Up Against The Wall: The Effects of Climate Warming on Soil Microbial Diversity and The Potential for Feedbacks to The Carbon Cycle

Earth’s climate is warming, and there is evidence that increased temperature alters soil C cycling, which may result in a self-reinforcing (positive), microbial mediated feedback to the climate system. Though soil microbes are major drivers of soil C cycling, we lack an understanding of how temperature affects SOM decomposition. Numerous studies have explored, to differing degrees, the extent to which climate change may affect biodiversity. While there is ample evidence that community diversity begets ecosystem stability and resilience, we know of keystone species that perform functions whose effects far outweigh their relative abundance. In this paper, we first review the meaning of microbial diversity and how it relates to ecosystem function, then conduct a literature review of field-based climate warming studies that have made some measure of microbial diversity. Finally, we explore how measures of diversity may yield a larger, more complete picture of climate warming effects on microbial communities, and how this may translate to altered carbon cycling and greenhouse gas emissions. While warming effects seem to be ecosystem-specific, the lack of observable consistency between measures is due in some part to the diversity in measures of microbial diversity

Microbiology 562: D. Batch Fermentation Module

In this module, we set up a fermentation of grains by yeast with hops to brew beer (D1). We make media and pour plates to grow and identify microbial contaminants (D2). Two weeks after setting up the primary fermentation, we prime and condition the fermentation (D3). While we wait for the priming and conditioning to finish, we do a bioinformatics analysis of microbial communities turning ethanol (a product of fermentation) to n-caproic acid, (D4), to illustrate the power of metagenomic sequencing in resolving microorganisms and their potential physiology. Then we identify and examine the microbial contaminants cultured in the primary fermentation (D5). When the beer is finished, we perform a sensory analysis (D6) followed by a field trip to the Berkshire Brewing Company in South Deerfield, MA, where we will tour their brewing facilities and microbiology lab.https://scholarworks.umass.edu/micro_ed_materials/1000/thumbnail.jp

Genome Sequences of \u3cem\u3eFrankineae\u3c/em\u3e sp. Strain MT45 and \u3cem\u3eJatrophihabitans\u3c/em\u3e sp. Strain GAS493, Two Actinobacteria Isolated from Forest Soil

Frankiaceae are bacterial endosymbionts that are also found free-living in soil. Here, we present the genome sequences of two novel bacterial members of the order Frankiales, class Actinobacteria, isolated from temperate terrestrial forest soils. The genomes for MT45 and GAS493 indicate a genetic capacity for carbohydrate degradation but not nitrogen fixation

Draft Genome Sequence of a Terrestrial Planctomycete, \u3cem\u3eSingulisphaera\u3c/em\u3e sp. Strain GP 187, Isolated from Forest Soil

Here we present the draft genome sequence of a novel species of the genus Singulisphaera (phylum Planctomycetes, family Isosphaeraceae), isolated from soil. Singulisphaera sp. strain GP 187 has a relatively large mobilome and numerous novel genes that may contriubte to the production of bioactive molecules

Bioinformatics Lab: A Course-Based Undergraduate Research Experience Curriculum

This is a computer lab course intended to give students technical and practical experience in analyzing sequencing data. We focus on bacterial genomes from recently isolated bacteria, so there is a possibility of discovery of new microbial diversity. Collaborative learning will be encouraged, but students will work individually to assemble, annotate, and analyze a bacterial genome. Each week will begin with a review on the topic to be covered for that week. When applicable, there will be pre-recorded lectures to introduce lab topics, and students are expected to have watched these before coming to class. Our time in class will be spent as a computer lab, where students will work collaboratively and at their own pace to complete their genome sequencing and analysis. The guided analysis will transition into independent study. Students will produce a final capstone report in the style of the Microbiology Resource Announcements published by the American Society of Microbiology. This course fulfils the Microbiology Major requirement as a Major Laboratory Elective, and the Microbiology Graduate requirement as a core graduate-level course in microbial science.https://scholarworks.umass.edu/micro_ed_materials/1002/thumbnail.jp

Changes in substrate availability drive carbon cycle response to chronic warming

As earth\u27s climate continues to warm, it is important to understand how the capacity of terrestrial ecosystems to retain carbon (C) will be affected. We combined measurements of microbial activity with the concentration, quality, and physical accessibility of soil carbon to microorganisms to evaluate the mechanisms by which more than two decades of experimental warming has altered the carbon cycle in a Northeast US temperate deciduous forest. We found that concentrations of soil organic matter were reduced in both the organic and mineral soil horizons. The molecular composition of the carbon was altered in the mineral soil with significant reductions in the relative abundance of polysaccharides and lignin, and an increase in lipids. Mineral-associated organic matter was preferentially depleted by warming in the top 3 cm of mineral soil. We found that potential extracellularenzyme activity per gram of soil at a common temperature was generally unaffected by warming treatment. However, by measuring potential extracellular enzyme activities between 4 and 30 °C, we found that activity per unit microbial biomass at in-situ temperatures was increased by warming. This was associated with a tendency for microbial biomass to decrease with warming. These results indicate that chronic warming has reduced soil organic matter concentrations, selecting for a smaller but more active microbial community increasingly dependent on mineral-associated organic matter

The transcriptional response of soil bacteria to long-term warming and short-term seasonal fluctuations in a terrestrial forest

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Chowdhury, P. R., Golas, S. M., Alteio, L., Stevens, J. T. E., Billings, A. F., Blanchard, J. L., Melillo, J. M., & DeAngelis, K. M. The transcriptional response of soil bacteria to long-term warming and short-term seasonal fluctuations in a terrestrial forest. Frontiers in Microbiology, 12, (2021): 666558, https://doi.org/10.3389/fmicb.2021.666558.Terrestrial ecosystems are an important carbon store, and this carbon is vulnerable to microbial degradation with climate warming. After 30 years of experimental warming, carbon stocks in a temperate mixed deciduous forest were observed to be reduced by 30% in the heated plots relative to the controls. In addition, soil respiration was seasonal, as was the warming treatment effect. We therefore hypothesized that long-term warming will have higher expressions of genes related to carbohydrate and lipid metabolism due to increased utilization of recalcitrant carbon pools compared to controls. Because of the seasonal effect of soil respiration and the warming treatment, we further hypothesized that these patterns will be seasonal. We used RNA sequencing to show how the microbial community responds to long-term warming (~30 years) in Harvard Forest, MA. Total RNA was extracted from mineral and organic soil types from two treatment plots (+5°C heated and ambient control), at two time points (June and October) and sequenced using Illumina NextSeq technology. Treatment had a larger effect size on KEGG annotated transcripts than on CAZymes, while soil types more strongly affected CAZymes than KEGG annotated transcripts, though effect sizes overall were small. Although, warming showed a small effect on overall CAZymes expression, several carbohydrate-associated enzymes showed increased expression in heated soils (~68% of all differentially expressed transcripts). Further, exploratory analysis using an unconstrained method showed increased abundances of enzymes related to polysaccharide and lipid metabolism and decomposition in heated soils. Compared to long-term warming, we detected a relatively small effect of seasonal variation on community gene expression. Together, these results indicate that the higher carbohydrate degrading potential of bacteria in heated plots can possibly accelerate a self-reinforcing carbon cycle-temperature feedback in a warming climate.Funding for this study was provided by the Department of Energy Terrestrial Ecosystem Sciences program under contract number DE-SC0010740. Sites for sample collection were maintained with funding in part from the National Science Foundation (NSF) Long-Term Ecological Research (DEB 1237491) and the NSF Long-Term Research in Environmental Biology (DEB 1456528) programs

Two decades of warming increases diversity of a potentially lignolytic bacterial community

As Earth\u27s climate warms, the massive stores of carbon found in soil are predicted to become depleted, and leave behind a smaller carbon pool that is less accessible to microbes. At a long-term forest soil-warming experiment in central Massachusetts, soil respiration and bacterial diversity have increased, while fungal biomass and microbially-accessible soil carbon have decreased. Here, we evaluate how warming has affected the microbial community\u27s capability to degrade chemically-complex soil carbon using lignin-amended BioSep beads. We profiled the bacterial and fungal communities using PCR-based methods and completed extracellular enzyme assays as a proxy for potential community function. We found that lignin-amended beads selected for a distinct community containing bacterial taxa closely related to known lignin degraders, as well as members of many genera not previously noted as capable of degrading lignin. Warming tended to drive bacterial community structure more strongly in the lignin beads, while the effect on the fungal community was limited to unamended beads. Of those bacterial operational taxonomic units (OTUs) enriched by the warming treatment, many were enriched uniquely on lignin-amended beads. These taxa may be contributing to enhanced soil respiration under warming despite reduced readily available C availability. In aggregate, these results suggest that there is genetic potential for chemically complex soil carbon degradation that may lead to extended elevated soil respiration with long-term warming

Application of phenotypic microarrays to environmental microbiology

Environmental organisms are extremely diverse and only a small fraction has been successfully cultured in the laboratory. Culture in micro wells provides a method for rapid screening of a wide variety of growth conditions and commercially available plates contain a large number of substrates, nutrient sources, and inhibitors, which can provide an assessment of the phenotype of an organism. This review describes applications of phenotype arrays to anaerobic and thermophilic microorganisms, use of the plates in stress response studies, in development of culture media for newly discovered strains, and for assessment of phenotype of environmental communities. Also discussed are considerations and challenges in data interpretation and visualization, including data normalization, statistics, and curve fitting

Draft Genome Sequence of the Lignin-Degrading Burkholderia sp. Strain LIG30, Isolated from Wet Tropical Forest Soil

Burkholderia species are common soil Betaproteobacteria capable of degrading recalcitrant aromatic compounds and xenobiotics. Burkholderia sp. strain LIG30 was isolated from wet tropical forest soil and is capable of utilizing lignin as a sole carbon source. Here we report the draft genome sequence of Burkholderia sp. strain LIG30