Common Terms and Definition in Microbiology Laboratory

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Common Terms and Definition in Microbiology Laboratory

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aerosol – a spray of live microbes ejected from sputtering

brightfield microscope – a microscope which the general background or field of view is bright while dense specimens appear darker objects; used for stained materials

capsule – thick layer of substance found on the surface of some bacteria that inhibits phagocytosis by white blood cells

capsule stain – involves the process of negative staining the slide and staining the cytoplasm of the bacteria making the capsule only the colorless structure which appears as a light halo around the bacteria

carbol fuchsin – the primary stain used in acid fast staining

citrate test – detects species of bacteria that survive on citrate as its carbon source

 coagulase – a bacterial enzyme which brings about the coagulation of blood or plasma and is produced by disease-causing forms of staphylococcus

 colony – visible mass of microorganisms originating from a single mother cell

compound microscope – microscope with two magnifying lens

 conclusion – logical judgment or analysis we make from our results

 condenser – lens system in microscope whose function is to focus the light onto the specimen

 conjugation – joining of two bacteria or unicellular organism for the transfer of genetic material by direct cell to cell contact or by bridge like connection called sex pilus

 contamination – the presence of undesirable microorganism that accidentally gets into a culture

 control group – the group in the experiment that does not receive treatment; used to compare how the experimental group do

 controlled variable – the factors in the experiment that we control and keep the same

 crystal violet – primary stain used in Gram staining

 darkfield microscope – creates the effect of a negative image; field of view is dark while cells and other objects are lit up; used to observe live, motile cells

 decolorizer – removes the primary stain from the gram-negative bacteria making it colorless

 dependent variable – the variable being tested, observed, and measured

 differential medium – a medium with diagnostic test built into it that changes color with different species of microbes

 differential staining – procedure that will dye different kinds of bacteria in contrasting color

 double blind – a type of experiment which neither the subjects nor the experimenters know which subjects are in the test and control groups

 electron microscope – a microscope that uses beam of electron rather than beam of light to observe a specimen

 endemic – when a disease prevalence is fairly stable in a location

 epidemic – occurs when a disease is spreading rapidly in a particular population

 ethyl alcohol – the decolorizer used in Gram staining

 fluorescence – the ability of a substance to absorbed UV light and emit back the light as a visible color

 Gram’s iodine – mordant used in Gram staining

 HCG – is a hormone that prevents menstruation from occuring during pregnancy

 Hfr cell – a bacterial cell with conjugative plasmid integrated into its chromosomal DNA

 immunocompromised – means more susceptible to infections

 independent variable – also called the experimental variable; anything that can be changed or manipulated

 lysozyme – an enzyme that dissolves the chemical bond between the NAG and NAM within the backbone of the peptidoglycan molecule in gram-positive bacteria

 malachite green – primary stain in spore staining

 methylene blue – counterstain used in acid fast staining

 microbial hot spots – warm and moist areas where the number of microorganisms is usually the highest

 minimum inhibitory concentration – lowest concentration of drug which prevent visible growth of bacteria

 mordant – a substance which causes the primary stain to become more tightly bound to the cell

 negative stain – a stain which involves staining the background of the slide

 nosocomial infection – infectious disease acquired during hospitalization

 nutrient agar – a general purpose medium that will support growth of many common bacteria

 ocular lens – also called eyepiece; the top lenses of the microscope which you look through

 ocular micrometer – also called the microscopic ruler inscribed into the eyepieces on the microscope

 opsonin – an antibody which binds to foreign microbes making them susceptible to phagocytosis

 pandemic – occurs when a disease is spreading globally or over one continent

 parfocal – means when one lens is focused, the others are also focused

 phase contrast microscope – a microscope that increases the contrast between cells or portions of cells that vary only slightly in density; used to observe unstained bacterial cells

 pour plate – is made by inoculating melted agar with bacteria and then pouring the agar into an empty petri plate to harden, thus the microbes are distributed evenly throughout the agar; creates an evenly distributed lawn of bacteria to be use for phage typing

 pseudopodia – extension of cytoplasm use for movement; also called false feet

pure culture – a medium growing with only one intended species of microorganism

 refraction – the bending of light

 normal flora – microorganisms that live naturally and permanently in various areas of the human body

 resolving power – defined as the closest distance two objects can be where you can still see them as separate objects

 result – refers to the actual data that you collect such as the number of colonies

R-plasmid – is a plasmid in bacteria that contains the antibiotic resistant gene

 Sabouraud agar – medium that are slightly acidic and have extra glucose; also used for fungal growth; used to check fungal spores in the air

 safranin – the counter-stain used in Gram staining

 scanning electron microscope – a microscope that reflects beam of electrons off the exterior of the specimen; produces 3D view of specimen’s surface

 selective medium – a medium that only allows certain species of microbes to grow and inhibits others

 simple microscope – microscope with single magnifying lens

 simple staining – defined as a procedure that stains all cells with the same color

 Snyder test – measures the amount of acid produced by normal flora in a medium containing sugar

 sporadic – occurs when a disease is infrequent and in scattered location

 stage – the platform below the objective lenses of a microscope used to hold the slide

 stage micrometer – term typically referring to a slide that comes with a known scale on its surface

 sterile – a term which means free of bacteria or living things

 streak plate – is performed by spreading an inoculum of bacteria across the surface of an agar plate in such a way as to produce isolated colonies

 Streptococcus mutans – oral bacteria involve with the development dental caries or tooth decay

 super-infection – second infection with microbial agent that is resistant to the treatment used against the first infection

 synthetic medium – medium made from scratch with every single ingredient defined and listed separately

 thermal death point – minimum temperature required to kill a bacteria with a given amount of time

 thermal death time – time required to kill a bacteria at a particular temperature

 transduction – is the process by which foreign DNA is introduced into a cell by a virus or viral vector

 transformation – is a process of horizontal gene transfer by which some bacteria take up foreign genetic material from the environment

 transient flora – microbes that are temporary and can be removed by handwashing

 transport medium – is a medium used to transport microbes from one place to another and limits the overgrowth of microbes

Sources:

Alderson, Gary D. Microbiology Experiments and Lab Techniques 14th Edition. Palomar College. Fountainhead Press. Accessed November 26, 2019. https://fountainheadpress.com/discipline/science/microbiology

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