Why do we invert petri dishes

Inversion also prevents contamination of other bacteria in the samples, in case Petri dishes were not thoroughly cleaned or other microbes happened to contaminate samples.

Petri dishes can be stored up to three months in cold storage before use in an incubator. Inverted Petri dishes also minimize the evaporation of water used to grow the samples sealed in the containers. Dishes are sealed with tape so that lids do not fall off when the inversion occurs, and the tape can be written on for labeling purposes.

The apparatus can also be stacked for easy storage in an incubator. Petri dishes were invented in by German physician Julius Petri. What is SQF Certification? What is IFS Certification? Javascript Disabled Detected You currently have javascript disabled. Why petri dishes should be placed upside down in the incubator? Started by hygienic , Feb 19 PM. You cannot start a new topic Please log in to reply. Posted 19 February - PM Hi every one : debate; Technically and practically , in Food Microbiological testing , especially samples incubation step , the petri dishes should be placed inside the incubator in upside dowen , so do you know , why it shoul incubate in this situation , not normal?

Thanked by 1 Member:. David J. Join our LinkedIn Group! United States. Posted 19 February - PM Yes hongyun. Posted 20 February - AM i agreed with dave that petri plates are placed upside down in ordor to avoid the absorption of moisture resulted due to condensation if it is not done colonies may not be distinct and clear. Reply to quoted posts Clear. Contact Us. If you have the plates upside down and there is condensation in the lid, there must be some heat source above that is driving water out of the agar and into the lid.

When the plates are incubated in the normal position , water evaporation from media occurs. These vapors condense on the lid of the Petri dish and drops fall on the colonies developed on the media surface. This causes colony mix-up with each other and spread throughout the plate surface. How long should agar plates be incubated? Why do we incubate plates at 37 degrees? Optimal Growth Conditions Thus, a microbiologist will incubate a particular strain of bacteria at its optimal temperature so that he can study it when it is healthy.

Organisms that grow best at human body temperature, which is approximately 37 degrees Celsius What are two reasons why it is important to invert the petri plates during incubation? Inverting the petri dish makes it more difficult for contaminants to enter the growing medium. How can you identify a pure culture? Pure cultures are the presence of single, isolated colonies of the same type.

You can confirm purity by preparing a smear and looking under the microscope. In regard to bacterial growth on solid media, define the term "colony". Why are agar plates incubated at 37 degrees? Generally pathogenic microorganisms are incubated at 37 degrees, as 37 is normal body temperature of humans so the pathogens grow greatly at this temperature. What are pure cultures?