I. REVIEW OF THE GENERAL PROCEDURE FOR THE ENRICHMENT, ISOLATION AND IDENTIFICATION OF BACTERIA as outlined in the lab manual:
|ENRICHMENT AND ISOLATION||PURE CULTURE WORK|
|CHARACTERIZATION & IDENTIFICATION|
|"Consider inoculum: what organisms may or may not be present.
"May pre-treat inoculum, e.g., by heat-shocking.
|"Usually is selective.
"May be skipped altogether.
|"Usually selective or selective-differential – but not always!!|
|Throughout procedure, appropriate media and incubation conditions must be considered.|
II. A "WORKSHEET" TO HELP US ORGANIZE AND SUMMARIZE THE SPECIFIC FACTORS that allow isolation of the various types of microorganisms in these experiments:
Purple "non-sulfur" photosynthetic bacteria
|Special properties of desired organism that can be exploited to help us "sort it out" from others.|
|Likely source material (habitat of organism or where the organism is a significant contaminant).||
|Treat sample to enhance isolation?|
|Need to use enrichment?|
|Factors to consider for the enrichment & plating media:*
"Selective by restriction of nutrients or addition of selective agents?
"Special sources of C, N, energy?
(Why is 2nd plating medium an all-purpose medium?)
|Special incubation conditions?||**||
|Detectable features of the desired organism that help us in picking and identifying it.||**|
|Any special, additional tests on the isolates? (That is, tests not essential to identification to the genus level.)||
* For the desired type of organism, the medium/media must include the required elements (including trace elements) and whatever growth factors are needed. Note that these organisms are all heterotrophs and organotrophs. (A review of Appendix D in the manual is useful.)
** See question 11B in the compilation of old quiz questions. How would we want to grow the purple non-sulfur photosynthetic bacteria to maximize their detection and minimize growth of other organisms – as phototrophs or as chemotrophs?
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|Page last modified on 10/22/10 at 8:00 PM, CDT.
John Lindquist, Department of Bacteriology,
University of Wisconsin – Madison