tempest on a toothpick

[Tom Cooper]

Paul Hengen's recent TIBS column (February 1997) has prompted me to 
clarify points regarding our observation that wooden toothpicks 
inhibit PCR reactions using Taq or Vent polymerase (BioTechniques 
18, 225 1995). We previously used wooden toothpicks to transfer 
bacterial colonies directly to PCR reactions for screening. It 
wasn't until we tried to reduce enzyme costs by lowing the amount of 
Taq per reaction that we noticed inhibition of the reaction by 
wooden toothpicks. The point of the paper is that by using plastic 
rather than wood, the amount of enzyme can be significantly reduced 
resulting in a significant savings for labs that do a lot of 
screening. We were not saying that all PCR reactions are inhibited 
by wooden toothpicks, only those using relatively small amounts of 
enzyme. My guess is that those who have no problems using wooden 
toothpicks could use less enzyme if they switched to plastic. This 
is a great technique whether you use wooden toothpicks with more 
enzyme or plastic toothpicks with less enzyme.

We have found a supplier of plastic toothpicks in the US (these are 
toothpicks, not the swords):  Soodhalter Plastics, Inc.:  Los 
Angeles, CA  90021  (213) 747-0231. They sell toothpicks for $22.50 
per 5,000 (however, $40.00 is the minimum order so you have to buy 
10,000. (Don't drop the box and don't autoclave plastic toothpicks). 
Please feel free to email me with questions.