Microbial Nutrition and Growth PDF

Microbial Nutrition Inorganic nutrient: - An atom or simple m...

Microbial Nutrition Inorganic nutrient: - An atom or simple molecule that contains a combination of Microbial Nutrition & atoms other than carbon. Growth - Found in the crust of the earth, bodies of water, and the atmosphere. Organic nutrients: - Contain carbon and hydrogen atoms and are the products of living things - Simple organic molecules such as methane - Large polymers (carbohydrates, lipids, proteins, nucleic acids) Copyright © McGraw-Hill Education. Permission required for reproduction or display. 1 Microbial Nutrition Chemical Analysis of the Microbial Essential nutrient: any substance that must be provided to an organism. Cytoplasm Macronutrients: required in relatively large Water – 70% of all components quantities and play principal roles in cell Proteins structure and metabolism Organic compounds – 97% of dry cell weight - Carbon, hydrogen, and oxygen Elements CHONPS – 96% of dry cell weight Micronutrients: also known as trace elements Most chemical elements available to the cell as - Present in much smaller amounts and are involved in compounds and not as pure elements enzyme function and maintenance of protein structure Only a few types of nutrients needed to synthesize - Examples: manganese, zinc, nickel over 5,000 different compounds  Chemicals What Microbes Eat Autotrophs and their Energy Sources Heterotroph: an organism that must obtain its carbon in an organic form  Photoautotrophs: Autotroph: an organism that uses inorganic CO2 as its - Photosynthetic: carbon source Produce organic molecules using CO2 - Has the capacity to convert CO2 into organic compounds  Chemoautotrophs: - Not nutritionally dependent on other living things - Chemoorganic autotrophs: use organic compounds for energy Phototroph: microbes that photosynthesize and inorganic compounds as a carbon source - Lithoautotrophs: use the inorganic carbon as carbon source and Chemotroph: microbes that gain energy from chemical inorganic minerals as energy source. compounds Heterotrophs and Heterotrophs and Their Energy Sources Their Energy Sources Parasites: Chemoheterotrophs: - Derive nutrients from the cells or tissues of a - Derive both carbon and energy from organic living host compounds - Pathogens: cause damage to tissues or even - Process these molecules through respiration or death fermentation - Range from viruses to helminths Saprobes: - Ectoparasites: live on the body - Free-living organisms that feed on organic detritus from dead organisms - Endoparasites: live in the organs and tissues - Decomposers of plant litter, animal matter, and - Intracellular parasites: live within cells dead microbes - Obligate parasites: unable to grow outside of - Recycle inorganic nutrients a living host Concept Check Which of the following terms describes an organism that derives its energy and carbon from organic molecules? A. Photoautotroph B. Chemoheterotroph C. Lithoautotroph D. Chemoautotroph E. Photoheterotroph Other Important Nutrients The Movement of Water: Osmosis Sodium (Na): important for certain types of cell transport. Osmosis: the diffusion of water through a Calcium (Ca): stabilizer of cell wall and endospores of selectively, or differentially, permeable bacteria. membrane Magnesium (Mg): component of chlorophyll and a - Has passageways that allow free diffusion of water, stabilizer of membranes and ribosomes. but block certain other dissolved molecules Iron (Fe): important component of the cytochrome - When the membrane is placed between solutions of proteins of cell respiration. differing concentrations of solute and the solute Zinc (Zn): essential regulatory element for eukaryotic cannot pass through the membrane, water will genetics. diffuse at a faster rate from the side that has more water to the side that has less water. - This will continue until the concentration of water is equalized on both sides of the membrane. How Microbes Eat: Transport Mechanisms Transport of necessary nutrients occurs across the cell membrane, even in organisms with cell walls. The driving force of transport is atomic and molecular movement. Diffusion: the phenomenon of molecular movement, in which atoms or molecules move in a gradient from an area of higher density or concentration to an area of lower density or concentration.  Isotonic versus Hypertonic solution Osmosis versus Diffusion Effects of Osmosis on Bacterial Cells  Endocytosis: Eating and Drinking By Cells Endocytosis: - Cell encloses the substance in its membrane - Simultaneously forms a vacuole and engulfs the substance Phagocytosis: - Accomplished by amoebas and white blood cells - Ingest whole cells or large solid matter Pinocytosis: – Ingestion of liquids such as oils or molecules in solution Active Transport Microbial interaction Active transport: - The transport of nutrients against the diffusion gradient or in the  In all but the rarest instances, microbes live in same direction as the natural gradient, but at a rate faster than by shared habitats: diffusion alone - The presence of specific membrane proteins (permeases and pumps)  Associations between similar or dissimilar - The expenditure of energy types of microbes. Examples of substances transported actively: monosaccharides, - Associations with multicellular organisms, such amino acids, organic acids, phosphates, and metal ions as animals or plants. - Interactions can be beneficial, harmful, or have The key difference between active and passive transport is that active no particular effect. transport forces molecules to cross the membrane with help of ATP - Interactions can be obligatory or non- energy whereas passive transport let the molecules to pass across the membrane through a concentration channel, requiring no cellular energy. obligatory to the members. - Often involve nutritional interactions. Strong Partnerships: Symbioses Associations But Not Partnerships Symbiosis: a general term to denote a situation in which two organisms live together in a close Synergism: partnership – An interrelationship between two organisms that is beneficial - Symbionts: members of a symbiosis to them but is not necessary for survival. Three main types of symbiosis occur: – Together the participants cooperate to produce a result that none of them could do alone. - Mutualism: organisms live in an obligatory but mutually – Dental caries, and some bloodstream infections involve mixed beneficial relationship. infections that are examples of bacteria interacting - Commensalism: the partner called the commensal synergistically. receives benefits, while its partner is neither harmed nor benefitted. - Parasitism: a relationship in which the host organism provides the parasitic microbe with nutrients and a habitat; parasite usually harms the host to some extent. Associations But Not Partnerships Biofilms: The Epitome of Synergy  Antagonism: an association between free-living species that arises when members of a Mixed communities of bacteria and other microbes that are community compete attached to a surface and to each other. Formation of a biofilm: - Antibiosis: the production of inhibitory compounds such as antibiotics into the surrounding – A “pioneer” colonizer initially attaches to a surface. environment that inhibit or destroy another microbe in – Other microbes then attach to those bacteria or a polymeric sugar or protein substance secreted by the microbial colonizers. the same habitat. – Attached cells are stimulated to release chemicals as the cell population - The first microbe has a competitive advantage by grows. increasing the space and nutrients available to it. - Common in the soil where mixed communities compete for space and food. Biofilms: The Epitome of Synergy Methods to control microbial growth  Sterilization: A treatment that kills or removes all  Quorum sensing: used by bacteria to interact living cells, including viruses and spores, from a with members of the same species as well as substance or object. members of other species that are close by  Structure of the biofilm:  Disinfection: A treatment that reduces the total - Large, complex communities form with different number of microbes on an object or surface, but does physical and biological characteristics. not necessarily remove or kill all of the microbes - The bottom may have very different pH and oxygen (Chlorination). conditions than the surface. - Cannot be eradicated by traditional methods  Sanitation: reduction of the microbial population to levels considered safe by public health standards (e.g. clean drinking water.) Physical and Chemical factors Methods to control microbial growth controlling microbial growth  Many microorganisms are beneficial, some are harmful.  Microbial activities- food spoilage and disease. Introduced concept of microbial control.  Microbial growth is controlled by physical and chemical methods.  These methods can kill or inhibit growth Methods to control microbial growth Physical methods for control of microbial  Antimicrobial agent: Agent kills microorganisms or growth inhibit their growth.  Antiseptic: A mild disinfectant agent suitable for use on  Heat skin surfaces.  Temperature  Germicide (e.g. Bactericide): “the agent kills” microbes. For example, a bactericide agent kills bacteria, fungicide,  Desiccation virucide, sporocide.  Osmotic pressure  Bacteriostatic: “the agent inhibits growth”. For  Filtration example, a bacteriostatic agent inhibits the growth of bacteria, but doesn’t necessarily kill it. (refrigeration).  Radiation  Degerming: Removal of microbes in a limited area. Physical methods for control of microbial Heat growth Kills microbes by denaturing enzymes. Damaging cell components. Heat resistance varies among different microbes. Enzymes, DNA, Cytoplasmic membranes disrupted. Thermal Death Point (TDP)  Used in food industry. Thermal Death Time (TDT)  Preparation of culture media in the lab. Decimal Reduction Time (DRT)  Sterilization of instrument.  Thermal Death Point (TDP) Decimal Reduction Time Lowest temperature to kill all the bacteria (or microbes) in 10 minutes. Decimal Reduction Time (DRT or D-value) Boiling- Kills many vegetative cells. Length of time. Inactivates viruses within 10 minutes To achieve a log reduction to 90% of a bacterial population killed at a given temperature No effect on spores. Reduces the number of organisms to 1/10 the initial level. The D value is a measure of the heat resistance of a microorganism. It is the time in minutes at a given temperature required to destroy 1 log cycle (90%) of the target microorganism. Thermal Death Time Rate of Microbial Death  Bacteria usually die at a constant Rate.  Thermal death Time (TDT)  Plotted logarithmically, this will give a straight line. Time required to kill all the bacteria at a given temperature. Developed for food canning. Applications in cosmetics and pharmaceuticals.  Autoclaving Pasteurization Two different processes: High Temperature Short Time ( HTST ) process -72℃ for 15s ( Quick heating and cooling ). Ultra High Temperature (UHT) sterilization - heating at 140 ℃ for 3 seconds. Milk kept at room temperature for 2 months. Minimal changes in flavor. Autoclaving is the most effective method of sterilizing the lab equipment specially for liquid handling products to kill harmful bacteria, viruses, fungi, and spores. The autoclaving process takes advantage of the phenomenon that the boiling point of water (or steam) increases when it is under high pressure. Pasteurization Low Temperatures Decreasing temperature decreases chemical Process used in preserving heat sensitive activity. foods. Low Temperature are Not Bactericidal. Milk, beer, and other beverages. Restrict enzyme activity. 63℃ for 30 Minutes. Ordinary refrigerator Temperature 0 – 7℃. Wine – Pasteur Do not Reproduce. Milk – Survive, Restrict rate of growth. Reduction of microorganisms in milk. Use – Food preservation, Drug, Culture Pasteurization is not a method of preservation. sterilization.  Dry Heat Sterilization Hepa filters Direct Flaming – Burning contaminants Incineration – Burns and physically destroys organisms used for: Hepa filters – High-Efficiency Particulate A. Needles Air Filters B. Inoculating Wires Porous membrane – 0.1 mm thick C. Glassware Variety of pore size. D. Body parts Microorganisms sucked through thick layer. Hot Air Sterilization – oxidation 160℃ for 1 hour used for: Filtration of small particles. A. Objects That Won’t Melt B. Glassware Capture a minimum of 99.97% of 0.3 microns contaminants. C. Metal Filtration Hepa Filters  The passage of a liquid or gas through a filter with pores small enough to retain Filtration is the primary method of microbes. eliminating pathogens from the air supply.  Separate bacteria from suspending liquid. 1. Operating Rooms  Filter – Nitrocellulose. 2. Hospitals, Surgical Mask.  High efficiency particulate air filters. 3. Pharmaceutical Manufacturing Facilities.  Desiccation Radiation  Its Efficiency is dependent on the wavelength Removing water from microbes.  Intensity, and duration. Viruses & Endospores can resist. Two types: Disruption of metabolism. Ionizing Use – food preservation. ✓ Destruction of DNA by gamma rays & high energy electron Stops Growth/ Microbes are still viable. beams. ✓ Use – Freeze-drying (Lyophilization) – remove water from a specimen. Sterilizing pharmaceuticals medical & dental supplies. Powdered milk – 85% water is removed. Food preservation and other industrial processes. ✓ More penetrating. ✓ Food is exposed to high levels of radiation to kill insects, bacteria and mold. Osmotic pressure Non–ionizing radiation Plasmolysis (Hypertonic) High zone of salt & sugar. ✓ Damage to DNA by UV light. Salt – preservation of fish, meat, food. ✓ Poor penetration High osmotic pressure. ✓ UV radiation is only useful for disinfecting outer surfaces. Loss of H2O.  Chemical Control Methods Halogens  Can be Used Alone or in Solution. Phenols and phenolics  Inactivated by Sunlight Halogens  Alter cellular components.  Inactivate enzymes. Alcohols Chlorine Heavy Metals and Their Compounds ▪ Purifies Drinking Water Surface-Active Agents ▪ 2-4 drops of Chlorine per Liter / 30 Min Quaternary Ammonium Compounds ▪ Forms an Acid – hypochlorous acid – Bactericidal Chemical Food Preservatives ▪ Gaseous form or in Solution as Calcium Hypochlorite. Aldehydes ▪ Good disinfectants on clean surfaces. Antibiotics ▪ Inexpensive / Chlorox. ▪ Never Mix with Other Cleaning Agents Types of Disinfectants Halogens ❖ Phenols and Phenolics: - Exert Influence By :  Iodine 1. Injuring Plasma membranes Least toxic of the disinfectants. 2. Inactivating Enzymes - Inactivates Enzymes 3. Denaturing Proteins Iodophore Use – Skin surface, Environmental surface, Instruments, Mucous membranes. Betadine Phenolics are long lasting. Wound treatment. No Effect on Spores. Effective antibacterial agents, fungi and many viruses.  Alcohol Surface Active Agents Denature Proteins and Dissolve Lipids. Include Soaps and Detergents. Evaporates Soaps – Anionic detergents. Fast Acting Skin degerming. Wet Disinfectants : Triclocarban (antibacterial agent used in liquid Aqueous Ethanol ( 60% - 95% ) soaps and body washes) – inhibit gram positive bacteria. Not effective against endospore. Limited Germicidal Action. Use – Thermometer, Instruments, before injection swabbing skin. Removal of Organisms by Scrubbing. Heavy Metals Cationic Detergents Silver, Mercury – germicidal or antiseptic Quaternary Ammonium Compounds ( QUATS ) - Denature Proteins - Cationic Detergents Attached to NH - Mercuric chloride – Bacteriostatic - Disrupt Plasma Membranes Copper sulphate – destroy green algae in reservoirs. - Most Effective on Gram-Positive Bacteria Zinc chloride – ingredients in mouth washes. Enzyme inhibition, protein denaturation. Zinc oxide – anti fungal in paints. Fungicide, Amoebocide. Two popular QUATS – Zephiran. Cepacol – Anti microbial  Antibiotics Organic Acids  Used to preserve cheese. Chemical Food Preservatives  Used in feed Given to Food Animals. - Sorbic Acid  Can be bacteriostatic and bactericide. - Benzoic Acid Inhibit fungus  Can block bacteria's growth or reproduction - Propionic Acid - Nitrate and Nitrite Salts / Meats ▪ To prevent Germination of Clostridium botulinum endospores. ▪ Calcium Propionate - Bread Aldehydes Antimicrobial. Inactivate proteins. Formaldehyde – preserve biological specimens. Glutaraldehyde – Sterilize hospital instruments. Most Effective of all Chemical Disinfectants. Carcinogenic. Oxidize Molecules Inside Cells.