Download 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.
 It play an important role in
transformation of grape
must into wine.

THE DIFFERENT COMPONENTS
OF THE BACTERIA CELL

1.
A.


Prokaryotic cell with an extremely
simple organization.
Cellular envelop
Cell wall
Composed of a peptidoglycan
Contian ribitol phosphate or glycerol
phosphate polymers
THE DIFFERENT COMPONENTS
OF THE BACTERIA CELL
B. Plasmic Membrane


A lipid bilayer
membrane lipid
• Phospholipid
• glycolipids .
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.
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)
THE DIFFERENT COMPONENTS
OF THE BACTERIA CELL

It also contain a characteristic
cyclopropanic acid : lactobacillic acid.
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.
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.

THE DIFFERENT COMPONENTS
OF THE BACTERIA CELL
3.The nucleus

The chromosome carries the essential
genetic information of cell.
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)
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.

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.
 MOLECULAR TAXONOMY
PHENOTYPIC TAXONOMIC,
MOLECULAR TAXONOMY AND
PHYLOGENY

Phylogeny
The evolutionary development 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).
CLASSIFICATION OF WINE LACTIC
ACID BACTERIA. DESCRIPTION OF
GENERA

Sequencing of the 16 S rRNA devide lactic acid
bacteria into three phylogenetic groups:
The group Lactobacillus
delbruekii
 The group Leuconostoc




One containing L.paramesenteroides
and heterofermentative
lactobacilli.
Two containing Leuconostoc sensu
stricto
The group Lactobacillus casei
CLASSIFICATION OF WINE LACTIC ACID
BACTERIA. DESCRIPTION OF GENERA
 Group
I: strict homofermenters (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
𝐶𝑂2 , lactic and acetic acids, ethanol;
pentose to lactic and acetic acids )
DESCRIPTION OF GENERA
In general, there are three
genera of lactic acid bacteria:
 Genus Leuconostoc
Oenococcus
 Genus Pediococcus
 Genus Lactobacillus
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.
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.
IDENTIFICATION OF LACTIC ACID
BACTERIA

Phenotypic Analysis
A release of CO2 manifests the
heterofermentative character 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.

IDENTIFICATION OF LACTIC
ACID BACTERIA

Phenotypic Analysis
•
Two stereoisomers of lactic acid(L
and D) identification of
heterofermentative cocci (Oenococcus
oeni, Leuconostoc mesenteroides)
form the D isomer, and of
Lactobacillus casei forms L-lactic
acid.
 PHENOTYPIC ANALYSIS
EXTRACTION AND VISUALIZATION
OF DNA FOR GENOMIC STUDY


Centrifugation
Electrophoresis
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
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.
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.
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.

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 .

IDENTIFICATION BY FATTY ACID
AND PROTEIN COMPOSITION

Protein Composition:

Bacteria cell protein constitute
another level of genomic expression
.
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.