Microbial Nutrition - Microbiology & Chemistry Program PDF

##### Microbial Physiology BOT 432  ##### What is microbial physiology? - An understanding of cell structure, growth factors, metabolism, and - Introduces the inter-relatedness of microbiology, and biochemistry, in the context of a functioning microbial cell - The...

##### Microbial Physiology BOT 432  ##### What is microbial physiology? - An understanding of cell structure, growth factors, metabolism, and - Introduces the inter-relatedness of microbiology, and biochemistry, in the context of a functioning microbial cell - The study of the mechanical, physical, and biochemical functions of  Growth of any organism ====================== - ### Available source of chemicals to use as nutrients - **Uptake of nutrients** - ### Suitable physical environment 4  ### Expected Learning Outcomes - - **Differentiate between organic and inorganic nutrients.** - - **Describe the main categories of nutritional types (patterns)among organisms.** - - **Distinguish between the energy and carbon sources for the four nutritional classes of microorganisms**. - - **Discuss diffusion and passive transport systems.** - **Describe the features of active transport and differentiate among its mechanisms.**  The Nutrition ============= #### Process by which chemical substances called nutrients are acquired from the environment and used in cellular activities such as metabolism and growth   ##### Microorganisms require ##### nutrients  - **Carbon = C** - **Hydrogen = H** - **Oxygen = O** - **Nitrogen = N** - **Phosphorus = P** - **Sulfur = S** - **Potasium = K** - **Calcium = Ca** - **Magnesium = Mg** - **Iron = Fe**  - **Manganese = Mn** - **Zinc = Zn** - **Cobalt = Co** - **Molybdenum = Mo** - **Nickel = Ni** - **Copper = Cu [ ]**  #### Determined in the laboratory.  ##### Chemical Analysis of Cell Contents ###### List is a brief summary of some nutritional patterns in the intestinal bacterium **Escherichia coli**. - **Water content** is the highest of all components (**70%**). - About **97%** of the dry cell weight is composed of **organic compounds** - **Proteins** are the most prevalent organic compound. - Chemical **elements** are needed in the overall scheme of cell growth, but most of them are available to the cell as **compounds** and not as pure elements.  ##### The source of nutrients is extremely varied  -    - Nutritionally dependent on other life forms, Because organic carbon usually originates from organisms. - Among the common organic molecules that can satisfy this requirement are **proteins**, **carbohydrates**, **lipids**, and **nucleic acids**. In most cases, **these nutrients provide several other elements** as well. - Not all heterotrophs can use the same organic carbon sources. - Some organic nutrients already exist in a form that is **simple enough for absorption** (for example, monosaccharides and amino acids), but many larger molecules **must be digested** by the cell before absorption.  - Organisms harvest the energy of **light** are called - Organisms obtain energy by metabolizing **chemical compounds** (oxidized organic or inorganic) are called **Chemotrophs** - Organisms can use reduced inorganic compounds as electron donors are called **Lithotrophs** - Chemolithotrophs and Photolithotrophs - Organisms can use organic compounds as electron donors are called **Organotrophs** - Chemoorganotrophs and Photoorganotrophs.     1. ### Amino acids - Required for the synthesis of proteins 2. ### Purines and pyrimidines - Required for synthesis of nucleic acids (DNA and RNA) 3. ### Vitamins - #### Needed as coenzymes and functional groups of certain enzymes  - ###### **E.coli** does not require any growth factors (need med. contain only glucose and 6 different inorganic salts) - **Neisseria** require at least 40 additional ingredients, including 7 ###### -i.e have complex nutrient requirements - **Enterococcus faecalis** needs 8 different vitamins for growth. ###### Many microorganisms are able to synthesize large quantities of vitamins needed for human use. - **Vitamin C** produced by **Corynebacterium** - **Vitamin B12** by **Streptomyces, Pseudomonas** - **Vitamin D** by **Saccharomyces** - **β-carotene** by **Dunaliella** (genus of algae) - **Riboflavin (B2)** by **Clostridium, Candida**   +-----------------------+-----------------------+-----------------------+ | **Photoautotroph** | | - | | | | | | (Photolithotroph) | | | | | | | | ***Primary | | | | producers*** | | | +=======================+=======================+=======================+ | **Photoheterotroph** | | - | | | | | | (Photoorganotroph) | | | +-----------------------+-----------------------+-----------------------+ | **Chemoautotroph** | | - - - - - | | | | | | **(**Chemolithotroph* | | | | *)** | | | | | | | | ***Primary producers | | | | in inhospitable | | | | environments*** | | | +-----------------------+-----------------------+-----------------------+ | **Chemoheterotroph | | | | (**Chemoorganotroph** | | | | )** | | | +-----------------------+-----------------------+-----------------------+ Photoautotroph Photoheterotroph Chemoautotroph - **Saprobes : are free-living microorganisms** that feed primarily on organic detritus from dead organisms - **Parasites derive nutrients from the cells or** tissues of a host. Light \+ H2O Light   - **Grow on dead organic remains of plants or animals. They decompose and decay organic remains into simpler compounds with the help of a variety of enzymes ([decomposers])** ##### - Parasites  - ##### - Symbionts - - **Symbionts, which live in close association with a host, often depend on organic compounds from their host for their energy and carbon sources for survival.**  - **Parasites** grow **in or on the body** of a host, which they **harm** to some degree. - **Parasites** can damage tissues (disease) or even cause death; - **Parasites** range from viruses to helminth worms, - **Parasites** can live 27 Species usually belongs in **only one** of the nutritional classes   - **Taken into the cell (**required nutrients) Transport **waste materials** - **Out of the cell** (into the environment). - - Cell wall (bacteria, algae, and fungi) is usually only a **partial, nonselective barrier (**organisms with **cell walls-**bacteria, algae, and fungi)  1. ### Passive transport (di - **Osmosis (water)** ##### Diffusion - **Diffusion (small molecules)** ### Active transport - \ Simple diffusion - **Facilitated diffusion**   - Means that the cell does not expend extra **energy** for - Follows physical laws - 2nd law of thermodynamics (not unique to living systems)- - The **inherent energy** of the molecules moving down a gradient does the work of transport   #####  Diffusion - **Diffusion** is a driving force in cell activities - Its effects are greatly controlled by  - Small molecules can pass **through** the cell membrane by a process called **diffusion** - Diffusion across a membrane does **not require energy** - The difference in the concentration of molecules across a membrane is called a **concentration gradient.** - Diffusion always occurs **down a concentration gradient** (from an area where it is more concentrated to an area where it is less concentrated) - ###### Diffusion **continues** until the concentration of the molecules is the same on both sides of a membrane   - The **rate of diffusion** depends on temperature, surface area, size of particles & type of molecules diffusing - Molecules **diffuse faster** at higher temperatures than at lower temperatures- called "**Thermal movement**" - Smaller molecules **diffuse faster than** larger molecules - Diffusion is driven by the **kinetic energy** of the molecules. - **Kinetic energy** keeps molecules in constant motion causing the molecules to move randomly away from each other in a liquid or a gas    ### Adaptations to Osmotic Variations in the Environment - **Bacteria** & **Algae** have a **cell wall** protects them from bursting even as the cytoplasmic membrane becomes **turgid** from pressure. - The **amoeba** has no cell wall to protect it, so it must expend - **Halobacteria** living in the Great Salt Lake and the Dead Sea - **Absorb salt** to make their cells isotonic with the environment; - Thus, they have a physiological need for a high salt concentration in their habitats  Simple Diffusion {#simple-diffusion-1} ---------------- (through phospholipid bilayer)  These molecules can diffuse right through the membrane\'s **lipid**   Facilitated Diffusion ---------------------   Facilitated Diffusion --------------------- - Diffusion across selectively permeable membranes **by** various types of proteins , sometimes called , which are embedded in the **plasma membrane**. - While there are hundreds of different proteins throughout the cell, only two types are found associated with facilitated diffusion: **channel proteins** and **carrier proteins.**  Facilitated Diffusion --------------------------------------------------------------------- 1. **Channel proteins** provide hydrophilic passageways, typically are used to transport **ions** in and out of the cell through "**porins**" ion channels 2. **Carrier proteins** transport molecules by changing their shape to move a specific molecule across the membrane. ie. **glucose, amino acids, nucleotides**  ### Active transport - Live in habitats characterized by **very dilute nutrient** sources - Exist under relatively **nutrient-starved conditions**  rate faster than by diffusion alone Presence of specific membrane proteins (-   pes o**Mi**f**cro**T**bia**r**l** a**Ph**n**ysi**s**olo**p**gy**o**--** r**Mi**t**crobiology & Chemistry program -- Prof Abeer A. Rushdy** 45  - ### Active transport systems - ##### Carrier-mediated active transport - **Group translocation system** - ##### ATP-binding cassette transporters (ABC transporters) - **Cotransport system**  - Specific membrane proteins that bind both ATP and the molecules to be transported. - Release of energy from the ATP drives the movement of - This can occur in either direction.  - A molecule is transported into the cell while being **chemically modified**. - **Couples** the transport of a nutrient with its conversion to a substance that is immediately useful inside the cell***.*** - Used primarily for the transport of sugars.  - ##### Important examples of active transport systems. - **Observed in Bacteria, Archaea, and eukaryotes**  - The **target solute** binds to **a soluble cassette protein** - Then interact with the **membrane transport proteins** to move the solute molecule inside the cell. - The cytoplasmic **ATP-hydrolyzing protein** supplies the energy for the transport event. **soluble cassette protein**   - If the two molecules are transported in the same direction it is called **symport** - If the two molecules are transported in opposite directions it is called **antiport**  ### Cytosis - #### Endocytosis  - Exocytosis  - Some cells can transport large molecules, particles, liquids, or even other cells **across the cell membrane**. - Because the cell usually **expends energy** to carry out this movement, it is also a form of **active transport**. - The substances transported do not pass physically through the membrane but are carried into the cell by **endocytosis.**  #### Bulk transport - First the cell encloses the substance in its membrane, simultaneously - **Amoebas and certain white blood cells** ingest whole cells or large solid matter by a type of endocytosis called **phagocytosis** "cellular eating"**.** - **Liquids, such as oils or molecules** in solution, enter the cell