Nutrition 2

• • Majority of microorganisms grow at a pH
• between 6 and 8

•Obligate acidophiles – grow at extreme acid pH

•Alkalinophiles – grow at extreme alkaline pH

•Dissolved solutes (salts, sugar) create osmotic pressure

•Most microbes exist under hypotonic or isotonic conditions

•Halophiles – require a high concentration of salt

•Osmotolerant – do not require high concentration of solute but can tolerate it when it occurs

1. No

2. Yes

1. Superoxide dismutase (SOD)

2. Catalase

3. Peroxidase

–Removes  superoxide (oxygen free radicals)

–Reaction:   2 O2-• + 2H+ -> H2O2 + O2

removes hydrogen peroxide

–Catalase reaction:  2 H2O2 -> 2 H2O + O2

removes hydrogen peroxide

–Peroxidase reaction: H2O2 + 2 H+ -> 2 H2O

1)Obligate (strict) aerobe – cannot grow without oxygen

1)Obligate (strict) anaerobe – cannot grow with oxygen

• 1)Facultative (Facultative anaerobe) –
• utilizes oxygen but can also grow without it

does not utilize oxygen but can survive and grow in its presence

requires small amount of oxygen

•Increased carbon dioxide

•Carbon dioxide incubators

–controls CO2 levels

–similar to conditions of human body

•Candle jar

–has increased CO2 levels

•Reducing Media

•Both used to growth pathogenic organisms

• •Anaerobic growth chamber
• –Hydrogen combines with oxygen

• •Anaerobic incubator
• –oxygen
• is replaced with N2 gas

• •Anaerobic media
• –Thioglycollate broth

2H2 + O2 -> 2H2O

• •Candle Jar
• –Burning candle uses O2 and produces CO2

•CO2 incubator

Carbon, Nitrogen, & Energy Sources

–carbon source – heterotroph, autotroph

–energy source – 

•chemotroph –gain energy from chemical compounds

•phototrophs – gain energy through photosynthesis

Carbon sources

Heterotroph

Autotroph

• •must obtain carbon in an organic form made by other living organisms such as
• proteins, carbohydrates, lipids and nucleic acids

•an organism that uses CO2, an inorganic gas as its carbon source

• –not nutritionally dependent on other
• living things

•Needed for amino acids and nucleotides

•Obtained from:

• –proteins
• –ammonium ions (NH4+)
• –nitrites (NO3-)

–obtain N from N2 in atmosphere

•Needed in very small amounts

•Most serve as cofactors for enzymes

•Examples:

–Iron (Fe)

–Copper (Cu)

–Zinc (Zn)

–Magnesium (Mg)

•Must be obtained from the environment

•Compounds required for growth

•Examples:

• –Vitamins
• –Amino Acids

• •Fastidious bacteria – require many growth
• factors