Microbiology Commons^™

Microbial Dark Matter Coming To Light: Challenges And Opportunities, Jian Yu Jiao, Lan Liu, Zheng Shuang Hua, Bao Zhu Fang, En Min Zhou, Nimaichand Salam, Brian P. Hedlund, Wen Jun Li

Life Sciences Faculty Research

Microbes are the most abundant and diverse cellular life forms on Earth and colonize a wide range of environmental niches. However, more than 99% of bacterial and archaeal species have not been obtained in pure culture [1] and we have only glimpsed the surface of this mysterious microbial world. This is so-called Microbial Dark Matter (MDM): the enormous diversity of yet-uncultivated microbes that microbiologists can only study by using cultivation-independent techniques. Recently, a number of international projects have dramatically increased our understanding of the extent and distribution of microbial diversity, including the Global Catalogue of Microorganisms (GCM), the Genomic Encyclopedia …

Expanding Magnetic Organelle Biogenesis In The Domain Bacteria, Wei Lin, Wensi Zhang, Greig A. Paterson, Qiyun Zhu, Xiang Zhao, Rob Knight, Dennis A. Bazylinski, Andrew P. Roberts, Yongxin Pan

Life Sciences Faculty Research

Background: The discovery of membrane-enclosed, metabolically functional organelles in Bacteria has transformed our understanding of the subcellular complexity of prokaryotic cells. Biomineralization of magnetic nanoparticles within magnetosomes by magnetotactic bacteria (MTB) is a fascinating example of prokaryotic organelles. Magnetosomes, as nano-sized magnetic sensors in MTB, facilitate cell navigation along the local geomagnetic field, a behaviour referred to as magnetotaxis or microbial magnetoreception. Recent discovery of novel MTB outside the traditionally recognized taxonomic lineages suggests that MTB diversity across the domain Bacteria are considerably underestimated, which limits understanding of the taxonomic distribution and evolutionary origin of magnetosome organelle biogenesis. Results: Here, …

Complete Genome Sequences Of Cluster P1 And Cluster C1 Mycobacterium Smegmatis Phages Jung And Ronan, Richard Van, William Nie, Feruz Abdela, Bardia Eivazi, Dolores Kickbusch, Michael Finkle, Cody Cris, Matthew Rubinstein, Baylor Akavan, Mahdeed Raja, Jessica Vergara, Wilson Andrade, Abimael Barajas, Jocelyn Sanchez, Maria Duenas, Kurt Regner, Christy Strong, Philippos K. Tsourkas, Jay Barilla

Life Sciences Faculty Research

We present the complete genome sequences of Mycobacterium smegmatis phages Jung and Ronan, isolated from soil in Las Vegas, Nevada. The phages were isolated and annotated by students enrolled in a course for undergraduate research experience (CURE). Jung is a cluster P1 mycobacteriophage, while Ronan is in cluster C1.

Transcriptional Control Of Virulence Genes In The Bacterial Pathogen Shigella Flexneri, Joy Asami Mckenna

UNLV Theses, Dissertations, Professional Papers, and Capstones

Shigella species, the causal agents of bacillary dysentery, use a type III secretion system (T3SS) to inject two waves of virulence proteins, known as effectors, into the human colonic epithelium to subvert host cell machinery. Transcriptional regulation of these virulence genes is controlled by the three-tiered VirF/VirB/MxiE signaling cascade. Of these, VirB has the largest regulon (~50 genes); however, VirB regulatory properties are poorly understood. To date, VirB is known to function to counter or 'anti-silence' transcriptional silencing mediated by the histone-like nucleoid structuring protein H-NS. To better understand VirB regulation, my colleagues and I chose to better define the …

Effect Of Botulinum Toxin Injection On Asymmetric Lower Face And Chin Deviation, Dongwook Kim, Ju-Hyun Park, Vittorio Favero, James Mah, Young-Soo Jung, Seong Taek Kim

Dental Medicine Faculty Publications

The purpose of this study was to compare the efficacy of botulinum toxin (BoNT) in masseter muscle reduction depending on the amount of chin deviation. Exploring distinctive effects of BoNT relative to the characteristics of facial asymmetry will aid in planning and predicting treatment outcomes. Sixteen adult volunteers were classified into two groups according to the degree of menton deviation observed in posteroanterior cephalograms. Eight had a menton deviation of 3 mm or more and the other eight had less than 3 mm. A total of 25 Units of BoNT was injected into the unilateral masseter muscle of the prominent …

Microbiome Shifts Associated With The Introduction Of Wild Atlantic Horseshoe Crabs (Limulus Polyphemus) Into A Touch-Tank Exhibit, Ariel D. Friel, Sean A. Neiswenter, Cale O. Seymour, Lauren Rose Bali, Ginger Mcnamara, Fabian Leija, Jack Jewell, Brian P. Hedlund

Life Sciences Faculty Research

The Atlantic horseshoe crab (Limulus polyphemus) is a common marine aquarium species and model organism for research. There is potential monetary and conservation value in developing a stable captive population of horseshoe crabs, however, one major impediment to achieving captivity is a lack of knowledge regarding captive diseases. We utilized 16S rRNA gene amplicon sequencing to track changes in the microbiomes of four body locations in three wild-caught (tracked over 14 months in captivity) and three tank-acclimated (>2 years in captivity) adult L. polyphemus in a touch tank at Shark Reef Aquarium at Mandalay Bay in Las Vegas, NV. …

Rapid Detection Of Toxin-Producing Cyanobacteria, Timothy Alba

UNLV Theses, Dissertations, Professional Papers, and Capstones

Lake Mead provides drinking water to millions of people in Nevada, California, and Arizona. In 2015, the Southern Nevada Water Authority detected the cyanobacteria-produced toxin microcystin in the lake for the very first time. This toxin is lethal in large doses, and in small doses it causes a myriad of serious health effects. Detecting microcystin directly is a time-consuming and expensive process that requires liquid chromatography tandem mass spectrometry or immunological analyses, which require a full day or more to process samples. In order to provide water managers with the methodology for a toxin monitoring plan, this work developed a …

Oral Localization Of Scardovia Wiggsiae, Graydon Ramos Carr

UNLV Theses, Dissertations, Professional Papers, and Capstones

Early childhood caries is one of the most prevalent diseases in the United States among children. The formation of caries is a complex, multifactorial process that is still being studied. Researchers have thought for years that Streptococcus mutans was the primary causative agent of early childhood caries. The recent discovery of a novel cariogenic pathogen, Scardovia wiggsiae and its significant contribution to the etiology of early childhood caries has led oral health researchers to re-evaluate this microorganism and its link to this disease. While there have been several projects undertaken within the University of Nevada, Las Vegas School of Dental …

The Significance Of Mfd And Oxidative Damage In Stationary-Phase Mutagenesis In Bacillus Subtilis, Holly Anne Martin

UNLV Theses, Dissertations, Professional Papers, and Capstones

The process of stationary-phase mutagenesis, also known as adaptative or stress-induced mutagenesis, is a phenomenon where bacterial cells accumulate mutations in non-replicative conditions. This process has mainly been studied in Escherichia coli and Bacillus subtilis; however, the underlying mechanisms found in each of these systems differ. Here, I use B.msubtilis to study previously understudied aspects of stationary-phase mutagenesis. In this dissertation, I describe work that has led to three major discoveries which are described below.

First in B. subtilis, Mfd is important for stationary-phase mutagenesis and its mutagenic function at regions of the genome that are transcriptionally upregulated has been …

The Influence Of G4 Dna Structures On Stationary Phase Mutagenesis In Bacillus Subtilis, Tatiana Ermi

UNLV Theses, Dissertations, Professional Papers, and Capstones

Until the late 1980’s it was widely understood that bacterial variance emerges randomly during growth. Research that followed has convincingly shown evidence for mutations arising in non-growing conditions, a phenomenon known as stationary-phase mutagenesis. In Bacillus subtilis, an elegant mutagenic mechanism has been elucidated in non-growing cells that biases mutations to transcribed regions of a subpopulation. One interesting possibility is that mutations can be further biased to hotspots within genes through alternate DNA structures known as non-B DNA. Non-B DNA have been linked to genomic instability and disease in humans, lesser is known about its role in bacteria. Here we …

Insight On Thermal Stability Of Magnetite Magnetosomes: Implications For The Fossil Record And Biotechnology, Jefferson Cypriano, Mounib Bahri, Kassioge Dembele, Walid Baaziz, Pedro Leao, Dennis A. Bazylinski, Fernanda Abreu, Ovidiu Ersen, Marcos Farina, Jacques Werckmann

Life Sciences Faculty Research

Magnetosomes are intracellular magnetic nanocrystals composed of magnetite (Fe3O4) or greigite (Fe3S4), enveloped by a lipid bilayer membrane, produced by magnetotactic bacteria. Because of the stability of these structures in certain environments after cell death and lysis, magnetosome magnetite crystals contribute to the magnetization of sediments as well as providing a fossil record of ancient microbial ecosystems. The persistence or changes of the chemical and magnetic features of magnetosomes under certain conditions in different environments are important factors in biotechnology and paleomagnetism. Here we evaluated the thermal stability of magnetosomes in a temperature range between 150 and 500 °C subjected …

Beneficial Endophytic Bacterial Populations Associated With Medicinal Plant Thymus Vulgaris Alleviate Salt Stress And Confer Resistance To Fusarium Oxysporum, Osama Aballa Abdelshafy Mohamad, Jin-Bao Ma, Yong-Hong Liu, Daoyuan Zhang, Shao Hua, Shirkant Bhute, Brian P. Hedlund, Wen-Jun Li, Li Li

Life Sciences Faculty Research

As a result of climate change, salinity has become a major abiotic stress that reduces plant growth and crop productivity worldwide. A variety of endophytic bacteria alleviate salt stress; however, their ecology and biotechnological potential has not been fully realized. To address this gap, a collection of 117 endophytic bacteria were isolated from wild populations of the herb Thymus vulgaris in Sheikh Zuweid and Rafah of North Sinai Province, Egypt, and identified based on their 16S rRNA gene sequences. The endophytes were highly diverse, including 17 genera and 30 species. The number of bacterial species obtained from root tissues was …

A High-Fat/High-Protein, Atkins-Type Diet Exacerbates Clostridioides (Clostridium) Difficile Infection In Mice, Whereas A High-Carbohydrate Diet Protects, Chrisabelle C. Mefferd, Shrikant S. Bhute, Jacqueline R. Phan, Jacob V. Villarama, Dung M. Do, Stephanie Alarcia, Ernesto Abel-Santos, Brian P. Hedlund

Chemistry and Biochemistry Faculty Research

Clostridioides difficile (formerly Clostridium difficile) infection (CDI) can result from the disruption of the resident gut microbiota. Western diets and popular weight-loss diets drive large changes in the gut microbiome; however, the literature is conflicted with regard to the effect of diet on CDI. Using the hypervirulent strain C. difficile R20291 (RT027) in a mouse model of antibiotic-induced CDI, we assessed disease outcome and microbial community dynamics in mice fed two high-fat diets in comparison with a high-carbohydrate diet and a standard rodent diet. The two high-fat diets exacerbated CDI, with a high-fat/high-protein, Atkins-like diet leading to severe CDI and …

Biogeographic Study Of Human Gut-Associated Crassphage Suggests Impacts From Industrialization And Recent Expansion, Tanvi P/ Honap, Krithivasan Sankaranarayanan, Stephanie L. Schnorr, Andrew T. Ozga, Christina Warinner, Cecil M. Lewis Jr.

Anthropology Faculty Research

CrAssphage (cross-assembly phage) is a bacteriophage that was first discovered in human gut metagenomic data. CrAssphage belongs to a diverse family of crAss-like bacteriophages thought to infect gut commensal bacteria belonging to Bacteroides species. However, not much is known about the biogeography of crAssphage and whether certain strains are associated with specific human populations. In this study, we screened publicly available human gut metagenomic data from 3,341 samples for the presence of crAssphage sensu stricto (NC_024711.1). We found that crAssphage prevalence is low in traditional, hunter-gatherer populations, such as the Hadza from Tanzania and Matses from Peru, as compared to …