Micro: Midterms

Bergey's Manual

bacteria were grouped by morphology (rod, coccus), staining reactions, presence of endospores, and other obvious features. Pratical but not logical

Bacteria

microscopic, unicellular, prokaryotic organisms.

Prokaryota

They do not have membrane-bound cell organelles and lack a true nucleus, hence are grouped under the domain

Backerion

• Bacteria, a singular bacterium, is derived from the Ancient Greek word

Bacilli

First bacteria

Bacteriology

A branch of microbiology that is called the study of bacteria

Ubiquitious

Bacteria are evolved to adapt and survive in any kind of ecological niches; from normal to extreme environments.

Psychrophiles

extreme cold

Thermophiles

extremely hot

Acidophiles

acidic pH

Alkaliphiles

basic pH

Barophiles

extreme pressure

Anaerobic

anoxic environments

Coccus

Spherical Shaped Bacteria

Cocci

Meaning berries

Bacillus

Rod-shaped bacteria

Bacilli

Little staffs

Coccus

Bacillus

Curved Rods

Pleomorphic

Cocci

usually round but can be oval, elongated, or flattened on one side

Cocci

divide to reproduce, the cells can remain attached to one another

Diplococci

Cocci that remain in pairs after dividing

Streptococci

those that divide and remain attached in chain like pattern

Tetrads

Those that divide in two planes and remain groups of four

Sarcinae

Those that divide in three planes and remain attached in cubelike groups of eight are

Staphylococci

Grapelike dusters or broad sheets

Diplococci

Streptococci

Tetrad

Sarcinae

Staphylococci

Bacillus

Rod shaped bacteria

Coccobacillus

in between bacilli and coccus

Bacillus

Diplobacillus

Streptobacillus

Coccobacillus

Bacillus

Streptobacilli

Coccobacillus

Spiral

bacteria have one or more twists; they are never straight

Vibrio

curved rods

Spirilia

helical shape, like a corkscrew, and fairly rigid bodies

Flagella

Spirillia uses this mechanism for motility

Spirochetes

helical and flexible move by means of axial filaments, which resemble flagella but are contained within a flexible external sheath.

Vibrio

Vibrio

Spirillia

Spirochetes

Spirochetes

monomorphic

Most bacteria maintain a single shape

Rhizobium, Corynebacterium

genetically pleomorphic. which means they can have many shapes, not just one

Unicellular

Cells of bacteria

Bacteria

They are prokaryotes and their cells are different from animal and plant cells

Flagella, Pili/Fimbriae

External Structure of Bacteria

Flagella

-long hair-like filamentous structures of about 4 – 5 μm long and 0.01 – 0.03 μm in diameter

Flagella

They confer motility to the bacteria.

Filament, Hook, Basal Body

Flagella are divided into three parts;

filament

threadlike part extending outside the cell wall. It is made up of flagellin protein.

Flagellin

Protein in the filament of a flagella

Basal Body

Anchors the plasma membrane and cell wall

Hook

short curved structure that joins filament with the basal body

Hook

produces repulsion like the propeller during the revolving of flagella.

basal body

set of rings embedded in the cell wall and plasma membrane.

Gram-negative bacteria

Contains two pairs of rings in basal body

Gram-positive bacteria

Contains one pair of rings in basal body

Basal body

It synthesizes polymers of the flagellum, produces energy for revolution, and regulates movements of the flagellum

Taxis

Particular stimulus

Motility, Chemotaxis, Pathenogenicity

Functions of flagella

Axial filament/endoflagella

bundles of fibrils that arise at the ends of the cell beneath an outer sheath and spiral around the cell

Axial filament/endoflagella

Movement of spirochetes

Borrelia burgdorferi and Treponema pallidum

Axial filament/endoflagella

Axial filaments

which are anchored at one end of the spirochete

rotation of the filaments

produces a movement of the outer sheath that propels the spirochetes in a spiral motion movemen

Gliding motility

provides a means for microbes to travel in environments with a low water content, such as biofilms and soil.

Atrichous

w/o projections

peritrichous

distributed over the entire cell

peritrichous

Monotrichous

- a single flagellum at one pole

Monotrichous

lophotrichous

a tuft of flagella coming from one pole

lophotrichous

amphitrichous

flagella at both poles of the cell;

amphitrichous

Fimbriae

have a tendency to adhere to each other and to surfaces biofilm production

Fimbriae of E. coli 0157

enable this bacterium to adhere to the lining of the small intestine, where it causes a severe watery diarrhea

Pili

usually longer than fimbriae and number only one or two per cell.

Pili

Involved in motility and DNA transfer

Twitching motility

a pilus extends by the addition of subunits of pilin, makes con tact with a surface or another cell, and then retracts (powerstroke) as the pilin subunits are disassembled

Pili/Fimbriae

They are the short, hollow, non-helical filamentous structure of about 0.5 μm in length and 0.01 μm in diameter

Pili/Fimbriae

They are exclusively found in Gram-Negative bacteria.

Pilin

Protein found in Pili

Pili

They are composed of protein ‘pilin’ arranged non-helically

Pili

They are short, numerous, and straight than flagella.

Sex pili

a special kind of pili that take part in bacterial conjugation.

Sex pili

They are larger than usual pili; 10-20 μm in length. They are few in number, just 1-4 in number.

F-pili, I-pili

Two classifications of Sex Pili

Adherence to host cells, Bacterial DNA transfer

Functions of Pili/Fimbriae