counting bacteria
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Counting Bacteria. Serial Dilutions. Because of their very ______ ______, counting the number of bacteria in a sample can be _________ Although _______ _______ are possible with a ______________, they require a lot of time and ___________. Why Count the Number of Bacteria??. - PowerPoint PPT PresentationTRANSCRIPT
Counting BacteriaCounting Bacteria
Serial DilutionsSerial Dilutions
Because of their very ______ ______, counting the number of bacteria in a sample can be _________
Although _______ _______ are possible with a ______________, they require a lot of time and ___________
Why Count the Number of Why Count the Number of Bacteria??Bacteria??
• ________ _____________:________ _____________:– How effective drugs are in killing How effective drugs are in killing
microorganisms?microorganisms?
• ___________________:___________________:– How many MO in CSF, blood, urineHow many MO in CSF, blood, urine
• ___________ ____________: - Contaminants in food, milk, water
Total Cell CountTotal Cell Count
• The most common method of The most common method of _______________ the total microbial _______________ the total microbial cells (______ ___ _________) cells (______ ___ _________)
• The ______ ___________ of cell The ______ ___________ of cell suspension in a __________ suspension in a __________ _____________ of known _______ _____________ of known _______ using a ________________ using a ________________
Total Cell Count – Both Total Cell Count – Both living and dead MOliving and dead MO
• Disadvantage: Disadvantage: ________________________________________________________________________________________________________________________________________________________________________________________________________________________
• Advantage: Advantage: __________________________________________________________________________________________________________________________________________________________________________________________________________________________
Total Cell Count – Both Total Cell Count – Both living and dead MOliving and dead MO
• Neubauer ___________ ___________Neubauer ___________ ___________
• Special _______ ____ _______ _______, Special _______ ____ _______ _______, microscopic marks on slide, known microscopic marks on slide, known __________________
•
Counting ChamberCounting Chamber
•Use special ______________ ____ Use special ______________ ____ __________________________________________
•Count specific areas of Count specific areas of __________________, multiply by __________________, multiply by __________________ ________________________________ ______________
Counting ChamberCounting Chamber
InstrumentationInstrumentation
• * * _____________________ (Light Meter)_____________________ (Light Meter)• Each single ____ stops some ______ from Each single ____ stops some ______ from
________________________________________________________________________________________• One side _____ ________, then test tube One side _____ ________, then test tube
containing MO, other side _______ containing MO, other side _______ ________________________________
• Needle reading from scale, then Needle reading from scale, then ________________ _____________ telling # of ________________ _____________ telling # of ____________________________________________________________________________________
Coulter CounterCoulter Counter
• Another method for _____________ Another method for _____________ __________________________
• An electronic instrument An electronic instrument “_____________ _________”“_____________ _________”
• Has a tiny tube (_____ ______ Has a tiny tube (_____ ______ _____________) that lets through _____________) that lets through only one cell at a timeonly one cell at a time
Viable Cell Count –Viable Cell Count – Living Cells OnlyLiving Cells Only
An easier method is to ______ ________ _____ __ _____ ______ (nutrient agar plate) and count the number of ________ _____ ______
If the bacteria are ______ ____ ______, each bacterial cell in the original sample should produce a _______ _______
Viable Count – Living Cells Viable Count – Living Cells onlyonly
Serial DilutionsSerial Dilutions
Bacterial samples must be _______ considerably to obtain ___________ ___________
To determine the ________ ___ ______ in a bacterial culture carry out _______ ____________
Serial DilutionsSerial Dilutions
Bacterial cell numbers are usually _______ _____ _____________________________
Plating out this sample, undiluted, would lead to the creation of a ___________________
Bacterial Lawn - many individual bacteria colonies that are ______________________ ____________________________________
Serial DilutionsSerial Dilutions
Bacterial cell numbers _____ __ __ _______
This is done by ______ ________ the amount of bacteria you have in your sample
A ______ _________ of bacteria sample is mixed with a _____ _______ (sterile broth or water), and then _______ ___________ are made
Serial DilutionsSerial Dilutions
A small amount of _____ ___ ____ _______ _________ ________ is then spread onto an ______ ________
The numbers of bacterial colonies that ______________________________
Serial DilutionsSerial Dilutions
Work ___________ using multiplication with the “___________ ____________”
________ ________ - the ______ ___ ______ that you have diluted the bacteria sample with the diluent solution
Make a determination of the numbers of bacteria in ______ ________ _________.
Serial DilutionSerial Dilution
Serial DilutionsSerial Dilutions
*Make ________ _____________*Make ________ _____________
*Spread a small amount from each tube *Spread a small amount from each tube onto _______ _______onto _______ _______
*Culture bacteria for a ________ __ *Culture bacteria for a ________ __ __________________
*Count colonies*Count colonies
________________________________________________________________
Membrane FiltrationMembrane Filtration
• ________ __________ can also be ________ __________ can also be used to determine the ________ used to determine the ________ ______________________________
• In this method ______ _____ In this method ______ _____ ___________ onto membrane filter ___________ onto membrane filter which is then placed over a which is then placed over a ________ ______ __________.________ ______ __________.
Membrane FiltrationMembrane Filtration
• The methodology is similar to The methodology is similar to conventional _______ ________ conventional _______ ________ _______________. _______________.
• Membranes have a printed Membranes have a printed millimeter ________ and colonies millimeter ________ and colonies can be counted under a _________ can be counted under a _________ _________________._________________.
Factors Factors essentialessential for __________ ________ for __________ ________
--proper ________________--proper ________________
--proper ___________________ (space, temperature)--proper ___________________ (space, temperature)
--No inhibiting factors--No inhibiting factors
Factors that _____________________ Factors that _____________________ ____________________________________________________________________________________
--lack of _____________--lack of _____________
--lack of __________ __________________--lack of __________ __________________
--presence of an ___________ __________--presence of an ___________ __________