[USCC] Compost microbiology

[Allison L H Jack]

>Jim Crockett wrote:


>The world of composting can be very humbling, at least to me.  I just spent
>20 minutes looking at some samples of fungal hyphae, and what I thought were
>fungal fruiting spores... and then I saw some of them moving... so, what are
>they? The moving critters appear to be about 0.5µm in diameter. Maybe others
>following list know much more than I do.  When I look at some of our
>microbes, whether at 40X, 200X or 400X DIC (Differential Interference
>Contrast), I believe we have a lot to learn about composting.

Jim what you might be seeing are zoospores.

Oomycetes used to be classified as fungi since their hyphae look very 
similar. Scientists have now reclassified the oomycetes so that they are 
closer related to red algae and marine diatoms. They are a fascinating and 
entirely unique group of organisms, containing many plant pathogens of 
note: Pythium damping off and Phytophthora spp. Many oomycetes produce 
motile infective propagules called zoospores. You might have seen them 
bursting out of a round zoosporangium and swimming off in all directions. 
They usually swim in a corkscrew pattern, not a straight line. They have 
two flagella and are very sensitive to vibration. If you vortex the 
solution they will usually encyst and begin germinating right before your eyes.

Dr. Deacon at the University of Edinburgh maintains an excellent site on 
zoospores if you're curious to learn more.
http://helios.bto.ed.ac.uk/bto/microbes/zoospore.htm

I work with vermicompost and am trying to understand how it protects plants 
from Pythium damping off. The material I'm working with right now is very 
effective at suppressing this pathogen. There are many scientists at 
universities all over the world dedicating their careers towards studying 
compost microbiology. It's a fascinating and complex field, and yes, very 
humbling because it is so complex :-).

-Allison

**************************************************************************************
Allison L H Jack
Graduate Student
Department of Plant Pathology
Cornell University
335 Plant Science
Ithaca, NY 14850
607.273.5762
************************************************************************************* 


"...Advancing a productive and sustainable agriculture"
from the College of Agriculture and Life Sciences mission statement