial taxa in Sphagnum peatlands included microbes that utilize insoluble organic substances, mono‐ and oligo‐saccharides. Most importantly, the methanotrophic microbes that oxidize methane only appeared in the keystone taxa of Sphagnum peatlands. Mixed plant community peatlands contained the highest concentrations of iron. Slow‐growing fungi and bacteria were in the keystone microbial taxa, indicating slow decomposition rates in these peatlands. Our study suggests that human activity and climate change‐induced peatland vegetation shift from Sphagnum to shrub leads to an unstable belowground community, indicating the degraded peatland, which may exacerbate in the future.

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Revisiting the concept of ‘enzymic latch’ on carbon in peatlands

Cited by 26 publications

References 63 publications

Constraints on potential enzyme activities in thermokarst bogs: Implications for the carbon balance of peatlands following thaw

Constraints on potential enzyme activities in thermokarst bogs: Implications for the carbon balance of peatlands following thaw

Quantifying the Inhibitory Impact of Soluble Phenolics on Carbon Mineralization fromSphagnum-rich Peatlands

From Sphagnum to shrub: Increased acidity reduces peat bacterial diversity and keystone microbial taxa imply peatland degradation

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