scholarly journals Simple Assay, Kinetics, and Biochemical Trends for Soil Microbial Catalases

2020 ◽  
Author(s):  
Michael Chabot ◽  
Ernesto Morales ◽  
Jacob Cummings ◽  
Nicholas Rios ◽  
Scott Giatpaiboon ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Community Structure ◽  
Kinetic Model ◽  
Microbial Communities ◽  
Microbial Ecology ◽  
Copy Number ◽  
Soil Microbial ◽  
Exogenous Stress ◽  
Simple Kinetic Model ◽  
Specific Activities

AbstractIn this report, we expand upon the enzymology and biochemical ecology of soil catalases through development and application of a simple kinetic model and assay based upon volume displacement. Through this approach, we (A) directly relate apparent Michaelis-Menten terms to the catalase reaction mechanism, (B) obtain upper estimates of the intrinsic rate constants for the catalase community and moles of catalase per 16S rRNA gene copy number, (C) utilize catalase specific activities (SAs) to obtain biomass estimates of soil and permafrost communities (LOD, ~104 copy number gdw−1), and (D) relate kinetic trends to changes in bacterial community structure. This model represents a novel approach to the kinetic treatment of soil catalases, while simultaneously incorporating barometric adjustments to afford comparisons across field measurements. As per our model, and when compared to garden soils, biological soil crusts exhibited ~2-fold lower values for , ≥105-fold higher catalase moles per biomass (250-1200 zmol copy number−1), and ~104-fold higher SAs per biomass (74-230 fkat copy number−1). However, the highest SAs were obtained from permafrost and high-elevation soil communities (5900-6700 fkat copy number−1). In sum, these total trends suggest that microbial communities which experience higher degrees of native oxidative stress possess higher basal intracellular catalase concentrations and SAs per biomass, and that differing kinetic profiles across catalase communities are indicative of phylum and/or genus-level changes in community structure. For microbial ecology, therefore, these measures effectively serve as markers for microbial activity and abundance, and additionally provide insights into the community responses to exogenous stress.ImportanceThe efficient management of oxidative stresses arising from environmental pressures are central to the homeostasis of soil microbial communities. Among the enzymes that manage oxidative stress are catalases, which degrade hydrogen peroxide into oxygen gas and water. In this report, we detail the development and application of a simple kinetic model and assay to measure catalase reaction rates and estimate soil biomass. Our assay is based upon volume displacement, and is low-cost, field-amenable, and suitable for scientists and educators from all disciplines. Our results suggest that microbial communities that experience higher degrees of native oxidative stress possess higher basal intracellular catalase concentrations and specific activities when expressed per biomass. For microbial ecology, therefore, these measures serve as biochemical markers for microbial activity and abundance, and provide insights into the community responses to exogenous stress; thereby providing a novel means to study active microbial communities in soils and permafrost.

scholarly journals Agricultural Pollution Risks Influence Microbial Ecology in Honghu Lake

2018 ◽  
Author(s):  
Maozhen Han ◽  
Melissa Dsouza ◽  
Chunyu Zhou ◽  
Hongjun Li ◽  
Junqian Zhang ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Physicochemical Properties ◽  
Microbial Communities ◽  
Microbial Ecology ◽  
Agricultural Pollution ◽  
Agricultural Activities ◽  
Sediment Samples ◽  
Water And Sediment ◽  
Honghu Lake

AbstractBackgroundAgricultural activities, such as stock-farming, planting industry, and fish aquaculture, can influence the physicochemistry and biology of freshwater lakes. However, the extent to which these agricultural activities, especially those that result in eutrophication and antibiotic pollution, effect water and sediment-associated microbial ecology, remains unclear.MethodsWe performed a geospatial analysis of water and sediment associated microbial community structure, as well as physicochemical parameters and antibiotic pollution, across 18 sites in Honghu lake, which range from impacted to less-impacted by agricultural pollution. Furthermore, the co-occurrence network of water and sediment were built and compared accorded to the agricultural activities.ResultsPhysicochemical properties including TN, TP, NO3--N, and NO2--N were correlated with microbial compositional differences in water samples. Likewise, in sediment samples, Sed-OM and Sed-TN correlated with microbial diversity. Oxytetracycline and tetracycline concentration described the majority of the variance in taxonomic and predicted functional diversity between impacted and less-impacted sites in water and sediment samples, respectively. Finally, the structure of microbial co-associations was influenced by the eutrophication and antibiotic pollution.ConclusionThese analyses of the composition and structure of water and sediment microbial communities in anthropologically-impacted lakes are imperative for effective environmental pollution monitoring. Likewise, the exploration of the associations between environmental variables (e.g. physicochemical properties, and antibiotics) and community structure is important in the assessment of lake water quality and its ability to sustain agriculture. These results show agricultural practices can negatively influence not only the physicochemical properties, but also the biodiversity of microbial communities associated with the Honghu lake ecosystem. And these results provide compelling evidence that the microbial community can be used as a sentinel of eutrophication and antibiotics pollution risk associated with agricultural activity; and that proper monitoring of this environment is vital to maintain a sustainable environment in Honghu lake.

scholarly journals Intercropping with Potato-Onion Enhanced the Soil Microbial Diversity of Tomato

2020 ◽  
Vol 8 (6) ◽  
pp. 834
Author(s):  
Naihui Li ◽  
Danmei Gao ◽  
Xingang Zhou ◽  
Shaocan Chen ◽  
Chunxia Li ◽  
...  
Keyword(s):  
Community Structure ◽  
Organic Carbon ◽  
Bacterial Community ◽  
Soil Organic Carbon ◽  
Microbial Communities ◽  
Fungal Community ◽  
Soil Microbial Communities ◽  
Tomato Seedling ◽  
Soil Microbial ◽  
Potato Onion

Intercropping can achieve sustainable agricultural development by increasing plant diversity. In this study, we investigated the effects of tomato monoculture and tomato/potato-onion intercropping systems on tomato seedling growth and changes of soil microbial communities in greenhouse conditions. Results showed that the intercropping with potato-onion increased tomato seedling biomass. Compared with monoculture system, the alpha diversity of soil bacterial and fungal communities, beta diversity and abundance of bacterial community were increased in the intercropping system. Nevertheless, the beta-diversity and abundance of fungal community had no difference between the intercropping and monoculture systems. The relative abundances of some taxa (i.e., Acidobacteria-Subgroup-6, Arthrobacter, Bacillus, Pseudomonas) and several OTUs with the potential to promote plant growth were increased, while the relative abundances of some potential plant pathogens (i.e., Cladosporium) were decreased in the intercropping system. Redundancy analysis indicated that bacterial community structure was significantly influenced by soil organic carbon and pH, the fungal community structure was related to changes in soil organic carbon and available phosphorus. Overall, our results suggested that the tomato/potato-onion intercropping system altered soil microbial communities and improved the soil environment, which may be the main factor in promoting tomato growth.

scholarly journals Phylogenetic Molecular Ecological Network of Soil Microbial Communities in Response to Elevated CO2

mBio ◽  
2011 ◽  
Vol 2 (4) ◽  
Author(s):  
Jizhong Zhou ◽  
Ye Deng ◽  
Feng Luo ◽  
Zhili He ◽  
Yunfeng Yang
Keyword(s):  
Microbial Communities ◽  
Microbial Ecology ◽  
High Throughput ◽  
Network Topology ◽  
Ecosystem Functioning ◽  
Soil Microbial Communities ◽  
Microbial Populations ◽  
Metagenomic Sequencing ◽  
Sequencing Data ◽  
Soil Microbial

ABSTRACT Understanding the interactions among different species and their responses to environmental changes, such as elevated atmospheric concentrations of CO2, is a central goal in ecology but is poorly understood in microbial ecology. Here we describe a novel random matrix theory (RMT)-based conceptual framework to discern phylogenetic molecular ecological networks using metagenomic sequencing data of 16S rRNA genes from grassland soil microbial communities, which were sampled from a long-term free-air CO2 enrichment experimental facility at the Cedar Creek Ecosystem Science Reserve in Minnesota. Our experimental results demonstrated that an RMT-based network approach is very useful in delineating phylogenetic molecular ecological networks of microbial communities based on high-throughput metagenomic sequencing data. The structure of the identified networks under ambient and elevated CO2 levels was substantially different in terms of overall network topology, network composition, node overlap, module preservation, module-based higher-order organization, topological roles of individual nodes, and network hubs, suggesting that the network interactions among different phylogenetic groups/populations were markedly changed. Also, the changes in network structure were significantly correlated with soil carbon and nitrogen contents, indicating the potential importance of network interactions in ecosystem functioning. In addition, based on network topology, microbial populations potentially most important to community structure and ecosystem functioning can be discerned. The novel approach described in this study is important not only for research on biodiversity, microbial ecology, and systems microbiology but also for microbial community studies in human health, global change, and environmental management. IMPORTANCE The interactions among different microbial populations in a community play critical roles in determining ecosystem functioning, but very little is known about the network interactions in a microbial community, owing to the lack of appropriate experimental data and computational analytic tools. High-throughput metagenomic technologies can rapidly produce a massive amount of data, but one of the greatest difficulties is deciding how to extract, analyze, synthesize, and transform such a vast amount of information into biological knowledge. This study provides a novel conceptual framework to identify microbial interactions and key populations based on high-throughput metagenomic sequencing data. This study is among the first to document that the network interactions among different phylogenetic populations in soil microbial communities were substantially changed by a global change such as an elevated CO2 level. The framework developed will allow microbiologists to address research questions which could not be approached previously, and hence, it could represent a new direction in microbial ecology research.

scholarly journals The impact of stand age and fertilization on the soil microbiome of Miscanthus × giganteus

2020 ◽  
Author(s):  
Lanying Ma ◽  
Fernando Igne Rocha ◽  
Jaejin Lee ◽  
Jinlyung Choi ◽  
Mauricio Tejera ◽  
...  
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Community Structure ◽  
Soil Microbial Communities ◽  
N Fertilizer ◽  
Soil Microbiome ◽  
Stand Age ◽  
Soil Microbial ◽  
Miscanthus Giganteus

Yield of the perennial grass Miscanthus × giganteus has shown an inconsistent and unpredictable response to nitrogen (N) fertilizer, yet fertilization underpins the crop’s environmental and economic sustainability. The interactions among soil microbial communities, N availability, and M. × giganteus and management may explain changes in plant productivity. In this study, soil samples from different stand ages of M. × giganteus in a replicated chronosequence field trial were used to investigate the effects of stand age and N fertilizer rates on microbial community structure. We hypothesized that there is a definable M. × giganteus soil microbiome and that this community varies significantly with stand age and fertilization. Our results showed that the main phyla in soil microbial communities, regardless of plant age, are similar but microbial community structures are significantly different. The variation in observed microbial communities generally decreases in older stand ages. The amount of N fertilizer applied also affected the microbial community structure associated with different aged M. × giganteus. Specifically, the relative abundance of Proteobacteria (Alphaproteobacteria and Gammaproteobacteria) and Acidobacteria (Subgroup Gp1) increased shortly after fertilization and were more associated with younger M. × giganteus. Further, our results show a significant relationship between bacterial alpha diversity and fertilization rates and that this response is also impacted by stand age. Overall, our results emphasize linkages between microbial community structure, plant age, and fertilization in M. × giganteus.

scholarly journals Nitrapyrin has far reaching effects on the soil microbial community structure, composition, diversity and functions

2020 ◽  
Author(s):  
Ruth Schmidt ◽  
Xiao-Bo Wang ◽  
Paolina Garbeva ◽  
Étienne Yergeau
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Community Structure ◽  
Fungal Community ◽  
Soil Microbial Community ◽  
Ammonia Oxidizers ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Fungal Community Structure

AbstractNitrapyrin is one of the most common nitrification inhibitors that are used to retain N in the ammonia form in soil to improve crop yields and quality. Whereas the inhibitory effect of nitrapyrin is supposedly specific to ammonia oxidizers, in view of the keystone role of this group in soils, nitrapyrin could have far-reaching impacts. Here, we tested the hypothesis that nitrapyrin leads to large shifts in soil microbial community structure, composition, diversity and functions, beyond its effect on ammonia-oxidizers. To test this hypothesis, we set-up a field experiment where wheat (Triticum aestivum cv. AC Walton) was fertilized with ammonium nitrate (NH4NO3) and supplemented or not with nitrapyrin. Rhizosphere and bulk soils were sampled twice, DNA was extracted, the 16S rRNA gene and ITS region were amplified and sequenced to follow shifts in archaeal, bacterial and fungal community structure, composition and diversity. To assess microbial functions, several genes involved in the nitrogen cycle were quantified by real-time qPCR and volatile organic compounds (VOCs) were trapped in the rhizosphere at the moment of sampling. As expected, sampling date and plant compartment had overwhelming effects on the microbial communities. However, within these strong effects, we found statistically significant effects of nitrapyrin on the relative abundance of Thaumarchaeota, Proteobacteria, Nitrospirae and Basidiomycota, and on several genera. Nitrapyrin also significantly affected bacterial and fungal community structure, and the abundance of all the N-cycle gene tested, but always in interaction with sampling date. In contrast, nitrapyrin had no significant effect on the emission of VOCs, where only sampling date significantly influenced the profiles observed. Our results point out far-reaching effects of nitrapyrin on soil and plant associated microbial communities, well beyond its predicted direct effect on ammonia-oxidizers. In the longer term, these shifts might counteract the positive effect of nitrapyrin on crop nutrition and greenhouse gas emissions.

scholarly journals Evaluation of DESS as a storage medium for microbial community analysis

2018 ◽  
Author(s):  
Kevin M Lee ◽  
Madison Adams ◽  
Jonathan L Klassen
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Ecology ◽  
Microbial Community Structure ◽  
Community Analysis ◽  
Microbial Community Analysis ◽  
Ant Colonies ◽  
And Storage ◽  
Phosphate Buffered Saline

Microbial ecology research requires sampling strategies that accurately represent the microbial community under study. These communities must typically be transported from the collection location to the laboratory and then stored until they can be processed. However, there is a lack of consensus on how best to preserve microbial communities during transport and storage. Here, we evaluated DESS (Dimethyl sulfoxide, Ethylenediamine tetraacetic acid, Saturated Salt) solution as a broadly applicable preservative for microbial ecology experiments. We stored fungus gardens grown by the ant Trachymyrmex septentrionalis in DESS, 15% glycerol, and phosphate buffered saline (PBS) to test the ability of these preservatives to maintain the structure of fungus garden microbial communities. Variation in microbial community structure due to differences in preservative type was minimal when compared to variation between ant colonies. Additionally, DESS preserved the structure of a defined mock community more faithfully than either 15% glycerol or PBS. DESS is inexpensive, easy to transport, and effective in preserving microbial community structure. We therefore conclude that DESS is a valuable preservative for use in microbial ecology research.

scholarly journals Responses of Bacterial and Fungal Community Structure to Different Rates of 1,3-Dichloropropene Fumigation

2019 ◽  
Vol 3 (3) ◽  
pp. 212-223 ◽  
Author(s):  
Yuan Zeng ◽  
Zaid Abdo ◽  
Amy Charkowski ◽  
Jane E. Stewart ◽  
Kenneth Frost
Keyword(s):  
Community Structure ◽  
Microbial Communities ◽  
Management Practices ◽  
Soil Microbial Communities ◽  
Alpha Diversity ◽  
Potato Production ◽  
Crop Species ◽  
Soil Microbial Community Structure ◽  
Soil Microbial ◽  
Sample Depth

1,3-Dichloropropene (1,3-D) is a well-known nematicidal soil fumigant on many crop species. Currently, little is known about its impact on soil microbial communities using culture-free methods. In this study, we investigated changes in soil bacterial and fungal diversity and composition at two depths (30.5 and 61 cm) in response to management practices of applying 1,3-D at four different rates (103, 122, 140, and 187 liters/ha) relative to an untreated control in potato production fields using 16S rRNA and internal transcribed spacer (ITS) amplicon sequencing. A total of 12,783 operational taxonomic units (OTUs) for 16S and 1,706 OTUs for ITS were obtained. Sequencing revealed that Proteobacteria, Firmicutes, Actinobacteria, and Ascomycota were dominant phyla in soils. Comparing alpha diversity of microbial communities at the different chemical rates with untreated plots showed that bacterial communities in plots treated with 1,3-D fumigation at 140 liters/ha were richer, which was supported by higher richness indices. Other diversity indices and overall soil microbial community structure were not significantly influenced by any rates of 1,3-D fumigation, although higher bacterial and fungal richness and diversity were observed in posttreatment soils and/or at 30.5 cm. Of the identified microbial families, the differential abundance of 45 bacterial and 24 fungal families was affected by sample depth, 1,3-D rate, or the interaction of sample depth and 1,3-D. The bacterial family Enterobacteriaceae, which includes species that specialize in decay of complex carbohydrates, increased in abundance post-1,3-D fumigation, and the fungal family Ophiocordycipitaceae, which includes nematode and insect pathogens, decreased, suggesting that the nematode and soil insect death caused by fumigation may selectively impact specific fungal and bacterial families.

scholarly journals From Diversity to Complexity: Microbial Networks in Soils

2021 ◽  
Author(s):  
Ksenia Guseva ◽  
Sean Darcy ◽  
Eva Simon ◽  
Lauren V. Alteio ◽  
Alicia Montesinos-Navarro ◽  
...  
Keyword(s):  
Network Analysis ◽  
Microbial Communities ◽  
Microbial Ecology ◽  
Soil Microbial Communities ◽  
Small Scale ◽  
Soil Microbial Ecology ◽  
Test Dataset ◽  
Soil Microbial ◽  
Network Properties ◽  
Plant Animal Interactions

Network analysis has been used for many years in ecological research to analyze organismal associations, for example in food webs, plant-plant or plant-animal interactions. Although network analysis is widely applied in microbial ecology, only recently has it entered the realms of soil microbial ecology, shown by a rapid rise in studies applying co-occurrence analysis to soil microbial communities. While this application offers great potential for deeper insights into the ecological structure of soil microbial ecosystems, it also brings new challenges related to the specific characteristics of soil datasets and the type of ecological questions that can be addressed. In this Perspectives Paper we assess the challenges of applying network analysis to soil microbial ecology due to the small-scale heterogeneity of the soil environment and the nature of soil microbial datasets. We review the different approaches of network construction that are commonly applied to soil microbial datasets and discuss their features and limitations. Using a test dataset of microbial communities from two depths of a forest soil, we demonstrate how different experimental designs and network constructing algorithms affect the structure of the resulting networks, and how this in turn may influence ecological conclusions. We will also reveal how assumptions of the construction method, methods of preparing the dataset, an definitions of thresholds affect the network structure. Finally, we discuss the particular questions in soil microbial ecology that can be approached by analyzing and interpreting specific network properties. Targeting these network properties in a meaningful way will allow applying this technique not in merely descriptive, but in hypothesis-driven research.

scholarly journals Evaluation of DESS as a storage medium for microbial community analysis

2018 ◽  
Author(s):  
Kevin M Lee ◽  
Madison Adams ◽  
Jonathan L Klassen
Keyword(s):  
Community Structure ◽  
Microbial Community ◽  
Microbial Communities ◽  
Microbial Ecology ◽  
Microbial Community Structure ◽  
Community Analysis ◽  
Microbial Community Analysis ◽  
Ant Colonies ◽  
And Storage ◽  
Phosphate Buffered Saline

Microbial ecology research requires sampling strategies that accurately represent the microbial community under study. These communities must typically be transported from the collection location to the laboratory and then stored until they can be processed. However, there is a lack of consensus on how best to preserve microbial communities during transport and storage. Here, we evaluated DESS (Dimethyl sulfoxide, Ethylenediamine tetraacetic acid, Saturated Salt) solution as a broadly applicable preservative for microbial ecology experiments. We stored fungus gardens grown by the ant Trachymyrmex septentrionalis in DESS, 15% glycerol, and phosphate buffered saline (PBS) to test the ability of these preservatives to maintain the structure of fungus garden microbial communities. Variation in microbial community structure due to differences in preservative type was minimal when compared to variation between ant colonies. Additionally, DESS preserved the structure of a defined mock community more faithfully than either 15% glycerol or PBS. DESS is inexpensive, easy to transport, and effective in preserving microbial community structure. We therefore conclude that DESS is a valuable preservative for use in microbial ecology research.

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