Ecosystem Resilience and Limitations Revealed by Soil Bacterial Community Dynamics in a Bark Beetle-Impacted Forest

ABSTRACT Forested ecosystems throughout the world are experiencing increases in the incidence and magnitude of insect-induced tree mortality with large ecologic ramifications. Interestingly, correlations between water quality and the extent of tree mortality in Colorado montane ecosystems suggest compensatory effects from adjacent live vegetation that mute responses in less severely impacted forests. To this end, we investigated whether the composition of the soil bacterial community and associated functionality beneath beetle-killed lodgepole pine was influenced by the extent of surrounding tree mortality. The most pronounced changes were observed in the potentially active bacterial community, where alpha diversity increased in concert with surrounding tree mortality until mortality exceeded a tipping point of ~30 to 40%, after which diversity stabilized and decreased. Community structure also clustered in association with the extent of surrounding tree mortality with compositional trends best explained by differences in NH4 + concentrations and C/N ratios. C/N ratios, which were lower in soils under beetle-killed trees, further correlated with the relative abundance of putative nitrifiers and exoenzyme activity. Collectively, the response of soil microorganisms that drive heterotrophic respiration and decay supports observations of broader macroscale threshold effects on water quality in heavily infested forests and could be utilized as a predictive mechanism during analogous ecosystem disruptions. IMPORTANCE Forests around the world are succumbing to insect infestation with repercussions for local soil biogeochemistry and downstream water quality and quantity. This study utilized microbial community dynamics to address why we are observing watershed scale biogeochemical impacts from forest mortality in some impacted areas but not others. Through a unique “tree-centric” approach, we were able to delineate plots with various tree mortality levels within the same watershed to see if surviving surrounding vegetation altered microbial and biogeochemical responses. Our results suggest that forests with lower overall tree mortality levels are able to maintain “normal” ecosystem function, as the bacterial community appears resistant to tree death. However, surrounding tree mortality influences this mitigating effect with various linear and threshold responses whereupon the bacterial community and its function are altered. Our study lends insight into how microscale responses propagate upward into larger-scale observations, which may be useful for future predictions during analogous disruptions. IMPORTANCE Forests around the world are succumbing to insect infestation with repercussions for local soil biogeochemistry and downstream water quality and quantity. This study utilized microbial community dynamics to address why we are observing watershed scale biogeochemical impacts from forest mortality in some impacted areas but not others. Through a unique “tree-centric” approach, we were able to delineate plots with various tree mortality levels within the same watershed to see if surviving surrounding vegetation altered microbial and biogeochemical responses. Our results suggest that forests with lower overall tree mortality levels are able to maintain “normal” ecosystem function, as the bacterial community appears resistant to tree death. However, surrounding tree mortality influences this mitigating effect with various linear and threshold responses whereupon the bacterial community and its function are altered. Our study lends insight into how microscale responses propagate upward into larger-scale observations, which may be useful for future predictions during analogous disruptions.

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Metagenomics: Retrospect and Prospects in High Throughput Age

Biotechnology Research International ◽

10.1155/2015/121735 ◽

2015 ◽

Vol 2015 ◽

pp. 1-13 ◽

Cited By ~ 20

Author(s):

Satish Kumar ◽

Kishore Kumar Krishnani ◽

Bharat Bhushan ◽

Manoj Pandit Brahmane

Keyword(s):

Community Dynamics ◽

Full Potential ◽

Basic Study ◽

Independent Manner ◽

Microbial Community Dynamics ◽

Current State ◽

Culture Independent ◽

Almost All ◽

Insight Into ◽

Generation Sequencing

In recent years, metagenomics has emerged as a powerful tool for mining of hidden microbial treasure in a culture independent manner. In the last two decades, metagenomics has been applied extensively to exploit concealed potential of microbial communities from almost all sorts of habitats. A brief historic progress made over the period is discussed in terms of origin of metagenomics to its current state and also the discovery of novel biological functions of commercial importance from metagenomes of diverse habitats. The present review also highlights the paradigm shift of metagenomics from basic study of community composition to insight into the microbial community dynamics for harnessing the full potential of uncultured microbes with more emphasis on the implication of breakthrough developments, namely, Next Generation Sequencing, advanced bioinformatics tools, and systems biology.

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Integrative study of microbial community dynamics and water quality along The Apatlaco River

Environmental Pollution ◽

10.1016/j.envpol.2019.113158 ◽

2019 ◽

Vol 255 ◽

pp. 113158 ◽

Cited By ~ 9

Author(s):

Luz Breton-Deval ◽

Alejandro Sanchez-Flores ◽

Katy Juárez ◽

Rosario Vera-Estrella

Keyword(s):

Water Quality ◽

Microbial Community ◽

Community Dynamics ◽

Microbial Community Dynamics ◽

Integrative Study

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Microbial diversity of the Arabian Sea in the Oxygen minimum zones by metagenomics approach

10.1101/731828 ◽

2019 ◽

Author(s):

Mandar S. Paingankar ◽

Kedar Ahire ◽

Pawan Mishra ◽

Shriram Rajpathak ◽

Deepti D. Deobagkar

Keyword(s):

Community Structure ◽

Microbial Community ◽

Arabian Sea ◽

Community Dynamics ◽

Oxygen Depletion ◽

Oxygen Minimum Zones ◽

Microbial Community Dynamics ◽

Nitrate Reducers ◽

Insight Into ◽

Oxygen Minimum

ABSTRACTLarge oxygen depleted areas known as oxygen minimum zones (OMZ) have been observed in the Arabian Sea and recent reports indicate that these areas are expanding at an alarming rate. In marine waters, oxygen depletion may also be related to global warming and the temperature rise, acidification and deoxygenation can lead to major consequences wherein the plants, fish and other biota will struggle to survive in the ecosystem.The current study has identified the microbial community structure using NGS based metagenomics analysis in the water samples collected at different depth from the oxygen depleted and non-OMZ areas of Arabian Sea. Environmental variables such as depth, site of collection and oxygen concentration appeared to influence the species richness and evenness among microbial communities in these locations. Our observations clearly indicate that population dynamics of microbes consisting of nitrate reducers accompanied by sulphate reducers and sulphur oxidizers participate in the interconnected geochemical cycles of the OMZ areas. In addition to providing baseline data related to the diversity and microbial community dynamics in oxygen-depleted water in the OMZ; such analysis can provide insight into processes regulating productivity and ecological community structure of the ocean.

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Structure-Based Long-Term Biodegradation of the Azo Dye: Insights from the Bacterial Community Succession and Efficiency Comparison

Water ◽

10.3390/w13213017 ◽

2021 ◽

Vol 13 (21) ◽

pp. 3017

Author(s):

Chao Zhu ◽

Zarak Mahmood ◽

Muhammad Saboor Siddique ◽

Heyou Wang ◽

He Anqi ◽

...

Keyword(s):

Bacterial Community ◽

Azo Dyes ◽

Azo Dye ◽

Community Dynamics ◽

Molecular Structures ◽

Methyl Red ◽

Biological Degradation ◽

Chemical Structures ◽

Microbial Community Dynamics ◽

Efficiency Comparison

In this study, microbial community dynamics were explored during biological degradation of azo dyes with different chemical structures. The effect of the different molecular structures of the azo dyes was also assessed against the simultaneous removal of color and the bacterial community. Winogradsky columns were inoculated with dewatered sludge and separately fed with six different azo dyes to conduct the sludge acclimatization process, and nine bacterial decolorizing strains were isolated and identified. The decolorization and biodegradation performances of the acclimated system and isolated strains were also determined. Results showed that the bacterial isolates involved in decolorization and the degradation of the azo dyes were mainly associated with the azo dye structure. After 24 h acclimatization at room temperature without specific illumination, immediate decolorization of methyl red (89%) and methyl orange (78%) was observed, due to their simple structure compared to tartrazine (73%). However, after 8 days of acclimatization, methyl red was easily decolorized up to 99%, and about 87% decolorization was observed for orange G (87%), due to its complex chemical structure. Higher degrees of degradation and decolorization were achieved with Pseudomonas geniculate strain Ka38 (Proteobacteria), Bacillus cereus strain 1FFF (Firmicutes) and Klebsiella variicola strain RVEV3 (Proteobacteria) with continuous shaking at 30 °C. The azo dyes with benzene rings were found to be easier to decolorize and degrade with similar microbial communities. Moreover, it seems that the chemical structures of the azo dyes, in a sense, drove the divergent succession of the bacterial community while reducing the diversity. This study gives a deep insight into the feasible structure-based artificial manipulation of bacterial communities and offers theoretical guidance for decolorizing azo dyes with mixed bacteria cultures.

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Ultrastructure of neuromuscular relationships in the canine heartworm (dirofilaria immitis)

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143018 ◽

1986 ◽

Vol 44 ◽

pp. 278-279

Author(s):

W. L. Steffens ◽

Nancy B. Roberts ◽

J. M. Bowen

Keyword(s):

Dirofilaria Immitis ◽

Domestic Dogs ◽

Structural Description ◽

Pharmacological Effects ◽

Free Living ◽

Canine Heartworm ◽

The World ◽

Synaptic Region ◽

Muscle Innervation ◽

Insight Into

The canine heartworm is a common and serious nematode parasite of domestic dogs in many parts of the world. Although nematode neuroanatomy is fairly well documented, the emphasis has been on sensory anatomy and primarily in free-living soil species and ascarids. Lee and Miller reported on the muscular anatomy in the heartworm, but provided little insight into the peripheral nervous system or myoneural relationships. The classical fine-structural description of nematode muscle innervation is Rosenbluth's earlier work in Ascaris. Since the pharmacological effects of some nematacides currently being developed are neuromuscular in nature, a better understanding of heartworm myoneural anatomy, particularly in reference to the synaptic region is warranted.

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On Metaphysics and the Political: A Polemics of Reading Baudelaire in the 1930s

Nottingham French Studies ◽

10.3366/nfs.2019.0252 ◽

2019 ◽

Vol 58 (2) ◽

pp. 249-259

Author(s):

Joseph Acquisto

Keyword(s):

Twentieth Century ◽

Political Crisis ◽

The Political ◽

Modern Poetry ◽

Progressive Politics ◽

The World ◽

Relationship Of ◽

The Relationship ◽

Insight Into

This essay examines a polemic between two Baudelaire critics of the 1930s, Jean Cassou and Benjamin Fondane, which centered on the relationship of poetry to progressive politics and metaphysics. I argue that a return to Baudelaire's poetry can yield insight into what seems like an impasse in Cassou and Fondane. Baudelaire provides the possibility of realigning metaphysics and politics so that poetry has the potential to become the space in which we can begin to think the two of them together, as opposed to seeing them in unresolvable tension. Or rather, the tension that Baudelaire animates between the two allows us a new way of thinking about the role of esthetics in moments of political crisis. We can in some ways see Baudelaire as responding, avant la lettre, to two of his early twentieth-century readers who correctly perceived his work as the space that breathes a new urgency into the questions of how modern poetry relates to the world from which it springs and in which it intervenes.

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