What is Metabolism The Greek metabole meaning change

What is Metabolism? • The Greek metabole, meaning change • It is the totality of an organism's chemical processes to maintain life. - Catabolism (Formation) - Anabolism (Breakdown)

Why do we must know the metabolism of bacteria ? • Because we want to know how to inhibit or stop bacteria growth and want to control their metabolism to prolong shelf-life of food products.

Benefits of studying metabolism of bacteria in food microbology 1. Can prolong shelf life of food product by control or block enzyme of the pathway (Chemical Preservatives) 2. Can be used to detection contamination by looking at metabolic activity

Chemical Preservative 1. Benzoic Acid Inhibit to enzyme in Glycolysis and TCA pathway 2. Sorbic Acid Inhibition by sorbic acid may cause cell death, slowing of growth

What are nutrients that bacteria want? C N O Sugar, Lipid Protein Air Energy, Biosynthesis Energy

Glycolysis • This is the most common pathway in bacteria for sugar catabolism (It is also found in most animal and plant cells). A series of enzymatic processes result in conversion of sugars into pyruvate, generating ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide). Chemical energy needed for biosynthetic purposes is stored in the newly formed compounds (ATP and NADH) Glycolysis also called Embden–Meyerhof–Parnas (EMP) pathway

Total energy in the form of ATP produced Balance sheet for ~P bonds of ATP: w How many ATP ~P bonds used? 2 w How many ~P bonds of ATP produced? (Remember there are two 3 C fragments from glucose. ) 4 w Net production of ~P bonds of ATP per glucose: 2

In aerobic organisms w Pyruvate produced in Glycolysis is oxidized to CO 2 via Krebs Cycle w NADH produced in Glycolysis & Krebs Cycle is reoxidized via the respiratory chain, with production of much additional ATP.

Krebs cycle

Krebs cycle or TCA cycle • The citric acid cycle — also known as the tricarboxylic acid cycle (TCA cycle), the Krebs cycle, or the Szent-Györgyi-Krebs cycle, is a series of enzyme-catalysed chemical reactions, which is of central importance in all living cells that use oxygen as part of cellular aerobic respiration. The net yield of aerobic respiration is 36 ATP molecule

Anaerobic Respiration or Fermentation • Anaerobic organisms lack a respiratory chain. The complete pathway, including Glycolysis and the reoxidation of NADH, is called fermentation. Fermentation, from glucose to lactate: Glucose Pyruvate + 2 ADP + 2 Pi 2 lactate + 2 ATP Anaerobic respiration of glucose yields only 2 “high energy” bonds of ATP.

What is fermentation techniques? Techniques for large-scale production of microbial products. It must both provide an optimum environment for the microbial synthesis of the desired product and be economically feasible on a large scale. 13

Some important fermentation products Product Organism Use Ethanol Saccharomyces cerevisiae Industrial solvents, beverages Glycerol Saccharomyces cerevisiae Production of explosives Lactic acid Acetone and butanol Lactobacillus bulgaricus Clostridium acetobutylicum Food and pharmaceutical Solvents -amylase Bacillus subtilis Starch hydrolysis 14

Overview of fermentation products formed from pyruvic acid by different bacteria

Some important fermentation products Important amino acids 16

Some important fermentation products Wines and beers 17

Some important fermentation products Medicines, Vitamins, proteins enzymes, vaccinations , interferons 18

Book • Microbial Biochemistry by Georges N. Cohen • 2 nd ed. , 2011, 500 p. 141 illus. , 6 in color. , Hardcover ISBN: 978 -90 -481 -9436 -0