The document discusses microbial nutrition and the requirements of microorganisms. It states that microbes require nutrients from their external environment, which they take up and metabolize for growth and energy. The main nutrients include carbon, nitrogen, phosphorus, sulfur, potassium, and trace elements. Carbon is generally obtained from organic sources while nitrogen can come from inorganic or organic sources. Microbes also require vitamins and growth factors. The composition of the E. coli cell is provided as an example. Different growth media are formulated to meet the nutritional needs of various microorganisms like Bacillus, Thiobacillus, E. coli and Leuconostoc.

1. Microbial Nutrition
 One of the characteristics of a living organism:
 able to carry out chemical reactions & arrange molecules into a
specific structure  GROWTH
 Microbial cell: consists of chemical substances
 The substances come from outside the cell and is
changed inside the cell - NUTRIENT(S)
 Chemical processes in the cell: METABOLISM

4. Microorganisms based on
Nutritional Requirements
Energy
Source
C source Example
Photoautotroph Light CO2 Cyanobacteria
Photoheterotroph Light Organic
substances
Green-purple
bacteria
Chemoautotroph or
Lithoautotroph
Organic
substances
CO2 Archea
Chemoheterotroph
or Heterotroph
Organic
substances
Organic
substances
Bacteria, Fungi

5. Composition of Microbial Cell
 Chemicals inside the cell:
 macromolecule
 Small molecules
 Small molecules are obtained from environment while
macromolecules are synthesized inside
 Basic composition: C, H, O, & N.
 90% of cell’s wet weight : water; cell’s dry weight :
macromolecules (protein)

6. E. coli cell composition
Element % dry
weight
Source Function
C
50 Organic substances, Main cellular components
O
20 H2O, organic
substances, CO2, &
O2
Cellular components &
plasma; O2 is final electron
acceptor in aerobe
respiration
N
14 NH3, NO3, organic
substances, N2
Amino acids component,
nucleic acids, nucleotides
& coenzymes
H
8 H2O, organic
substances, H2
Cellular component & cell
plasma/fluids

7. E. Coli composition
Element % dry
weight
Source Function
P 3 Inorganic
phosphate(PO4)
Nucleic acid component,
nucleotides, phospholipids, LPS,
techoic acid
S 1 SO4, H2S, So,
Organic S
Component of cysteine,
methionine, glutathione, some
conenyzmes
K 1 Salts Main inorganic cation (K+),
cofactor for certain enzymes
Mg 0,5 Magnesium
salts
Cation (Mg2+), cofactors
Ca 0,5 Salts Ca2+, cofactors, endospore
Fe 0,2 Salts Cytochrome components &
protein Fe nonheme, cofactor

8. Nutrient
 Nutrient :
 Macronutrients:
 Needed in large amounts
 C, H, O, N, P, S, K, Mg, Ca, Na, Fe
 Micronutrients:
 Needed in small amounts
 Co, Cu, Mn, Mo, Ni, Se, etc
 others: growth factor

9. Macronutrient: Carbon (C)
 50% of microbial cell
 Mostly taken up in organic form
 exceptions: some bacterial groups
 Amino acids, fatty acids, organic acids, sugars,
aromatics etc can serve as carbon source

10. Macronutrient: Nitrogen (N)
 Nitrogen:
 main component of protein, nucleic acid etc
 Sources: organic and inorganic
substances
 In the environment: N is in inorganic form:
NH3, NO3, N2.
 Bacteria: can use NH3 or NO3 but there
are bacteria that can use N2
 Fungi: cannot use N2

11. Macronutrient: P, S, K
 Phosphor (P):
 Organic and Inorganic
 Synthesis of nucleic acids + phospholipids
 Sulphur (S)
 Inorganic: SO4, H2S
 Component of cysteine & methionine, vitamins
 Some microorganisms can use S
 Kalium (K):
 Needed by all microorganisms

12. Macronutrient: Mg, Ca, Na, Fe
 Magnesium (Mg):
 ribosome stabilization, cell membrane & nucleic acid
 Enzyme activation
 Calcium (Ca):
 Stabilizes bacterial cell wall
 Stabilizes endospore
 Natrium (Na):
 Needed by some microorganisms, reflects habitat
 Iron (Fe):
 Plays role in cellular respiration
 Main component of cytochromes & electron transport

13. Micronutrients & Growth Factors
 Micronutrients
 Also known as trace elements
 Important for cell function
 Usually added in the form of solution
 May be obtained from water
 Growth Factors:
 Organic substances, needed in small amounts
 Not needed by every microorganism
 Can be synthesized or obtained from environment
 Vitamins, amino acids, purin, pyrimidines

14. Vitamin requirements of bacteria
Vitamin Coenzyme form Function
p-Aminobenzoic
acid (PABA)
Precursor for folic acid
Folic Acid Tetrahydrofolate Transfer C-1 units, thymine
synthesis, purines, serine,
methionine & pantothenate
Biotin biotin Synthesis reactions that
need CO2 fixation
Riboflavin (B2) FMN (flavin
mononucleotide) &
FAD (flavin adenine
dinucleotide)
Redox reactions

15. Growth Medium
 In the laboratory, microorganism is grown on
medium
 By form:
 solid
 solidifying agent (agar)
 broths
 composition:
 Chemically defined (synthetic) medium
 The composition and concentration of components are
exactly known
 Chemically undefined (complex) medium
 There are components which concentration are not
known

16.  By function:
 General
 Enrichment
 Selective
 Differential
 The selective-differential can be found on
one medium
 Each microorganism has different nutritional
requirements

17. Growth Medium of
Bacillus sp. & Thiobacillus sp.
 10 gr sucrose
 2.5 gr K2HPO4
 2.5 gr KH2PO4
 1.0 gr (NH4)2HPO4
 0.2 gr MgSO4.7H2O
 0.01 gr FeSO4.7H2O
 0.007 grMnSO4.7H2O
 0.52 gr NH4Cl
 0.28 gr KH2PO4
 0.25 gr MgSO4 7H2O
 0.07 gr CaCl2 2H2O
 1.56 gr Elemental
Sulphur
 5 % C02
 1000 ml H2O
Medium Bacillus sp. Medium Thiobacillus sp.

18. Growth Medium
E. coli & Leuconostoc
 Glucose 4-10 gr
 K2HPO4 7 gr
 KH2PO4 2 gr
 (NH4)2SO4 1 gr
 MgSO4 0,1 gr
 CaCl2 0,02 gr
 Trace elements 2-10 ug
 Aquadest 1000 ml
 pH 7
 K2HPO4 0,6 gr
 KH2PO4 0,6 gr
 NH4Cl 3 gr
 MgSO4 0,1 gr
 Glucose 25 gr
 Na-acetate 20 gr
 Amino acids 100-200 ug
 Purin, pirimidin 10 mg
 Vitamin 0,01-1 mg
 Trace elements
 Aquadest 1000 ml
 pH 7
Medium E. coli
Medium Leuconostoc