Microbiology List: FW: Difco Media/ EM Science

Yersinia yersinia at cybernex.net
Wed Nov 29 15:42:03 EST 2000

Jacklyn Hodges writes,

<When Difco and BBL merged, things have not been the same with the media.>

I did know they had merged, but I don't recall when. For awhile, I was 
out of the media prep business, and then when I got back to doing it - 
December 1999 through Sept. 2000 -  I noticed certain things, at least 
with TSB and lactose broth. Namely, that sometimes I would make a batch 
and the stuff wouldn't dissolve; despite being warmed and constantly 
stirred on a magnetic hotplate, it would be cloudy - never mind cloudy, 
*opaque* would be a better word for it. Then even when the media *looked* 
right, most of the time the pH would be off, and I mean *off*! Such as 
6.3 or 6.4 for TSB (which is supposed to be 7.3 +/- 0.2) and 6.0 or 6.1 
for lactose (which is supposed to be 6.9 +/- 0.2). The agar was better, I 
didn't have problems with that, but that broth sure threw me, and I 
couldn't understand it because I'd been making Difco media on and off 
since 1992. This post of yours, Jaclyn, suddenly made me think of my 
fairly recent problems with Difco media; that on top of a serious problem 
getting hold of 1% chapman tellurite solution to use in making VJ agar, 
which happened during the summer of 2000. So when exactly, did this merge 
take place, and is it possible that my own aforementioned problems were 
the result of that?



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