MCB3020 Week 10: Microbial Growth Control

Coliform

Group of microbes that include Enterobacter, E. coli and Klebsiella pneumoniae, widely used indicator for contamination in water

Filtration and Chlorination

The two most important developments in water quality history that happened in 1906 and 1913.

Sedimentation

Water purification step where particles are removed from the water.

Coagulation and flocculation

Water purification step where additional aggregates are formed that settle out

Filtration

Water purification step where parasites are removed, charcoal is added to remove taste, odor, and chemicals

Disinfection

Water purification step where chlorine or chloramines are used to maintain residual

Chlorination

Historically, this is the most common drinking water disinfectant that is usually in the form of bleach or gas. Kills bacterial and viral pathogens, but is ineffective against Cryptosporidium and Giardia

Chloramines

Widely used disinfectant that overtook chlorine, more stable and has less of an effect on taste

UV

Disinfection method that does not leave residual but is effective against Cryptosporidium and Giardia

Ozone

Disinfection method that doesn't leave residual, works as an oxidizer where the gas is generated on site

Wastewater treatment

The goal of ____ is to reduce nutrients or biochemical oxygen demand

Primary treatment

This method of wastewater treatments uses physical separation methods to separate solid and particulate organic and inorganic materials from the wastewater, many pathogens and many nutrients are still present

Secondary treatment

This method of wastewater treatment aims to break down solid and dissolved organic matter and reduce the organic nutrient load using biological processes

Tertiary treatment

This method of wastewater treatment involves the purification processes for drinking water and further reduces the level of inorganic nutrients down, very expensive to execute and is not widely adopted

Sterilization

The killing or removal of all viable organisms within a growth medium

Inhibition

Heat sterilization that effectively limits microbial growth

Decontamination

Heat sterilization that involves the treatment of an object to make it safe to handle

Disinfection

Heat sterilization that directly targets the removal of all pathogens, not necessarily all microbes or endospores

Heat sterilization

The most widely used method of controlling microbial growth, high temperatures denature macromolecules

Decimal reduction time

Amount of time required to reduce viability tenfold

Pasteurization

Process of using precisely controlled heat to reduce the microbial load in heat-sensitive liquids where they are heated and then cooled rapidly, doesn't kill all organisms

Autoclave

Sealed heating device that uses steam under pressure, the pressure doesn't kill but the high temperature does

Moisture content

Susceptibility to food spoilage is based in large part on ___

Food preservation

Methods of this include using the cold, pickling and acidity, drying and dehydration, heating, chemical preservation, or fermentation

Bacteriostatic

Stops the growth of bacteria, doesn't kill

Bacteriocidal

Kills the bacterial cells, body of the bacteria is still there

Bacteriolytic

Kills the bacterial cells, bodies of the bacteria aren't there

Disk diffusion assay

Test to see how resistant a bacteria is to a drug, result indicated by the zone of inhibition which is the diameter depending on the concentration, solubility, diffusion into cell, and effectiveness of agent

Sanitizer

Antimicrobial agent that reduces microbial numbers by using detergents like Lysol or ethanol

Antiseptic

Non-toxic antimicrobial agent that can be used on tissue, includes things like ethanol, triclosan, and listerine, often practiced by handwashing and oral care

Salvarsan

One of the first effective antimicrobial drugs, uses a dye containing arsenic which was used against syphilis

Selective toxicity

The ability to inhabit or kill a pathogen without harming the host or with limited side effects

Growth factor analogs

Structurally similar to growth factors, but they don't function in the cell

Sulfa drugs

Inhibits folic acid synthesis in nucleotides

Nucleic acid base analogs

Used against viral and fungal infections, exact same as a growth factor with the addition of bromine or fluorine

Quinolones/fluoroquinolones

Interferes with DNA gyrase which prevents DNA division, effective against both gram + and gram - bacteria, Ciprofloxacin is an example

Antibiotics

Naturally produced antimicrobial agents that commonly target ribosomes, cell walls, DNA replication or the membrane

Mode of action

Antimicrobial agents will target cell wall synthesis, DNA gyrase, DNA-directed RNA polymerase, RNA elongation, protein synthesis (50S or 30S inhibitors), protein synthesis (tRNA), lipid biosynthesis, cytoplasmic membrane structure and function, or folic acid metabolism

Cell wall synthesis

This mode of action is targeted by vancomycin, penicillin, and cephalosporins

DNA gyrase

This mode of action is targeted by ciprofloxacin

DNA-directed RNA polymerase

This mode of action is targeted by streptovaricins

RNA elongation

This mode of action is targeted by actinomycin

Protein synthesis

This mode of action is targeted by erythromycin, tetracyclines, streptomycin, gentamicin, kanamycin, and mupirocin

Lipid biosynthesis

This mode of action is targeted by platensimycin

Cytoplasmic membrane

This mode of action is targeted by polymyxins

Folic acid metabolism

This mode of action is targeted by sulfonamides

B-lactam

Most important antibiotic group of all time that includes penicillins and it's derivatives

Penicillin

Drug apart of the B-lactam antibiotic group that derived from a fungus, primarily effective against gram-positive bacteria, targets cell wall synthesis, low toxicity

Aminoglycosides

Antibiotic group including streptomycin and kanamycin, inhibits protein synthesis, not commonly used as it's neurotoxic and is only used as a last resort

Macrolides

Antibiotic group containing lactone rings bound to sugars, includes erythromycin, most heavily used antibiotics particularly for respiratory infections

Tetracyclines

Antibiotic group that inhibits protein synthesis

Platensimycin

Antibiotic group considered to be a newer structural class, inhibits fatty acid synthesis, effective against MRSA

Antimicrobial drug resistance

Acquired ability of a microbe to resist the effects of a chemotherapeutic agent, reasons including the organism lacks the structure that the antibiotic inhibits, impermeable to antibiotic, inactivates the antibiotic, modifies the target of the antibiotic, developed a resistant biochemical pathway, or is able to pump out the antibiotic (efflux)

Biochemical oxygen demand

Measure of the amount of oxygen that microorganisms need to decompose organic matter in a water sample, high amount of this means there's a great amount of organic pollution in the water