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dectection of orgs2A
Physical, and Chemical methods
| Question | Answer |
|---|---|
| The physical, chemical, molecular, and immunological methods are based on | metabolic activity, growth response, measurement of parts of cell |
| Father of Biosensor | Professor Leland C. Clark Jr |
| Biosensor | is an analytical device use to rapidly detect pathogens, allergens as well as pesticide residues in food. |
| biosensors converts a biological response into an ------- ----- | electrical signal |
| The key component of a biosensor is the | transducer |
| transducer makes use of a ------ change accompanying the reaction | physical |
| general working principle of biosensor type: Calorimetric biosensors | Heat output (or absorbed) by the reaction |
| general working principle of biosensor type: Electrochemical biosensors | Changes in electrical or electronic output |
| general working principle of biosensor type: Amperometric biosensors) | Redox reaction |
| general working principle of biosensor type: Optical biosensors | Light output or light absorbance difference between the reactants and products |
| general working principle of biosensor type: Piezo-electric biosensors) | Based on mass of the reactants or products |
| detects bacteria in food products; sensors detect changes in refractive indices when cell bind to receptor which are immobilized on the transducer. | Optical biosensor |
| 2 main parts of biosensor: | bioelement and transducer |
| TRUE OR FLASE: optical biosensor- It provides a rapid, efficient and alternative method for detecting foodborne pathogens to ensure the safety of RTE foods and can be used as stand-alone devices for on-site monitoring. | TRUE |
| In biosensor, cell, tissues, organelle, enzyme, antibody, and nucleic acids, are collectively called? | biolement |
| A simple, sensitive, and rapid chemiluminescent fiber-optic biosensor utilizing monoclonal antibodies to Staphylococcus aureus was developed to detect the pathogen in food. | Optical Biosensors with Membranes |
| the S. aureus cells were selectively labeled with a monoclonal ---------- ----- (POD) conjugate, collected by membrane filtration, and detected with a luminometer and an enhanced chemiluminescent luminol reagent. | horseradish peroxidase |
| the science of measuring components (cells) and the properties of individual cells in liquid suspension. | Flow cytometry |
| Fluidic devices under laminar flow define the trajectories and velocities that cells traverse the detector, and among the cell properties that can be detected are --------, -------, ------ | fluorescence, absorbance, and light scatter. |
| Is biosensor and flow cytometry are used for physical or chemical method for detection of microbes in food? | physical method |
| Chemical method for detection; for Staphylococcus aureus | Thermostable nuclease |
| Chemical method for detection; for Gram negative bacteria, | Limulus amoebocyte lysate (LAL) assay |
| Chemical method for detection; for live cells; determination of microbial load on chicken carcasses as well as pork and beef | ATP assay |
| Chemical method for detection; aerobic and anaerobic microbial species that are of significance in foods, by measurement of 14CO2 evolved from the metabolism of 14Cglucose. | Radiometry |
| Chemical method for detection; to identify/differentiate microbial species or strains use substrates MUG | Fluorogenic/chromogenic substrate |
| DNAse produced by 95% of enterotoxigenic strains of S. aureus | thermostable nuclease |
| enzyme produced by 93% of enterotoxigenic strains of S. aureus | coagulase |
| Nature or properties of thermostable nuclease | heat-stable, detected faster, detectable in unconcentrated cultures of food specimen |
| about how many hours can we detect thermostabke nuclease than enterotoxin? | can be detected 3 hrs vs several days |
| What bacteria produces nuclease but is not as stable to heating as is that produced by S. aures? | S. epidermis |
| Thermostable nuclease will withstand boiling for ? | 15 minutes |
| What s a measure of the heat resistance of a microorganism; It is the time in minutes at a given temperature required to destroy 1 log cycle (90%) of the target microorganism | D value |
| What protein The LimulusAmoebocyte lysate (LAL) test employ? | lysate protein |
| lysate protein is obtained from the blood (actually haemolymph) cells (amoebocytes) of the? | horseshoe crab (Limulus polyphemous). |
| The lysate protein is the most sensitive substance known for endotoxins and the presence of endotoxins causes --- ---- of the lysate material. | gel formation |
| The method has been applied successfully to monitor milk and milk products, microbial quality of raw fish and cooked turkey rolls. | LAL ttest/assay |
| In LAL assay if endotoxins are present there is clotting or no clotting observed? | clotting is observed |
| the primary source of energy in all living organisms. It disappears within 2 hours after cell death, and the amount per cell is generally constant. | Adenosine triphosphate (ATP) |
| One of the simplest ways to measure ATP is by use of the firefly? | luciferin-luciferase system. |
| In the presence of ATP, luciferase emits light, which is measured with a liquid scintillation spectrometer or a? | luminometer. |
| The amount of light produced by firefly luciferase is -------proportional to the amount of ATP added. | directly |
| The ATP assay is widely used as a rapid and on-the-spot method for monitoring food handling surfaces by swabbing designated areas and reading the ---- ---- ---- (RLU) from a luminometer | relative light units |
| luciferin + ATP+ O2 = _____________ +ppi+Amp+CO2+ light 562nm | oxyluciferin |
| cons of atp | number of atp is not equal to bacterial count; species not known |
| 14 CO2 evolved from the metabolism of ? | 14 C glucose |
| Bacteria that cannot utilize glucose use what to produce 14 co2? | 14C-formate or 14C-glutamate |
| Radiometry has been used to detect organisms in ? | frozen orange juice concentrate |
| MUG substrate meaning | 4-methylumbelliferyl-p-D-glucuronide (MUG) |
| MUG is the most widely used of the fluorogenic substrates, and it is hydrolyzed by ? | 3-D-glucuronidase (GUD) |
| MUG is the most widely used of the fluorogenic substrates, and it is hydrolyzed by 3-D-glucuronidase (GUD) to release the ----, which is detected with long-wave ultraviolet light. | fluorescent 4-methyl-umbelliferyl moiety |
| bacterium which is the primary producer of GUD | e. coli |
| other GUD positive bacteria: | A few salmonellae and shigellae are also GUD positive, as are some corynebacteria |
| TWO TESTS IN FLUOROGENIC AND CHROMOGENIC SUBSTRATES | Direct disk test and Tube test |
| IN FLUOROGENIC AND CHROMOGENIC SUBSTRATES, the disks are examined for fluorescence using what in a darkened room? | ultraviolet light (360nm) |
Created by:
honeybunch
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