Friday, 8 May 2015

The Petri Dish

The petri dish, which is a small glass or plastic container used for growing bacteria and other microorganisms, was named after German bacteriologist Julius R. Petri (1852-1921).

Julius R. Petri (1852-1921), a German bacteriologist, invented the first petri dish. He used this shallow, circular glass dish with a loose-fitting cover to culture bacteria and other microorganisms. Then, in the mid 1960’s injection moulding technology sufficiently developed so that petri dishes could be manufactured out of clear polystyrene plastic. These dishes were merely clones of the first, glass petri dish. They were large, heavy and over-constructed. In fact, they were almost twice the weight of most conventional plastic petri dishes manufactured today.

The first plastic dishes were inexpensive as crude oil and its by-products were cheap commodities. However, in the mid-1970's, the Organization of Petroleum Exporting Countries (OPEC) took advantage of shifting market conditions, and the geopolitical and economic disruptions in the Middle East which caused the price of petroleum-based products to skyrocket.

As the supply of polystyrene became restricted, the price started to soar; as a result, the cost of plastic petri dishes also escalated. Customer-pressure then forced petri dish manufacturers to cut back on the excess size and weight of the petri dishes to reduce cost. The 25-gram "DINOSAUR" petri dishes became extinct.

In the mid-80’s, further development in raw material and a better understanding of the injection moulding process, allowed most manufacturers to reduce the weight of their petri dishes to the 15 to 17 grams range. The Petri dish remains largely unchanged and has become an industry standard.
Phoenix Biomedical Products Inc., a Mississauga-based, Canadian company, has manufactured polystyrene petri dishes used for diagnostic testing in medical, industrial and research laboratories since 1980.

Posted by Tim Sandle