microbio practical ex 1-3

How to calculate total magnification

magnification of objective lens x ocular lens (x10)

When to use refractive oil

only on lens that say "oil"

Why do we use refractive oil?

bends light less than air

What are culture mediums

have nutrients that bacteria use for growth

What is broth

liquid medium

Why is agar used?

liquefies at 100C and solidifies at 40C so organisms can be cultivated without fear of liquefying

Agar slants

medium cooled in a slanted position

What are agar slants used for

maintaining pure cultures

What are agar deep tubes used for

study of gaseous requirements

What is dry air sterilization used for?

empty glassware and pipettes

What is moist air sterilization used for?

thermolabile solutions, culture media, syringes,

What is filtration sterilization used for?

removing organisms from thermolabile solutions by passage through filters that retain bacteria

What is ethylene oxide sterilization used for?

Plastic dishes and pipettes, living tissues

What is beta-propiolactone used for?

living tissue

What is subculturing?

transferring microorganisms from one vessel to another for maintenance and study

What is an incubator used for?

maintain optimum temperature during necessary growth period

What is shaking water-bath used for?

uniform transfer of heat to culture vessel and agitation causes aeration resulting in acceleration of growth

What medium can shaking water bath be used for?

broth medium

What type of microbial growth are we looking for in nutrient agar slants?

abundance of growth, pigmentation, optical characteristics, and form

Filiform

continuous threadlike growth with smooth edges

Echinulate

continuous threadlike growth with irregular edges

beaded

nonconfluent to semiconfluent colonies

effuse

thin spreading growth

arborescent

treelike grwoth

rhizoid

rootlike growth

What type of growth are we looking for on nutrient agar plates?

size, pigmentation, form, margin, elevation

circular

unbroken peripheral edge

irregular

indented peripheral edge

entire margin

sharply defined even

lobate margin

marked indentations

undulate margin

wavy indentations

serrate margin

toothlike appearance

filamentous margin

threadlike spreading edge

flat elevation

none

raised elevation

slightly elevated

convex elevation

dome-shaped elevation

umbonate elevation

raised with elevated convex central region

What type of growth are we looking for in nutrient broth cultures?

uniform fine turbidity, flocculent, pellicle, sediment

What does uniform fine turbidity mean?

finely dispersed growth throughout

What does flocculent mean?

flaky aggregates dispersed throughout

what does pellicle mean?

thick padlike growth on surface

What does sediment mean?

concentration of growth at the bottom of broth may be granular, flaky, or flocculant

What type of growth are we looking for with nutrient gelatin?

liquefication patterns

Crateriform liquification

liquefied surface area is saucer shaped

napiform liquification

bulbous shaped liquefaction at surface

infundibuliform liquification

funnel shaped

saccate liquification

elongated, tubular

stratiform liquification

complete liquefication of the upper half of the medium

Why do we streak plate?

rapid form of qualitative isolation method

What is the spread plate technique?

uses a previously diluted mixture of microorganisms to evenly distribute a liquid sample across an agar surface to enable the counting, isolation, and enumeration of viable microorganisms