Other Life Sciences Commons^™

Genome Sequence Of Sn1, A Bacteriophage That Infects Sphaerotilus Natans And Pseudomonas Aeruginosa, K.M. Damitha Gunathilake, Denise M. Tremblay, Pier-Luc Plante, Ellen Jensen, Kenneth Nickerson, Sylvain Moineau

Kenneth Nickerson Papers

Phage SN1 infects Sphaerotilus natans and Pseudomonas aeruginosa strains. Its genome consists of 61,858 bp (64.3% GC) and 89 genes, including 32 with predicted functions. SN1 genome is very similar to Pseudomonas phage M6, which contains hypermodified thymidines. Genome analyses revealed similar base-modifying genes as those found in M6.

Phage SN1 was isolated in 1979 from activated sludge samples obtained from a wastewater treatment plant (Lincoln, Nebraska, USA) using S. natans ATCC 13338 as the host (1, 2). An early study showed that the siphophage SN1 has unusual bases in its genome as confirmed by cellulose thin-layer chromatography (1). Its …

Tissue Decay Tested In Modern Metasequoia Leaves: Implications For Early Diagenesis Of Leaves In Fossil Lagerstätten, Caitlyn R. Witkowski, Qin Leng, Christopher W. Reid, Liang Feng, Hong Yang

Science and Technology Department Faculty Journal Articles

Sedimentary deposits yielding extraordinarily-preserved fossils (known as Lagerstätten) may provide significant insights into the physiology and environments of ancient plants, particularly when the fossils represent their original characteristics with limited diagenetic modifications. To better understand molecular, isotopic, and morphological changes during the early stages of diagenesis, degradation experiments were conducted in two time series: 1) a laboratory decay series using fungi on leaves over the course of a month and 2) a natural decay series with leaves collected from different stages of leaf senescence and early diagenesis. Both experiments used modern leaves of the dawn redwood Metasequoia glyptostroboides …

The Coxsackievirus And Adenovirus Receptor Has A Short Half-Life In Epithelial Cells, Poornima Kotha Lakshmi Narayan, James M. Readler, Mahmoud S. Alghamri, Trisha L. Brockman, Ray Yan, Priyanka Sharma, Vladislav Snitsarev, Katherine J.D.A Excoffon, Abimbola O. Kolawole

Department of Biology Faculty Scholarship and Creative Works

The coxsackievirus and adenovirus receptor (CAR) is an essential cellular protein that is involved in cell adhesion, cell signaling, and viral infection. The 8-exon encoded isoform (CAREx8) resides at the apical surface of polarized epithelia, where it is accessible as a receptor for adenovirus entering the airway lumen. Given its pivotal role in viral infection, it is a target for antiviral strategies. To understand the regulation of CAREx8 and determine the feasibility of receptor down regulation, the half-life of total and apical localized CAREx8 was determined and correlated with adenovirus transduction. Total and apical CAREx8 has a relatively short half-life …

Farnesol Secretion As A Possible Driving Force For Maintaining Candida Albicans As A Diploid, Kenneth Nickerson, Cory Boone, Kory Parker

Kenneth Nickerson Papers

Candida albicans is a pathogenic dimorphic fungus which is invariably found as a diploid in patients. C. albicans secretes the sesquiterpene farnesol both as a quorum sensing molecule which blocks the yeast to hypha conversion and as a virulence factor for pathogenicity. 20-25 μM farnesol kills other competing yeasts and fungi, often by triggering apoptosis, and yet wild type diploid C. albicans tolerates 300-500 μM farnesol. The recent availability of 10 haploid strains of C. albicans (5 mating type aand 5 mating type α) allowed us to compare their production of and sensitivity to farnesol. On average, the heterozygous diploid …

Sterol Biosynthesis In Four Green Algae: A Bioinformatic Analysis Of The Ergosterol Versus Phytosterol Decision Point, Adam Voshall, Nakeirah T.M. Christie, Suzanne L. Rose, Maya Khasin, James L. Van Etten, Jennifer E. Markham, Wayne Riekhof, Kenneth Nickerson

Kenneth Nickerson Papers

Animals and fungi produce cholesterol and ergosterol, respectively, while plants produce the phytosterols stigmasterol, campesterol, and β-sitosterol in various combinations. The recent sequencing of many algal genomes allows the detailed reconstruction of the sterol metabolic pathways. Here, we characterized sterol synthesis in two sequenced Chlorella spp., the free-living C. sorokiniana, and symbiotic C. variabilis NC64A. Chlamydomonas reinhardtii was included as an internal control and Coccomyxa subellipsoidea as a plant-like outlier. We found that ergosterol was the major sterol produced by Chlorella spp. and C. reinhardtii, while C. subellipsoidea produced the three phytosterols found in plants. In silico analysis of the …

Sickness Behaviors Across Vertebrate Taxa: Proximate And Ultimate Mechanisms, Patricia C. Lopes, Susannah S. French, Douglas C. Woodhams, Sandra A. Binning

Biology, Chemistry, and Environmental Sciences Faculty Articles and Research

There is nothing like a pandemic to get the world thinking about how infectious diseases affect individual behavior. In this respect, sick animals can behave in ways that are dramatically different from healthy animals: altered social interactions and changes to patterns of eating and drinking are all hallmarks of sickness. As a result, behavioral changes associated with inflammatory responses (i.e. sickness behaviors) have important implications for disease spread by affecting contacts with others and with common resources, including water and/or sleeping sites. In this Review, we summarize the behavioral modifications, including changes to thermoregulatory behaviors, known to occur in vertebrates …

Pre-Covid-19 Social Determinants Of Health Among Mexican Migrants In Los Angeles And New York City And Their Increased Vulnerability To Unfavorable Health Outcomes During The Covid-19 Pandemic, Mireya Vilar-Compte, Pablo Gaitán‐Rossi, Lucía Félix‐Beltrán, Arturo V. Bustamante

Department of Public Health Scholarship and Creative Works

COVID-19 has disproportionally affected underrepresented minorities (URM) and low-income immigrants in the United States. The aim of the study is to examine the underlying vulnerabilities of Mexican immigrants in New York City (NYC) and Los Angeles (LA), its correspondence with area-level COVID-19 morbidity and mortality, and to document the role of trusted and culturally sensitive services offered during the pandemic through the Ventanillas de Salud (i.e. VDS, Health Windows) program. The study uses a mixed-methods approach including a cross-sectional survey of Mexican immigrants in LA and NYC collected in the Mexican Consulates at the onset of the pandemic, complemented with …

Implementation Of Planetary Protection Requirements On Robotic Missions, Lauren M. Tran

STAR Program Research Presentations

NASA has developed mandatory planetary protection requirements for all outbound and inbound space missions beyond Earth orbit. Planetary Protection policies are set by COSPAR (Committee of Space Research) under the international provisions of the United Nation’s OST (Outer Space Treaty). It aims to promote responsible scientific exploration of the solar system, as well as support the study of chemical evolution and origins of life that may be present. All robotic missions must be categorized depending on their planetary destination and the mission type (flyby, orbiter, or lander). Round trip missions are all classified as Category V missions (restricted or unrestricted), …

Synthesis, Secretion, And Perception Of Abscisic Acid Regulates Stress Responses In Chlorella Sorokiniana, Maya Khasin, Rebecca E. Cahoon, Sophie Alvarez, Richard Beckeris, Seong-Il Eyun, Qidong Jia, Jean-Jack Riethoven, Kenneth Nickerson, Wayne R. Riekhof

Kenneth Nickerson Papers

Abscisic acid (ABA) is a phytohormone that has been extensively characterized in higher plants for its roles in seed and bud dormancy, leaf abscission, and stress responses. Genomic studies have identified orthologs for ABA-related genes throughout the Viridiplantae, including in unicellular algae; however, the role of ABA in algal physiology has not been characterized, and the existence of such a role has been a matter of dispute. In this study, we demonstrate that ABA is involved in regulating algal stress responses. Chlorella sorokiniana strain UTEX 1230 contains genes orthologous to those of higher plants which are essential for ABA …

Itraq-Based Proteomics Analysis And Network Integration For Kernel Tissue Development In Maize, Long Zhang, Yongbin Dong, Qilei Wang, Chunguang Du, Wenwei Xiong, Xinyu Li, Sailan Zhu, Yuling Li

Department of Biology Faculty Scholarship and Creative Works

Grain weight is one of the most important yield components and a developmentally complex structure comprised of two major compartments (endosperm and pericarp) in maize (Zea mays L.), however, very little is known concerning the coordinated accumulation of the numerous proteins involved. Herein, we used isobaric tags for relative and absolute quantitation (iTRAQ)-based comparative proteomic method to analyze the characteristics of dynamic proteomics for endosperm and pericarp during grain development. Totally, 9539 proteins were identified for both components at four development stages, among which 1401 proteins were non-redundant, 232 proteins were specific in pericarp and 153 proteins were specific in …

How Science Makes America Great, Kenneth Nickerson

Kenneth Nickerson Papers

The proposed Federal Budget cuts funding for NIH, NSF, and CDC by 16% each and for the EPA by a whopping 31%. Ouch! The situation seems ironic because of President Trump’s slogan “Make America great again!”, which I agree with wholeheartedly. In addition to being a scientist, I also love history (especially military history) and science is at the top of my list of what has made the United States great. ... Why do we do it? I’m in science because it is rewarding. It is invigorating to discover how nature works. Scientists may act individually and in relative obscurity, …

Bioethics In The Work Of Ernest Everett Just: + Missing - Some 400 Pages, Theodore Walker

Perkins Faculty Research and Special Events

Biology + ethics = bioethics. Here we see that Howard University biologist Ernest Everett Just (born 1883, died 1941) connected biology to ethics.

According to Just, various forms of specific biology (including especially cell biology) plus “general biology” are necessary for explaining adequately the origin of ethical behaviors. Social ethical behaviors, especially mutual aid and cooperative interactions with others and the environment, are essential to evolutionary advances among living creatures, ranging from humans to cells. Accordingly, theory of ethics (moral theory) should have roots in biology.

Also, Just wrote an unpublished book-length manuscript—“some 400 typed pages” (Just 1940)—on seeking the …

Quorum Sensing In Candida Albicans: Farnesol Versus Farnesoic Acid, Wayne R. Riekhof, Kenneth Nickerson

Kenneth Nickerson Papers

Candida albicans is a clinically important dimorphic fungus that exhibits either a budding yeast or a mycelial-hyphal or pseudohyphal growth, depending on environmental conditions. The yeast-to-mycelia morphologic transition, which is generally regarded as an important virulence determinant, depends on the inoculum size of liquid cultures. The yeast form is favored when cultures are inoculated at > 10⁶ cells∙mL^–1, whereas the mycelial form is favored at inoculum densities < 10⁶∙mL^–1. Farnesoic acid (FA) and farnesol (FOH) are two related sesquiterpene quorum- sensing molecules that, upon accumulation, prevent the yeast-to-mycelial conversion. Oh et al. showed that C. albicans …

Deciphering Fungal Dimorphism: Farnesol’S Unanswered Questions, Kenneth Nickerson, Audrey L. Atkin

Kenneth Nickerson Papers

Candida albicans excretes E,E-farnesol as a virulence factor and quorum sensing molecule that prevents the yeast to hyphal conversion. Polke et al. (2016) identified eed1Δ/Δ as the first farnesol hypersensitive mutant of C. albicans. eed1Δ/Δ also excretes 10X more farnesol and while able to form hyphae, it cannot maintain hyphae. This mutant enables new research into unanswered questions, including the existence of potential farnesol receptors and transporters, regulation of farnesol synthesis, and relationships among farnesol, germ tube formation and hyphal maintenance. The eed1 farnesol hypersensitivity can be explained by higher internal concentrations of farnesol or lower thresholds for response. One …

Comparative Genomics, Transcriptomics, And Physiology Distinguish Symbiotic From Free-Living Chlorella Strains, Cristian F. Quispe, Olivia Sonderman, Maya Khasin, Wayne R. Riekhof, James L. Van Etten, Kenneth Nickerson

Kenneth Nickerson Papers

Most animal–microbe symbiotic interactions must be advantageous to the host and provide nutritional benefits to the endosymbiont. When the host provides nutrients, it can gain the capacity to control the interaction, promote self-growth, and increase its fitness. Chlorella-like green algae engage in symbiotic relationships with certain protozoans, a partnership that significantly impacts the physiology of both organisms. Consequently, it is often challenging to grow axenic Chlorella cultures after isolation from the host because they are nutrient fastidious and often susceptible to virus infection. We hypothesize that the establishment of a symbiotic relationship resulted in natural selection for nutritional and metabolic …

Characterization Of Induced Rnai Silencing Of Vaccinia Virus Essential Genes, Kewa Jiang

Honors Scholar Theses

Vaccinia virus (VACV) is a large double-stranded DNA virus and the prototypical member of the family Poxviridae and is most notable for its use as the vaccine that eradicated smallpox (variola virus). More recently, VACV has been used to develop recombinant vaccines and immunotherapies. However, many of these processes require VACV replication to be tightly controlled. RNA interference (RNAi) is a powerful tool for in vitro silencing of mRNAs that are complementary to 19-21 base pairs (bp) of double-stranded RNA (dsRNA). This project outlines the design and preliminary analysis of two inducible RNAi silencing constructs targeting multiple VACV essential genes …

Killer Toxin From Several Food-Derived Debaryomyces Hansenii Strains Effective Against Pathogenic Candida Yeasts, Nabaraj Banjara, Kenneth Nickerson, Mallory J. Suhr, Heather E. Hallen-Adams

Kenneth Nickerson Papers

Candida yeasts are the dominant fungi in the healthy human microbiome, but are well-known for causing disease following a variety of perturbations. Evaluation of fungal populations from the healthy human gut revealed a significant negative correlation between the foodborne yeast, Debaryomyces hansenii, and Candida species. D. hansenii is reported to produce killer toxins (mycocins) effective against other yeast species. In order to better understand this phenomenon, a collection of 42 D. hansenii isolates was obtained from 22 cheeses and evaluated for killer activity against Candida albicans and Candida tropicalis over a range of temperatures and pH values. Twenty three …

Concomitant Uptake Of Antimicrobials And Salmonella In Soil And Into Lettuce Following Wastewater Irrigation, J. Brett Sallach, Yuping Zhang, Laurie Hodges, Daniel D. Snow, Xu Li, Shannon L. Bartelt-Hunt

Department of Civil and Environmental Engineering: Faculty Publications

The use of wastewater for irrigation may introduce antimicrobials and human pathogens into the food supply through vegetative uptake. The objective of this study was to investigate the uptake of three antimicrobials and Salmonella in two lettuce cultivars. After repeated subirrigation with synthetic wastewater, lettuce leaves and soil were collected at three sequential harvests. The internalization frequency of Salmonella in lettuce was low. A soil horizon-influenced Salmonella concentration gradient was determined with concentrations in bottom soil 2 log CFU/g higher than in top soil. Lincomycin and sulfamethoxazole were recovered from lettuce leaves at concentrations as high as 822 ng/g and …

Candida Albicans Quorum Sensing Molecules Stimulate Mouse Macrophage Migration, Jessica C. Hargarten, Tyler C. Moore, Thomas M. Petro, Kenneth W. Nickerson, Audrey L. Atkin

Kenneth Nickerson Papers

The polymorphic commensal fungus Candida albicans causes life-threatening disease via bloodstream and intra-abdominal infections in immunocompromised and transplant patients. Although host immune evasion is a common strategy used by successful human fungal pathogens, C. albicans provokes recognition by host immune cells less capable of destroying it. To accomplish this, C. albicans white cells secrete a low-molecular-weight chemoattractive stimulant(s) of macrophages, a phagocyte that they are able to survive within and eventually escape from. C. albicans opaque cells do not secrete this chemoattractive stimulant( s). We report here a physiological mechanism that contributes to the differences in the interaction of C. …

Proteomic Adaptations To Starvation Prepare Escherichia Coli For Disinfection Tolerance, Zhe Du, Renu Nandakumar, Kenneth W. Nickerson, Xu Li

Kenneth Nickerson Papers

Despite the low nutrient level and constant presence of secondary disinfectants, bacterial re-growth still occurs in drinking water distribution systems. The molecular mechanisms that starved bacteria use to survive low-level chlorine-based disinfectants are not well understood. The objective of this study is to investigate these molecular mechanisms at the protein level that prepare starved cells for disinfection tolerance. Two commonly used secondary disinfectants chlorine and monochloramine, both at 1 mg/L, were used in this study. The proteomes of normal and starved Escherichia coli (K12 MG1655) cells were studied using quantitative proteomics. Over 60-min disinfection, starved cells showed significantly higher disinfection …

Spatial Variation In Carbon And Nitrogen In Cultivated Soils In Henan Province, China: Potential Effect On Crop Yield, Xuelin Zhang, Qun Wang, Frank S. Gilliam, Yilun Wang, Feina Cha, Chaohai Li

Biological Sciences Faculty Research

Improved management of soil carbon (C) and nitrogen (N) storage in agro-ecosystems represents an important strategy for ensuring food security and sustainable agricultural development in China. Accurate estimates of the distribution of soil C and N stores and their relationship to crop yield are crucial to developing appropriate cropland management policies. The current study examined the spatial variation of soil organic C (SOC), total soil N (TSN), and associated variables in the surface layer (0–40 cm) of soils from intensive agricultural systems in 19 counties within Henan Province, China, and compared these patterns with crop yield. Mean soil C and …

A Glutathione-Independent Glyoxalase Of The Dj-1 Superfamily Plays An Important Role In Managing Metabolically Generated Methylglyoxal In Candida Albicans, Sahar Hasim, Nur Ahmad Hussin, Fadhel Alomar, Keshore R. Bidasee, Kenneth W. Nickerson, Mark A. Wilson

Kenneth Nickerson Papers

Methylglyoxal is a cytotoxic reactive carbonyl compound produced by central metabolism. Dedicated glyoxalases convert methylglyoxal to D-lactate using multiple catalytic strategies. In this study, the DJ-1 superfamily member ORF 19.251/GLX3 from Candida albicans is shown to possess glyoxalase activity, making this the first demonstrated glutathione-independent glyoxalase in fungi. The crystal structure of Glx3p indicates that the protein is a monomer containing the catalytic triad Cys¹³⁶- His¹³⁷-Glu¹⁶⁸. Purified Glx3p has an in vitro methylglyoxalase activity (K_m = 5.5 mM andk_cat = 7.8 s^-1) that is significantly greater than that of …

Nutrient Limitation In Three Lowland Tropical Forests In Southern China Receiving High Nitrogen Deposition: Insights From Fine Root Responses To Nutrient Additions, Feifei Zhu, Muneoki Yoh, Frank S. Gilliam, Xiankai Lu, Jiangming Mo

Biological Sciences Faculty Research

Elevated nitrogen (N) deposition to tropical forests may accelerate ecosystem phosphorus (P) limitation. This study examined responses of fine root biomass, nutrient concentrations, and acid phosphatase activity (APA) of bulk soil to five years of N and P additions in one old-growth and two younger lowland tropical forests in southern China. The old-growth forest had higher N capital than the two younger forests from long-term N accumulation. From February 2007 to July 2012, four experimental treatments were established at the following levels: Control, N-addition (150 kg N ha^–1 yr^–1), P-addition (150 kg P ha^–1 yr^{–1 …}

Histone Biotinylation In Candida Albicans, Sahar Hasim, Swetha Tati, Nandakumar Madayiputhiya, Renu Nandakumar, Kenneth W. Nickerson

Kenneth Nickerson Papers

Candida albicans is an opportunistic fungal pathogen in humans. It is a polymorphic fungus: it can live as yeasts, hyphae, or pseudohyphae. Biotin is required for cell growth and fatty acid metabolism because it is used as a cofactor for carboxylases such as acetyl-CoA carboxylase, and pyruvate carboxylase. In addition, we have discovered that biotin is used to modify histones in C. albicans. Biotinylation was detected by Western blots using a monoclonal antibiotin HRP-conjugated antibody as well as with qTOF and LC/MS/MS mass spectrometry. As a precaution, the antibiotin antibody was dialyzed against neutravidin prior to use. During this study, …

Candida Albicans Czf1 And Efg1 Coordinate The Response To Farnesol During Quorum Sensing, White-Opaque Thermal Dimorphism, And Cell Death, Melanie L. Langford, Jessica C. Hargarten, Krista D. Patefield, Elizabeth Marta, Jill R. Blankenship, Saranna Fanning, Kenneth W. Nickerson, Audrey L. Atkin

Kenneth Nickerson Papers

Quorum sensing by farnesol in Candida albicans inhibits filamentation and may be directly related to its ability to cause both mucosal and systemic diseases. The Ras1-cyclic AMP signaling pathway is a target for farnesol inhibition. However, a clear understanding of the downstream effectors of the morphological farnesol response has yet to be unraveled. To address this issue, we screened a library for mutants that fail to respond to farnesol. Six mutants were identified, and the czf1/czf1 mutant was selected for further characterization. Czf1 is a transcription factor that regulates filamentation in embedded agar and also whiteto- opaque switching. We found …

Quorum Sensing And Other Aspects Of The Biology Of Candida Albicans, Kenneth W. Nickerson

Kenneth Nickerson Papers

Most dimorphic fungi exhibit cell density dependent effects in that they grow as yeasts when inoculated at > 10⁶ cells per ml and as mycelia when inoculated at < 10⁶ cells per ml. For Candida albicans, we discovered (2001) that this phenomenon (quorum sensing) is due to the production and secretion of the C₁₅ isoprenoid trans-trans farnesol. Since then, we found that C. albicans cells treated with sublethal levels of zaragozic acid (2003) or fluconazole (2004) produced 10-40X more farnesol and that these fluconazole treated cells were ca. 5X more toxic to mice following tail vein injection. This suggestion …

Quorum Sensing Activity In Ophiostoma Ulmi: Effects Of Fusel Oils And Branched Chain Amino Acids On Yeast-Mycelial Dimorphism, A. Berrocal, J. Navarrete, C. Oviedo, K. W. Nickerson

Kenneth Nickerson Papers

Aims: For Ophiostoma (Ceratocystis) ulmi, the ability to undergo morphological change is a crucial factor for its virulence. To gain an understanding of quorum- sensing activity in O. ulmi as it relates to yeast-mycelium dimorphism control, this study examines the effects of branched-chain amino acids as well as their fusel alcohols and fusel acids as quorum sensing molecules.

Methods and Results: In a defined medium containing glucose, proline and salts, O. ulmi grew as yeasts when the culture was inoculated with a high density of spores (2-10⁷ CFU ml^-1) and as mycelia when inoculated …

Impact Of Crop And Residue Management On The Physical And Chemical Stabilization Of Soil Organic Matter At Farm Level, Ana B. Wingeyer

Department of Agronomy and Horticulture: Dissertations, Theses, and Student Research

This dissertation explores changes over time in soil organic matter (SOM) stabilization of two irrigated production fields: a continuous maize sequence that was converted from no-till to conservation deep tillage (Site 1), and a no-till maize-soybean rotation (Site 2). An integrated approach using humic acid extractions and density-based physical fractionation of SOM within aggregate size classes was developed to evaluate the changes in SOM stabilization (physical protection, organo-mineral associations and humification). At Site 1, loss of SOM in the surface layer was compensated for by increased SOM in deeper soil layers with no net change in C stocks. Whole field …

Zap1 Control Of Cell-Cell Signaling In Candida Albicans Biofilms, Shantanu Ganguly, Andrew C. Bishop, Wenjie Xu, Suman Ghosh, Kenneth W. Nickerson, Frederick Lanni, Jana Patton-Vogt, Aaron P. Mitchell

Kenneth Nickerson Papers

Biofilms of Candida albicans include both yeast cells and hyphae. Prior studies indicated that a zap1/ mutant, defective in zinc regulator Zap1, has increased accumulation of yeast cells in biofilms. This altered yeast-hypha balance may arise from internal regulatory alterations or from an effect on the production of diffusible quorum-sensing (QS) molecules. Here, we develop biosensor reporter strains that express yeastspecific YWP1-RFP or hypha-specific HWP1-RFP, along with a constitutive TDH3-GFP normalization standard. Seeding these biosensor strains into biofilms allows a biological activity assay of the surrounding biofilm milieu. A zap1/ biofilm induces the yeast-specific YWP1-RFP reporter in a wild-type …

A Multidisciplinary Approach To Food Safety Evaluation: Hummus Spoilage And Microbial Analysis Of Kitchen Surfaces In Residential Child Care Institutions (Rcci) In Massachusetts, U.S.A., Elsina E. Hagan

Masters Theses 1911 - February 2014

Food borne illnesses continues to be a public health challenge in the United States (U.S.); an estimated 9.4 million incident cases occurred in 2011. In view of this challenge we conducted two food safety studies; 1) related to product formulation (hummus spoilage challenge study) and 2) evaluating the microbial safety of domestic kitchen surfaces in Residential Child Care Institutions (RCCI pilot study).

Hummus is of Mediterranean origin but is currently eaten globally. This challenge study evaluates a variety of industrial hummus formulations (four in total, differing in pH and/or addition of a preservative (natamycin). Two batches were setup: batch 1; …