Microbiology of Microbial Metabolism

Summary

This lecture delves into microbial metabolism, exploring the generation and utilization of energy in both prokaryotic and eukaryotic cells. It distinguishes between autotrophs, which produce glucose from atmospheric carbon dioxide through photosynthesis, and heterotrophs, which rely on organic molecules from other organisms. The script covers the processes of catabolism and anabolism, cellular respiration, and the role of glucose as a key energy molecule. It also explains aerobic and anaerobic respiration, highlighting the efficiency of aerobic respiration in ATP production and the importance of the electron transport chain in eukaryotic mitochondria versus the plasma membrane in prokaryotic cells.

Takeaways

• 🌱 Autotrophs are organisms that perform photosynthesis, using carbon dioxide from the atmosphere as their carbon source and producing glucose in the presence of sunlight.
• 🍂 Heterotrophs rely on the carbon produced by other organisms, obtaining carbon mostly in the form of glucose from complex organic molecules.
• 🔄 Carbon, hydrogen, oxygen, and water are continuously cycled between autotrophic and heterotrophic organisms, highlighting their interdependence.
• ☀️ Photosynthetic autotrophs are energy producers, utilizing sunlight as their energy source, while heterotrophs depend on the energy produced by others.
• 🌡️ Metabolism encompasses all chemical transformations in a cell, driven by enzyme-catalyzed reactions that form metabolic pathways.
• 📉 Catabolism is the breakdown of molecules that releases energy, whereas anabolism is the synthesis of larger molecules from smaller ones, requiring energy.
• 🔋 Cellular respiration is the process of producing ATP, which is essential for energy utilization, and involves the cycling between ATP and ADP.
• 🌿 Glucose is a key energy molecule, serving as a currency exchanged between plants and animals, and is also a building block in plants.
• 🔄 Glucose can undergo various fates: storage, oxidation (glycolysis), or oxidation via the pentose phosphate pathway for nucleic acid production.
• 🚫 Anaerobic bacteria cannot survive in oxygen-rich environments and produce lactic acid as a byproduct of anaerobic metabolism.
• 🌿 The electron transport chain, a part of aerobic metabolism, occurs in the inner mitochondrial membrane in eukaryotic cells and in the plasma membrane in prokaryotic cells.

Q & A

What is microbial metabolism?

Microbial metabolism refers to the generation or production of energy as well as the utilization of energy in both prokaryotic and eukaryotic cells. It involves the sum of all chemical transformations that occur within a cell or organism, driven by enzyme-catalyzed reactions.

What differentiates autotrophs from heterotrophs in terms of carbon source?

Autotrophs are organisms that engage in photosynthesis and use carbon dioxide from the atmosphere as their source of carbon, producing glucose in the presence of sunlight. Heterotrophs, on the other hand, rely on the production of carbon from other organisms and cannot use atmospheric carbon dioxide directly; they obtain carbon mostly in the form of complex organic molecules like glucose.

How is the carbon cycle interconnected between autotrophs and heterotrophs?

The carbon cycle is interconnected as carbon, hydrogen, oxygen, and water are constantly cycled between autotrophic and heterotrophic organisms. Autotrophs require carbon dioxide for photosynthesis, which is produced by heterotrophs during respiration, while heterotrophs depend on the glucose produced by autotrophs.

What is the role of glucose in cellular metabolism?

Glucose is a crucial energy-carbohydrate molecule, often referred to as a 'currency molecule' because it is exchanged between plants and animals. It serves as a building block in plants, a source of energy in animals, and is involved in various metabolic pathways including glycolysis, the pentose phosphate pathway, and the citric acid cycle.

What are the three main stages of aerobic metabolism?

The three main stages of aerobic metabolism are glycolysis (conversion of glucose to pyruvate), the citric acid cycle (conversion of acetyl-CoA to CO2 and other products), and oxidative phosphorylation (electron transport chain and ATP production).

How does anaerobic respiration differ from aerobic respiration?

Anaerobic respiration occurs in environments without oxygen and uses an inorganic molecule other than oxygen as the final electron acceptor. In contrast, aerobic respiration requires oxygen as the final electron acceptor and occurs in oxygenated environments.

What is the significance of the electron transport chain in ATP production?

The electron transport chain, also known as oxidative phosphorylation, is significant in ATP production as it is the stage where the most ATP is generated. It involves the transfer of electrons through a series of protein complexes in the mitochondrial inner membrane or the plasma membrane of prokaryotes, ultimately leading to the production of ATP.

How does the process of glycolysis take place in different types of cells?

Glycolysis, the initial breakdown of glucose to pyruvate, occurs in the cytoplasm of both eukaryotic and prokaryotic cells. However, the subsequent steps of cellular respiration, such as the citric acid cycle and the electron transport chain, occur in the mitochondria of eukaryotic cells and in the cytoplasm and plasma membrane of prokaryotic cells.

What is the outcome of anaerobic metabolism in bacteria?

The outcome of anaerobic metabolism in bacteria is the production of lactic acid or other fermentation products, depending on the type of bacteria. Unlike in humans, where lactic acid can be recycled by the liver, bacteria do not have this capability and simply produce these byproducts.

Which human tissues might anaerobic bacteria inhabit?

Anaerobic bacteria might inhabit human tissues that are not exposed to oxygen, such as the bladder. This is because these bacteria do not require oxygen for metabolism and would not be able to survive in oxygen-rich environments.

What is the final electron acceptor in aerobic respiration?

The final electron acceptor in aerobic respiration is oxygen. It is required at the end of the electron transport chain to complete the process of oxidative phosphorylation and ATP production.

Outlines

00:00

🌱 Microbial Metabolism and Energy Utilization

This paragraph introduces the concept of microbial metabolism, focusing on energy production and utilization in both prokaryotic and eukaryotic cells. It explains the difference between autotrophs, which can produce glucose from carbon dioxide through photosynthesis, and heterotrophs, which rely on other organisms for their carbon source. The importance of the carbon cycle between these two types of organisms is highlighted, as well as the impact of deforestation on global warming due to the reduction in oxygen production. Metabolism is defined as the sum of all chemical transformations in a cell, driven by enzyme-catalyzed reactions forming metabolic pathways. The paragraph also distinguishes between catabolism, the energy-releasing breakdown of molecules, and anabolism, the energy-requiring synthesis of complex molecules from simpler ones.

05:02

🔋 Cellular Respiration and Energy Conversion

The second paragraph delves into cellular respiration, which is the process of producing ATP, the energy currency of the cell. It explains the cycle between ATP and ADP, highlighting that energy is released when ATP is broken down and required when ADP is converted back to ATP. The paragraph differentiates between aerobic respiration, which occurs in oxygen-rich environments and requires oxygen as the final electron acceptor, and anaerobic respiration, which occurs in the absence of oxygen and uses an inorganic molecule as the final electron acceptor. Glucose is identified as a crucial energy molecule, with three main fates: storage, oxidation through glycolysis, and oxidation via the pentose phosphate pathway, which is essential for nucleic acid synthesis.

10:05

🚀 Glucose Metabolism and Its Pathways

This paragraph explores the various pathways of glucose metabolism, emphasizing the three possible outcomes for glucose: storage, oxidation, and the pentose phosphate pathway. It discusses the fermentation process in yeast, which can produce ethanol, and contrasts this with anaerobic and aerobic respiration in bacteria. The paragraph outlines the three stages of aerobic metabolism: glycolysis, the citric acid cycle, and oxidative phosphorylation, which ultimately produce carbon dioxide and water. The efficiency of ATP production through these pathways is also discussed, with aerobic respiration being the most efficient.

15:10

🌿 Metabolism in Eukaryotic and Prokaryotic Cells

The fourth paragraph compares the metabolism processes in eukaryotic and prokaryotic cells. It explains that glycolysis occurs in the cytoplasm of both cell types, while the citric acid cycle and the electron transport chain take place in different locations: the mitochondria for eukaryotes and the cytoplasm or plasma membrane for prokaryotes. The paragraph also touches on anaerobic metabolism, which does not require oxygen and results in the production of lactic acid in humans and other byproducts in bacteria. The human body's ability to utilize anaerobic metabolism for short periods, as seen in sprinters, is also mentioned.

20:10

🌐 Electron Transport Chain and Cellular Respiration

The final paragraph wraps up the discussion on microbial metabolism by focusing on the electron transport chain's role in eukaryotic cells, which occurs on the inner mitochondrial membrane, and in prokaryotic cells, which occurs on the plasma membrane. It also prompts reflection on where anaerobic and aerobic bacteria might reside in the human body, based on the presence or absence of oxygen in different tissues. The paragraph concludes by reinforcing the efficiency of aerobic respiration in ATP production compared to anaerobic respiration and fermentation.

Keywords

💡Microbial Metabolism

Microbial metabolism refers to the set of chemical processes that occur within microorganisms to maintain life. It is central to the video's theme as it discusses how different types of microorganisms—prokaryotic and eukaryotic—generate and utilize energy. The script explains that microbial metabolism is divided into two main processes: catabolism, which breaks down molecules to release energy, and anabolism, which builds complex molecules from simpler ones, requiring energy.

💡Autotrophs

Autotrophs are organisms that can produce their own food from inorganic substances, specifically carbon dioxide, using energy from sunlight or chemical reactions. In the context of the video, autotrophs are highlighted as photosynthetic organisms that convert atmospheric carbon dioxide into glucose, which is a crucial process for the carbon cycle and a key energy source for other organisms.

💡Heterotrophs

Heterotrophs are organisms that cannot produce their own food and must obtain it from other organisms, typically in the form of complex organic molecules like glucose. The script emphasizes that heterotrophs rely on the products of other organisms for their carbon and energy needs, illustrating the interdependence between autotrophs and heterotrophs in the ecosystem.

💡Photosynthesis

Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesize foods with the help of chlorophyll pigments. The video script explains that most autotrophs are photosynthetic, obtaining energy from the Sun and using carbon dioxide from the atmosphere to produce glucose, which is vital for their survival and for the carbon cycle.

💡Catabolism

Catabolism is the process of breaking down complex molecules into simpler ones, releasing energy in the process. The script describes catabolism as a key component of metabolism where organic nutrient molecules are converted into smaller end products, which is essential for energy production in both autotrophic and heterotrophic organisms.

💡Anabolism

Anabolism is the set of metabolic processes that construct complex molecules from simpler ones, requiring energy. In the script, anabolism is contrasted with catabolism and is shown as necessary for the synthesis of biomolecules like lipids, proteins, and carbohydrates, which are fundamental to the structure and function of cells.

💡Cellular Respiration

Cellular respiration is the process by which cells convert biochemical energy from nutrients into adenosine triphosphate (ATP) and then release waste products. The script explains that cellular respiration is a critical process for energy production, involving the breakdown of glucose to produce ATP, which is used by the cell for various functions.

💡ATP

ATP, or adenosine triphosphate, is the primary energy currency of the cell. The script mentions ATP as the molecule that stores and transfers energy within cells. It is produced during cellular respiration and is used to power various cellular processes, highlighting its importance in the energy dynamics of the cell.

💡Aerobic Respiration

Aerobic respiration is the process of converting glucose and oxygen into carbon dioxide, water, and energy in the presence of oxygen. The script describes aerobic respiration as occurring in bacteria that live in oxygenated environments, emphasizing the requirement of oxygen as the final electron acceptor in the process.

💡Anaerobic Respiration

Anaerobic respiration is a type of cellular respiration that occurs without oxygen. The script explains that anaerobic bacteria live in environments without oxygen and use an inorganic molecule other than oxygen as the final electron acceptor, illustrating the diversity of metabolic pathways in different microorganisms.

💡Glycolysis

Glycolysis is the metabolic pathway that converts glucose into pyruvate, releasing energy in the form of ATP. The script describes glycolysis as the first stage of cellular respiration, occurring in the cytoplasm, and as a crucial step in breaking down glucose whether the process is aerobic or anaerobic.

💡Citric Acid Cycle

The citric acid cycle, also known as the Krebs cycle or TCA cycle, is a series of chemical reactions that generate energy through the oxidation of acetyl-CoA derived from carbohydrates, fats, and proteins. The script mentions the citric acid cycle as the second stage of aerobic respiration, taking place in the mitochondria of eukaryotic cells or the cytoplasm of prokaryotic cells, and as a key process in energy production.

💡Oxidative Phosphorylation

Oxidative phosphorylation is the process of producing ATP using electrons from the citric acid cycle and oxygen as the final electron acceptor. The script describes oxidative phosphorylation as the final stage of aerobic respiration, occurring in the mitochondrial inner membrane of eukaryotic cells or the plasma membrane of prokaryotic cells, and as the primary source of ATP production.

💡Fermentation

Fermentation is an anaerobic metabolic process that converts sugar to acids, gases, or alcohol, depending on the organism and substrate. The script discusses fermentation as an alternative pathway for energy production in yeast and some bacteria when oxygen is not available, resulting in the production of different end products like ethanol.

Highlights

Lecture discusses microbial metabolism, focusing on energy production and utilization in prokaryotic and eukaryotic cells.

Differentiation between autotrophs, which use carbon dioxide for photosynthesis, and heterotrophs, relying on organic molecules for carbon.

The interdependence of autotrophs and heterotrophs in the carbon cycle, emphasizing the ecological impact of deforestation.

Definition and explanation of metabolism as the sum of chemical transformations in a cell, driven by enzyme-catalyzed reactions.

Catabolism and anabolism as opposing processes of energy release and synthesis, respectively.

Cellular respiration defined as the production of ATP, the energy currency of the cell.

Aerobic respiration requires oxygen and is essential for energy production in oxygen-rich environments.

Anaerobic respiration occurs in oxygen-deprived environments, with inorganic molecules as electron acceptors.

Glucose as the primary energy molecule, with roles in storage, oxidation, and pentose phosphate pathway.

Glycolysis, the initial breakdown of glucose into pyruvate, as a key step in energy production.

The pentose phosphate pathway's role in nucleic acid synthesis and its importance in producing ribose sugars.

Glucose storage in animals as glycogen and in plants as starch, highlighting different storage mechanisms.

The three possible fates of glucose: fermentation, anaerobic respiration, and aerobic respiration.

Aerobic metabolism's three stages: glycolysis, citric acid cycle, and oxidative phosphorylation.

Differences in the location of metabolic processes between eukaryotic and prokaryotic cells.

Anaerobic metabolism's production of lactic acid, contrasting it with aerobic metabolism's production of CO2 and H2O.

Examples of human tissues where anaerobic bacteria can live, such as the bladder, due to lack of oxygen exposure.

The location of the electron transport chain in eukaryotic cells, occurring on the inner mitochondrial membrane.

The efficiency comparison of ATP production between aerobic, anaerobic, and fermentation pathways.

Transcripts

[Music]

[Music]

in this lecture we're going to talk

about microbial metabolism and that's

generation or production of energy as

well as utilization of energy in both

the prokaryotic cells and the eukaryotic

cells so organisms in carbon it depends

as we discussed earlier on whether or

not the organism can utilize directly

carbon dioxide or if organisms rely on

the production from of carbon from other

organisms so the autotrophs are the

organisms that engage in photosynthesis

and they use carbon dioxide from the

atmosphere as their source of carbon and

they're they're able to produce glucose

from the atmospheric carbon in the

presence of sunlight so most autotrophs

are photosynthetic and they actually

obtain their energy from the Sun now the

heterotrophs on the other hand those are

the organisms that rely on the

production of glucose from or the

production of carbon for that matter

from other organisms that is they cannot

use atmospheric carbon dioxide they must

obtain their carbon from the environment

mostly in the form of complex organic

molecules called glucose those are the

simple form of carbohydrate and they

must so they're by definition they

subsist on the products of other

organisms so carbon hydrogen oxygen and

water are constantly cycled between the

heterotopic and the autotrophic worlds

and in this slide you can say that

basically both are dependent on one

another

so the autotrophs cannot produce glucose

unless they have carbon dioxide that is

expired or during respiration we all

exhale carbon dioxide and that is what

is used by the autotrophs to produce

oxygen and glucose so for instance with

the global warming crisis one of the

drivers of the possibility that we are

undergoing global warming is the cutting

down of all these forests so when we

remove the capacity to produce oxygen of

course then that's a serious problem and

the plants also they're dependent on the

carbon dioxide that's produced by the

heterotrophs

and we certainly have an overabundance

of carbon dioxide because the cars

produce carbon dioxide as well so

metabolism now just so that we get our

terms

understood metabolism is the sum of all

chemical transformations that occur in a

cell or in an organism and that these

chemical reactions are all if not or

most if not all driven by a series of

enzyme catalyzed reaction and that these

reactions constitute the metabolic

pathway now catabolism is the

degradation or the breakdown of

metabolism where organic nutrient

molecules are converted into smaller and

simpler end products and the process of

catabolism releases energy

the term anabolism is the opposite of

catabolism and that's synthesis so

that's actually taking small molecules

and building them up into larger more

calm

flex ones and as we have been learning

throughout the lectures the three

biomolecular

groups of molecules the lipids proteins

and carbohydrates all start out in

simpler forms and then go through

anabolism where energy is required for

these simpler molecules to become more

complex so cellular respiration is

defined as the production of ATP and ATP

is utilized in terms of producing energy

so when ATP first of all when ATP is

broken down into ADP we get energy so in

order to produce ATP from ADP it

requires energy so we're constantly

cycling back and forth between these two

forms of energy molecules and when

they're broken down energy is released

and when they're built up when that

extra phosphate is added to ADP then

that requires energy

so aerobic respiration is occurs in

bacteria that live in environments with

oxygen so they live in oxygenated

environments and in order for this

energy production to occur oxygen is

required and the reason for that is at

the end of the reaction oxygen is the

electron acceptor now anaerobic

respiration occurs in bacteria that live

in environments without oxygen and in

fact oxygen will kill or eradicate these

anaerobic bacteria so the final electron

acceptor for those bacteria is an

inorganic not a molecule that is not

oxygen

so glucose is the most important energy

carbohydrate molecule I call it a

currency molecule it's the molecule

that's exchanged between plants and

animals it's the molecule that flows in

our bloodstream and provides energy to

all of our cells and it it is the

molecule as I explained that is also the

building block molecule in plants so

glucose has three major outcomes it can

be stored it can be glucose can be

oxidized and now oxidized is another

word for being broken down and it can be

oxidized or broken down into pyruvate

and that process is called glycolysis

we'll have a little more in-depth

discussion about that and ultimately

glucose will be turned into ATP and then

other metabolic intermediates glucose

can be oxidized by the pentose phosphate

pathway now you're wondering what is

that well actually that's the pathway

that produces the nucleic acids now

during our discussion about the DNA and

RNA the backbone of the DNA molecule

remember DNA has like a ladder so the

backbone of that molecule are all ribose

which are sugar molecules and in order

to produce those molecules we need to go

through this pentose phosphate pathway

so basically this is a synthesis of what

I just said which is glucose can get

stored and in animals it's stored in the

form of glycogen and in plants it's

stored in the form of star

okay now glucose can also go down and be

oxidized or broken down into pyruvate

or glucose can be oxidized via the

pentose phosphate pathway now it's

important to get a clear sense about

terminology so remember we talked about

catabolism earlier so catabolism is just

another word for oxidation okay and

anabolism is another word for synthesis

which is another word for being broken

down or for being built up so I like to

make sure that students understand that

these terms can are basically mean very

similar things and sometimes that one

can get confused by it all and and the

intention isn't to do that it's just the

way in which terms are used now the

other that reminds me the other word for

anabolism is reduction and that's used

in a more chemical sense so reduction is

actually the opposite of oxidation okay

so also the glucose pathway can further

go into glycolysis and the citric acid

cycle so here there are three directions

so to speak that glucose can go through

in terms of being broken down so glucose

can be fermented into ethanol in yeast

it can actually undergo anaerobic

respiration over here or glucose can

undergo aerobic respiration

now the Arabic pathways the more common

one and this pathway

generally produces much more ATP than

the anaerobic pathway and the reason for

this is very complex biochemically and

we'll review that in another lecture

but basically pyruvate goes through the

glycolysis or glucose goes through

glycolysis to pyruvate which then goes

through the citric acid cycle and then

oxidative phosphorylation until we get

to our ultimate end product which again

is member co2 and water so aerobic

metabolism to really review these two

more specifically occurs in three stages

there's glycolysis which is glucose

going to pyruvate

there's citric acid cycle where we get

formation of a settle Cowen's i'm a and

then the final stage is oxidative

phosphorylation so in summary this is

what we have we have glucose plus oxygen

being produced to yield carbon dioxide

and water

now here's another picture in more

detail of aerobic metabolism so you'll

see again that we go through this

process called glycolysis and we produce

pyruvate then pyruvate gets turned into

a settle Cowen's i'm a and the settle

coenzyme a travels through the citric

acid cycle which then ultimately yields

or comes to this oxidative

phosphorylation stage some people call

it the respiratory electron transport

chain and this is the part where ATP is

produced now everything below this place

here this process all

occurs in the mitochondria whereas the

glycolysis process occurs in the

cytoplasm and as I said before this

process is a lot more direct and

produces a much larger amount of ATP so

it's a much more efficient way to

produce energy now this is a picture of

respiration and fermentation in terms of

bacteria and yeast

so remember yeast can produce energy

through fermentation and through

fermentation we get these other types of

products where pyruvate is our Peruvian

is carried by NADH which is an electron

transporter from glycolysis into

fermentation in products and that that

is different from respiration which

occurs in the presence of oxygen and

here we get the various processes where

we end up with the electron transport

chain which as you can see right here

requires oxygen to produce water so this

is actually at the very end stage and

here is our production of ATP now in

terms of thinking about carbohydrate

catabolism in terms of the different

eukaryotic and prokaryotic cells that

glycolysis occurs in the cytoplasm of

both types of cells the intermediate

acetylcholine a step occurs in the

cytoplasm of both cells the Krebs or

citric acid cycle as some other people

call it the Krebs cycle or citric acid

cycle occurs in the mitochondria of

periodic cells but occurs in the

cytoplasm of prokaryotes and this is a

short abbreviation for the electron

transport chain that occurs in the

mitochondrial inner membrane but occurs

in the plasma membrane of the

prokaryotic cells so anaerobic

metabolism on the other hand remembers

remember does not require oxygen and the

byproduct of lactic of our anaerobic

metabolism is lactic acid now in humans

that lactic acid can actually be

recycled back by the liver but in terms

of the bacteria they just produce lactic

acid and they go through their various

types of conversions but remember they

don't have a liver okay so they can't

undergo the same kind of process but

certainly they can exist in an anaerobic

environment and you know the truth is

humans for a very short time can also

undergo movement and energy production

and utilization also without oxygen but

we don't last very long the example

there is sprinters essentially mostly

rely on anaerobic metabolism but they

can only undergo anaerobic metabolism

for a very short time so here are the

different types of are the different

ways in which ATP can be produced so we

can produce ATP through photosynthesis

or photosynthetic pigments in

combination with light we can start with

glucose over here we generate ATP and

depending on the type of metabolism that

occurs we can have the electron carriers

at the end or nad p or nad or fa

and then we end up with oxygen or we

require oxygen in terms of that final

electron acceptor for aerobic

respiration we can exist on other

molecules for anaerobic or fermentation

we have an organic compound so our first

example which cellular respiration

pathway is the most efficient at

producing ATP is an aerobic anaerobic or

fermentation well the answer is as we

talked about throughout the discussion

today

the answer is aerobic but we can

certainly produce ATP by these other

pathways we just don't get as much of it

what kinds of human tissue do you think

anaerobic bacteria live in so to answer

this question you really need to think

about what parts of the human body are

not exposed to oxygen well how about an

example great example there is the human

bladder so we have bacteria so for

instance if we have a urinary tract

infection

that bacteria is often anaerobic if you

can imagine bacteria living in human

bladder that bacteria is not going to

get exposed to oxygen at all really but

what about aerobic bacteria well that

one isn't as challenging to think about

number one what is the tissue exposed to

oxygen number one is the respiratory

tract well guess what pneumonia I think

what do you think

I think pneumonia is an aerobic bacteria

so sometimes with these questions you

may not remember the exact bacteria

whether it's anaerobic or aerobic

but you can think about what tissue does

it infect and what tissue doesn't live

in and lo and behold maybe you can take

a very educated guess so the third

example has to do with where does the

electron transport chain occur in the

eukaryotic cell

well the eukaryotic cell is very lucky

because it has this wonderful organelle

called the mitochondria now remember

we've talked about the mitochondria

several times in these lectures and not

only does the mitochondria have this

wonderful outer membrane but it also has

an inner compartments or compartments

and there is an inner space and actually

that last stage is occurring on the

inner mitochondrial membrane

now unfortunately the prokaryotic cell

is not that lucky and that cell has to

have that same function go on in the

plasma membrane so here in the

prokaryotic cell the actual last stage

that oxidative phosphorylation electron

transport occurs in the inner lining of

the plasma membrane so that concludes

our discussion about microbial

metabolism thank you very much for

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