Ÿ  Ecologically (what to know the habitat/niche)

Ÿ  Invovled in biochemical cycles

Ÿ  Cause disease in plants, animals, and humans

Ÿ  Microorganisms are also able to destroy what we humans consider to be valuable materials, including wood and textile, that could result in severe economic loss

Ÿ   reduce or prevent the transmission of diseases and infections

Ÿ  prevent contamination and the growth of undesirable microorganisms, in other words we can practice speciesism

Ÿ   prevent or retard the spoilage and the deterioration of materials by microorganisms

How can we control Microorganisms

Ÿ  By removing them from the habitat

Ÿ  Killing them

Ÿ  Inhibiting their metabolic growth

Ÿ  All by physical/chemical agents or by physical/chemical processes

material or individual is contaminated with microorganisms

any agent or process that reduces the microbiota (aka microbial flora or microbial life forms) to a safe public health level. We mean reducing the population of cells, so low that they wont do much or any damage at all. Still viable/dangerous, still living and growing, just population is so low most people will not be bothered by their presence.

Ÿ  We sanitize food handling equipment

Ÿ  We sanitize utensils use in food prep

Ÿ  Food processing plants, devices used to produce food

Ÿ  Dairy equipment

Ÿ  Utensils/dishes used in restaurants

Ÿ  One way to control microorganisms is to kill them. Death to microorganisms is referred to an irreversible loss of the ability to reproduce.

Ÿ  The first ones to die would be the ones that are more genetically weak. Those that are more genetically hearty would survive for longer period of time. They are not all exactly the same so it would take longer to kill. They are not dying at the same rate!!

Ÿ  they control the growth and metabolic activity of microorganisms in a variety of ways

Ÿ  Mesophiles-

Ÿ  doesn’t achieve sterility because it doesn’t kill heat resistant spores…all in the family of Bacillaceae. Genus- Bacillus, Sporolactobacillus, Sporosarcina, Clostridium etc

Ÿ  Boiling water- which is 100^oC  will kill the vegetative form of the pathogenic and non-pathogenic bacterial life forms but not necessarily their spores. You have to boil for 15-30 minutes to kill the vegetative form. 100^oC might not be hot enough to destroy the spores, so you will sanitize but not necessarily sterilize

Ÿ  is not as effective as moist heat in sterilizing, but it can kill the vegetative form of pathogens as well as non-pathogens as well as their spores on objects such as glassware, metals and surgical instruments when you expose those objects to a temperature of at least 160^oC for at least 2 hours. You cant put everything into an autoclave so you can use dry heat like a hot air oven.

Ÿ  “drying out” of cells. It is a microbial static agent, it doesn’t kill. Dessication chambers remove all the water from the cells. What will happen when you send the cells into stasis by drying out the cells there is a slight decline in viability of cells, growth and metabolic activity.

Ÿ  high concentration to low concentration of whatever the substance is to establish equilibrium.

Ÿ  movement of water in response to a diffusion gradient, the concentration of solutes

Water always moves to dilute the solute

Ÿ  the solute concentration in the external environment is greater.  Therefore water will leave the internal cell (to reach equilibrium) and cell loses water. But bacteria also have a cell wall, rigid structure that gives  strength and resilience to the cell and helps maintain structure and form. If this cell is losing water, then plasmolysis will occur, the Cell isn’t going to get any smaller but the cytoplasm is. The distance between the cell wall and cell membrane is great, so you have periplasmic space. Cell goes into stasis and there is going to be a cessation of growth and metabolic activity.

Ÿ  Hypotonic- the solute concentration on the outside is less than it is in the inside. Water will move into the cell which will increase osmotic pressure,  and when the osmotic pressure goes beyond what the cell wall can withstand it will undergo lysis and die. All because of change in osmotic pressure

Ÿ  One type that is used frequently is UV, ultraviolet light adversely affect microorganisms because it can be absorbed by the DNA and cause sufficient damage to the DNA, and interfere with DNA replication. Inhibits growth and other metabolic activities

Ÿ  UV- cause the production of organic peroxides that are toxic to microorganisms, which would also adversely affect the growth and activity of microorganisms

Ÿ  Can actually kill microorganisms by denaturing the proteins, causing a cavitation of cells and raising the temperature to lethal levels

phenols are highly fungicidal

Ÿ  Mode of action-

Ÿ  can disrupt the cell and cause precipitation of the cellular proteins,

Ÿ  can also inactivate enzymes,

Ÿ  destroy the selectiveness of the cell membrane causing it to leak out its consequents.

Ÿ  Problem with phenols- they don’t discriminate against which proteins they destroy,  so they destroy microbial proteins as the proteins of the host as well. Quite toxic to use because they don’t discriminate.

Ÿ  first person to use phenolitic compounds, used carbolic acid (is a phenolitic compound) to develop aseptic surgical techniques

Ÿ  alkyl derivative, CH3, can be used as either a disinfectant or more than that as a preservative. Used to treat wood, especially utility poles. Also a carcinogen