Nutrition & Food Science Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/2798
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Item DEVELOPMENT OF CHITIN NANOCRYSTALS AND THEIR APPLICATIONS IN FOOD AND AGRICULTURAL AREAS(2024) Jia, Xiaoxue; Wang, Qin; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Seafood industry generates millions of tons of waste annually, with crustacean shells being a significant component. Discarding these shells not only exacerbates environmental pollution but also represents a missed opportunity for resource recovery. This dissertation research aims to address these environmental challenges by repurposing crustacean shell waste into high-value nanomaterials, specifically chitin nanocrystals (ChNCs), and exploring their applications in the food, agricultural, and environmental sectors. The primary objective of this study is to investigate the fabrication, functionalization, and potential industrial applications of ChNCs, thereby offering a sustainable alternative to conventional synthetic materials.Traditional chitin nanocrystals ChNCs obtaining methods rely on strong acids, posing environmental risks. This research introduces a more sustainable phosphoric acid (PA) hydrolysis method, which uses significantly lower acid quantities, reduces environmental impact, and avoids corrosive waste. Moreover, the novel PA hydrolysis occurs in the solid state and can be handled by hand, simplifying operation. This method efficiently yields uniform ChNCs with positive surface charges (~+27 mV), suitable for scalable industrial applications. Additionally, 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) oxidation was employed to produce oxidized chitin nanocrystals (O-ChNCs) with negative surface charges (~ −56 mV). ChNCs and O-ChNCs were investigated as stabilizers in Pickering emulsions. Both were able to significantly enhance the stability of oil-in-water (O/W) emulsions, particularly when pH > 9. O-ChNCs further demonstrated encapsulation efficiencies of up to 80% for bioactive compounds like quercetin, highlighting their potential in food and nutraceutical delivery systems. Additionally, ChNCs and O-ChNCs were incorporated into a colorimetric sensor array (CSA) to monitor beef freshness. The negative charged O-ChNC-based sensor exhibited sensitivity to spoilage gases, achieving 99.3% accuracy in beef freshness detection with the aid of deep learning algorithms. This innovation provides a non-invasive cost-effective method to food quality and safety monitoring. Furthermore, ChNCs were deacetylated to form chitosan nanocrystals (ChsNCs), and subsequently modified with zinc to create a ChsNCs@Zn composite for the removal of per- and polyfluoroalkyl substances (PFASs) from water. The composite achieved 50% PFAS removal within 5 minutes and ultimately achieved 68% removal, showcasing strong adsorption capabilities and offering a potential sustainable solution for PFAS remediation in contaminated water sources. In summary, this research is driven by the need to solve the environmental problem of seafood waste, while also tackling challenges in food stability and safety, as well as water purification. The findings contribute to advancing sustainable materials and practices in response to pressing environmental challenges.Item ROLE OF TRPV4 MECHANOSENSING REGULATING MACROPHAGE FUNCTIONS IN INFLAMMATORY DISEASES(2024) Dutta, Bidisha; Rahaman, Shaik O; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Macrophages are the most versatile cells of the hematopoietic system with roles in homeostasis, host-tissue development, innate immune response and tissue repair. Although the inflammatory activation and maintenance signals are tightly regulated, an imbalance in them results in unchecked inflammation resulting in cellular and tissue damage. Macrophages can affect most if not all phases of inflammation owing to their ability to adopt distinct functional states, secrete cytokines and phagocytose pathogens and debris. Recent evidence suggests that beyond biochemical cues, mechanical forces, like changing matrix stiffness in the tissue microenvironment, can shape immune cell functions involved in inflammation. These cells convert mechanical stimuli to biochemical signals in a process called mechanotransduction, regulating a multitude of cellular functions. However, knowledge about the molecular mediators of mechanotransduction and their functions in macrophage phenotypic and functional change is largely missing, highlighting the need for studying mechanosensory molecules such as ion channels. The present study focuses on the role of a specific mechanosensitive ion channel, Transient Receptor Potential Vanilloid 4 (TRPV4), in the regulation of macrophage mediated inflammatory responses. Given its emerging role in inflammatory diseases like fibrosis, arthritis, foreign body response (FBR), TRPV4’s contribution to macrophage behavior in inflammation is of growing interest. Employing cellular imaging and molecular biology techniques such as Ca2+ influx assays, immunohistochemistry, immunoblotting, and single nuclei RNA sequencing we delineate mechanisms by which biomechanical stimuli-mediated activation of TRPV4 affects macrophage function. We elucidate TRPV4’s role in macrophage mechanotransduction, providing a mechanistic understanding of inflammatory disease pathophysiology which could lead to the development of potential therapeutics for disease intervention.Item MACHINE LEARNING AND GENOMICS FOR IMPROVED FOOD SAFETY AND RISK ASSESSMENT OF SALMONELLA ENTERICA IN CHICKEN(2024) Benefo, Edmund Ofosu; Pradhan, Abani K; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Salmonella enterica is a leading cause of foodborne illnesses worldwide and is commonly associated with poultry. Salmonella has many closely related serovars, yet these serovars exhibit significant variability in many characteristics including host range, virulence, growth behavior, stress response, and antimicrobial resistance. In the past, this intricate and dynamic population heterogeneity of Salmonella severely hampered control efforts, but, today, this has improved through the sequencing of Salmonella genomes. Whole genome sequencing (WGS) provides a better understanding of the evolutionary and ecological adaptations that underlie the survival of Salmonella against antimicrobials, oxidative agents, non-optimal temperatures, and other stressors in the environment and their hosts. Coupling machine learning with WGS expands on these advantages by enabling the identification of genetic patterns that may not be immediately apparent. The overall goal of this research was to explore how machine learning and genomics can be integrated to improve food safety. First, a machine learning model was developed to identify stress response genes in Salmonella isolated from different poultry processing stages. It was found that beyond genes encoding for cold and heat shock proteins, other genes involved in lipopolysaccharide biosynthesis, DNA repair and replication, and biofilm formation are involved in Salmonella’s overall stress response mechanism. Additionally, a machine learning model was developed to predict antimicrobial resistance (AMR) phenotypes in Salmonella isolates using WGS data. The model predictions were comparable to existing bioinformatic methods for AMR prediction and identified AMR genes that are typically not the resistance determinants public health agencies focus on. Expanding this approach for AMR surveillance could lead to the discovery of novel AMR genes. Lastly, a quantitative microbial risk assessment for Salmonella in chicken that incorporated Salmonella heterogeneity in growth and virulence was developed. The findings revealed that variations in virulence have a greater impact on the risk of salmonellosis than variations in growth rate. Overall, this research contributes to efforts to enhance food safety measures and reduce chicken-associated Salmonella illnesses.Item Three Clostridium species with Health Imparting Properties: In vitro Screening for Probiotic Potential(2024) Mochama, Victor Moronge; Obanda, Diana; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research aimed to unlock the probiotic potential of the genus Clostridium, which is often overshadowed by the predominant focus on pathogenic species. The study specifically targeted three promising Clostridium species: C. disporicum, C. celatum, and C. vincentii, which have shown potential in mitigating diet-induced obesity. Despite the challenges presented by the anaerobic growth requirements of Clostridium bacteria, the study capitalized on their capacity to sporulate. This characteristic provides an avenue to use them as probiotics, with resilient and dormant spores capable of surviving food processing and harsh stomach conditions. The resilience of these spores was examined by exposing them to oxygen, heat, gastrointestinal juices, and bile salts. The spores survived oxygen exposure, exhibited resilience to both bile salts and gastric acids, and demonstrated a survival temperature of 70°C. When exposed to suitable germination conditions in vitro, the spores successfully germinated. The study assessed the colonization potential of the bacteria by evaluating their adhesion ability, and all bacteria were found to have the adhesion ability. Furthermore, a safety assessment was conducted by examining hemolytic activity and antibiotic susceptibility to selected antibiotics. The bacteria were found to be susceptible to the antibiotics and did not exhibit hemolytic activity. Bile salt hydrolase (BSH) activity and antibacterial activities were also assessed, and none of the bacteria exhibited BSH activity or antibacterial activity. Antioxidant tests revealed that C. vincentii had the highest antioxidant properties. Assessment of anti-inflammatory properties showed that C. celatum downregulated the gene expression of cytokine inflammation markers IL-6, IL-1, and iNOS while upregulating TGF-β expression. In summary all 3 bacterial species showed good probiotic potential from the in vitro tests. Particularly the formation of resistant spores that later germinated to vegetative cells that produced molecular patterns with antioxidant and anti-inflammatory properties. This necessitates further studies on their probiotic properties.Item Investigation into the Impact of Food Matrix on Bacterial Survival during Gastric Digestion(2024) Gao, Zhujun; Tikekar, Rohan V.; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Over the years, food safety research often focused on the bacterial survival during food processing and storage, whereas physiological studies extensively explored the host-pathogen interaction in gastrointestinal tract. There is a need to understand the intermediate step on pathogen survival during gastric digestion and the potential impact from its food carrier. This study utilized water-in-oil (W-O) and oil-in-water (O-W) emulsion as well as deionized water (DI) as the fundamental model food matrices to study the potential protection by food matrix during simulated gastric digestion. Using Salmonella enterica subsp. enterica serovar Typhimurium as a sample foodborne pathogen, this study investigated the survival kinetics of bacteria using various models of simulated gastric digestion. In a simplified static pH simulated gastric digestion model, inoculated W-O and O-W emulsion matrices were challenged with simulated gastric fluid (SGF) containing HCl and pepsin with mixing using a stomacher for two hours. W-O emulsion showed significant protection of Salmonella survival compared to O-W emulsion and DI water. This protective effect appeared to be matrix dependent regardless of the inoculation location of Salmonella (in dispersed phase vs. in continuous phase). Within the same emulsion type, inoculating Salmonella in water phase or oil phase did not show significant difference in its survivability during simulated gastric digestion. The study was then extended to an improved gastric digestion model where the chyme pH dropped from 4.0 to 1.5 over three hours, and the chyme mixing was achieved by an orbital shaker. In addition, the new SGF was modified to be HCl solution with pepsin, amano lipase A, mucin and NaCl. Under this digestion condition, there was no significant difference in Salmonella survival between W-O emulsion, O-W emulsion, and DI water. Moreover, the dispersed-continuous phase ratio of emulsion composition also showed no impact on Salmonella survival. The simulated gastric digestion model setup was also further analyzed including the role of individual digestive enzyme, the pH impact, and the mechanical mixing approach. In the dynamic pH simulated gastric digestion model, partial activity from lipase accelerated the disruption of emulsion structure for both W-O and O-W emulsion matrices. Mild mixing using an orbital shaker also showed difference in Salmonella survival compared to vigorous mixing using a stomacher. Lastly, this study expanded from using Salmonella as the single bacteria strain into a tailored natural microbiome community. Natural microbiome communities from Golden Delicious (GD) and Empire (EP) apples were manually enriched using bacteria culturing broth at pH 5 and pH 7, respectively. The enriched apple microbiome was then collected and analyzed using 16S rRNA sequencing to study the microbial composition. With a significant decrease in Alpha diversity, the culturable apple microbiome was successfully enriched from less than 3 log CFU/ml to more than 8 log CFU/ml. There was no known foodborne human pathogens detected in the enrichment, and the most abundant genera appeared to be potential plant growth promoting bacteria. The collected apple microbiome was then inoculated in various food matrices to study its survivability during dynamic pH simulated gastric digestion including DI water, apple sauce (AS), chicken puree (CK), sweet potato puree (SP), and W-O emulsion. The enriched apple microbiome showed remarkably high survivability in W-O emulsion throughout the full three-hour digestion treatment. CK also exhibited moderate protective effect compared to SP at the same condition. There was no significant difference between DI and AS on bacterial survivability. In addition, the apple microbiome enriched at two pH levels (5 & 7) showed similar bacteria inactivation kinetics. In conclusion, this study revealed the potential impact from food matrix on bacterial survival during simulated gastric digestion. W-O emulsion offered significant protection of certain bacteria strains or communities in specific simulated gastric digestion models. The parameters in gastric digestion models also affected bacterial survival. Future work should focus on exploring the potential impact from other types of food matrices, expanding the microbial survival study into other bacterial strains as well as a more complex microbiome community, and further comparing the various gastric digestion models.Item Antiproliferative Activity of Soybean and Tempeh Extracts on Human Colorectal Cancer Cells(2024) Fan, Rongjie; Lee, Seong-Ho; Wei, Cheng-I; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Tempeh, an indigenous Indonesian soybean product, is produced through a fermentation process of soybean that enhances the bioavailability of its beneficial nutrients such as proteins and phytoestrogens. Recent studies suggest that the fermentation process of tempeh may enhance the biofunctionality properties of soybeans including anticancer activity. The current study is designed to present a comparative analysis to see if defatted extracts of unfermented soybeans and tempeh (fermented soybeans) possess anti-proliferative activity in human colorectal cancer (CRC) cells. The experimental methods involve the production and extraction of soybeans extract (SE) and tempeh extract (TE) at a concentration of 35 g/100 mL (w/v) with 70% ethanol, followed by rotary evaporation and freeze-drying. MTT assays indicated that both SE and TE exhibited inhibitory activity in viability of human CRC cells, with TE demonstrating a more pronounced dose-dependent inhibition of cell growth compared to SE. Cell cycle analysis led to a significant increase of G1 arrest in both SE and TE-treated cells. The induction of apoptosis was observed from the cells treated with both SE and TE. Western blot analysis revealed an increase of PARP cleavage for both treatments, demonstrating activation of apoptotic pathways in SE and TE-treated cells.Item FUNCTIONAL FOODS THAT MANIPULATE THE GUT MICROBIOTA COMPOSITION AND REGULATE THE INTESTINAL IMMUNE SYSTEM-Urtica dioica a CASE STUDY(2024) Fan, Si; Obanda, Diana; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The prevalence of obesity and its comorbidities, such as insulin resistance and type 2 diabetes are major concerns. Diet-induced obesity and insulin resistance are associated with gut microbiota dysbiosis, specifically, a reduction in diversity and an increase in bacteria taxa linked with host tissue inflammation and extra energy harvest. Prevention strategies focusing on modification of diet and physical activity levels are beneficial, effective, and cost-efficient but difficult to maintain in the long term.Urtica dioica is widely used as a food in several cultures and its extract has been widely studied for intervention against several diseases, but the molecular mechanisms involved are unclear. In addition, most studies have focused on the extract but not the plant as a whole food. Because U. dioica exerts pleiotropic effects in several tissues, we hypothesized that its phytochemicals get into the systemic circulation to reach target tissues, such as abdominal adipose tissue and skeletal muscle but also impact obesity and insulin resistance through pathways involving the gut microbiota and ultimately the gut immune system. The data presented herein was acquired in a mouse model of obesity and insulin resistance. Supplementing the food with whole U. dioica vegetable, attenuated high fat (HF) diet-induced weight gain, fat accumulation, insulin resistance and changed the gut microbiota composition, by increasing diversity and promoting the proliferation of species from the genus Clostridium. This taxon has associated with lower body weight and activation of regulatory T cells (Tregs) in the intestinal immune system. In a second study, we confirmed that U. dioica induced T cells antigenic stimulation, promoted the activation of Tregs and overall protected against HF diet inflammation. Furthermore, besides attenuating HF diet induced fat accumulation, U. dioica promoted the browning or beiging of adipose tissue as evidenced by enhanced gene expression of key markers of this process. Brown or beige adipose tissue displays enhanced fat oxidation. Finally using enteroids derived from small intestinal tissue, we show that in presence of excess nutrients, supplementation with U. dioica reduces the amount fatty acids and glucose absorbed. In conclusion, supplementing a HF diet with U. dioica attenuates fat accumulation and insulin resistance via mechanisms involving the gut microbiota composition and function, the gut immune system and associated inflammation and moderation of amounts of macronutrients absorbed.Item UNDERSTANDING THE INTERACTIONS OF COLD ATMOSPHERIC PLASMA AND THE PLANT STRESS RESPONSE TO IMPROVE FRESH PRODUCE SAFETY(2023) Gilbert, Andrea Rochelle; Tikekar, Rohan V; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Cold atmospheric plasma (CAP) is a surface modification technology that produces oxidative species that inactivate microorganisms. This technology has been shown to be an effective sanitization technology for use on a variety of food products and leafy greens are a uniquely promising application. CAP products, such as reactive oxygen species (ROS), reactive nitrogen species (RNS), UV light, and ozone, are environmental stressors with antimicrobial effects that plants already encounter in their natural environment, and fresh produce will produce a stress response when treated by CAP and this stress response is not limited to directly treated tissue. The stress responses of baby spinach, red leaf lettuce, baby kale and live basil were evaluated post-CAP treatment. In all evaluated fresh produce CAP treatment resulted in a significant (p<0.05) increase in ROS. This increase in reactive oxygen species was not limited to the plant tissues directly treated by CAP. In live basil, ROS generation was detected on indirectly treated leaves sharing the same stem, and in spinach the increase in ROS levels continued for 12 hours post-treatment. To further understand how the elevated ROS levels affected plant tissues the flavonoid content was evaluated in baby spinach, red leaf lettuce and baby kale. Baby spinach CAP treatment resulted in a significant increase in flavonoids at 50w and 120w power level. Flavonoids in red leaf lettuce were only significantly affected in directly treated leaf tissue. In baby kale, CAP treatment significantly reduced flavonoid content in both direct and indirectly treated leaf tissue. To understand the differences between the two leafy greens species and the effect of ozone and UVB treatment, two products treated with CAP, were also evaluated on baby spinach and baby kale. The two non-CAP treatments resulted in the opposite effects in baby spinach and baby kale, and an examination into the response of the stress hormones salicylic acid and jasmonic acid was inconclusive. The novel interactions of this sanitization treatment with the plant stress response may provide useful opportunities to improve both the food safety and nutritional quality of fresh produce. In addition to the research project, I composed a needs assessment survey instrument to evaluate food safety compliance among small and very small food processors in the northeastern United States in cooperation with the Northeast Center for the Advancement of Food Safety. The survey instrument was sent to food safety professionals and regulators in the region. Results of the survey revealed that the food safety concepts that processors struggled to learn were often those cited by regulators during inspections.Item EVALUATING THE EFFECTS OF MODIFIABLE LIFESTYLE AND CARDIOVASCULAR HEALTH FACTORS ON DIABETES LIFE EXPECTANCY IN NHANES AND BRAIN AGING IN UK BIOBANK(2024) Feng, Li; Lei, David K.Y. DL; Ma, Tianzhou TM; Nutrition; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation explored the impact of lifestyle and cardiovascular health factors on aging, particularly focusing on individuals with diabetes, the effects of blood pressure on brain aging, and the influence of cardiovascular health and genetic predispositions on brain white matter aging.The first study examined the trends in lifestyle quality among US adults with type 2 diabetes from 1999 to 2018 using NHANES data, involving 7,410 participants. A healthy lifestyle score encompassing smoking, drinking, physical activity, and diet showed a slight increased over the years. Notably, disparities remained significant by socioeconomic groups. The study found that adherence to low-risk lifestyle factors was associated with a 55%-57% lower risk of all-cause mortality, emphasizing the importance of lifestyle modification in diabetes management, and it was independent of cardiovascular risk control. The second study investigated the causal effect of elevated blood pressure on white matter brain aging in a cohort of 228,473 European ancestries aged 40-69 from the UK Biobank by using two-sample Mendelian randomization. Our result revealed that high blood pressure, particularly diastolic, accelerated the machine-learning-derived white matter brain age gap, based on white matter microstructure integrity measured by fractional anisotropy derived from diffusion tensor imaging data, with a causal effect evidence found in late middle-aged women. This underscores the importance of blood pressure control in preventing brain aging, especially in post-menopausal women. Lastly, the impact of Life's Essential 8 (LE8), a comprehensive measure of cardiovascular health (lifestyle part: diet, smoke, physical activity, sleep; health part: BMI, blood sugar, blood pressure, blood lipid), on white matter brain aging was assessed, with a particular focus on how the APOE4 genotype modifies the relationship. Analyzing data from 18,817 European ancestries aged 40-60 from the UK Biobank, the study revealed that higher LE8 scores correlated with a younger brain age. Interestingly, the effect varied significantly with APOE4 status, highlighting the need for personalized health strategies based on genetic profiles. In conclusion, these studies collectively highlight the crucial role of modifiable lifestyle and health factors in managing chronic diseases, controlling blood pressure, and maintaining brain health, with an emphasis on the integration of genetic profiles for personalized healthcare.Item EVALUATION OF THE COPPER HOMEOSTASIS AND SILVER RESISTANCE ISLAND AND ITS ROLE IN PERSISTENCE OF SALMONELLA ENTERICA(2023) Haendiges, Julie; Tikekar, Rohan; Food Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Salmonella enterica is one of the leading bacterial cause of foodborne illness in the UnitedStates. Although there are many serovars, only a small subset causes human illness. Since Salmonella is ubiquitous in the environment, the Food and Drug Administration has established regulations for food processors to ensure that the products are free of contamination. Low-moisture foods are commonly ready-to-eat, and due to the low water activity do not promote growth of bacteria. However, Salmonella has been shown to persist in these foods. There havebeen two outbreaks and multiple recalls in the United States due to contaminated pistachios. Based on a retrospective study, results show that there is evidence of a contamination in the growing orchard and a significant number of Salmonella isolates from the environments contain the Copper Homeostasis and Silver Resistance Island (CHASRI) cassette. This raises several questions: what is the prevalence of CHASRI among different Salmonella isolates from food and environmental sources? Does presence of CHASRI enable Salmonella to survive better against copper stress? And whether presence of CHASRI provide cross-protection against other stresses such as desiccation and thermal treatment? This dissertation attempts to answer those questions. The prevalence of the CHASRI in Salmonella was determined by the use of publicly availablewhole genome sequencing data. The CHASRI was found in 61 different serovars and types of sources. The presence of the CHASRI in isolates from low-moisture foods that have caused previous outbreaks (peanut butter, nuts, spices) was interesting to note, and leads to future studies on correlations between this island and virulence. Based on results of phylogenetic analysis of CHASRI sequences from closed genomes, we determined there were four types of CHASRI found in Salmonella. Traditionally, the Salmonella Genomic Island-4 (SGI-4) is found but in addition the CHASRI can incorporate by itself, within a variant of SGI-4, or via a rare plasmid. Interestingly, the sequence of the CHASRI from SGI-4 and the variant SGI-4 were highly different. The high SNP differences in sequence along with the difference in the arsenic operon led to the conclusion that these variants arose independently. A Salmonella Senftenberg strain (CFSAN047523), isolated from pistachios, was used to createthree knockouts (∆cus, ∆pco, and ∆CHASRI). Previous studies have looked at the minimum inhibitory concentration (MIC) of strains with and without the CHASRI but have omitted the minimum bactericidal concentration (MBC). In this study, we used the knockouts to test for both MIC and MBC. While the MIC was similar for the strains, the MBC was greater in the wild type and partial CHASRI knockouts. Growth and inactivation kinetics were measured in different concentrations of copper sulfate. At higher levels of copper sulfate, the presence of the CHASRI made cells more resilient to inactivation by copper sulfate. Evidence shows that the stress response in Salmonella has the ability to crosstalk and provideprotection against multiple stresses. To investigate this phenomenon further, our isolates were tested against a multitude of stresses to evaluate for cross-protection that may be due to theCHASRI. Cells undergoing copper stress were better equipped to survive lethal copper concentrations and desiccation if the CHASRI was present. The presence of Salmonella in final pistachio products that have been fully processed identifies that some adaptation and stress response is occurring in the processing facility. Inoculated pistachios with the wild type and ∆CHASRI strain were thermally processed to test for survivors. This study showed that the presence of the CHASRI gave the isolate an advantage to survive thermal processing after desiccation. Overall, this study presents the prevalence of the CHASRI in Salmonella enterica as well as theimportant role it plays in copper tolerance. The evidence of cross-protection and tolerance to copper leads to future research regarding gene expression and virulence assessment.