How does the ethylene oxide penetrate the Coats and the Cortex of an endospore to kill the bacterial spore

suneel joshi

Dear

Ethylene oxide (EO) sterilization is dependent upon four parameters: EO concentration, temperature, moisture, and exposure time. Each parameter affects the other dependent parameters.
Endospores are surrounded by tick protein and peptidoglycan walls and the interior of spore is largely dehydrated, has much CA2+-dipicolinic acid. Moisture is needed to hydrate the endospores, making them susceptible to be destructed by EO. To be effective EO must break active bonds formed by Amino acids in microorganism (alkylation). The gas penetration into the cell structure is only possible with the help of the hydrating humidity. Besides, humidity also helps transferring EO through packaging material.
For the effectiveness of EO sterilization a minimum of 35% relative humidity is required.
Although sufficient moisture is needed for sterilization, visible drops of water are adverse. Water drops protect microorganism from EO and can inhibit sterilization. Also, excessive moisture increases the possibility of the formation of ethylene glycol, which is not removed by aeration.

Kind regards
Josy Holdener