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The gastrointestinal (GI) tract is home to a complex and diverse microbial ecosystem that contributes to health or disease in many aspects. While bacterial species are the majority in the GI tract, their cohabitants, fungal species, should not be forgotten. Children with autism spectrum disorder (ASD) often suffer from GI disorders and associated symptoms, implying a role the bacterial and fungal gut microbiota play in maintaining human health. The irregularities in GI symptoms can negatively affect the overall quality of life or even worsen behavioral symptoms the children present. Even with the increase in the availability of next-generation sequencing technologies, the composition and diversities of fungal microbiotas are understudied, especially in the context of ASD. We therefore aimed to investigate the gut mycobiota of 36 neurotypical children and 38 children with ASD. We obtained stool samples from all participants, as well as autism severity and GI symptom scores to help us understand the effect the mycobiome has on these symptoms. By targeting the fungal internal transcribed spacer (ITS) and bacterial 16S rRNA V4 regions, we obtained fungal and bacterial amplicon sequences, from which we investigated the diversities, composition, and potential link between two different ecological clades. From fungal amplicon sequencing results, we observed a significant decrease in the observed fungal OTUs in children with ASD, implying a lack of potentially beneficial fungi in ASD subjects. We performed Bray-Curtis principal coordinates analysis and observed significant differences in fungal microbiota composition between the two groups. Taxonomic analysis showed higher relative abundances of Candida , Pichia, Penicillium , and Exophiala in ASD subjects, yet due to a large dispersion of data, the differences were not statistically significant. Interestingly, we observed a bimodal distribution of Candida abundances within children with ASD. Candida's relative abundance was not significantly correlated with GI scores, but children with high Candida relative abundances presented significantly higher Autism Treatment Evaluation Checklist (ATEC) scores, suggesting a role of Candida on ASD behavioral symptoms. Regarding the bacterial gut microbiota, we found marginally lower observed OTUs and significantly lower relative abundance of Prevotella in the ASD group, which was consistent with previous studies. Taken together, we demonstrated that autism is closely linked with a distinct gut mycobiota, characterized by a loss of fungal and bacterial diversity and an altered fungal and bacterial composition.
ContributorsPatel, Jigar (Author) / Krajmalnik-Brown, Rosa (Thesis director) / Kang, Dae Wook (Committee member) / Adams, James (Committee member) / School of Molecular Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
The effect of an anaerobic reductive environment produced by the oxidation of zero valent iron (ZVI) on the microbial reductive dechlorination of trichloroethylene and its applicability to in-situ bioremediation processes was investigated using microcosms and soil column studies. I learned that microbial dechlorination requires a highly reductive environment, as represented by negative values for oxidation-reduction potential (ORP), which can be maintained through the addition of reducing agents such as ZVI, or to a lesser extent, the fermentation of added substrates such as lactate. Microcosm conditions represented distance from an in-situ treatment injection well and contained different types of iron species and dechlorinating bioaugmentation cultures. Diminishing efficacy of microbial reductive dechlorination along a gradient away from the injection zone was observed, characterized by increasing ORP and decreasing pH. Results also suggested that the use of particular biostimulation substrates is key to prioritizing the dechlorination reaction against competing microbial and abiotic processes by supplying electrons needed for microbial dechlorination.
ContributorsMouti, Aatikah (Author) / Krajmalnik-Brown, Rosa (Thesis director) / Delgado, Anca (Committee member) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2017-12
Description
Hydrogen is a key indicator of microbial activity in soils/sediments and groundwater because of its role as an electron donor for reducing sulfate and nitrate and carrying out other metabolic processes. The goal of this study was to quantitatively measure the total biological hydrogen demand (TBHD) of soils and sediments in anaerobic environments. We define the total biological hydrogen demand as the sum of all electron acceptors that can be used by hydrogen-oxidizing microorganisms. Three sets of anaerobic microcosms were set up with different soils/sediments, named Carolina, Garden, and ASM. The microcosms included 25g of soil/sediment and 75 mL of anaerobic medium. 10 mL of hydrogen were pulse-fed for 100 days. Hydrogen consumption and methane production were tracked using gas chromatography. Chemical analysis of each soil was performed at the beginning of the experiment to determine the concentration of electron acceptors in the soils/sediments, including nitrate, sulfate, iron and bicarbonate. An analysis of the microbial community was done at t = 0 and at the end of the 100 days to examine changes in the microbial community due to the metabolic processes occurring as hydrogen was consumed. Carolina consumed 9810 43 mol of hydrogen and produced 19,572 2075 mol of methane. Garden consumed 4006 33 mol of hydrogen and produced 7,239 543 mol of methane. Lastly, ASM consumed 1557 84 mol of hydrogen and produced 1,325 715 mol of methane. I conclude that the concentration of bicarbonate initially present in the soil had the most influence over the hydrogen demand and microbial community enrichment. To improve this research, I recommend that future studies include a chemical analysis of final soil geochemistry conditions, as this will provide with a better idea of what pathway the hydrogen is taking in each soil.
ContributorsLuna Aguero, Marisol (Author) / Krajmalnik-Brown, Rosa (Thesis director) / Delgado, Anca (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Gift-giving economies are economic models that freely give resources rather than barter for them or purchase them from market. Need-based transfers fit into this economic model by freely giving resources on the basis of need, provided the giver can spare the resources. The Maasai are an East African pastoral tribe that practices need-based transfers through a tradition they call osotua. If they have a partner with an established osotua relationship, then they will give any amount of cattle that partner request, provided they can spare the cattle. Cheating each other is unheard of in this tradition, but for this simulation I am introducing cheating into this economic model through feigning need. If a cheater is not in need, they will act like they are in need. If they are in need, then the cheater will request more cattle than what they need to survive. I am testing two different responses to cheating: walking-away and punishing. In the walk-away condition, the victim ends their osotua partnership and establishes a new one. In the punishment condition, a portion of the cheater's stolen cattle is destroyed.
ContributorsDunkelberger, Sophia (Author) / Aktipis, Athena (Thesis director) / Presson, Clark (Committee member) / Johnson, Kathryn (Committee member) / School of Social and Behavioral Sciences (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Perceptions of the self differ between cultures, generally between those cultures in the West and East. Some of the ways that these individuals from these cultures may differ are in their self-construal, their collectivist and individualist tendencies, and how they perceive control in their lives. The current study proposes that some of these differences are influenced by different concepts individuals hold regarding the "soul", or inner self. These concepts may be promoted by the different religious beliefs prominent in different regions. The Soul Perception Index, being developed through this study, measures belief in multiple souls, a universal soul, a single soul, or no soul. It was predicted that a belief in a single soul will correlate with an individual view of the self (individualism, independent self-construal, internal locus of control), and a universal or multi-soul belief will correlate with an interdependent view of the self (collectivism, interdependent self-construal, and external locus of control). We found that these variables did not significantly differ in their relationships with soul belief. However, Indian Hindu participants and Chinese participants seemed to score highly on all self-view variables and all soul perception types indicating that individuals from these cultures may be more predisposed to hold opposing beliefs simultaneously while US Christians are not.
ContributorsNaidu, Esha Svetha (Author) / Cohen, Adam (Thesis director) / Glenberg, Arthur (Committee member) / Johnson, Kathryn (Committee member) / School of Historical, Philosophical and Religious Studies (Contributor) / Department of Psychology (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
In the United States, the prevalence of pediatric obesity has increased to 17% in the general population and even more so in the Hispanic pediatric population to 22.4%. These children are at a higher risk for associated comorbidities, including cardiovascular disease and insulin resistance. The purpose of the following study is to determine the effectiveness of the Nutrition and Health Awareness curriculum at reducing childhood obesity by evaluating alterations in the gut microbial composition, diet, and overall health of the students throughout the five-week program. Nutrition and Health Awareness (NHA) is a student organization that strives to reduce the prevalence of obesity, diabetes, and cardiovascular diseases, specifically in children, by providing active nutrition education services through peer mentoring in elementary schools and community programs. This study went through ASU's Institutional Review Board process and all forms were translated into Spanish. The control group maintained their normal routines and the experimental group received the 5 week NHA program and then continued with their normal routines. Anthropometric measures (Body Mass Index, waist-to-hip ratio, and blood pressure), diet measures (Hispanic food frequency questionnaire), fecal swabs, and content surveys were collected on weeks 0, 5, and 8. Contrary to expected, alpha diversity, kilocalorie intake, and macronutrient intake decreased as the study progressed for both the control and experimental groups. Anthropometric measurements were relatively stable. Though not statistically significant, the greatest difference in time points is between weeks 1 and 8. This decrease in alpha diversity and kilocalorie intake could be due to a change in environment since the children started school on week 8. Future implications of this study are that parental involvement is necessary for an effective, sustainable change in these children. More research in different settings is necessary to determine NHA's effectiveness
ContributorsPatel, Kapila Cristina (Author) / Krajmalnik-Brown, Rosa (Thesis director) / Whisner, Corrie (Committee member) / School of Nutrition and Health Promotion (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
Microorganisms can produce metabolites in the gut including short chain fatty acids, vitamins, and amino acids. Certain metabolites produced in the gut can affect the brain through changes in neurotransmitter concentrations. Serotonin, a neurotransmitter, is associated with mood, appetite, and sleep. Up to 90% of serotonin synthesis is located in the gut, by human enterochromaffin cells. Bacteria known to biosynthesize tryptophan, precursor to serotonin, include Escherichia coli, Enterococcus and Streptococcus. Tryptophan is synthesized by bacteria with the enzyme tryptophan synthase and requires Vitamin B6 (Pyridoxal). We hypothesize that gut isolates from surgical weight loss patients can enhance tryptophan production, which relies on vitamin B6 availability. Our goal was to isolate bacteria in order to test for tryptophan production and to determine how Vitamin B6 concentrations could affect tryptophan production. We isolated gut bacteria was from successful surgical weight loss patient with selective pressures for Enterobacter isolates and Enterococcus isolates. We tested the isolates were tested to determine if they could biosynthesize tryptophan in-vitro. Bacterial cultures were enriched with yeast and enriched with serine and indole, substrates necessary for tryptophan biosynthesis. We analyzed the supernatant samples for tryptophan production using GC-FID. Bacterial isolates most closely related to E. coli and Klebsiella based on 16S rRNA gene sequences, produced tryptophan in vitro. While under serine & indole media conditions, R1, the isolate most similar to Klebsiella produced more tryptophan than R14, the isolate most similar to E. coli. We tested the R1 isolate with a gradient of vitamin B6 concentrations from 0.02 µg/mL to 0.2 µg/mL to determine its effect on tryptophan production. When less than 0.05 µg/mL of Vitamin B6 was added, tryptophan production at 6 hours was higher than tryptophan production with Vitamin B6 concentrations at 0.05 µg/mL and above. The production and consumption of tryptophan by Klebsiella under 0 µg/mL and 0.02 µg/mL concentrations of Vitamin B6 occurred at a faster rate when compared to concentrations 0.05 µg/mL or higher of Vitamin B6.
ContributorsYee, Emily L. (Author) / Krajmalnik-Brown, Rosa (Thesis director) / Ilhan, Zehra (Committee member) / W. P. Carey School of Business (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
This research examined the influence that Christian and Hindu religious beliefs have on environmentalism; specifically, whether beliefs that one would return to this earth after death (i.e., a belief in reincarnation) and how the world might end may explain more positive attitudes toward the environment. Participants were 533 self-identified Christians and Hindus in the United States and India who completed an online survey assessing religiosity, positive attitudes towards environmentalism, afterlife beliefs, and eschatological beliefs. Christians showed significantly lower ratings of environmentalism compared with Hindus. There were also significant negative differences found based on beliefs about heaven, eschatology beliefs, and increased religiosity in Christians, and significant positive differences found based on reincarnation, eschatology beliefs, and increased religiosity in Hindus. Overall, these results suggest that Christians are less likely to have positive attitudes toward environmentalism compared with Hindus, and that beliefs about the afterlife and the end of the world were significant predictors of environmentalist attitudes.
ContributorsParde, Madeline Morgan (Author) / Cohen, Adam (Thesis director) / Glenberg, Arthur (Committee member) / Johnson, Kathryn (Committee member) / Department of Psychology (Contributor) / Sanford School of Social and Family Dynamics (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Under current climate conditions northern peatlands mostly act as C sinks; however, changes in climate and environmental conditions, can change the soil carbon decomposition cascade, thus altering the sink status. Here I studied one of the most abundant northern peatland types, poor fen, situated along a climate gradient from tundra (Daring Lake, Canada) to boreal forest (Lutose, Canada) to temperate broadleaf and mixed forest (Bog Lake, MN and Chicago Bog, NY) biomes to assess patterns of microbial abundance across the climate gradient. Principal component regression analysis of the microbial community and environmental variables determined that mean annual temperature (MAT) (r2=0.85), mean annual precipitation (MAP) (r2=0.88), and soil temperature (r2=0.77), were the top significant drivers of microbial community composition (p < 0.001). Niche breadth analysis revealed the relative abundance of Intrasporangiaceae, Methanobacteriaceae and Candidatus Methanoflorentaceae fam. nov. to increase when MAT and MAP decrease. The same analysis showed Spirochaetaceae, Methanosaetaceae and Methanoregulaceae to increase in relative abundance when MAP, soil temperature and MAT increased, respectively. These findings indicated that climate variables were the strongest predictors of microbial community composition and that certain taxa, especially methanogenic families demonstrate distinct patterns across the climate gradient. To evaluate microbial production of methanogenic substrates, I carried out High Resolution-DNA-Stable Isotope Probing (HR-DNA-SIP) to evaluate the active portion of the community’s intermediary ecosystem metabolic processes. HR-DNA-SIP revealed several challenges in efficiency of labelling and statistical identification of responders, however families like Veillonellaceae, Magnetospirillaceae, Acidobacteriaceae 1, were found ubiquitously active in glucose amended incubations. Differences in metabolic byproducts from glucose amendments show distinct patterns in acetate and propionate accumulation across sites. Families like Spirochaetaceae and Sphingomonadaceae were only found to be active in select sites of propionate amended incubations. By-product analysis from propionate incubations indicate that the northernmost sites were acetate-accumulating communities.
These results indicate that microbial communities found in poor fen northern peatlands are strongly influenced by climate variables predicted to change under current climate scenarios. I have identified patterns of relative abundance and activity of select microbial taxa, indicating the potential for climate variables to influence the metabolic pathway in which carbon moves through peatland systems.
ContributorsSarno, Analissa Flores (Author) / Cadillo-Quiroz, Hinsby (Thesis advisor) / Garcia-Pichel, Ferran (Committee member) / Krajmalnik-Brown, Rosa (Committee member) / Childers, Daniel (Committee member) / Arizona State University (Publisher)
Created2022
Description
Widespread use of halogenated organic compounds for commercial and industrial purposes makes halogenated organic pollutants (HOPs) a global challenge for environmental quality. Current wastewater treatment plants (WWTPs) are successful at reducing chemical oxygen demand (COD), but the removal of HOPs often is poor. Since HOPs are xenobiotics, the biodegradation of HOPs is usually limited in the WWTPs. The current methods for HOPs treatments (e.g., chemical, photochemical, electrochemical, and biological methods) do have their limitations for practical applications. Therefore, a combination of catalytic and biological treatment methods may overcome the challenges of HOPs removal.This dissertation investigated a novel catalytic and biological synergistic platform to treat HOPs. 4-chlorophenol (4-CP) and halogenated herbicides were used as model pollutants for the HOPs removal tests. The biological part of experiments documented successful co-oxidation of HOPs and analog non-halogenated organic pollutants (OPs) (as the primary substrates) in the continuous operation of O2-based membrane biofilm reactor (O2-MBfR). In the first stage of the synergistic platform, HOPs were reductively dehalogenated to less toxic and more biodegradable OPs during continuous operation of a H2-based membrane catalytic-film reactor (H2-MCfR). The synergistic platform experiments demonstrated that OPs generated in the H2-MCfR were used as the primary substrates to support the co-oxidation of HOPs in the subsequent O2-MBfR. Once at least 90% conversation of HOPs to OPs was achieved in the H2-MCfR, the products (OPs to HOPs mole ratio >9) in the effluent could be completely mineralized through co-oxidation in O2-MBfR. By using H2 gas as the primary substrate, instead adding the analog OP, the synergistic platform greatly reduced chemical costs and carbon-dioxide emissions during HOPs co-oxidation.
ContributorsLuo, Yihao (Author) / Rittmann, Bruce (Thesis advisor) / Krajmalnik-Brown, Rosa (Committee member) / Torres, Cesar (Committee member) / Arizona State University (Publisher)
Created2022