PENDAHULUAN MIKROBIOLOGI KESEHATAN KLASI (1)

PENDAHULUAN MIKROBIOLOGI
KESEHATAN : KLASIFIKASI DAN
STRUKTUR SEL BAKTERI
Dr. Leonardus Widyatmoko

TUJUAN
Setelah mempelajari materi pada hari ini
diharapkan anda dapat :
• Memahami klasifikasi mikroba dan taksonomi
bakteri
• Mampu membedakan antara sel prokariot
(bakteri) dengan eukariot
• Mampu memahami struktur sel bakteri
• Mampu memahami perbedaan pada dinding
sel bakteri

SUMBER PUSTAKA
• Mahon textbook of Diagnostic Microbiology
4th Ed.
• Jawetz et all Medical Microbiology 25th Ed.

Sebuah Ilustrasi

KLASIFIKASI BAKTERI

ISTILAH
• Taksonomi

– Pengelompokan suatu organisme dalam suatu hierarki
yang menggambarkan kedekatan hubungan di alam

• Klasifikasi

– Proses pengelompokan ke dalam suatu grup taksonomi

• Nomenklatur

– Penamaan suatu organisme menurut suatu konsensus
internasional berdasarkan karakteristiknya

• Identifikasi

– Praktik pengenalan suatu organisme dengan menggunakan
algoritme/metode tertentu

Nomenklatur

Klasifikasi

Identifikasi

Taksonomi

Persamaan dan perbedaan dalam GENOTIPE (susunan
genetik) dan FENOTIPE (Tampilan fisik dan fungsional)

CONTOH

KLASIFI
KASI

Nomenklatur

Klasifikasi Phylogenetik :Pemahaman evolusi
dan kedekatan hubungan pada bakteri

STRUKTUR SEL PROKARIOT DAN
EUKARIOT

MICROBIAL WORLD
The Microbial World

Eukaryotes

Prokaryotes (Bacteria)

Perbandingan Prokariot dan Eukariot

Perbandingan Prokariot dan Eukariot

STRUKTUR SEL BAKTERI

SIZE OF BACTERIA
• Unit for measurement :
Micron or i ro eter,μ :
μ = -3mm
• Size:
Varies with kinds of bacteria, and
also related to their age and
external environment.



Cocci: sphere, 1μ
 Bacilli: rods , 0.5-1 μ in width -3 μ in length
 Spiral a teria: ~3 μ i le gth a d .3- .6 μ i width

BACTERIAL STRUCTURE OVERVIEW
Essential structures :
cell wall
cell membrane

Cytoplasm
nuclear material

Particular structures :
capsule
flagella
pili
spore

1884: Christian Gram: First publication for the Gram
stain method
Cell membrane

Flagellum
Nucleoid
Cell wall

Gram +
Pili

Gram Granule

Capsule
Cell (inner) membrane
Outer membrane
Ribosomes
Cell wall

Gram, C. 1884. Ueber die isolirte Farbung
der Schizomyceten in SchnittÄund
Trockenpraparaten. Fortschritte der
Medicin, Vol. 2, pages 185-189.

Cell wall/Dinding sel
• Merupakan
bagian terluar,
dengan ketebalan
15-30nm dan
sekitar 10-25%
dari berat

Cell wall :Lapisan Peptidoglycan
• Tersusun oleh N-acetyl glucosamine (NAG) dan N-acetylmuramic acid (NAM):
ditemukan pada bakteri gram positif dan negatif
• Terdapat struktur tetrapeptide yang menempel pada NAM : menjadi tempat
perlekatan AB pada bakteri
• Pada gram positif bakteri membentuk jalinan ross ridging : melindungi dari
proses osmotik

Special components of Gram positive
cell wall
Teichoic acid

SPA / M POTEIN

Special components of Gram
negative cell wall

COMPARISON

Hasil Pengecatan Gram

Streptococcus Gram +

Neisseria Gram -

Hasil Pengecatan ZN:

Mycobacterium tuberculosis Acid-fast stain. 1000X magnification.

Functions of Cell Wall
• Maintaining the cell's characteristic shape- the
rigid wall compensates for the flexibility of the
phospholipid membrane and keeps the cell from
assuming a spherical shape
• Countering the effects of osmotic pressure
• Providing attachment sites for bacteriophages
• Providing a rigid platform for surface appendagesflagella, fimbriae, and pili all emanate from the
wall and extend beyond it
• Play an essential role in cell division

• Be the sites of major antigenic determinants of
the cell surface。
• Resistance of Antibiotics

Wall-less forms of Bacteria.

• When bacteria are treated with 1) enzymes that are lytic for
the cell wall e.g. lysozyme or 2) antibiotics that interfere
with biosynthesis of peptidoglycan, wall-less bacteria are
often produced.
• Usually these treatments generate non-viable organisms.
Wall-less bacteria that can not replicate are referred to as
spheroplasts (when an outer membrane is present) or
protoplasts (if an outer membrane is not present).

Cell
membrane
•

•

•

Berperan dalam proses biosintesis DNA, polimerisasi dinding sel dan
e ra lipid elalui proses sele tive per ea ility u tuk tra spor
ke dalam sel
Terjadi proses transpor elektron dan fosforilasi oksidatif
Mengekskresi exoenzim hidrolitik

Cytoplasm
• Composed largely of water, together with proteins, nucleic
acid, lipids and small amount of sugars and salts
• Ribosomes: numerous, 15-20nm in diameter with 70S;
distributed throughout the cytoplasm; sensitive to
streptomycin and erythromycin site of protein synthesis


Plasmids: extrachromosomal
genetic elements
 Inclusions: sources of stored
energy, e,g volutin

Plasmid

Plasmids are small，circular/line，
extrachromosomal，double-stranded DNA
molecules。They are capable of self-replication and
contain genes that confer some properties，such as
antibiotic resistance，virulence factors。Plasmids
are not essential for cellular survival.



granulose

Inclusions are
aggregates of various
compounds that are
normally involved in
storing energy
reserves or building
blocks for the cell.
Inclusions accumilate
when a cell is grown
in the presence of
excess nutrients and
they are often
observed under
laboratory conditions.

Inclusions of
Bacteria
Corynebacterium

Nucleus

• Lacking nuclear
membrane, absence
of nucleoli, hence
known as nucleic
material or nucleoid,
one to several per
bacterium.

Capsules and slime layers









Attachment
Protection from
phagocytic engulfment.
Resistance to drying.
Depot for waste products.
Reservoir for certain
nutrients.
Mucoid
colony

• These are structures surrounding the outside of the cell envelope. They
usually consist of polysaccharide; however, in certain bacilli they are
composed of a polypeptide (polyglutamic acid). They are not essential
to cell viability and some strains within a species will produce a capsule,
whilst others do not. Capsules are often lost during in vitro culture.

Some bacterial

species are mobile and possess
locomotory organelles - flagella. Flagella consist of a
number of proteins including flagellin
The diameter of a flagellum is thin, 20 nm, and
long with some having a length 10 times the
diameter of cell. Due to their small diameter,
flagella cannot be seen in the light microscope
unless a special stain is applied. Bacteria can have
one or more flagella arranged in clumps or spread
all over the cell.





Identification
of Bacteria
Pathogenesis
Motility of
bacteria

Monotrichate/Amphitrichate/Lophotrichate/Peritrichate

Flagella

Pili
• Pili are hair-like projections of the cell , They are
known to be receptors for certain bacterial viruses.
Chemical nature is pilin
• Classification and Function
a. Common pili or fimbriae: fine , rigid numerous,
related to bacterial adhesion
b. Sex pili: longer and coarser, only 1-4, related to
bacterial conjugation

Pilli vs Flagel

Shigella: common pili

Salmonella: common pili &
peritrichious flagella

Pilli sex & konjugasi

Endospores
(spores)





• Dormant cell
• Resistant to adverse
conditions
- high temperatures
- organic solvents

Identification of
Bacteria
Pathogenesis
Resistance

• Produced when starved
• Contain calcium dipicolinate
DPA, Dipicolinic acid
• Bacillus and Clostridium

Proses sporulasi