Morphology in submerged culture

Lejeune Robert rlejeune at
Wed Mar 1 12:37:01 EST 1995

In article <3h5huh$gqj at>
mspear at (mspear) writes:

> James E Gannon (bact at wrote:
> > I have just begun working with submerged (liquid grown) cultures of 
> > Rhizopus.  Form the same spore prep, some times I get discrete bead like 
> > morphology and others I get an "uncontrolled" filamentous mass?  What 
> > specifically controls morphological type under submerged conditions?  
> > <bact at
> In some species the speed of agitation or ammount of bubbling can have
> an effect like you discribe.

A lot of different factors can influence the formation of pellets (the
so called *discrete beads*). In your case, if you use exactle the same
spores, same inoculation procedure, same sterilization procedure, same
everything else, then you shouldn't get any differences in morphology.
When you inoculate with spores, the pH during the germination is a good
candidate as source of your problem. e.g. A. oryzae spores agglomerate
at high pH (>5-6) and one gets pellets. If the pH is lowered, just for
the duration of the germination, then you get free mycelium.

Robert Lejeune

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