Physiology of Microorganisms Lecture 1 PDF

Physiology of Microorganisms Lec 1  Microbial physiology ‘‘structure-function relationships in microorganisms, especially how microbes respond to their environment’’ The habitat is an important concept because microorganisms are greatly affecte...

Physiology of Microorganisms Lec 1  Microbial physiology ‘‘structure-function relationships in microorganisms, especially how microbes respond to their environment’’ The habitat is an important concept because microorganisms are greatly affected by where they live. Microbial habitats including soils, rivers, lakes, oceans, on the surface of living and dead things, inside other organisms, on man-made structures, and everything in between provide nutrients and protect cells from harsh conditions. Microbial physiology and metabolism provides information on sources of energy and its utilization by microorganisms. Microorganisms play important role in environment as producers, consumers and decomposers microbial physiology has greater application in industry, developing medicine and even in agriculture Microorganisms like tiny factories to produce several enzymes, metabolites of industrial importance which are regulated by specific genes under the influence of environmental factors. Regulating these two parameters will provide greater output of the metabolites of the choice. Primary metabolites include amino acids nucleotides, and fermentation end products such as ethanol and organic acids, which are considered essential for proper growth of Microbial secondary metabolites are low molecular mass products, not essential for growth of the producing cultures, but very important for human health. They include antibiotics, antitumor agents, cholesterol- lowering drugs, and others alkaloids, antibiotics, naphthalenes, nucleosides, phenazines, quinolines, terpenoids, peptides and growth factors  Microorganisms degrade different carbon sources and converting them both aerobically and anaerobically to metabolites of commercial value. This diverse metabolic activity is generally not observed in any other group of living organisms. The syllabus of the course is designed keeping in mind the recent developments in microbial physiology and will be useful to all those who want to learn and update their knowledge on physiology of microorganisms. Bacterial structure  Unicellular prokaryotic cell Present in different shape, size and arrangement The cell lack nucleus and membrane-bound cell organelles Bacterial DNA is found in the cytoplasm and not packaged to form chromatin as in eukaryotic cell Bacteria cell is 10 times smaller than the human cell The diameter of a -6 bacteria cell is ¬ 1µm (10 m).The outer covering of a bacteria cell is the cell wall, which is rigid and provides structural integrity The bacteria cell wall is made up of peptidoglycan or murein. Bacteria cells may contain external appendages like cilia, flagella, etc. Bacteria shape: 1. Spherical - Cocci a-Monococcus: single spherical cell b-Diplococcus: arranged in pairs after cell division. diplococcus bacteria are: Gram-negative bacteria- Neisseria spp , Moraxella catarrhalis. Gram- positive bacteria- Streptococcus pneumoniae, Enterococcus spp, etc. c-Streptococcus: the cocci are joined in a plane and arranged in a chain pattern. These are non-motile, aerobic and gram-positive bacteria that cause many diseases.Examples of streptococci are Streptococcus mutans, Streptococcus pyogenes, Streptococcus bovis, Streptococcus agalactiae, etc.  Gram-positive Gram-negative Gram-positive bacteria have the following Gram-negative bacteria have the following characteristics: characteristics: Membranes: Gram-positive bacteria do not Membrane: Gram-negative bacteria have a protective outer membrane. have two membranes - one external and Cell wall: They have a thick peptidoglycan one internal. cell wall. Cell wall: These bacteria also have a Shape: Gram-positive bacteria are sphere- thinner peptidoglycan cell wall than Gram- or rod-shaped, or they have branching positive bacteria, which sits between their filaments,. two membranes Toxins: These bacteria also contain certain Shape: They can be spherical-, rod-, toxins that can cause a number of food-borne or spiral-shaped. diseases. Toxins present in Gram-positive Toxins: If something disturbs the cell bacteria include: wall of Gram-negative bacteria, they can emetic toxin release endotoxins. diarrheal enterotoxins neurotoxins enterotoxin  Tetrads: Tetrads are arranged in a group of 4 cells. The cell division occurs in two different planes. Examples of tetrads cocci bacteria are Micrococcus spp, Pediococcus, etc. Staphylococcus: Cells are arranged in an irregular cluster, which looks like grapes. This is due to the division in three planes. Examples of staphylococcus are staphylococcus aureus, Staphylococcus haemolyticus, etc. Sarcinae: Sarcinae bacteria are anaerobic gram-positive bacteria. They occur as a group of 8 cells. It is found in the family Clostridiaceae. It is found in the large intestine and skin. Examples of f sarcinae are: Clostridium maximum, Sarcina auranatica, Sarcina ventriculi, Clostridium maximum, Microcioccus luteus  2. Rod-shaped-Bacilli Bacillus: Single unattached cell, that looks like a rod. Examples are Bacillus cereus, Salmonella enterica, etc. Diplobacilli: Two rods are attached to each other and found in pairs after cell division. Examples are Moraxella bovis, Klebsiella rhinoscleromatis, etc.  Streptobacilli: Due to cell division in one plane, bacilli are arranged in a chain. Genus Streptobacillus contains gram-negative, aerobic or facultative anaerobic bacteria. Examples are Streptobacillus moniliformis, Streptobacillus felis, etc Coccobacilli: These are short compared to other bacilli and oval in shape, they appear like a coccus. Examples are Chlamydia trachomatis, Haemophilus influenzae, Gardnerella vaginalis, etc. Palisades: The bacilli after cell division bend and therefore arranged in a palisade, fence-like structure, Example: Corynebacterium diptheria  3. Spiral Bacteria These bacteria are spiral or helical in shape. Based on the thickness, flexibility and motility of the cell, they are further divided into two types: a. Spirillum: These are gram-negative, rigid bacteria having external flagella. Examples are Spirillum, Campylobacter jejuni, Helicobacter pylor, etc b. Spirochete: These bacteria are spiral, thin and flexible. They have internal periplasmic flagella These are pathogenic species that cause various serious diseases. Examples are Leptospira, Treponema pallidum, etc. 4. Comma-shaped -Vibro These are curved and appear like a comma These are mostly gram-negative bacteria They are known to cause various foodborne diseases Vibrio sp are facultative anaerobes and have 2 chromosomes which replicate independently Examples are Vibrio cholerae, Vibrio parahaemolyticus, etc.