Influence of moisture and freeze–thaw on leaf microbial community dynamics

2010 ◽  
Vol 40 (2) ◽  
pp. 394-400 ◽  
Author(s):  
C. Corrigan ◽  
M. Oelbermann
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Microbial Community ◽  
Sugar Maple ◽  
Community Dynamics ◽  
Nitrogen Concentration ◽  
Fagus Grandifolia ◽  
Nutrient Inputs ◽  
Freezing And Thawing ◽  
Freeze Thaw

In forest ecosystems, litterfall that collects in trapping devices, to quantify organic matter and nutrient inputs, is exposed to periods of wetting, drying, freezing, and thawing. These fluctuating environmental conditions may influence the microbial community structure inhabiting the leaves and may result in the loss of mobile nutrients, leading to an underestimation of actual organic matter and nutrient inputs. The objectives of this study were to evaluate the influence of (i) different quantities of moisture (LOW = 30 mm, MED = 60 mm, HI = 100 mm) and (ii) freeze–thaw (FT) on leaf (sugar maple ( Acer saccharum Marsh.), American basswood ( Tilia americana L.), and American beech ( Fagus grandifolia Ehrh.)) microbial activity and community structure. There was a significantly greater (p < 0.05) CO2 production rate in LOW and FT treatments for sugar maple and beech, and in HI and FT treatments for basswood. A similar trend occurred for leaf nitrogen concentration but not for carbon (C). Utilization of C substrates was up to 10% greater in the FT treatments. Principal components analysis on the activity of C source utilization showed a distinct clustering between leaf species and between treatments following a pattern similar to that of microbial respiration. Results from this study suggested that the collection of litter should take place more frequently during seasons when frost is imminent.

scholarly journals Microbial Community Structure Affects Marine Dissolved Organic Matter Composition

2016 ◽  
Vol 3 ◽  
Author(s):  
Elizabeth B. Kujawinski ◽  
Krista Longnecker ◽  
Katie L. Barott ◽  
Ralf J. M. Weber ◽  
Melissa C. Kido Soule
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Microbial Community ◽  
Dissolved Organic Matter ◽  
Microbial Community Structure ◽  
Organic Matter Composition

Linking Microbial Community Dynamics in BIOX® Leaching Tanks to Process Conditions: Integrating Lab and Commercial Experience

2017 ◽  
Vol 262 ◽  
pp. 38-42 ◽  
Author(s):  
Mariette Smart ◽  
Robert J. Huddy ◽  
Catherine J. Edward ◽  
Charl Fourie ◽  
Trust Shumba ◽  
...  
Keyword(s):  
South Africa ◽  
Community Structure ◽  
Microbial Community ◽  
Research University ◽  
Community Dynamics ◽  
Operating Conditions ◽  
Process Conditions ◽  
Significant Shift ◽  
Engineering Research ◽  
Microbial Community Dynamics

In the commercial BIOX® process, an acidophilic mixed bacterial and archaeal community dominated by iron and sulphur oxidising microorganisms is used to facilitate the recovery of precious metals from refractory gold-bearing sulphidic mineral concentrates. Characterisation of the microbial communities associated with commercial BIOX® reactors from four continents revealed a significant shift in the microbial community structure compared to that of the seed culture, maintained at SGS (South Africa). This has motivated more detailed study of the microbial community dynamics in the process. Microbial speciation of a subset of the BIOX® reactors at Fairview mines (Barberton, South Africa) and two laboratory maintained reactors housed at Centre for Bioprocess Engineering Research, University of Cape Town, has been performed tri-annually for three years by quantitative real-time polymerase chain reaction. The laboratory BIOX® culture maintained on Fairview concentrate was dominated by the desired iron oxidiser, Leptospirillum ferriphilum, and sulphur oxidiser, Acidithiobacillus caldus, when operated under standard BIOX® conditions. Shifts in the microbial community as a result of altered operating conditions were transient and did not result in a loss of the microbial diversity of the BIOX® culture. The community structure of the Fairview mines BIOX® reactor tanks showed archaeal dominance of these communities by organisms such as the iron oxidiser Ferroplasma acidiphilum and a Thermoplasma sp. for the period monitored. Shifts in the microbial community were observed across the monitoring period and mapped to changes in performance of the commercial process plant. Understanding the effect of changes in the plant operating conditions on the BIOX® community structure may assist in providing conditions that support the desired microbial consortium for optimal biooxidation to maximize gold recovery.

Land use change in Amazonian Dark Earth and Acrisol: Responses of organic carbon, organic matter composition and microbial carbon utilisation

2020 ◽  
Author(s):  
Klaus Jarosch ◽  
Luis Carlos Colocho Hurtarte ◽  
Konstantin Gavazov ◽  
Aleksander Westphal Muniz ◽  
Christoph Müller ◽  
...  
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Community Structure ◽  
Microbial Community ◽  
Organic Carbon ◽  
Land Use Change ◽  
Microbial Community Structure ◽  
Secondary Forest ◽  
Soil Types ◽  
Amazonian Dark Earth

&lt;p&gt;The conversion of tropical forest for cassava cultivation is widely known to decrease the soil organic matter (OM) and nutrient contents of highly weathered soils in the tropics. Amazonian Dark Earth (ADE) might be affected less due to their historical anthropogenic amelioration with e.g. charcoal, ceramics and bones, leading to higher soil OM and nutrient concentrations. In this study, we analysed the effect of land use change on the OM dynamics and its composition under tropical conditions, using ADE and an adjacent Acrisol (ACR) as model systems. Soil samples were obtained south of Manaus (Brazil), from a secondary forest and an adjacently located 40-year-old cassava plantation. The land use change induced a severe decrease of organic carbon (OC) concentrations in ADE (from 35 to 15&amp;#160;g&amp;#160;OC&amp;#160;kg&lt;sup&gt;&amp;#8209;1&lt;/sup&gt;) while OC in the adjacent ACR was less affected (18 to 16&amp;#160;g&amp;#160;OC&amp;#160;kg&lt;sup&gt;&amp;#8209;1&lt;/sup&gt;). Soils were analysed by &lt;sup&gt;13&lt;/sup&gt;C NMR spectroscopy to obtain information on how the conversion of secondary forest to cassava affected the chemical composition of OM. Our results show that land use change induces differences in the OM composition: The OM in ADE changes to a more decomposed state (increase of alkyl:O/N-alkyl ratio) whereas the OM in ACR changes to a less decomposed state (decrease of alkyl:O/N-alkyl ratio). According to a molecular mixing model, land use change influenced mostly the proportion of lipids, which might be related with a change of the plant input. The incubation of the soils with &lt;sup&gt;13&lt;/sup&gt;C glucose enabled resolving how soil microorganisms were affected by land use change. In both soil types ADE and ACR, land use change caused a reduction of the total &lt;sup&gt;13&lt;/sup&gt;C glucose respiration by approximately one third in a 7-days incubation, implying lower microbial activity. Microorganisms in both soil types appear to be more readily active in soils under forest, since we observed a distinct lag time between &lt;sup&gt;13&lt;/sup&gt;C glucose addition and respiration under cassava planation. This indicated differences in microbial community structure, which we will assess further by determining the &lt;sup&gt;13&lt;/sup&gt;C label uptake by the microbial biomass and the microbial community structure using &lt;sup&gt;13&lt;/sup&gt;C PLFA analysis. Preliminary results from synchrotron-based STXM demonstrate a distinct arrangement of OM at fine-sized charcoal-particle interfaces. Samples of soils receiving &lt;sup&gt;13&lt;/sup&gt;C label will be further analysed by NanoSIMS with the hypothesis that charcoal interfaces foster nutrient dynamics at the microscale. Despite the high loss of OC in the ameliorated ADE through land use change, the remaining OM might improve the nutrient availability thanks to charcoal interactions compared to the ACR. Our results contribute to a better understanding of the sensitivity of OM upon land use change and how the microbial community is responding to land use change in highly weathered tropical soils.&lt;/p&gt;

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