Aldehydesfunction in microbial growth by denaturing proteins and inactivat-
ing nucleic acids. Two types are glutaraldehyde that is a liquid and formaldehyde
that is a gas.GLUTARALDEHYDE AND FORMALDEHYDE
Glutaraldehyde is used in a two percent solution to kill bacteria, fungi, and
viruses on medical and dental equipment. Healthcare workers and morticians
dissolve gaseous formaldehyde in water, making a 37 percent solution of for-
malin. Formalin is used in disinfecting dialysis machines, surgical equipment,
and embalming bodies after death.
Gaseous agents,such as ethylene oxide, propylene oxide, and beta-propiolactone,
are used on equipment that cannot be sterilized easily with heat, chemicals, or
radiation. Certain items, like pillows, mattresses, dried or powered food, plastic-
ware, sutures, and heart-lung machines, are placed in a closed chamber, then filled
with these gases. Gaseous agents denature proteins.SURFAC TANTS
Surfactantsare chemicals that act on surfaces by decreasing the tension of water
and disrupting cell membranes. Examples are household soaps and detergents.Quiz
- What microorganisms can use oxygen when it is present and continue to
grow without it?
(a) Obligate aerobes
(b) Facultative anaerobes
(c) Obligate anaerobes
(d) Free radicals - What microorganisms require oxygen?
(a) Obligate aerobes
(b) Facultative anaerobes
(^116) CHAPTER 6 Microbial Growth and Controlling It