Microbes can be damaged or killed by elements of their physical environment such as temperature, radiation, or exposure to chemicals; these effects can be exploited in efforts to control pathogens, often for the purpose of food safety.
[1] Active microbes, such as Corynebacterium aquaticum, Pseudomonas putida, Comamonas acidovorans, Gluconobacter cerinus, Micrococcus diversus and Rhodococcus rhodochrous, have been retrieved from spent nuclear fuel storage pools at the Idaho National Engineering and Environmental Laboratory (INEEL).
The spores of gram-positive bacteria contain storage proteins that bind tightly to DNA, possibly acting as a protective barrier to radiation damage.
A case study of an irradiated Escherichia coli population found a growing number of bacteriophage-resistant mutants induced by the light.
PEF treatment is an adequate process for inactivation of microbes in acids and other thermosensitive media, but holds inherent resistance dangers because of incomplete destruction.
[12] The frequencies used in diagnostic ultrasound are typically between 2 and 18 MHz, and uncertainty remains about the extent of cellular damage or long-term effects of fetal scans.
Freezing temperatures curb the spoiling effect of microorganisms in food, but can also preserve some pathogens unharmed for long periods of time.
[13] Syrup, honey, brine, alcohol and concentrated sugar or salt solutions display an antibacterial action due to osmotic pressure.
[18] Autoclaves generate steam at higher than boiling point and are used to sterilise laboratory glassware, surgical instruments, and, in a growing industry, medical waste.
A danger inherent in using high temperatures to destroy microbes, is their incomplete destruction through inadequate procedures with a consequent risk of producing pathogens resistant to heat.
Anurag Sharma, a geochemist, James Scott, a microbiologist, and others at the Carnegie Institution of Washington performed an experiment with Diamond Anvil Cell and utilized "direct observations" on microbial activity to over 1.0 Gigapascal pressures.
If the cells survived the squeezing and were capable of carrying out life processes, specifically breaking down formate, the dye would turn clear.
According to Art Yayanos, an oceanographer at the Scripps Institute of Oceanography in La Jolla, California, an organism should only be considered living if it can reproduce.
There is practically no debate whether microbial life can survive pressures up to 600 MPa, which has been shown over the last decade or so to be valid through a number of scattered publications.
[20] What is significant in this approach of Sharma et al. 2002 work is the elegantly straightforward ability to monitor systems at extreme conditions that have since remained technically inaccessible.