Sterilize media and containers used for growth of bacteria
Keep cultures, media, and containers covered as much as possible
Ex: always keeps lids on petri plates when not in use
Sterilize transfer materials such as inoculating loops, sticks, pipettes, and forceps before touching or handling cultures
Autoclaved sticks or sterile disposable loops for transferring bacteria
Do not contaminate yourself, your lab manual, or your workspace
Be careful to avoid spilling cultures, if a spill does occur notify your TA immediately and follow his/her instructions on how to disinfect the area
Proper attire (lab coat, gloves, safety glasses)
color,size, texture are also used as characteristics
1. Shape may be described as round, irregular, or punctiform (tiny, pinpoint).
2. The margin may be entire (smooth, with no irregular- ities), undulate (wavy), lobate (lobed), filamentous (unbranched strands), or rhizoid (branched like roots).
3. The surface may be smooth, rough, or wrinkled. 4. The texture may be moist, mucoid (sticky), butyrous
(buttery), dry, shiny, or dull. 5. Elevations include flat, raised, convex, pulvinate
(very convex), and umbonate (raised in the center).
6. Other useful features include color and optical prop- erties such as opaque (you can't see through it) and translucent (light passes through).
Its false negative and poor sensitivity
The PR (phenol red) broth is deferential media, which is commonly used to distinguish gram negative enteric bacteria, namely E.coli, E. faecalis, etc. The organisms which use carbohydrate turn the media into yellow and produce gas bubbles; whreas organism's which use peptone turn the media into fascia color.
For example, E. faecalis produces only acid, but no gas hence, it is represented as A/- and E.coli produce both gas and acid, so it is represented with A/G. The Micrococcus luteus provides no reaction and it is represented as -/-.
Here, the Micrococcus luteus grow in the media, but do not produce compounds, which change the color of phenol red-media. This type of microbes have poor sensitivity, because they do not produce either alkaline or acidic compounds. Hence, they exhibit a false negative result.
5th EditionCharlotte W. Pratt, Donald Voet, Judith G. Voet 11th EditionLisa A. Urry, Michael L. Cain, Peter V Minorsky, Steven A. Wasserman 1st EditionJanet L. Hopson, Postlethwait 9th EditionCain, Jackson, Minorsky, Reece, Urry, Wasserman