Hand print on a large TSA plate from my 8 1/2 year old son after playing outside.

Hand print

submitted by
Sturm on June 04, 2015
Article Copyright:
Attribution + Noncommercial + NoDerivs
Author(s):
Tasha Sturm, Cabrillo College
Unknown organism seen on a TSA plate used to do a handprint. Organism was seen on the outside of the imprint so not sure if it came from the hand or was contaminant. Colony was circular, tan/white, rhizoid growth in the center with a smooth margin and mucoid throughout.
Unknown organism seen on a TSA plate used to do a handprint. Organism was seen on the outside of the imprint so not sure if it came from the hand or was contaminant. Colony was circular, tan/white, rhizoid growth in the center with a smooth margin and mucoid throughout.

Comments

Tasha makes this comment Sat Jun 6 02:01:54 2015

Thanks! I used a large Kirby Bauer plates (15 x 150 mm) with TSA. I pour the plates myself and get them from either Hardy or Fisher.

Tasha makes this comment Sat Jun 6 03:52:31 2015

Look at this site: https://catalog.hardydiagnostics.com/cp_prod/Hardy_Part_Description.aspx these are the sterile plates I used. Tryptic Soy Agar (TSA) can be purchased through a number of companies (Fisher Scientific, Hardy Diagnostics, Neogen). Most sell it in the powdered form, add water, autoclave, cool to about 55 degrees then pour into the plate, cover with the lid then let solidify. Once the plates are cool then place the hand on the plate making sure to gently pressing the fingers/palm to make contact with the agar. Cover the plate with the lid and place in a 37 degree C incubator for 24-48 hrs......incubate agar side up. This will grow the normal flora on the hand like Staph., Micrococcus, etc. Take the plate out and let it incubate/set out with the lid on at room temp (22 degrees C) for several days (3+ days). Normal flora will continue to grow (slowly) and yeast/fungi will start to grow....usually colored colonies (red/pink/yellow). It will also help bacteria like Serratia turn red. Once grown the plate should be treated as a Biohaz and disposed of properly. The plate should not be opened if mold/fungi is present without proper respiratory protection. Hope this helps.

Tasha makes this comment Sun Jun 7 04:35:45 2015

I am saving the plate to show the micro students in 1 1/2 weeks. I did take a few close up photo's of some colonies which were also posted: http://www.microbeworld.org/component/jlibrary/?view=article&id=13870 and http://www.microbeworld.org/component/jlibrary/?view=article&id=13869 The big blob in the lower right is the image "unknown from handprint #2" and is most likely a Bacillus sp which is commonly found in dirt.....saw a fair # of what looks like Bacillus. The other image is either a yeast or Bacillus as well. We do this at the beginning of the semester and this is pretty common. The white being Staph and the colored colonies probably yeast. The colored colonies tend to show up after the plates are refrigerated or left at room temp for a few days. Once summer school starts I might do some G stains if I have time but micro is not the only class I tech and it looks to be a fairly busy summer.

Sarah Mahan makes this comment Tue Jun 9 15:15:36 2015

bharat, the large colony on the lower right part of the plate looks like Streptomyces. They're commonly found in soil, and form large, irregular colonies with fungal-like mycelial growth patterns. They're also well-known for producing an array of antibiotics (hence the lack of other growth near that colony). I used to take LB plates home for my daughter and she'd find all sorts of things (leaves, rocks, twigs) and make prints with them. TSA gives a much more colorful display! Very cool!

Tasha makes this comment Tue Jun 9 15:17:06 2015

The large blob on the lower right is more than likely a Bacillus, see cloes up image: http://www.microbeworld.org/component/jlibrary/?view=article&id=13869 Looks like it out grew everything around it and that is also an area on the plate( the palm) that may not have gotten the contact because of the conture of the hand.

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2015-06-09
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