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Food Micro Lectue 7
Food Micro Midterm 2
What are the three types of microbial detection testing? | Investigational testing, acceptance testing, professional reasons |
Investigational testing is used to determine if a _____ is present. | hazard |
Investigational testing verifies that ____ ____ have been met in HACCP. | critical limits |
Challenge testing is a part of _____ testing. | investigational |
______ testing must comply with legal or contractual requirements. | Acceptance |
_____ testing is useful in determining the quality of incoming materials and purchase specifications. | Acceptance |
Professional reasons usually involve _____ studies to establish methodology. | collaborative |
In environmental sampling, one must be aware of ____ cells. | VBNC (viable but non culturable cells) |
What are the three types of diluents used for quantitative detection? | Buffered peptone water, 0.1% peptone water, physiological saline |
How is the most probable number (MPN) technique advantageous over plate count? | Can detect a lower number of bacteria. |
What are the cons to MPN? | Not as accurate, needs a lot of glassware. |
What is the sensitivity of direct microscopic count? | 1 cell/field (1000x magnification) ~1E6/mL |
What are the cons to DMC? | Cannot distinguish between viable and dead cells; un-uniformally stained. |
Describe the direct epifluorescent filter technique (DEFT). | Filtration of "stomached" food suspensions through nylon filters; used widely in the dairy industry; captures viable cells only. |
Plaque forming units are commonly used in the detection of _____. | viruses |
What are two rapid methods of cell detection? | Measure of ATP, flow cytometry (particle enumeration). |
_____ detection can be done through microbial enrichment. | Qualitative |
T or F: Sub-lethally injured bacteria will grow on selective media. | False |
How can the number of injured microorganisms be counted? | Grow on non-selective and selective media and find the difference between them. |
What are the three criterion for media selection? | productivity (ability to support growth), selectivity (discourage growth of competitors), electivity (easy differentiation between cells) |
Name three types of media which can be used for aerobic plate count. | brain heart infusion, trypticase soy agar, plate count agar |
Total Plate Count and Viable Plate Count are ________ media. | non-selective. |
Yeast and mold will grow on _____ _____ agar. | rose bengal |
How can bacteria be identified based on structure? | size, shape, extra-cellular characters, differential staining |
Name three ways to identify bacteria biochemically. | Growth media, serological tests, protein analysis. |
Define serotype. | Groups within a single species of microorganism with distinctive surface structures. |
How are Salmonella serotyped? | By a pattern of O antigens present. |
What does ELIA stand for and how does it work? | Enzyme-Linked ImmunoSorbant Assay; a plate-based technique which can detect substances such as peptides, proteins, antibodies, etc. |
What are three genomic methods of identifying bacteria? | PCR, DNA fingerprinting, sequencing. |
Define whole genome sequencing. | Determining the complete DNA sequence of an organism's genome at one time. |
____ are a form of global gene expression profiling. | Microarrays |
RT-PCR uses ______ in order to detect levels of ____ ____. | fluorophores, gene expression |
What does PFGE stand for? | Pulsed-Field Gel Electrophoresis |
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goberoi