Somayyeh Poshtiban

Bio: Somayyeh Poshtiban is an academic researcher from University of Alberta. The author has contributed to research in topics: Campylobacter jejuni & Resonance. The author has an hindex of 5, co-authored 6 publications receiving 368 citations. Previous affiliations of Somayyeh Poshtiban include National Institute for Nanotechnology.

Recent advances in bacteriophage based biosensors for food-borne pathogen detection.

Abstract: Foodborne diseases are a major health concern that can have severe impact on society and can add tremendous financial burden to our health care systems. Rapid early detection of food contamination is therefore relevant for the containment of food-borne pathogens. Conventional pathogen detection methods, such as microbiological and biochemical identification are time-consuming and laborious, while immunological or nucleic acid-based techniques require extensive sample preparation and are not amenable to miniaturization for on-site detection. Biosensors have shown tremendous promise to overcome these limitations and are being aggressively studied to provide rapid, reliable and sensitive detection platforms for such applications. Novel biological recognition elements are studied to improve the selectivity and facilitate integration on the transduction platform for sensitive detection. Bacteriophages are one such unique biological entity that show excellent host selectivity and have been actively used as recognition probes for pathogen detection. This review summarizes the extensive literature search on the application of bacteriophages (and recently their receptor binding proteins) as probes for sensitive and selective detection of foodborne pathogens, and critically outlines their advantages and disadvantages over other recognition elements.

Phage receptor binding protein-based magnetic enrichment method as an aid for real time PCR detection of foodborne bacteria.

Abstract: We present a novel phage receptor binding protein-based magnetic separation and pre-enrichment method as an alternative to the immunomagnetic separation methods by replacing antibodies with bacteriophage receptor binding proteins (RBPs) We couple the proposed RBP-based magnetic separation with real time PCR for rapid, sensitive and specific detection of Campylobacter jejuni cells in artificially contaminated skim milk, milk with 2% fat and chicken broth Recovery rates, assessed by real time PCR, were greater than 80% for the samples spiked with as low as 100 cfu mL−1 of C jejuni cells The specificity of capture was confirmed using Salmonella Typhimurium as a negative control where no bacteria were captured on the RBP-derivatized magnetic beads The combination of RBP-based magnetic separation and real time PCR improved PCR sensitivity and allowed the detection of C jejuni cells in milk and chicken broth samples without a time consuming pre-enrichment step through culturing The total sample preparation and analysis time in the proposed RBP-based enrichment method coupled with real time PCR was less than 3 h

Bacteriophage receptor binding protein based assays for the simultaneous detection of Campylobacter jejuni and Campylobacter coli.

Abstract: Campylobacter jejuni and Campylobacter coli are the most common bacterial causes of foodborne gastroenteritis which is occasionally followed by a debilitating neuropathy known as Guillain-Barre syndrome. Rapid and specific detection of these pathogens is very important for effective control and quick treatment of infection. Most of the diagnostics available for these organisms are time consuming and require technical expertise with expensive instruments and reagents to perform. Bacteriophages bind to their host specifically through their receptor binding proteins (RBPs), which can be exploited for pathogen detection. We recently sequenced the genome of C. jejuni phage NCTC12673 and identified its putative host receptor binding protein, Gp047. In the current study, we localized the receptor binding domain to the C-terminal quarter of Gp047. CC-Gp047 could be produced recombinantly and was capable of agglutinating both C. jejuni and C. coli cells unlike the host range of the parent phage which is limited to a subset of C. jejuni isolates. The agglutination procedure could be performed within minutes on a glass slide at room temperature and was not hindered by the presence of buffers or nutrient media. This agglutination assay showed 100% specificity and the sensitivity was 95% for C. jejuni (n = 40) and 90% for C. coli (n = 19). CC-Gp047 was also expressed as a fusion with enhanced green fluorescent protein (EGFP). Chimeric EGFP_CC-Gp047 was able to specifically label C. jejuni and C. coli cells in mixed cultures allowing for the detection of these pathogens by fluorescent microscopy. This study describes a simple and rapid method for the detection of C. jejuni and C. coli using engineered phage RBPs and offers a promising new diagnostics platform for healthcare and surveillance laboratories.

Bacteriophage tail-spike protein derivitized microresonator arrays for specific detection of pathogenic bacteria

Abstract: Increasing concerns about food safety have prompted strong interest in the development of new pathogen detection technologies. The currently used techniques usually rely on specially equipped laboratories and are labor-intensive and time-consuming. Microresonator-based biosensors incorporating specific biorecognition probes are promising for the development of highly sensitive bacterial detection sensors. We present an optimized microresonator array platform that uses phage tail-spike proteins as a recognition probe. This array is composed of one thousand beams in a small area (i.e. 13.5 mm 2 area) and therefore offers large surface area for capture of bacteria. These resonators feature a high natural frequency due to the optimized beam design, with the first resonance frequency at f 0 = 1.095 ± 0.005 MHz. Theoretical analysis of these devices indicates a high mass sensitivity with a threshold for the detection of added mass as small as δm = 52 fg (lighter than a single bacterial cell). FEA and the experimental results show that the frequency shift is mainly due to the mass loading effect of adsorbed bacteria. We have successfully demonstrated the application of these arrays for specific detection of Campylobacter jejuni cells after immobilization of devices with phage GST-Gp48 tail-spike proteins. TSP-functionalized devices did not show any sensitivity to Escherichia coli bacteria confirming the specificity of detection.

Atomic layer deposition of TiN for the fabrication of nanomechanical resonators

Abstract: Films of titanium nitride were grown by atomic layer deposition (ALD) over a range of temperatures from 120 °C to 300 °C, and their deposition rates were characterized by ellipsometry and reflectometry. The stress state of the films was evaluated by interferometry using a wafer bowing technique and varied from compressive (−18 MPa) to tensile (650 MPa). The crystal structure of the films was assessed by x-ray diffraction. The grain size varied with temperature in the range of 2–9 nm. The chemical composition of the films was ascertained by high-resolution x-ray photoelectron spectroscopy and showed the presence of O, Cl, and C contaminants. A mildly tensile (250 MPa) stressed film was employed for the fabrication (by electron beam lithography and reactive ion etching) of doubly clamped nanoresonator beams. The resonance frequency of resonators was assayed using an interferometric resonance testing apparatus. The devices exhibited sharp mechanical resonance peaks in the 17–25 MHz range. The uniformity and controllable deposition rate of ALD films make them ideal candidate materials for the fabrication of ultranarrow (<50 nm) nanobeam structures.

Global Epidemiology of Campylobacter Infection

Abstract: Campylobacter jejuni infection is one of the most widespread infectious diseases of the last century. The incidence and prevalence of campylobacteriosis have increased in both developed and developing countries over the last 10 years. The dramatic increase in North America, Europe, and Australia is alarming, and data from parts of Africa, Asia, and the Middle East indicate that campylobacteriosis is endemic in these areas, especially in children. In addition to C. jejuni, there is increasing recognition of the clinical importance of emerging Campylobacter species, including Campylobacter concisus and Campylobacter ureolyticus. Poultry is a major reservoir and source of transmission of campylobacteriosis to humans. Other risk factors include consumption of animal products and water, contact with animals, and international travel. Strategic implementation of multifaceted biocontrol measures to reduce the transmission of this group of pathogens is paramount for public health. Overall, campylobacteriosis is still one of the most important infectious diseases that is likely to challenge global health in the years to come. This review provides a comprehensive overview of the global epidemiology, transmission, and clinical relevance of Campylobacter infection.

Rapid methods for the detection of foodborne bacterial pathogens: principles, applications, advantages and limitations

Abstract: The incidence of foodborne diseases has increased over the years and resulted in major public health problem globally. Foodborne pathogens can be found in various foods and it is important to detect foodborne pathogens to provide safe food supply and to prevent foodborne diseases. The conventional methods used to detect foodborne pathogen are time consuming and laborious. Hence, a variety of methods have been developed for rapid detection of foodborne pathogens as it is required in many food analyses. Rapid detection methods can be categorized into nucleic acid-based, biosensor-based and immunological-based methods. This review emphasizes on the principles and application of recent rapid methods for the detection of foodborne bacterial pathogens. Detection methods included are simple polymerase chain reaction (PCR), multiplex PCR, real-time PCR, nucleic acid sequence-based amplification (NASBA), loop-mediated isothermal amplification (LAMP) and oligonucleotide DNA microarray which classified as nucleic acid-based methods; optical, electrochemical and mass-based biosensors which classified as biosensor-based methods; enzyme-linked immunosorbent assay (ELISA) and lateral flow immunoassay which classified as immunological-based methods. In general, rapid detection methods are generally time-efficient, sensitive, specific and labor-saving. The developments of rapid detection methods are vital in prevention and treatment of foodborne diseases.

Waterborne Pathogens: Detection Methods and Challenges

Abstract: Waterborne pathogens and related diseases are a major public health concern worldwide, not only by the morbidity and mortality that they cause, but by the high cost that represents their prevention and treatment. These diseases are directly related to environmental deterioration and pollution. Despite the continued efforts to maintain water safety, waterborne outbreaks are still reported globally. Proper assessment of pathogens on water and water quality monitoring are key factors for decision-making regarding water distribution systems’ infrastructure, the choice of best water treatment and prevention waterborne outbreaks. Powerful, sensitive and reproducible diagnostic tools are developed to monitor pathogen contamination in water and be able to detect not only cultivable pathogens but also to detect the occurrence of viable but non-culturable microorganisms as well as the presence of pathogens on biofilms. Quantitative microbial risk assessment (QMRA) is a helpful tool to evaluate the scenarios for pathogen contamination that involve surveillance, detection methods, analysis and decision-making. This review aims to present a research outlook on waterborne outbreaks that have occurred in recent years. This review also focuses in the main molecular techniques for detection of waterborne pathogens and the use of QMRA approach to protect public health.

Genetically Engineered Phages: a Review of Advances over the Last Decade

Abstract: Soon after their discovery in the early 20th century, bacteriophages were recognized to have great potential as antimicrobial agents, a potential that has yet to be fully realized. The nascent field of phage therapy was adversely affected by inadequately controlled trials and the discovery of antibiotics. Although the study of phages as anti-infective agents slowed, phages played an important role in the development of molecular biology. In recent years, the increase in multidrug-resistant bacteria has renewed interest in the use of phages as antimicrobial agents. With the wide array of possibilities offered by genetic engineering, these bacterial viruses are being modified to precisely control and detect bacteria and to serve as new sources of antibacterials. In applications that go beyond their antimicrobial activity, phages are also being developed as vehicles for drug delivery and vaccines, as well as for the assembly of new materials. This review highlights advances in techniques used to engineer phages for all of these purposes and discusses existing challenges and opportunities for future work.

Phage Therapy in the Food Industry

Abstract: Despite advances in modern technologies, the food industry is continuously challenged with the threat of microbial contamination. The overuse of antibiotics has further escalated this problem, resulting in the increasing emergence of antibiotic-resistant foodborne pathogens. Efforts to develop new methods for controlling microbial contamination in food and the food processing environment are extremely important. Accordingly, bacteriophages (phages) and their derivatives have emerged as novel, viable, and safe options for the prevention, treatment, and/or eradication of these contaminants in a range of foods and food processing environments. Whole phages, modified phages, and their derivatives are discussed in terms of current uses and future potential as antimicrobials in the traditional farm-to-fork context, encompassing areas such as primary production, postharvest processing, biosanitation, and biodetection. The review also presents some safety concerns to ensure safe and effective exploitation of bacteriophages in the future.