Types Of Bacterial Nutrition PDF

TYPES OF BACTERIAL NUTRITION Fastidious: complex nutritional requirement Ex: blood, thiosulfate, cysteine Non fastidious: basic nutritional requirements a. Carbon- for synthesis of cellular components Lithotrophs/autotroph...

TYPES OF BACTERIAL NUTRITION Fastidious: complex nutritional requirement Ex: blood, thiosulfate, cysteine Non fastidious: basic nutritional requirements a. Carbon- for synthesis of cellular components Lithotrophs/autotrophs- derives from inorganic substance Heterotrophs/organotrophs- derived carbon from organic substances (carbohydrate) b. Nitrogen- synthesis of proteins, RNA and DNA c. Ions and Minerals: Sulfur, magnesium, iron d. salt- for halophilic organism e. water and moisture- humidified incubators and sealing of agar plates BACTERIAL METABOLISM Metabolism defined as the sum of all chemical processes that take place in living organism and results in its growth, energy generation, waste disposal, and other functions in relation to cell nutrient and distribution. Anabolism- constructive phase Catabolism- destructive phase ENERGY PRODUCTION it is accomplished by the breakdown if chemical substrates through the degradative process of catabolism that is coupled with oxidation-reductio reactions. Glucose is an essential nutrient for energy production in organism. to produce energy from glucose, microorganism use two general processes: respiration and fermentation. Respiration it is an efficient ATP generating process in which molecules are oxidized and results in an inorganic molecule as the final electron acceptor in this process, glucose is completely broken down and results energy production it is carried out by the obligate aerobes and facultative anaerobes In an aerobic respiration, oxygen is the final electron acceptor, while anaerobic respiration, one of the exogenous substances, such as nitrite, sulfate, is the final electron acceptor Processes in Respiration 1. Glycolysis (Embden-Meyerhof-Parnas Pathway) It is the first stage in carbohydrate metabolism it is the oxidation of glucose to pyruvic acid it is the major route of glucose metabolism in most cells 2. Krebs Cycle (Tricarboxylic Acid or TCA) It is the most important process for the complete oxidation of a substrate under aerobic conditions. In this process, an enzyme system converts pyruvate into carbon dioxide and an acid this cycle is used to generate energy in the form of adenosine triphosphate The coenzyme for this process is the acetyl coenzyme A. Fermentation it does not require oxygen (anerobic process), the use of Krebs cycle, or an electron transport chain. it releases energy from sugar or other organic molecules, such as amino acids and purines  it forms a mixture of end products of lactate, butyrate, ethanol, and acetoin) in the medium, the analysis of these products is useful for the identification of anaerobic bacteria. it is carried out by obligate and facultative anaerobes. TYPE OF FERMENTAITON 1. Alcoholic Fermentation it turns sugar into ethanol and carbon dioxide 2. Homolactic Fermentation Pyruvate is reduced to lactate (Streptococcus and Lactobacillus), which is used to make yogurt, it means that only one acid is produce fermentation. 3. Heterolactic Fermentation this process produced substances other than lactate, such as alcohol, carbon dioxide, formic acid, and acetic acid 4. Mixed acid fermentation it involved the production of ethanol and acids, such as lactic, acetic, succinic, and formic acid it utilizes formic hydrogenolyses that converts formic acid into an equal amount of hydrogen and carbon dioxide. 5. Butanediol fermentation In this process, pyruvate is converted into acetoin then reduced to 2,3-butanediol with NADH, small amounts of ethanol and mixed acids are also synthesized. Some bacteria undergo this process are Enterobacter, Serratia, Erwinia, and Bacillus. 6. Butyric acid Fermentation it involves the conversion of pyruvate into butyric acid along with acetic acid, carbon dioxide, and hydrogen Some bacteria exhibiting this kind of reaction are Clostridium, Fusobacterium, and Eubacterium some bacteria exhibiting this kind reaction are Clostridium, Fusobacterium, and Eubacterium (obligate anaerobes) ENERGY UTILIZATION Once energy is obtained, bacteria, as well as other organism, utilize it in various ways for the biosynthesis of new cell component for the maintenance of the physical and chemical integrity of the cell for the activity of the locomotor organelles for heat production MICROBIAL NUTRITION PHYSIOLOGIC REQUIREMENTS OF BACTERIA 1. Aerobes/Obligate aerobes with catalase and superoxide dismutase these organisms require oxygen and grow well with room air. air contains 15%-20% oxygen, and 1% Carbon dioxide Examples: Bordetella, Brucella, Mycobacterium,Neisseria, and Pseudomonas 2. Anaerobes they do not require oxygen to grow and survive Type of Anaerobes a. Obligate Anaerobes they do not require the presence of oxygen, and they die after prolonged exposure to air without catalase and superoxide dismutase Examples: Clostridium and Bacteriodes b. Facultative they are the most clinically significant bacteria these organisms grow either on the presence or absence of oxygen; hence they are considered as 'aerobes that can grow anaerobically they do not require oxygen but grow better in its presence Examples: Enterobacteriaceae, Staphylococcus, Streptococcus c. Aerotolerant these organisms can survive in the presence of oxygen but unable to perform metabolic processes unless situated in an anaerobic environment Example: Lactobacillus, Clostridium pe fringes, and Cutibacterium 3. Microaerophile it is an organism that requires only 2% to 10% for growth this environment can also be obtained in specially designed jar and bags Example: Campylobacter, Helicobacter, and Treponema 4. Capnophiles requires increased concentration of CO2 (5%-10%) and 15% Oxygen Example: Neisseria, HACEK THIOGLYCOLLATE BROTH ACCORDING TO CARBON DIOXIDE REQUIREMENT Capnophile require an increased CO2 (5% to 10% CO2) Most aerobic and facultative aerobic bacteria needed (0.03% CO2) Example: Haemophilus influenza I. As to the carbon Source Autotrophs use carbon as the sole source of carbon heterotrophs utilized, reduced organic material from other bacteria. II. As to the energy source  Phototrophs are organism that use light as their energy source Chemotrophs make use of the energy produced by the oxidation of organic or inorganic compounds. III. As to the electron source Lithotrophs reduce inorganic molecules to be used in biosynthesis or energy conservation Organotrophs require organic substance (carbohydrates and lipids) for growth and multiplication. ACCORDING TO TEMPERATURE REQUIREMENT the optimum for most clinically significant bacteria is 35C to 37C 1. Psychrophiles/Cryophiles these organisms grow well at 0C to a maximum of 20c Cold enrichment medium Examples: Listeria monocytogenes (0.5C-45C) and Yersinia enterocolitica 2. Mesophiles they grown between 20C to 45C best at 37C these are the most commonly encountered pathogenic bacteria in the clinical laboratory. 3. Thermophiles/ Hyperthermophiles these organisms grow between 50C to 60C Examples: Geobacillus stearothermophilus, Thermus aquatica, Sulfolobu, Pyrococcus, Pyrodictum 4.Extermophiles These are prokaryotes that are able to survive in unusual conditions like the absence of oxygen, increased temperature, and living below the earth's surface. Example: Bacillus infernus (strict anaerobe) Thermal death time- is the lowest/minimum time required to kill organisms under constant temperature Thermal death point- is the lowest temperature required to kill organism in a constant time ACCORDING TO PH pH scale is a measure of the hydrogen ion concentration TYPES OF ORGANISM ACCORDING TO pH TOLERANCE 1. Acidophiles- grow between pH 0 to 5.5 Ex: Lactobacillus acidophilus (tomato juice agar) 2. Neutrophiles- grow between pH 5.5 and 8.0 (most clinically significant bacteria) 3. Alkalophiles- grow between pH 8.5 and 11.5 Ex. Vibrio Enrichment media used: Alkaline Peptone Water CULTURE AND CULTURE MEDIA TYPE OF CULTURE 1. Pure Culture it contains a single species  for identification and antimicrobial susceptibility testing of 1 organism a. streak/spread plate method b. pour plate method c. selective medium d. animal inoculation 2. Mixed Culture It contains more than one species 3. Stock Culture It is composed of several species contained in a separate culture medium (one species per culture medium) it should be cultivated in a large volume of broth and then divided into small vials; this lengthens the shelf life the sample culture to at least a year. Classification of Culture Media According to consistency 1. Liquid it does not contain any amount of agar; for rapid culture it allows the growth of aerobes, anaerobes, and facultative anaerobes Example: Brain heart infusion, trypticase soy broth, and thioglycolate broth 2. Semi-solid medium it contains 0.5% to 1% agar it is used to observe bacterial motility and detect indole and sulfide production Example: Sulfide Indole motility 3. Solid medium Liquifiable- it contains 2% to 3% agar , with liquid state when heated non-liquefiable- non-agar biphasic- both liquid and solid Examples: triple sugar iron, MacConkey agar, Blood agar plate, and chocolate agar plate \ ACCORDING TO COMPOSITION 1. Synthetic or defined medium it is a medium in which the components are known it is designed for research purposes as either a liquid or solid medium 2. non-synthetic medium it is a medium in which some of the substances are unknown (peptones, meat, and yeast extracts) 3. Tissue culture medium HELA 229 cells are human cervical tissue cells while McCoy cells are W138 cells are fibroblast. Use for the isolation of Chlamydia Embryonated cells are utilized for the propagation of Rickettsia ACCORDING TO DISPENSING OR DISTRIBUTION OF CULTURE MEDIA Tube media are prepared as either liquid, slant, butt and slant, butt plated media are distributed into a dish or plate ACCORDING TO USE 1. Simple media/ General purpose media/ Supportive these are routine in the laboratory and without additional requirements these are media that support the growth of most non-fastidious bacteria. they are usually composed of meat and soybean extracts 2. Enrichment media (Liquid Type) broth permit growth of certain bacteria while inhibitory to other (normal flora enhance the growth of pathogens in the specimen with more pathogenic organisms They propagate certain group of bacteria from a mixture of organisms these contain specific nutrients and without additional supplements Alkaline Peptone Water- adjusted to pH 8.4 is best for Vibrio species before inoculation into thiosulfate- citrate-bile-salt-sucrose (TCBS) Thioglycolate broth is general support enrichment medium that promotes the growth of almost all non- fastidious organism Gram-negative broth enhances the growth Salmonella and Shigella 3. Enriched media and non-selective media these are media with additional supplements such as blood, vitamins, and yeast extracts which are necessary for the growth of fastidious organisms these are solid type of media examples: BAP and CAP Blood agar plate- 5% defibrinated sheep's blood (2nd choice: Horse, 3rd choice:rabbit Human BAP- Gardnerella Buffered Charcoal Yeast Extract 4. Differential media  these media allow the visualization of metabolic differences between group of bacteria MAC separates lactose fermenters from non-lactose fermenters BAP distinguishes hemolytic pattern EMB differentiates E. coli from other lactose fermenting bacteria HEA identifies the Salmonella from shigella 5. Selective these media are incorporated with antibiotics, dyes, or chemicals to inhibit the growth of organism while promoting the growth of the desired bacteria Other selective media and their purpose: a. Gentamicin blood for Streptococcus b. Bacitracin chocolate agar for Haemophilus c. Blood agar plate with ampicillin for Aeromonas d. Phenylethyl alcohol agar for Gram positive bacteria To inhibitory substances to create selective medium: a. To inhibit Gram-positive bacteria: Crystal violet/Gentian Violet/carbon fuchsin, and bile salt b. to inhibit Gram-negative bacteria: Potassium tellurite and sodium azide c. to inhibit swarming of swarming bacteria: Alcohol and chloral hydrate 6. Special Media it is used to isolate bacteria with specific growth requirements LJ medium is a protein rich that is composed of whole eggs and malachite green TCBS is selective for Vibrio in which sterilization is through boiling, and never by autoclaving Since the sterilization of both LJ and TCBS media is not by routine autoclaving, they are classified as "special culture media". BLOOD CULTURE SYSTEM the blood culture bottle utilized for the isolation of aerobic and anaerobic Antimicrobial Removal Device or resins- added into the medium to absorb any antibiotics that have been taken by the individual and are present in the blood at the time of sample collection. Manual Blood Culture System: biphasic MAC and BAP Automated Blood Culture System: BACTEC system (the detection of carbon dioxide produced after consumption of the substrate by the bacteria, indicates microbial growth) QUALITY CONTROL OF CULTURE MEDIA After plating or transferring the media to tubes, a representative uninoculated sample of each batch of preparation should be incubated overnight at 35C to observe for the presence of bacterial growth CULTURAL CHARACTERISTICS One of the major features is their appearance following their growth on various media the color of the colonies and the culture media, the abundance of growth, and odor of the culture make each genus or species unique. MANNER OF REPORTING 1. Agar Plate Colonies a. Size colonies are range from small (pinpoint) to large while other appears mucoid or slimy Pseudomonas and Proteus spread across the entire agar surface (swarming)  b. Margin and Elevation Margin of colonies is mostly smooth or entire filiform, lobate, and undulate margins are observable as to elevation, colonies may appear raised, flat convex, or sometimes umbonate c. Chromogenesis colonies maybe pigmented or colored, but not all bacteria have this distinctive feature some bacteria retain the pigment within the cell while other bacteria color the medium d. Optical Features colonies appear opaque, translucent, shiny, or opalescent e. Odor Growth of bacteria may produce putrid, fruity, or ammoniacal, or aromatic 2. Growth on slant amount- growth may be scanty, moderate, or abundant margin or edge- same with the description on agar plate consistency- colonies appear butyrous or butter like, viscous, dry, and brittle Chromogenesis- colonies may be pigmented odor 3. Growth on nutrient broth it may appear as turbid (106 CFU/mL of broth is needed to create turbidity) it may appear viscous in appearance. 4. Growth in Gelatin slant it is confined within the zone of inoculation also known as thead-like or a beaded-like string pearl pattern. sometimes the bacterial growth exhibits liquefaction of gelatin that starts evenly from the top of the agar slant and occurs as a funnel-like pattern. 5. Growth in Blood Culture Bottles for manual procedure, blood culture bottles are examined macroscopically for turbidity and hemolysis using transmitted light Biphasic medium (Septi-Chek) or BACTEC system culture bottles from manual and automated system with evidence "flagged" should be removed from the incubator and equipment. A portion of the fluid should be processed for gram staining and subculture (agar plates) to confirm whether a pathogen is present in sample. BACTERIAL GROWTH CURVE The generation time of bacteria in a culture varies according to their cellular properties. It takes 20 minutes for a fast-growing bacterium such as Escherichia coli or as long as 24 hours for slow growing bacterium such as Mycobacterium tuberculosis. Stages of Bacterial Growth 1. Lag phase or Period of Rejuvenescence it is a period when there is no cell division or an abrupt increase in cell number it is the start of biosynthesis although there is no increase in cell mass it is adjustment phase 2. Log or Exponential Phase it is the period when organisms are actively growing and dividing it is the stage in which the bacteria increase logarithmically since cellular production is most active during this period most sensitive to antimicrobial it is the phase in which the organisms utilized in physiological, biochemical, and antimicrobial testing 3. Stationary or Plateau Phase it is the period when there is balance between cell division and dying organism although the number of viable microorganism remains constant. it is the phase in which metabolic activities of surviving cells slow down and nutrient are becoming limited it is the phase in which dead debris starts to accumulate 4. Death or decline phase it is the period when there is cessation of bacterial growth as the number of dead cells exceeds the living microorganism it is the stage in which there is a loss of nutrients and increase in the amount of toxic waste. 1. Generation- it is the doubling of the cell number 2. Generation time/ Doubling time- it is the number required for bacteria to double their population 3. Transverse Binary Fission- it is the most common asexual reproductive process in which a single cell divides into two daughter cells.