Detection of Foodborne Pathogens by Micro-filtration using a Continuous Cell Concentrator Device

Protecting consumers from foodborne illness is an important health concern facing the food industry today. An important deficiency exposed by foodborne illness is the inability to track contaminated food back to the source in a timely manner. Although there are established methods that detect bacterial pathogen contamination, they are limited in distinguishing viable bacteria reliably and quickly. Currently, food pathogen testing requires lengthy culture steps, which many times are delayed even longer due to the lack of in-house testing labs. Typically, two to three days elapses between when the food is sampled and the test results are available. This study uses a Cell Continuous Concentration Device (C3D) to recover cells using microfiltration that have been cultured in water and food related solutions. The results of the experiment allow us to see how much we recovered from the original sample. We created a pretreatment that consisted of a surfactant (TWEEN 80) and Sodium hexametaphosphate (SHMP) which will efficiently recover cells depending on the solution being concentrated. This pretreatment recovered 60-70% of the microorganisms (Escherichia coli and Salmonella) when recovering with DI water, PBS, and chicken. The recovery rates were 20% or below before this pretreatment was put into place. The end goal is to detect a single pathogenic cell. This pretreatment will continue to be used on the vegetable wash and chicken to produce results that are more useful to the end goal. These recovery rates are increasing as new pretreatments are being discovered

Rapid Sample Processing of Foodborne Pathogens Using Cross-Flow Microfiltration

Foodborne illnesses are a prominent issue, causing 48 million illnesses annually. The Escherichia coli O157:H7 outbreak in romaine lettuce is a recent example. The source of the pathogen was contaminated irrigation water. The most common methods for detecting foodborne pathogens involve cultivation and enrichment of food samples. The enrichment steps are time-consuming, taking 24 to 72 hours to complete. Our study aims to accelerate irrigation water sample preparation for pathogenic microorganism fast detection through cross-flow microfiltration. This is accomplished by a device called a continuous cell concentration and recovery device (C3D). The C3D uses cross-flow microfiltration in a hollow fiber module containing a polyethersulphone membrane with 0.2 µm pore size. This is small enough that the liquids and dissolved particles in the sample will be leaked out into a waste container, and any microorganisms present will be trapped. After concentration, the trapped microorganisms are returned into a sample recovery vial, effectively reducing the sample from 500 mL down to a 5-10 mL sample. Further concentration is achieved by centrifugation to a final volume of 0.5-1.0 mL. This concentrates environmental and pathogenic bacteria that may be present in a water sample to a detectable level. A C3D with four separate hollow fiber modules was developed and calibrated to further increase efficiency. Overall, this process has the potential to decrease the time needed for the sample to reach a detectable level from up to 72 hours down to just 6-8, which is within the window of a single shift of a plant

DNA Bound Avicel Network: The Beginnings of a Self-Healing Material

Self-healing materials could potentially provide many improvements to engineering projects, including reduced maintenance and cost, and increased lifespan. It is desired to create a self-healing material proof of concept, which can then be altered for eventual application to the surfaces of small satellites with the goal of increasing material lifetimes. The intrinsic properties and abilities of DNA base pairing will be studied as a first test of proof of concept. The exploratory research reported in this short communication utilizes oxidation of small (50µm) particles of Avicel using TEMPO, followed by activation of Avicel particles via an EDC (1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride) reaction. The cellulose prepared in this manner will next be reacted with short sequences of single stranded DNA (oligonucleotides) with the cellulose, although this has not yet been achieved. Complementary strands will be bound to a second aliquot of particles. The particles will be combined to test if they hybridize (bind in a directed manner), resulting in a network of Avicel particles glued together by DNA. A Malvern wet particle size instrument was used to determine zeta potential of the cellulose particles, and in the future will be used to compare the size of particles before and after chemical alterations. Colored nanoparticles will be used to dye the individual aliquots of the derivatized celluloses so that a change in color may be observed when cellulose derivatized with complimentary strands of DNA are brought in contact with each other. After washing to remove unbound particles, a change in color would be expected to occur, thus indicating binding. While this is a work in progress, key developments at this point are the experimental design, development of research hypotheses, and successful oxidation of cellulose. These experiments are part of a longer term project that is studying whether intrinsic self-healing materials are possible. Alterations in the particle and in binding sequences to be placed on the particles have potential for automobile, airline, satellites and spacecraft, military, and healthcare applications, where self-healing principles at a nano-scale would enable micro-damage to be identified and healing processes to occur

Secretome Data from Trichoderma Reesei and Aspergillus Niger Cultivated in Submerged and Sequential Fermentation Methods

The cultivation procedure and the fungal strain applied for enzyme production may influence levels and profile of the proteins produced. The proteomic analysis data presented here provide critical informa- tion to compare proteins secreted by Trichoderma reesei and Aspergillus niger when cultivated through submerged and sequential fermenta- tion processes, using steam-explosion sugarcane bagasse as inducer for enzyme production. The proteins were organized according to the families described in CAZy database as cellulases, hemicellulases, proteases/peptidases, cell-wall-protein, lipases, others (catalase, ester- ase, etc.), glycoside hydrolases families, predicted and hypothetical proteins. Further detailed analysis of this data is provided in “Secre- tome analysis of Trichoderma reesei and Aspergillus niger cultivated by submerged and sequential fermentation process: enzyme production for sugarcane bagasse hydrolysis” C. Florencio, F.M. Cunha, A.C Badino, C.S. Farinas, E. Ximenes, M.R. Ladisch (2016) [1]

Rheology of enzyme liquefied corn stover slurries: The effect of solids concentration on yielding and flow behavior

The measurement of yield stress and shear thinning flow behavior of slurries formed from unpretreated corn stover at solids loadings of 100–300 g/L provides a key metric for the ability to move, pump, and mix this lignocellulosic slurry, particularly since corn stover slurries represent a major potential feedstock for biorefineries. This study compared static yield stress values and flow hysteresis of corn stover slurries of 100, 150, 200, 250, and 300 g/L, after these slurries were formed by adding pellets to a cellulase enzyme solution (Celluclast 1.5 L) in a fed-batch manner. A rotational rheometer was used to quantitate relative yield stress and its dependence on processing history at insoluble solids concentrations of 4%–21% (wt/vol). Key findings confirmed previous observations that yield stress increases with solids loadings and reaches ~3000 Pa at 25% (wt/vol) solids concentration compared to ~200 Pa after enzyme liquefaction. While optimization of slurry forming (i.e., liquefaction) conditions remains to be done, metrics for quantifying liquefaction extent are needed. The method for obtaining comparative metrics is demonstrated here and shows that the yield stress, shear thinning and shear thickening flow behaviors of enzyme liquefied corn stover slurries can be analyzed using a wide-gap rheometry setup with relative measuring geometries to mimic the conditions that may exist in a mixing vessel of a bioreactor while applying controlled and precise levels of strain

Transitional justice and the political 'work' of domestic tourism

The relationship between tourism and transitional justice is little-researched. This paper explores the importance of domestic tourism for enabling citizens to encounter and engage with wider transitional justice projects. This issue is explored with reference to a memorial museum in Romania which interprets political violence and state repression. Semi-structured interviews with 52 domestic tourists were undertaken (using purposive sampling to select participants) and the interviews were analysed using thematic analysis. Most visitors reported general sightseeing motives for visiting the museum and may not have anticipated engaging with transitional justice messages. However, their engagement went beyond sightseeing in a range of ways. Visitors participated in acts of memory-work, acknowledged the victims of repression, and recognized the core message of transitional justice – “never again”. They also reflected on the relationship between the recent past and the present, and recognized the role of the museum as a resource for future generations. These experiences were shared by those who had lived through state repression and those who had not. The findings indicate that domestic tourism is a meaningful but overlooked context through which citizens can engage with broader transitional justice projects