Applied Microbiology Nutrition and Growth.2641

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Applied MicrobiologyApplied Microbiology

66thth lecture: Chapter lecture: Chapter 77

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Nutrition and GrowthNutrition and Growth

nutritionnutrition – process by which chemical substances (nutrients) – process by which chemical substances (nutrients) are acquired from the environment and used for cellular are acquired from the environment and used for cellular activitiesactivities

essential nutrientsessential nutrients - must be provided to an organism - must be provided to an organism Two categories of essential nutrients:Two categories of essential nutrients:

• macronutrientsmacronutrients – required in large quantities; play principal – required in large quantities; play principal roles in cell structure and metabolism roles in cell structure and metabolism

proteins, carbohydrates, lipidsproteins, carbohydrates, lipids• micronutrientsmicronutrients or trace elementsor trace elements – required in small – required in small

amounts; involved in enzyme function and maintenance of amounts; involved in enzyme function and maintenance of protein structureprotein structure

manganese, zinc, nickel, vitamins, co-factorsmanganese, zinc, nickel, vitamins, co-factors

Microbial NutritionMicrobial Nutrition

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NutrientsNutrients

Inorganic nutrientsInorganic nutrients– atom or molecule that contains a – atom or molecule that contains a combination of atoms other than carbon and hydrogencombination of atoms other than carbon and hydrogen• metals and their salts (magnesium sulfate, ferric nitrate, metals and their salts (magnesium sulfate, ferric nitrate,

sodium phosphate), gases (oxygen, carbon dioxide) and watersodium phosphate), gases (oxygen, carbon dioxide) and water

Organic nutrientsOrganic nutrients- contain carbon and hydrogen atoms - contain carbon and hydrogen atoms and are usually the products of living thingsand are usually the products of living things• methane (CH4), carbohydrates, lipids, proteins, and nucleic methane (CH4), carbohydrates, lipids, proteins, and nucleic

acidsacids

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Nutrition and GrowthNutrition and GrowthChemical Analysis of Microbial CytoplasmChemical Analysis of Microbial Cytoplasm

70% water70% water ProteinsProteins 96% of cell is composed of 6 96% of cell is composed of 6

elements:elements:• carboncarbon• hydrogenhydrogen• oxygenoxygen• phosphorousphosphorous• sulfursulfur• nitrogennitrogen

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Sources of Essential NutrientsSources of Essential Nutrients

Carbon sources:Carbon sources:

HeterotrophHeterotroph – must obtain carbon in an – must obtain carbon in an organicorganic form form made by other living organisms such as proteins, made by other living organisms such as proteins, carbohydrates, lipids and nucleic acidscarbohydrates, lipids and nucleic acids

AutotrophAutotroph - an organism that uses CO - an organism that uses CO22, an , an inorganicinorganic gas gas as its carbon sourceas its carbon source• not nutritionally dependentnot nutritionally dependent on other living thingson other living things

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Nitrogen Sources:Nitrogen Sources:

Main reservoir is nitrogen gas (NMain reservoir is nitrogen gas (N22); 79% of earth’s ); 79% of earth’s atmosphere is Natmosphere is N22..

Nitrogen is part of the structure of proteins, DNA, RNA & Nitrogen is part of the structure of proteins, DNA, RNA & ATP – these are the ATP – these are the primary source of N for heterotrophsprimary source of N for heterotrophs..

Some bacteria & algae use Some bacteria & algae use inorganic N nutrientsinorganic N nutrients (NO (NO33--, NO, NO22

--, , or NHor NH33).).

Some bacteria can Some bacteria can fix Nfix N22..

Regardless of how N enters the cell, it must be converted to Regardless of how N enters the cell, it must be converted to NHNH33, the only form that can be combined with carbon to , the only form that can be combined with carbon to synthesis amino acids, etc.synthesis amino acids, etc.

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Oxygen Sources:Oxygen Sources:

Major component of carbohydrates, lipids, nucleic acids, Major component of carbohydrates, lipids, nucleic acids, and proteinsand proteins

Plays an important role in structural and enzymatic Plays an important role in structural and enzymatic functions of cellfunctions of cell

Component of Component of inorganic saltsinorganic salts (sulfates, phosphates, (sulfates, phosphates, nitrates) and waternitrates) and water

OO22 makes up 20% of makes up 20% of atmosphereatmosphere

Essential to metabolism of many organismsEssential to metabolism of many organisms

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Hydrogen Sources:Hydrogen Sources:

Major element in Major element in all organic compoundsall organic compounds and and several several inorganicinorganic ones (water, salts and gases) ones (water, salts and gases)

Gases are produced and used by microbes.Gases are produced and used by microbes.

Roles of hydrogen:Roles of hydrogen:• maintaining pHmaintaining pH• forming H bonds between moleculesforming H bonds between molecules• serving as the source of free energy in oxidation-reduction serving as the source of free energy in oxidation-reduction

reactions of respirationreactions of respiration

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Phosphorous (Phosphate Sources):Phosphorous (Phosphate Sources):

Main inorganic source is Main inorganic source is phosphatephosphate (PO (PO44-3-3) derived from ) derived from

phosphoric acid (Hphosphoric acid (H33POPO44) found in rocks and oceanic mineral ) found in rocks and oceanic mineral depositsdeposits

Key component of nucleic acids, essential to geneticsKey component of nucleic acids, essential to genetics

Serves in energy transfers (ATP)Serves in energy transfers (ATP)

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Sulfur Sources:Sulfur Sources:

Widely distributed in environment, rocks; sediments contain Widely distributed in environment, rocks; sediments contain sulfate, sulfides, hydrogen sulfide gas and sulfursulfate, sulfides, hydrogen sulfide gas and sulfur

Essential component of some vitamins and the amino acids: Essential component of some vitamins and the amino acids: methionine and cysteinemethionine and cysteine

Contributes to stability of proteins by forming disulfide Contributes to stability of proteins by forming disulfide bondsbonds

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Other Nutrients Important in Microbial MetabolismOther Nutrients Important in Microbial Metabolism

PotassiumPotassium – essential to protein synthesis and membrane – essential to protein synthesis and membrane functionfunction

SodiumSodium – important to some types of cell transport – important to some types of cell transport

CalciumCalcium – cell wall and endospore stabilizer – cell wall and endospore stabilizer

Magnesium Magnesium – component of chlorophyll; membrane and – component of chlorophyll; membrane and ribosome stabilizerribosome stabilizer

IronIron – component of proteins of cell respiration – component of proteins of cell respiration

ZincZinc, copper, nickel, manganese, etc., copper, nickel, manganese, etc.

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Growth Factors: Essential Organic NutrientsGrowth Factors: Essential Organic Nutrients

Some organic compounds cannot be synthesizedSome organic compounds cannot be synthesized by by some organisms (some bacteria, humans,…) some organisms (some bacteria, humans,…) because they lack the genetic and metabolic because they lack the genetic and metabolic mechanisms to synthesize themmechanisms to synthesize them

Must be Must be provided as a nutrientprovided as a nutrient• essentialessential amino acids, vitamins amino acids, vitamins

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Nutritional TypesNutritional Types

Main determinants of nutritional type are:Main determinants of nutritional type are:

• carbon sourcecarbon source – – heterotroph, autotrophheterotroph, autotroph

• energy sourceenergy source – – chemotrophchemotroph – gain energy from chemical – gain energy from chemical

compoundscompounds phototrophsphototrophs – gain energy through photosynthesis – gain energy through photosynthesis

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Main C-source-> glucose

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More TerminologyMore Terminology

Aerobe -> organism uses oxygen in metabolismAnaerobe -> organism uses no oxygen in metabolism

Obligate/strict -> restricted to narrow habitatFacultative -> not being restricted

Tolerance -> capacity to survive in a range of conditions

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Transport: Movement of Chemicals Transport: Movement of Chemicals Across the Cell MembraneAcross the Cell Membrane

Passive transportPassive transport – does – does not require energynot require energy; substances ; substances exist in a exist in a gradientgradient and move from areas of higher and move from areas of higher concentration towards areas of lower concentrationconcentration towards areas of lower concentration• diffusiondiffusion• osmosis – diffusion of waterosmosis – diffusion of water• facilitated diffusion – requires a carrierfacilitated diffusion – requires a carrier

Active transportActive transport – – requires energyrequires energy and carrier proteins; and carrier proteins; gradient independentgradient independent• active transportactive transport• group translocation – transported molecule chemically alteredgroup translocation – transported molecule chemically altered• bulk transport – endocytosis, exocytosis, pinocytosisbulk transport – endocytosis, exocytosis, pinocytosis

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Transport: Movement of Chemicals Across the Cell MembraneTransport: Movement of Chemicals Across the Cell Membrane

Osmosis – Transport of water

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Cell response to different osmotic content

Osmotic shock

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Endocytosis

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Environmental Factors That Influence MicrobesEnvironmental Factors That Influence Microbes

Environmental factors fundamentally Environmental factors fundamentally affect the function of affect the function of metabolic enzymes.metabolic enzymes.

Factors include:Factors include:• temperaturetemperature• oxygen requirementsoxygen requirements• pHpH• electromagnetic radiationelectromagnetic radiation• barometric pressurebarometric pressure

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3 Cardinal Temperatures3 Cardinal Temperatures

Minimum temperatureMinimum temperature – lowest temperature that permits – lowest temperature that permits a microbe’s growth and metabolisma microbe’s growth and metabolism

Maximum temperatureMaximum temperature – highest temperature that – highest temperature that permits a microbe’s growth and metabolismpermits a microbe’s growth and metabolism

Optimum temperatureOptimum temperature – promotes the fastest rate of – promotes the fastest rate of growth and metabolismgrowth and metabolism

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3 Temperature Adaptation Groups3 Temperature Adaptation Groups

PsychrophilesPsychrophiles – optimum temperature below 15 – optimum temperature below 15ooC; C; capable of growth at 0capable of growth at 0ooCC

Mesophiles Mesophiles – optimum temperature 20– optimum temperature 20oo-40-40ooC; most C; most human pathogenshuman pathogens

ThermophilesThermophiles – optimum temperature greater than 45 – optimum temperature greater than 45ooCC

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3 Temperature Adaptation Groups3 Temperature Adaptation Groups

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Gas Requirements - OxygenGas Requirements - Oxygen

As oxygen is utilized it is transformed into several toxic As oxygen is utilized it is transformed into several toxic products:products:

• singlet oxygen (Osinglet oxygen (O22), superoxide ion (O), superoxide ion (O22--), peroxide ), peroxide

(H(H22OO22), and hydroxyl radicals (OH), and hydroxyl radicals (OH--)) Most cells have developed enzymes that neutralize these Most cells have developed enzymes that neutralize these

chemicals:chemicals:• superoxide dismutase, catalasesuperoxide dismutase, catalase

If a microbe is not capable of dealing with toxic oxygen, it is If a microbe is not capable of dealing with toxic oxygen, it is forced to live in oxygen free habitats.forced to live in oxygen free habitats.

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Gas Requirements - Categories of Oxygen RequirementGas Requirements - Categories of Oxygen Requirement

AerobeAerobe – utilizes oxygen and can detoxify it – utilizes oxygen and can detoxify it Obligate aerobeObligate aerobe - cannot grow without oxygen - cannot grow without oxygen Facultative anaerobeFacultative anaerobe – utilizes oxygen but can also grow – utilizes oxygen but can also grow

in its absencein its absence MicroaerophilicMicroaerophilic – requires only a small amount of oxygen – requires only a small amount of oxygen

AnaerobeAnaerobe – does not utilize oxygen – does not utilize oxygen Obligate anaerobeObligate anaerobe - lacks the enzymes to detoxify - lacks the enzymes to detoxify

oxygen so cannot survive in an oxygen environmentoxygen so cannot survive in an oxygen environment Aerotolerant anaerobesAerotolerant anaerobes – do no utilize oxygen but – do no utilize oxygen but

can survive and grow in its presencecan survive and grow in its presence

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Effects of pHEffects of pH

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

Obligate acidophilesObligate acidophiles – grow at extreme acid pH – grow at extreme acid pH

AlkalinophilesAlkalinophiles – grow at extreme alkaline pH – grow at extreme alkaline pH

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Osmotic PressureOsmotic Pressure

Most microbes exist under hypotonic or isotonic conditionsMost microbes exist under hypotonic or isotonic conditions

HalophilesHalophiles – require a high concentration of salt – require a high concentration of salt

OsmotolerantOsmotolerant – do not require high concentration of – do not require high concentration of solute but can tolerate it when it occurssolute but can tolerate it when it occurs

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Ecological Associations Among MicroorganismsEcological Associations Among Microorganisms SymbioticSymbiotic – organisms live in close nutritional relationships; – organisms live in close nutritional relationships;

required by one or both membersrequired by one or both members• mutualismmutualism – obligatory, dependent; both members benefit – obligatory, dependent; both members benefit• commensalismcommensalism – commensal member benefits, other – commensal member benefits, other

member not harmedmember not harmed• parasitismparasitism – parasite is dependent and benefits; host is – parasite is dependent and benefits; host is

harmedharmed

Non-symbioticNon-symbiotic – organisms are free-living; relationships not – organisms are free-living; relationships not required for survivalrequired for survival• synergismsynergism – members cooperate and share nutrients – members cooperate and share nutrients• antagonismantagonism – some member are inhibited or destroyed – some member are inhibited or destroyed

by othersby others

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Interrelationships Between Microbes and HumansInterrelationships Between Microbes and Humans

Human body is a rich habitat for symbiotic bacteria, fungi, Human body is a rich habitat for symbiotic bacteria, fungi, and a few protozoa - and a few protozoa - normal microbial floranormal microbial flora

Commensal, parasitic, and synergistic Commensal, parasitic, and synergistic

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The Study of Microbial GrowthThe Study of Microbial Growth

Microbial growth occurs at two levels: growth at a Microbial growth occurs at two levels: growth at a cellular level with cellular level with increase in sizeincrease in size, and , and increase in increase in populationpopulation

Division of bacterial cells occurs mainly through Division of bacterial cells occurs mainly through binary binary fissionfission (transverse)(transverse)• parent cell enlarges, duplicates its chromosome, and parent cell enlarges, duplicates its chromosome, and

forms a central transverse septum dividing the cell into forms a central transverse septum dividing the cell into two daughter cellstwo daughter cells

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Binary fission (cell division)

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Rate of Population GrowthRate of Population Growth

Time required for a complete fission cycle is called the Time required for a complete fission cycle is called the generation,generation, or or doublingdoubling time time

Each new fission cycle increases the population by a factor of Each new fission cycle increases the population by a factor of 2 – 2 – exponentialexponential or or logarithmic logarithmic growth.growth.

Generation times vary from minutes to days.Generation times vary from minutes to days.

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Population GrowthPopulation Growth

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Rate of Population GrowthRate of Population Growth

Equation for calculating population size over time:Equation for calculating population size over time: NNƒ ƒ = (N= (Nii)2)2nn

NNƒƒ is total number of cells in the population. is total number of cells in the population. NNi i is starting number of cells.is starting number of cells. Exponent Exponent nn denotes generation time. denotes generation time. 22n n number of cells in that generationnumber of cells in that generation

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The Population Growth CurveThe Population Growth Curve

In laboratory studies, populations typically display a In laboratory studies, populations typically display a predictable pattern over time – predictable pattern over time – growth curvegrowth curve..

Stages in the normal growth curve:Stages in the normal growth curve: Lag phaseLag phase – “flat” period of adjustment, enlargement; little – “flat” period of adjustment, enlargement; little

growthgrowth Exponential growth phaseExponential growth phase – a period of maximum – a period of maximum

growth will continue as long as cells have adequate growth will continue as long as cells have adequate nutrients and a favorable environmentnutrients and a favorable environment

Stationary phaseStationary phase – rate of cell growth equals rate of cell – rate of cell growth equals rate of cell death caused by depleted nutrients and Odeath caused by depleted nutrients and O22, excretion of , excretion of organic acids and pollutantsorganic acids and pollutants

Death phaseDeath phase – as limiting factors intensify, cells die – as limiting factors intensify, cells die exponentially in their own wastesexponentially in their own wastes

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The Population Growth CurveThe Population Growth Curve

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Methods of Analyzing Population GrowthMethods of Analyzing Population Growth

Turbidometry – most simpleTurbidometry – most simple Degree of cloudiness, turbidity, reflects the relative Degree of cloudiness, turbidity, reflects the relative

population sizepopulation size

Enumeration of bacteria:Enumeration of bacteria:• viable colony count viable colony count • direct cell count – count all cells present; automated or direct cell count – count all cells present; automated or

manualmanual

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Methods of Analyzing Population GrowthMethods of Analyzing Population Growth

Turbidometry Turbidometry

Cells scatter light -> intensity of light drops

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Applied Microbiology Nutrition and Growth.2641