Chemical structure and Chemical structure and metabolism of bacteriametabolism of bacteria
Principal elements of the cell Principal elements of the cell and their physiological functions and their physiological functions
(1)(1)Element Cell
dry weight
Physiological functions
Carbon (C) 50 Constituent of all organic cell components
Oxygen (O) 20 Constituent of cellular water and most organic cell components; molecular oxygen serves as an electron acceptor in aerobic respiration
Nitrogen (N) 14 Constituent of proteins, nucleic acids, coenzymes
Hydrogen (H)
8 Constituent of cellular water and organic cell components
Phosphorus (P)
3 Constituent of nucleic acids, phospholipids, coenzymes
Sulfur (S) 1 Constituent of some amino acids in proteins and some coenzymes
Potassium (K)
1 Important inorganic cation and cofactor for some enzymatic reactions. It stabilizes ribosomes
Principal elements of the cell Principal elements of the cell and their physiological functions and their physiological functions
(2)(2)Element Cell dry
weightPhysiological functions
Sodium (Na) 1 One of the principal inorganic cations in eukaryotic cells and important in membrane transport
Calcium (Ca) 0,5 Important inorganic cation and cofactor for some enzymatic reactions
Magnesium (Mg)
0,5 Important inorganic cation and cofactor for many enzymatic reactions
Chlorine (Cl) 0,5 Important inorganic cation
Iron (Fe) 0,2 Constituent of cytochromes and some proteins
Trace elements:Cobalt, Zinc, Molybdenum, Manganese (Mn)
0,3 The elements are required in very small amounts.Part of enzymes, required for enzyme activity
Macromolecules Macromolecules ((Stouthamer, Stouthamer, 19731973))
Organic compounds Organic compounds % dry weight % dry weight
Proteins Proteins 52,452,4
Carbohydrates Carbohydrates 16,616,6
Lipids Lipids 3,43,4
RNARNA 15,415,4
DNADNA 3,23,2
Others Others 2,72,7
Bacteria biopolimers Bacteria biopolimers
Biopolimer Biopolimer ContenContent in cellt in cell
Functions Functions
DNADNA 3-4%3-4% HeredityHeredity, , variability variability
RNARNA 4-15%4-15% Transmission of genetic information, Transmission of genetic information, protein synthesisprotein synthesis, , stored nutrient stored nutrient substratesubstrate
Proteins Proteins До 50%До 50% Enzymatic activityEnzymatic activity, , antigen antigen propertiesproperties, , toxicitytoxicity andand virulencevirulence
CarbohydratCarbohydrates es
10-30%10-30% Constituent of capsule or slime layer. Constituent of capsule or slime layer. FunctionsFunctions: : antigen properties,antigen properties, virulencevirulence ((ViVi--antigenantigen). ). Nutrient substrateNutrient substrate
Lipids Lipids 1,5-38%1,5-38% Constituent of fats, phospholipidsConstituent of fats, phospholipids. . FunctionsFunctions: : toxicitytoxicity, , pyrogenic pyrogenic propertiesproperties, , resistance to environment resistance to environment factors and antibiotics factors and antibiotics
Environmental factors that Environmental factors that influence microbes influence microbes
TemperatureTemperatureOxygen Oxygen pHpHOsmotic pressureOsmotic pressure
Environment factors fundamentally affect the function of metabolic enzymes.
Temperature adaptation groupsTemperature adaptation groups
PsychrophilePsychrophiles s are microorganisms that have an optimum temperature below 150C and is capable of growth at 00C.
These organisms are usually found in such environments as the Arctic and Antarctic regions.
MesophilesMesophiles
are microorganisms that grow at intermediate temperature and have their optimum within the range of 200C to about 500C.
This grope includes the majority of disease-causing bacteria.
Their optimum temperature for growth is according to temperature of human body (35-400C)
ThermophilesThermophiles
are microbes that grow optimally at temperatures greater than 450C, and can exist with temperature between 500C and 800C.
Heat-loving microbes live in soil and water associated with volcanic activity and in habitats directly exposed to the sun.
Extreme thermophiles
are microorganisms whole optumum growth temperature is above 800C.
Effects of pHEffects of pH
Optimum pH for most mictobes ranges approximately from 6 to 8.
Most human pathogens grow optimally at a pH of 6,5 to 7,5.
Acidophiles are microorganisms which prefer lower pH (yeasts and molds)
Alkalinophiles prefer higher pH
Osmotic pressure and salinityOsmotic pressure and salinity
Osmotolerant (halotolerant) are microorganisms that can grow in solutions with high solute concentrate (salinity).
Osmophiles (halophiles) are microorganisms that require a high solute concentration (salinity).
General gropes of bacteria with General gropes of bacteria with respect to oxygen requirementsrespect to oxygen requirements
Obligate (strict) aerobesObligate (strict) aerobesObligate (strict) anaerobesObligate (strict) anaerobesFacultative anaerobesFacultative anaerobesMicroaerophilesMicroaerophilesAerotolerant microorganisms Aerotolerant microorganisms Capnophiles Capnophiles
Obligate aerobes Obligate aerobes
There are microorganisms that cannot grow without oxygen because they metabolize sugars through a pathway that requires oxygen.
Obligate anaerobes Obligate anaerobes
There are microorganisms that cannot multiply is any oxygen is present.
Some members are actually killed by traces of oxygen because they cannot modify the toxic forms of oxygen produced in metabolism.
Some of their enzymes are denatured by oxygen.
Among the more important anaerobic pathogens are some species of Clostridium, Bacteroides
Facultative anaerobesFacultative anaerobes
There are microorganisms that does not require oxygen for their metabolism and capable of growth in the absence of oxygen.
This type of organism metabolizes by aerobic respiration when oxygen is present, but, in its absence, it adopts an anaerobic mode of metabolism such as fermentation.
A large member of bacterial pathogens fall into this group (Enterobacteriaceae, Staphylococcus).
Microaerophiles Microaerophiles
These microorganisms require small amounts of oxygen (2% to 10%), but higher concentration are toxic.
Disease-causing microaerophilic microorganisms are Helicobacter pylori (the agent of gastrointestinal ulcers), Actinomyces israelii.
Aerotolerant anaerobes Aerotolerant anaerobes
These microorganisms grow in the presence or absence of oxygen, but unlike facultative anaerobes, they derive no benefit from oxygen.
Medically important member of this grope is Streptococcus pyogenes (agent of strep throat).
Capnophiles Capnophiles
There are microorganisms that grow better at a higher CO2 tension than is normally present in the atmosphere.
Special CO2 incubators are used for cultivation of capnophile bacteria.
Medically important member of this grope is Streptococcus pneumonia (agent of pneumonia), Neisseria (agents of gonorrhea and meningitis), Brucella (agent of undulant fever).
Enzyme content of bacteria with Enzyme content of bacteria with different requirement for oxygen different requirement for oxygen Name Name Enzyme content for OEnzyme content for O22
detoxificationdetoxificationStrict aerobeStrict aerobe Catalase – Catalase – HH22OO22 H H22O + OO + O22
Superoxide dismutaseSuperoxide dismutase
OO22- - +2H+ +2H+ OO22 + H + H22OO22 H H22O + OO + O22
Facultative Facultative anaerobe anaerobe
Catalase Catalase
Superoxide dismutaseSuperoxide dismutase
MicroaerophiMicroaerophilele
Small amount of catalase and Small amount of catalase and superoxide dismutasesuperoxide dismutase
AerotolerantAerotolerant Superoxide dismutaseSuperoxide dismutase
Strict Strict anaerobeanaerobe
Neither catalase nor superoxide Neither catalase nor superoxide dismutasedismutase
Metabolic strategies among Metabolic strategies among heterotrophic microorganismsheterotrophic microorganisms
Scheme Scheme Pathways Pathways involvedinvolved
Final elect-Final elect-ron ron acceptoracceptor
Net Net productsproducts
Chief Chief microbe microbe typetype
Aeronic Aeronic restiration restiration
Glycolysis, Glycolysis, TCA cycle, TCA cycle, electron electron transporttransport
OO22 38 ATP, CO38 ATP, CO22, , HH22OO
Aerobes, Aerobes, facultative facultative anaerobesanaerobes
Anaerobe metabolismAnaerobe metabolism
FermentatiFermentative ve
Glycolysis Glycolysis Organic Organic molecules molecules
2 ATP, CO2, 2 ATP, CO2, ethanol, ethanol, lactic acidlactic acid
Facultative, Facultative, aerotolerantaerotolerant, strict , strict anaerobesanaerobes
Respiration Respiration Glycolysis, Glycolysis, TCA cycle, TCA cycle, electron electron transporttransport
Various Various inorganic inorganic salts salts
COCO22, ATP, , ATP, organic organic acids, Hacids, H22O, O, CHCH44, N, N22
Anaerobes, Anaerobes, some some facultativesfacultatives
Metabolism Metabolism
is the sum of cellular chemical changes; it involves scores of reactions that interlink in linear or branched pathways.
Metabolism is a complementary process consisting of anabolism and catabolism
Features of bacterial Features of bacterial metabolismmetabolism
High enzyme activity High enzyme activity Different pathways of metabolism Different pathways of metabolism Metabolism is supple and efficientMetabolism is supple and efficient
AnabolisAnabolismm
is any process that results in synthesis of cell molecules and structures.
It is a building and bond-making process that forms larger molecules from smaller ones, and it usually requires the input of energy.
CatabolisCatabolismm is the inverse process in which large
molecules are degraded.
During the catabolism energy is released and can be stored in form of adenosine triphosphate (ATP).
Bacterial enzymes Bacterial enzymes Genetical classification Genetical classification
Constitutive enzymesConstitutive enzymes Induced (or inducible) enzymesInduced (or inducible) enzymes РепресибельніРепресибельні
Biochemical classification Biochemical classification Oxidoreductase Oxidoreductase Transferase Transferase Hydrolase Hydrolase Lyase Lyase Isomerase Isomerase Lygase Lygase
Microbiological classificationMicrobiological classification Endoenzymes Endoenzymes Exoenzymes Exoenzymes Pathogenicity enzymesPathogenicity enzymes
Endoenzymes (b) and Endoenzymes (b) and exoenzymes (a)exoenzymes (a)
Constitutive (c) and Constitutive (c) and induced (d) enzymesinduced (d) enzymes
Some enzymes and their Some enzymes and their function function
Name Name EnzymEnzyme classe class
SubstratSubstrate e
Action Action
Lactase Lactase HydrolaHydrolasese
LactoseLactose Breaks lactose down into glucose Breaks lactose down into glucose and galactoseand galactose
PenicillinasPenicillinasee
HydrolaHydrolasese
Penicillin Penicillin Hydrolyzes beta-lactam ringHydrolyzes beta-lactam ring
DNA DNA polymeraspolymerasee
Transfe-Transfe-rase rase
DNA DNA nucleosidenucleosidess
Synthesizes a strand of DNA using Synthesizes a strand of DNA using the complementary strand as a the complementary strand as a modelmodel
Aldolase Aldolase Lyase Lyase Fructose Fructose diphosphatdiphosphatee
Catalyzes the conversion of the Catalyzes the conversion of the substrate to two 3-carbon substrate to two 3-carbon fragmentsfragments
Lactate de-Lactate de-hydrogenahydrogenasese
Oxido-Oxido-reductasreductase e
Pyruvic Pyruvic acidacid
Catalyzes the conversion of Catalyzes the conversion of pyruvic acid to lactic acidpyruvic acid to lactic acid
Oxidase Oxidase Oxido-Oxido-reductasreductasee
Molecular Molecular oxygen oxygen
Catalyzes the reduction (addition Catalyzes the reduction (addition of electrons and hydrogen) to Oof electrons and hydrogen) to O22
Nutritional categories of Nutritional categories of microbes by carbon and energy microbes by carbon and energy
sourcesourceCategory
Carbon source
Energy source
Examples
Autotroph
CO2 Nonliving environment
Photo-autotroph
CO2 Sunlight Photosynthetic organism, such as algae, plants, cyanobacteria
Chemo-autotroph
CO2 Simple inorganic chemicals
Only certain Only certain bacteria, such bacteria, such as as methanogens methanogens
Nutritional categories of Nutritional categories of microbes by carbon and energy microbes by carbon and energy
sourcesourceCategory Carbo
n source
Energy source Examples
Heterotroph
Organic Other organisms
Chemo-heterotroph
Organic Metabolic conversion of the nutrients from other organisms
Protozoa, fungi, many bacteria
Saprobe Organic Metabolizing the organic matter of dead organisms
Fungi, bacteria
Parasite Organic Utilizing the tissues, fluids of a live host
Various parasites and pathogens; can be bacteria, fungi, protozoa
Extracellular digestion in Extracellular digestion in bacteriabacteria
Substrate degradation in Gram-Substrate degradation in Gram-positive and Gram-negative positive and Gram-negative
bacteria bacteria
Gram-positive Gram-negative
How microbes take in How microbes take in moleculesmolecules
In passive transport, nutrient exist in a gradient from a high concentration outside the cell to a low concentration inside the cell. The molecules diffuse into the cell without consumption of energy
In active transport, the cell actively picks up nutrients from a solution in which the nutrients are not in a gradient (it requires of energy)
In bulk transport, large solids or mass of liquids enter the cell intact by engulfment. It type of active transport.
Features of diffusion and active Features of diffusion and active transporttransport
Type of Type of transportransport t
Energy Energy requirerequired d
ConcentratioConcentration on outside n on outside and inside of and inside of cellcell
Mechanisms of Mechanisms of transport transport
Passive Passive diffusion diffusion
No No Same Same Diffuses through Diffuses through cytoplasmic membranecytoplasmic membrane
FacilitateFacilitated d diffusion diffusion
No No Same Same Permeases in Permeases in cytoplasmic membrane cytoplasmic membrane involvedinvolved
Active Active transportransport t
Yes Yes Higher on Higher on insideinside
Binds to protein in Binds to protein in periplasmic space, which periplasmic space, which then interacts with a then interacts with a receptor protein in the receptor protein in the cytoplasmic membranecytoplasmic membrane