IL SILLABO - dbt.univr.it · Università degli Studi di Verona – Facoltà di Scienze MM. FF. e...

Università degli Studi di Verona – Facoltà di Scienze MM. FF. e NN.

Corso di Laurea Triennale in Biotecnologie a.a. 2011-2012 Corso di Microbiologia Generale ● Titolare: Prof. Giovanni Vallini

IL SILLABO

IL TESTO DI RIFERIMENTO

Filogenesi e Diversità Microbica

2Fe2+ + 2H+ → 2H2 + 2Fe3+

In the late 1970s, Prof. Carl R. Woese, with

the University of Illinois at Urbana, Illinois –

USA. spearheaded a study of evolutionary

relationships among prokaryotes. Instead

of physical characters, he relied on RNA

sequences to determine how closely

related these microbes were.

Mitochondria and the respiratory

bacterium, Agrobacterium, are

derived from a common

ancestor; likewise, chloroplast

and the cyanobacterium,

Synechococcus, arise from a

common origin. This is good

evidence for the idea of

evolutionary endosymbiosis, i.e.,

that the origin of eucaryotic

mitochondria and chloroplasts is

in procaryotic cells that were

either captured by, or which

invaded, eucaryotic cells and

subsequently entered into a

symbiotic association with one

cell living inside of the other.

Structure of a phospholipid bilayer, typically recurring in Bacteria and Eukarya

(a) The ester linkage as found in the lipids of Bacteria and Eukarya.

(b) The ether linkage of lipids from Archaea. (c) Isoprene, the

parent structure of the hydrophobic side chains (R) of

archaeal lipids. By contrast, in lipids of Bacteria and Eukarya,

R are fatty acids.

Major lipids of Archaea and the structure of archaeal membranes. (c, d) Membrane

structure in Archaea. (c) Lipid bilayer. (d) Lipid monolayer

Structure of the repeating units of peptidoglycan occurring in Bacteria

and cell wall pseudomurein of Archaea

Schematic side view of cell wall profiles from different archaea.

Pseudoperiplasmic space is shown in blue.

Schematic of bacterial cell walls. Gram-positive bacteria have a thick, amorphous,

multilayered coat of peptidoglycan, teichonic and lipoteichonic acid as their cell

wall and in some cases have surface-layer (S-layer) glycoproteins as the outermost

layer above the peptidoglycan (also known as murein), for example, Gram-

negative bacteria have an outer asymmetric bilayer membrane composed of two

leaflets, an outer one containing lipopolysaccharides (LPSs), and an inner one

containing mainly phospholipids, a gel-like periplasm containing peptidoglycan

and the cytoplasmic membrane. CM, cytoplasmic membrane; SL, S-layer.

Action of diphtheria toxin.

The toxin-binding (B)

portion attaches to the

cell membrane, and the

complete molecule enters

the cell. In the cell, the A

subunit dissociates and

catalyzes a reaction that

ADP-ribosylates and thus

inactivates elongation

factor 2 (EF-2). This factor is

essential for ribosomal

reactions at the acceptor

and donor sites, which

transfer triplet code from

messenger RNA (mRNA) to

amino acid sequences via

transfer RNA (tRNA).

Inactivation of EF-2 stops

building of the

polypeptide chain.

Demonstration of ribotyping. DNA is

isolated from a cultured isolate, restricted

and size separated in an agarose gel.

The gel is then hybridized with labeled

rRNA probe, which binds to fragments

containing copies of the rRNA operon.

Following probe detection, fragments

with bound probe are visualised, forming

a characteristic RFLP.

Demonstration of restriction fragment length polymorphism (RFLP). The DNA

fragment is restricted into 3 pieces (1, 2 and 3) by a restriction enzyme. The

restricted DNA is then inserted into a well in an agarose gel and the

fragments are separated by electrophoresis. The separation is based on

fragment size, with the smallest fragments migrating further into the gel. This

pattern, termed RFLP, represents a characteristic fingerprint of this DNA

fragment.

Dendrogram concerning Achromobacter sp. isolates. based on cluster

analysis of EcoRI ribotype patterns obtained by automated ribotyping

with the RiboPrinter microbial characterization system.

MAIN INTERNATIONAL CULTURE COLLECTIONS OF MICROORGANISMS

Deutsche Sammlung von Mikroorganismen und Zellkulturen

American Type Culture Collection

IL SILLABO - dbt.univr.it · Università degli Studi di Verona – Facoltà di Scienze MM. FF. e...

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