In article <314943AA.5275 at teclink.net>, rmcgehee at teclink.net says...
>>I am looking for information on the aggregation of A. tumefaciens or
>other similar bacteria. I have run into a problem when the A.
>tumefaciens aggregates in certain media. Can anyone give me a reason
>why this occurs?
>>Also, what is the chemical tryptone responsible for in LB growth medium.
> I have found that my bacteria grows well without that substance present
>in its medium.
I'm not sure if this is the reason for what you observe, but many strains
of A. tumefaciens produce extracellular heteropolysaccharides. These
sticky, slimy gums may help the cells stick to each other or to surfaces,
especially in the presence of certain divalent cations. Nitrogen
limitation often causes an increase in extracellular polysaccharide
production in mirobes.
Regarding the media question, I don't know. Perhaps the medium was
formulated for a variety of bacteria, some of which require more than