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New Chemical Compound to Control Microbial Contamination: Looking for Volunteers to test it.

Our group has developed a new preservative/biocide process 
called (PPM) which can be used in plant tissue culture labs as a 
substitute for commonly used antibiotics such as Carbenicillin and 
Cefotaxime.  At the same time it controls fungi contamination.
PPM is non-toxic. 


We are looking for volunteers to test PPM.  Our research 
shows that PPM does not impair in vitro seed germination, callus 
proliferation and callus regeneration.  (Our research in other areas has 
just begun and we are looking for collaboration.   For example, we are 
presently testing the effect of PPM on protoplast culture and against 
Agrobacterium tumefaciens.)  

Despite the most stringent use of sterile techniques, the contamination
of  cell and tissue cultures remain a persistent problem that can result
in losses ranging from small number of cultures to the loss of whole 
batches.  PPM can be used as a standard additive in cell culture media 
to substantially prevent microbial contamination.  PPM prevents the 
germination of both bacteria and fungi spores, it is heat stable and 
therefore can be autoclaved with the media. 

PPM is less expensive than antibiotics, making it affordable for wide 
and routine use.   

In addition to being heat stable, PPM significantly simplifies the 
working procedures as follows:

1)    Media can be dispensed outside the laminar flow hood (LFH)
exposed to the ambient air.  The plates should be covered soon after 
agar solidification.  In the event that media dispensing is done by a 
pump, we recommend passing autoclaved hot water through the 
hoses prior to and after media dispensing.

2)   Heat sensitive or heat stable liquid media does not need to be
sterilized by Millipore filters or autoclaved provided that it will be
stored in sterile containers and that the stock solutions are not 
contaminated.  In rich media containing 200 mg/liter or more of amino
acids or proteins, it is recommended to filter the media with the PPM.

3)    Working in the LFH the utensils (forceps or scalpels) do not
 need to be flamed.  They should be periodically dipped in 70% alcohol.
The LFH does not need to be certified and the work can be done as well 
outside the LFH on a clean surface for a period not exceeding one hour.

4)   For Agrobacterium users.  After the co-cultivation with the 
bacteria,  rinse the leaves, cotyledons, hypotyles,  etc. gently with
 tap water.  Then blot them on clean paper towels (or Kimwipes).
 Place the explants in the media which contains the PPM. 

PPM has certain limitations.  It is less effective when exposed to high 
density  of bacteria or  fungi spores found on plant seed coats.  For in 
vitro germination, the seeds should be conventionally surface sterilized 
with bleach.  However, after sterilization, the seeds can be rinsed
 under tap water in a non-sterile strainer and left to dry  in the LFH. 
Protoplast isolation solution should be sterilized  mechanically
through Millipore filters with the PPM.  If the utensil ends have
touched active bacteria, fungi culture  or otherwise suspected of 
being contaminated, they should be sterilized by autoclavation
or by use of an electric heating element.

In cases where the seeds or explants contain endogenous bacteria 
or fungi, a dose of PPM in the 0.5-1.0 ml/liter range will reduce
 the occurrence of contamination.  To obtain better protection,
 the PPM dose can be elevated up to 4 ml/liter  However at those 
higher doses, PPM might impair some biological function.

In conclusion, PPM most definitely will facilitate the work in any plant 
tissue laboratory.  However, conditions in each lab may vary and the 
effectiveness of PPM may vary based on the application.  It is 
advisable that the staff should follow the above guidelines and thus 
find out for themselves how much "freedom" they achieve by using 
PPM and whether or not PPM works for their particular application.

The principal scientist who developed the PPM application 
is Dr. Assaf Guri, former Senior Scientist at DNAP.
PPM is patent pending.  The recommended dose is 0.4 - 1.0 ml/liter.
PPM should be stored between 4 to 8 degrees C.

Safety Issues:  PPM is non-toxic. 
Inhalation and contact with skin and eyes should be avoided.  

PPM is NOT a combination of antibiotics and fungicides.

PPM is inactive at a PH higher than 8.

We are currently looking for labs to participate in further tests 
on plant tissue cultures. 
We will provide PPM at no cost.

For more information on how you can participate in testing 
PPM or for more information on PPM in general, 
please contact Martin Kalin at (Tel):(202) 463-0904 ext. 134. 
(fax): (202) 822-6410 or at marty@mk.ibek.com.
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