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