Microbiology and Parasitology SEP 313

Carbohydrate Catabolism

• Carbohydrate catabolism involves breaking down carbohydrates to generate energy.
• Glycolysis is the primary pathway for glucose oxidation, yielding pyruvic acid.
• Glycolysis produces two ATP and two NADH molecules from one glucose molecule.
• Enzymes catalyze reactions involving specific substrates, transforming them into products.

Metabolism Overview

• Metabolism encompasses both the buildup (anabolism) and breakdown (catabolism) of nutrients in cells.
• ATP (Adenosine Triphosphate) serves as the main energy currency for cells.
• Microorganisms utilize Cellular Respiration and Fermentation to extract energy from glucose.

Types of Metabolic Pathways

• Catabolic pathways (exergonic) break down complex molecules into simpler ones, releasing energy.
• Anabolic pathways (endergonic) synthesize macromolecules, requiring energy from catabolic reactions.
• Cellular Respiration involves oxidation of molecules with an external electron acceptor, typically an inorganic molecule.
• Aerobic Respiration uses oxygen as the final electron acceptor.
• Anaerobic Respiration employs an electron acceptor other than oxygen or certain organic molecules.

Fermentation

• Fermentation releases energy from sugars without requiring oxygen; it can occur in its presence.
• It does not use the Krebs cycle or electron transport chain, using organic compounds as final electron acceptors.
• Lactic Acid Fermentation converts pyruvic acid to lactic acid, while Alcohol Fermentation reduces acetaldehyde to ethanol.

Lipid Catabolism

• Lipid catabolism refers to the breakdown of fats and oils for energy.
• Lipases are enzymes produced by microbes to convert lipids into fatty acids and glycerol.

Protein Catabolism

• Protein catabolism involves breaking down proteins into amino acids.
• Deamination is the removal of an amino group from amino acids, converting it to ammonium ions.
• Decarboxylation and desulfurization are additional modifications in protein processing.

Microbial Growth Requirements

• Physical requirements for microbial growth include temperature, pH, and osmotic pressure.
• Most bacteria thrive at a neutral pH (6.5-7.5), with few acidophiles growing below pH 4.
• Osmotic pressure influences water movement across membranes, requiring specific conditions for bacterial survival.

Chemical Requirements

• Carbon is essential for organic compound formation and is the backbone of living matter.
• Nitrogen, sulfur, and phosphorus are crucial, with nitrogen making up 14% of bacterial dry weight.
• Trace elements act as cofactors for enzyme function.

Growth Factors

• Oxygen requirements categorize microbes as obligate aerobes, facultative anaerobes, anaerobes, aerotolerant anaerobes, and microaerophiles.
• Organic growth factors like vitamins and amino acids must be provided if the organism cannot synthesize them.

Bacterial Division and Growth

• Bacteria primarily reproduce through binary fission, creating two identical cells.
• Generation time varies among species and affects growth rate.

Methods for Culture Counting

• Plate counts estimate viable microbes, with results expressed in colony-forming units (CFU).
• Filtration collects bacteria on a membrane filter, which can then be cultured and counted.
• The Most Probable Number (MPN) method provides statistical estimates for microbial populations in liquid media.
• Direct Microscopic Counts involve counting microbes in a defined volume under a microscope.
• Turbidity measurement with a spectrometer assesses the density of bacterial suspensions indirectly.

This quiz covers carbohydrate catabolism within microbial metabolism, with a specific focus on the breakdown of glucose to produce energy. Key concepts include the pathways of glycolysis and overall metabolic processes in microorganisms. Perfect for BSSE 3A students looking to enhance their understanding of microbiology.