soil bacteria

Kevin P. O'Connell oconne18 at pilot.msu.edu
Wed Oct 12 23:28:00 EST 1994


In Article <CxIxto.5C2 at rug.nl> "Lenja V. Bystrykh" says:
> In article <mpowell-111094084233 at levinmac3.nichd.nih.gov> mpowell at lmgvax.nichd.nih.gov (Mike Powell) writes:
> >In article <1704BE896S85.MIKEFER at UNIVSCVM.CSD.SCAROLINA.EDU>,
> >MIKEFER at UNIVSCVM.CSD.SCAROLINA.EDU wrote:
> >
> >>  
> >> As a portion of a micro lab, I have had my students isolate bacteria from
> >> soil. We are now in the process of identifying the isolates. Pseudomonas
> >> and Bacillus spp. are predominant, but we have isolated a small Gram - cocci
> >> (tiny).
  
This is slightly off the topic, but we had some fun isolating bacteria in the
lab this week.  An undergrad who I supervise made a liter of tryptone-
yeast extract agar (for Rhizobium genetics) and left it in our 60C drying
oven to remain liquid until she could pour it.  She left for the day and
forgot the flasks.  On returning the next day, she found both flasks turbid!
  
I had her streak out the agar on TY plates and incubate at 30 and 60C.  
Colonies appeared at 60 but not 30C.  Under the phase scope, we saw large
rods with phase-bright endospores.  A quick cruise thru Bergey's gave a 
few possibilities; I suspect Bacillus stearothermophilus (source of BstEII).
I relate this to add to what another poster mentioned about looking for
soil bacteria at temps below 37C; having the students lookat warmer temps
as well would also be productive, and lead to some nice discussion on 
bacterial diversity and microbial ecology.  We evidently have a nice niche in 
our drying oven!  (BTW, yes the flasks had foil on them, but a fan 
circulates air in the oven and I suspect the wee beasts were wafted in...
either that, or we'd better have a real serious look at our autoclave!)
Kevin O'C.
NSF Center for Microbial Ecology
Michigan State Univeristy 



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