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Lactic Acid Bacteria

Lactic Acid Bacteria. Lecturer: HUL Seingheng Students: I3-B GCA, Group10 TEV Kunthea THAING Sreythuok YAM Koemfy YANN Sokhoun YUN Pheakdey 2010-2011. INTRODUCTION. Lactic acid bacteria are present in all grape musts and wines.

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Lactic Acid Bacteria

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  1. Lactic Acid Bacteria Lecturer: HUL Seingheng Students: I3-B GCA, Group10 TEV Kunthea THAING Sreythuok YAM Koemfy YANN Sokhoun YUN Pheakdey 2010-2011

  2. INTRODUCTION • Lactic acid bacteria are present in all grape musts and wines. • It play an important role in transformation of grape must into wine.

  3. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL • Prokaryotic cell with an extremely simple organization. • Cellular envelop • Cell wall • Composed of a peptidoglycan • Contianribitol phosphate or glycerol phosphate polymers

  4. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL B. Plasmic Membrane • A lipid bilayer • membrane lipid • Phospholipid • glycolipids .

  5. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL B. Plasmic Membrane • Phospholipids consist of a glycerol molecule which has a primary alcohol and secondary alcohol function esterified by fatty acids.

  6. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL B. Plasmic Membrane • Glycolipids • Generally glycosides of glycerides • Are formed by glycosidic bonds between a fatty acids(possess a long hydrocarbon chain and a terminal carboxylic acid function)

  7. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL • It also contain a characteristic cyclopropanic acid : lactobacillic acid.

  8. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL 2. The cytoplasm • The cytoplasm contains the main elements for cell operation : enzyme , nuclear material and sometimes reserve substance.

  9. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL 3. The nucleus • The bacteria nucleus consist of a single circular chromosome of double straned DNA suspended in in the cytoplasm without any separation . • Its size varies depending on the species and strain of bacteria.

  10. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL 3.The nucleus • The chromosome carries the essential genetic information of cell.

  11. THE DIFFERENT COMPONENTS OF THE BACTERIA CELL 4. Multiplication of Bacteria • All bacteria multiply by binary division(a cell gives two completely identical daughter cells)

  12. TAXONOMY • The objective of taxonomy is to identify , describe and class microorganism. • Highest level is prokaryote • Lowest level is species • Lactic acid bacteria belong to Gram-positive group(violet coloration). • It is the primary production of metabolism of glucose.

  13. Phenotypic Taxonomy, Molecular Taxonomy and Phylogeny • Phenotypic Taxonomic • Include morphological, physiological, biochemical and immunological characters. • Molecular Taxonomy • Classification according to similarities in their genome. • Among Gram-positives, lactic acid bacteria belong to the Phylum Clostridium.

  14. Molecular Taxonomy

  15. Phenotypic Taxonomic, Molecular Taxonomy and Phylogeny • Phylogeny • The evolutionarydevelopment of a species or of a taxonomic group of organisms. • Another type of analysis consist of sequencing the 16 S , 23 S and 5 S RNA (ribosomals).

  16. Classification of Wine Lactic Acid Bacteria. Description of Genera • Sequencing of the 16 S rRNAdevide lactic acid bacteria into three phylogenetic groups: • The group Lactobacillus delbruekii • The group Leuconostoc • One containing L.paramesenteroidesand heterofermentative lactobacilli. • Two containing Leuconostocsensustricto • The group Lactobacillus casei

  17. Classification of Wine Lactic Acid Bacteria. Description of Genera • Group I:stricthomofermenters(has never been identified in wine) ,do not ferment pentose. • Group II:facultative herterofermenters(pentose are fermented to lactic and acetic acids ) • Group III: strict herterofermenters(ferment glucose to , lactic and acetic acids, ethanol; pentose to lactic and acetic acids )

  18. Description of Genera • In general, there are three genera of lactic acid bacteria: • Genus LeuconostocOenococcus • Genus Pediococcus • Genus Lactobacillus

  19. IDENTIFICATION OF LACTIC ACID BACTERIA • General Principle • Since the beginning of microbiology, the identification of bacteria has been based on their phenotypic characters. • For long time, lactic acid bacteria of wine were identified by their phenotypes but now with DNA analysis.

  20. IDENTIFICATION OF LACTIC ACID BACTERIA • Phenotypic Analysis • Microscopic observation is couple with the Gram coloration test, which is used to verify that bacteria are Gram-positive. • Determine the character of homofermentative or heterofermentative.

  21. IDENTIFICATION OF LACTIC ACID BACTERIA • Phenotypic Analysis • A release of CO2 manifests the heterofermentativecharacter of the strain. • Conversely, the exclusive formation of lactic acid attests to acid attests to a homofermentative character. • Determine the optical nature of lactic acid formed from glucose.

  22. IDENTIFICATION OF LACTIC ACID BACTERIA • Phenotypic Analysis • Two stereoisomers of lactic acid(L and D) identification of heterofermentativecocci (Oenococcusoeni, Leuconostocmesenteroides) form the D isomer, and of Lactobacillus casei forms L-lactic acid.

  23. Phenotypic Analysis

  24. Extraction and Visualization of DNA for Genomic Study • Centrifugation • Electrophoresis

  25. Identification Based on Restriction Fragment Length Polymorphism • This method consists of hydrolyzing the DNA with the help of restriction enzymes. • Restriction have 3 form • Restriction products • Restriction polymorphism • Restriction profile

  26. Identification by Specific Probe DNA/DNA Hybridization • Hybridization is a technique often used in molecular genetics and it is very well adapted for the identification of species and even strains. • DNA/DNA hybridization is also an excellent tool for identifying strains that differ in phenotype but belong to the same species.

  27. Identification by Polymerization Chain Reaction(PCR) • PCR consists of using polymerization to amplify one or more DNA fragments, located by specific sequences. • The PCR technique uses two oligonucleotide primers, chosen for their complementary sequences: each one is complementary to a single strand of the DNA target.

  28. Identification by Polymerization Chain Reaction(PCR) • The products of PCR are analyzed by electrophoresis. • The specificity of PCR is based on the level of hybridization between the oligonucleotides and the template.

  29. Identification by Fatty Acid and Protein Composition • Fatty acid • The total fatty acids are dosed in the form of esters after sapomification. • Bacteria can only be identified by their composition in total fatty acids. when the culture of the cells to be analyzed is standardized .

  30. Identification by Fatty Acid and Protein Composition • Protein Composition: • Bacteria cell protein constitute another level of genomic expression .

  31. conclusion • This presentation is based on lactic acid bacteria . • It mention about the different methods to identify lactic acid bacteria. • Lactic acid bacteria play an important role in the transformation of grape musts into wine.

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