chapter 8 (finish end)

What is the composition of bacteria (ecoli) by major polymers using % of total dry weight of cells

• DNA - 3

• RNA - 21

• Protein - 55 (bacteria and fungi are full of protein)

• Peptidoglycan - 3.5

• Phospholipids - 9

• Lipopolysaccharide- 3.5

What do fungi aid in for bacteria

They make enzymes (to break down bacteria) and amylase

What are nutritional types defined by

• energy, carbon and hydrogen/electron (H/e-) source

4 types of ways bacteria get Nutrtion

1. Phototroph (energy source)

2. Chemotroph (energy source)

3. Autotroph (carbon source)

4. Heterotroph (carbon source)

5. Lithrotroph (H/e- source)

6. Organotroph (H/e- source)

Phototroph

Bacteria that can utilize sunlight

Chemotroph

Bacteria that oxidize organic or inorganic compounds

Autotroph

CO2 reduced by bacteria to CHx

Heterotroph

Obtain carbon from reduced organic compounds

Lithotroph

Uses reduced inorganic compounds as H/e- source

Organotroph

Use organic compounds as H/e- source

• most important

4 main classes of bacterial nutritional types (IMPORTANT)

1. Chemolithotrophic autotrophs

2. Photoorganotrophic heterotrophs

3. Photolithotrophic autotrophs

4. Chemoorganic heterotrophs (MOST IMPORTANT)

Example of chemolithotrophic autotrophs

Thiobacillus (Fe 2+. > Fe+3 + e-, CO2)

Example of photoorganotrophic heterotrophs

Rhodospirillum

• green non sulfur bacteria

• Are photosynthetic but uses Amino acids and sugars as electron donors

Example of photolithotrophic autotrophs

Cyanobacteria, plant like photosynthesis

• fixes atmospheric CO2

Example of chemoorganic heterotroph

• ecoli, pathogens, degraders

Calvin cycle

Is an autotrophic fixation of CO2 that is energy consuming

• primary carbon source

• mostly restricted to photosynthetic bacteria

• Type of oxygenic photosynthesis for higher plants and is preformed by Cyanobacteria

2 other carbon sources

1. reverse TCA cycle

• succinyl-CoA + CO –> a-ketoglutarate

• a-ketoglutarate + CO2 -> isocitrate

2. Methanogenesis - CO2 binds to a CH3 carrier, some fixed carbon is diverted to produce cellular carbon

Heterotrophic carbon sources

• utilizes preformed organic compounds such as ….

• Carbohydrates (simple sugars, amino sugars, sugar acids)

• Amino acids

• Alcohols, hydrocarbons

• Organic acids (citric, lactic, acetic, succinic acids)

Nitrogen

Growth limiting nutrient in any environment

4 Nitrogen sources

1. Atmospheric N2 is fixed or reduced to be biologically useful (done by bacteria)

2. Preformed amino acids and N containing bases

3. Can be provided in growth media as a nitrate (KNO3) or ammonium salt (NH4No3)

4. Can be provided as an organic compounds such as amino acid or urea (protein hydrolysate like tryptic soya)

Which bacteria’s can naturally fix N2

Free living bacteria

• Cyanobacteria

• Klebsiella

Symbiotic bacteria

• Rhizobium

How to use nitrogen as a source

1. NO3 or NO2 (organic nitrogen) reduced to NH3 (amino group)by bacteria

2. NH3 is assimilated into cellular material

3. NH3 → glutamate → glutamine

Phosphorous

may be a limiting nutrient

Phosphorus source

• organic phosphorus is the major source of phosphorus for bacteria (such as in DNA, RNA, nucleotides and phospholipids)

• Can also be provided in growth media as a phosphate salt (Na2HPO4)

Sulphur sources

1. Inorganic sulphur - such as SO4 2- salts which are taken up by the cell and reduced to the SH2 level

2. Organic sulphur - such as in cysteine and methionine