Peatlands are significant global carbon sinks, where plant litter accumulation outpaces the rate of microbial degradation, which can result in significant emissions of methane and carbon dioxide. The Pastaza-Marañón foreland basin (PMFB) in the western Amazon contains the largest expanse of tropical peatlands in South America, characterized by a diversity of soil properties, including pH and mineral concentration. The PMFB is predicted to decrease in its carbon capture capacity along with a rise in greenhouse gas emissions as the climate changes. Therefore, it is imperative to understand the impact that soil properties have on the abundance of functions, microbial physiology, and interspecies interactions between microbial community members. Metagenomic sequencing of soil samples from three geochemically distinct peatlands revealed site-specific enrichment of functions related to carbon, nitrogen, phosphorus, and sulfur cycling. Additionally, 519 metagenome-assembled genomes (MAGs) were recovered, revealing variations in microbial populations responsible for organic matter degradation and nutrient (nitrogen and sulfur) cycling across sites. From these MAGs, a novel family within the Bathyarchaeia was identified, Candidatus Paludivitaceae. This family is putatively capable of carboxydotrophy, able to use CO for energy and biomass. Subsequently they could detoxify the environment of CO benefiting other community members and playing an indirect role in modulating carbon cycling. To experimentally investigate interactions of peatland microbes, co-culture experiments assessed the impact of carbon substrates (4-hydroxybenzoic acid, mannitol, and arginine) on microbial interactions from heterotrophs isolated from two geochemically distinct peatlands. Results indicate substrate and peatland type significantly influence nature and frequency of microbial interactions. The response of microbial genera to carbon substrate also varied showing the role of metabolic traits and substrate preferences in determining growth patterns of microbes. This research advances our understanding of microbial ecology in tropical peatlands and better informs predictions as the climate changes.

Precision agriculture (PA) integrating information technology arouses broad interests and has been extensively studied to increase crop production and quality. Sensor probe technology, as one of the PA technologies, provides people with accurate real-time data, which has become an essential part of precision agriculture. Herein a novel microbial sensor probe (MiProbE) is applied to monitor and study the growth of tomatoes (Solanum lycopersicum L.) in real-time at germination and seedling stages. The result showed the raw Miprobe signals present day/night cycles. Alginate-coated probes effectively avoided signal response failure and were more sensitive to the treatments than uncoated probes. The probe signals from successfully germinated tomato seeds and non-germinated seeds were different, and the signal curve of the probe was closely related to the growth conditions of tomato seedlings. Specifically, the rising period of the probe signals coincided with the normal growth period of tomato seedlings. All probes exhibited sudden increases in signal strength after nutrient treatments; however, subsequent probe signals behaved differently: algae extract-treated probe signals maintained a high strength after the treatments; chemical fertilizer-treated probe signals decreased earlier after the treatments; chemical fertilizers and algae extract-treated probe signals also maintained a higher strength after the treatments. Moreover, the relationship between ash-free dry weight and the signal curve indicated that the signal strength positively correlates with the dry weight, although other biological activities can affect the probe signal at the same time. Further study is still needed to investigate the relationship between plant biomass and Miprobe signal.

Bacteria are often regarded s pathogens, with deleterious impacts on the human body. However, it is known that the presence of trillions of bacteria on and in the human body impart beneficial effects on human health. Like a fingerprint, each individual’s microbiome is unique. The composition of bacteria in one person’s gut is different from the gut bacteria in another individual. Together, the human gut microbiome is a complex mix of organisms that is commonly referred to as “the second brain.� Its role in the human body goes beyond digestion and immune system function. The health of the microbiome factors into risk for illnesses as diverse as depression, obesity, bowel disorders and autism (Perlmutter et al., 2015). In context of the myriad of bacteria that live on and within the human body, the composition of bacteria in the gut may have the most significant impact on an individual’s well-being. This “superorganism� co-evolved with its host in order to provide essential and mutually beneficial functions (Ragonnaud et al., 2021).

Affecting millions of Americans, depression is one of the leading causes of the Global Burden of Disease (GBD), followed by anxiety (Gibson-Smith et al., 2018). Communication that occurs between the human brain and the gut microbiome has been found to be a major contributor towards mental health. The human gut microbiome is comprised of many microbes that can communicate with the brain through the gut-brain axis. However, factors such as stress and diets can interfere with this process, especially after increasing the permeability of the intestine (Khoshbin et al., 2020). Perturbation of the gut-brain axis has been implicated across a wide scale of neurodegenerative disorders, with respect to psychopathology (Bonaz et al., 2018). The environment of the gut, along with which species reside there, can help determine the link between gut function and disease. Therefore, it may be possible to prevent the degradation of an individual’s immune function and well-being through alteration of the gut microbiome. (abstract)

Desert organisms lead harsh lives owing to the extreme, often unpredictable environmental conditions they endure. Climate change will likely make their existence even harsher. Predicting the ecological consequences of future climate scenarios thus requires understanding how the biota will be affected by climatic shifts. Biological soil crusts (biocrusts) are an important ecosystem component in arid lands, one that covers large portions of the landscape, improving soil stability and fertility. Because cyanobacteria are biocrust’s preeminent primary producers, eking out an existence during short pulses of precipitation, they represent a relevant global change object of study. I assessed how climate scenarios predicted for the Southwestern United States (US) will affect biocrusts using long-term, rainfall-modifying experimental set-ups that imposed either more intense drought, a seasonally delayed monsoon season, or a shift to smaller but more frequent precipitation events. I expected drought to be detrimental, but not a delay in the monsoon season. Surprisingly, both treatments showed similar effects on cyanobacterial community composition and population size after four years. While successionally incipient biocrusts were unaffected, mature biocrusts lost biomass and diversity with treatment, especially among nitrogen-fixing cyanobacteria. In separate experiments, I assessed the effect of rainfall with modified event size and frequency after a decade of treatment. Small, frequent rainfall events surprisingly enhanced the diversity and biomass of bacteria and cyanobacteria, with clear winners and losers: nitrogen-fixing Scytonema sp. benefited, while Microcoleus vaginatus lost its dominance. As an additional finding, I could also show that water addition is not always beneficial to biocrusts, calling into question the notion that these are strictly water-limited systems.

Finally, results interpretation was severely hampered by a lack of appropriate systematic treatment for an important group of biocrust cyanobacteria, the “Microcoleus steenstrupii complex”. I characterized the complex using a polyphasic approach, leading to the formal description of a new family (Porphyrosiphonaceae) of desiccation resistant cyanobacteria that includes 11 genera, of which 5 had to be newly described. Under the new framework, the distribution and abundance of biocrust cyanobacteria with respect to environmental conditions can now be understood. This body of work contributes significantly to explain current distributional patterns of biocrust cyanobacteria and to predict their fate in the face of climate change.

White-nose syndrome (WNS) is a fungal infection devastating bat populations throughout eastern North America. WNS is caused by a fungus, Pseudogymnoascus destructans (Pd), that invades the skin of hibernating bats. While there are a number of treatments being researched, there is currently no effective treatment for WNS that is deployed in the field, except a few being tested on a limited scale. Bats have lowered immune function and response during hibernation, which may increase susceptibility to infection during the winter months. Antimicrobial peptides (AMPs) are a crucial component of the innate immune system and serve as barriers against infection. AMPs are constitutively expressed on skin and facilitate wound healing, stimulate other immune responses, and may also stay active on bat skin during hibernation. AMPs are expressed by all tissues, have direct killing abilities against microbes, and are a potential treatment for bats infected with Pd. In this investigation, the fungicidal activity of several readily available commercial AMPs were compared, and killing assay protocols previously investigated by Frasier and Lake were replicated to establish a control trial for use in future killing assays. Another aim of this investigation was to synthesize a bat-derived AMP for use in the killing assay. Sequences of bat-derived AMPs have been identified in bat skin samples obtained from a large geographic sampling of susceptible and resistant species. Contact was made with GenScript Inc., the company from which commercially available AMPs were purchased, to determine the characteristics of peptide sequences needed to synthesize an AMP for lab use. Based on recommendations from GenScript Inc., peptide sequences need to have a hydrophobicity of less than 50% and a sequence length of less than 50 amino acids. These criteria serve as a potential barrier because none of the known bat-derived sequences analyzed satisfy both of these requirements. The final aim of this study was to generate a conceptual model of the immune response molecules activated when bats are exposed to a fungal pathogen such as Pd. Overall, this work investigated sources of variability between trials of the killing assay, analyzed known bat-derived peptide sequences, and generated a conceptual model that will serve as a guideline for identification of immune response molecules on the skin of bats in future proteomics work.

Across large areas of eastern and midwestern North America, a severe reduction in multiple populations of bat species has been observed as the result of the emerging fungal disease, white-nose syndrome (WNS). WNS is caused by a psychrophilic (i.e. cold loving) fungus, Pseudogymnoascus destructans (Pd), that invades the skin of bats during hibernation. Recent studies have shown that during hibernation, bats have decreased immune system activity which would suggest increased susceptibility to infection. Antimicrobial peptides (AMPs) are an important component of the innate immune system and are expressed constitutively within all tissues that serve as barriers against infection. Killing pathogens at the level of the skin could prevent the need for more complex immune responses likely inhibited during hibernation, and therefore AMPs could be critical in combating infection by Pd and reducing population loss of susceptible bat species. In this investigation, the fungicidal activity of commercially available AMPs derived from the skin of multiple taxa, including amphibians, catfish, and humans were compared in order to study immunity at the level of the skin. Additionally, our aim was to create optimal methods for a low-cost antimicrobial-assay protocol that would provide quantitative results. We found that killing abilities at various concentrations of dermaseptin S-1 against Ca ATCC 10231 were consistent with literature values, while our values for magainin 2 and parasin 1 were far from the values previously recorded by other studies. It is possible that some differences can be accounted for by the difference in antimicrobial assay procedures, but our findings suggest potential differences to the well-known killing abilities of certain peptides nonetheless. Overall, the protocol established for the antimicrobial assays using serial dilutions and Sabouraud Dextrose plates was successful.

Across large areas of eastern and midwestern North America, a severe reduction in multiple populations of bat species has been observed as the result of the emerging fungal disease, white-nose syndrome (WNS). WNS is caused by a psychrophilic (i.e. cold loving) fungus, Pseudogymnoascus destructans (Pd), that invades the skin of bats during hibernation. Recent studies have shown that during hibernation, bats have decreased immune system activity which would suggest increased susceptibility to infection. Antimicrobial peptides (AMPs) are an important component of the innate immune system and are expressed constitutively within all tissues that serve as barriers against infection. Killing pathogens at the level of the skin could prevent the need for more complex immune responses likely inhibited during hibernation, and therefore AMPs could be critical in combating infection by Pd and reducing population loss of susceptible bat species. In this investigation, the fungicidal activity of commercially available AMPs derived from the skin of multiple taxa, including amphibians, catfish, and humans were compared in order to study immunity at the level of the skin. Additionally, our aim was to create optimal methods for a low-cost antimicrobial-assay protocol that would provide quantitative results. We found that killing abilities at various concentrations of dermaseptin S-1 against Ca ATCC 10231 were consistent with literature values, while our values for magainin 2 and parasin 1 were far from the values previously recorded by other studies. It is possible that some differences can be accounted for by the difference in antimicrobial assay procedures, but our findings suggest potential differences to the well-known killing abilities of certain peptides nonetheless. Overall, the protocol established for the antimicrobial assays using serial dilutions and Sabouraud Dextrose plates was successful.

This study takes a broad look into the existing research on the relationship between two physiological topics, nutrition and immunity in vertebrates, specifically the mammalian and avian branches. This was achieved by critiquing available studies on different types of immune cells, and how variable energy availability, as well as specific pathogens, impact cell function. Notably, most studies examined individuals with compromised immune systems, which reveals an existing knowledge gap in the linkages between nutrition and immunity in healthy organisms. Links between immunity and nutrition were identified across the studies, with the three main energy molecules, carbohydrates, lipids, and proteins, implicated in functional roles as immune modulators. Stimulatory and inhibitory effects occur dependent on elevated and depleted nutrient levels, and multiple cell types are sensitive to changes in nutrient availability. Further studies should be conducted on healthy individuals of model species, as well as wildlife and other non-model species to identify and describe the effects of host nutritional status on the spread of pathogens and the implications at the population level for humans, domestic animals, and wildlife.

Sexually transmitted diseases like gonorrhea and chlamydia, standardly treated with antibiotics, produce over 1.2 million cases annually in the emergency department (Jenkins et al., 2013). To determine a need for antibiotics, hospital labs utilize bacterial cultures to isolate and identify possible pathogens. Unfortunately, this technique can take up to 72 hours, leading to several physicians presumptively treating patients based solely on history and physical presentation. With vague standards for diagnosis and a high percentage of asymptomatic carriers, several patients undergo two scenarios; over- or under-treatment. These two scenarios can lead to consequences like unnecessary exposure to antibiotics and development of secondary conditions (for example: pelvic inflammatory disease, infertility, etc.). This presents a need for a laboratory technique that can provide reliable results in an efficient matter. The viability of DNA-based chip targeted for C. trachomatis, N. gonorrhoeae, and other pathogens of interest were evaluated. The DNA-based chip presented several advantages as it can be easily integrated as a routine test given the process is already well-known, is customizable and able to target multiple pathogens within a single test and has the potential to return results within a few hours as opposed to days. As such, implementation of a DNA-based chip as a diagnostic tool is a timely and potentially impactful investigation.