detail information about the actinomycetes

1. ST. PIOUS X DEGREE AND PG COLLOEGE FOR WOMEN
M.SC MICROBIOLOGY I SEMESTETR
PAPER I- GENERAL MICROBIOLOGY AND MICROBIAL PHYSIOLOGY
SEMINAR
TOPIC: ACTINOMYCETES
BY:- P. DHARANI
ROLLNO:- 029

2. Actinomyces means “ ray fungus”.
They are unicellular, gram +ve, filamentous, anaerobes or
microaerophilic in nature.
The fermentative types of actinomycetes are found in body cavities
of humans and animals.
They can grow on simple lab media but they are slow growing.
They are causative agents for few human diseases such as
actinomycosis & various abscesses and plant diseases such as potato
scab, blueberry etc.

3. CHARECTERISTICS
Actinomycetes share the following physicochemical properties:
Actinomycetes usually have 1-2 µm diameter.
They generally possess a rod shape with a filamentous or
branched structure. The filaments contain mumaric acid.
Most of the species are aerobic, while a few are anaerobes to
facultative aerobes.
Cell wall and internal structures are similar to bacteria. The cell
wall of actinomycetes consists of mycolic acid.
The growth or reproduction of actinomycetes is slower than the
bacteria and fungi. Hence, actinomycetes are sometimes called as
“Slow growers”.
They are having 60-78% of G+C content.
Actinomycetes are most abundant in soil (106-108g) and marine
habitat.
The majority of species are usually non-motile, non-capsulated

5. They produce filamentous hyphae and there is no endospore
Production.
 These are secondary metabolite producers and the representing
genera- Streptomyces, etc.
LIFE CYCLE OF ACTINOMYCETES

6. The life cycle of actinomycetes completes in six steps:
1. Germination
2. Vegetative growth
3. Coiling
4. Septation
5. Spore maturation
6. Release of spore
CLASSIFICATION
 Actinomycetes have seven families, based on the hyphal and
reproductive structures, they are:
i. Streptomycetaceae: e.g. Streptomyces
ii. Nocardiaceae: e.g. Nocardia
iii. Micromonosporaceae: e.g. Micromonospora
iv. Actinoplanaceae: e.g. Actinoplanes
v. Dermatophilaceae: e.g. Geodermatophilus
vi. Frankiaceae: e.g. Frankia
vii. Actinomycetaceae: e.g. Actinomyces

7. The disease caused is known as actinomycosis, it is a chronic
suppurative and Granulomatous characterized by multiple abscesses,
tissue disruption, fibrosis and Formation of sinuses.
It is an endogenous infection and more often affects immuno
compromised Individuals.
Actinomycosis have 4 clinical forms:
1. Cervicofacial : lumpy jaw which effects the cheeks and sub maxillary
regions.
2. Thoracic: effects the lungs
3. Abdominal: effects the Illeocaecal region- tissues with low O2 supply
4. Pelvic
Smelly pus is discharged from the sinuses in actinomycosis, this pus
contains yellow sulphur granules, which gives very bad odor.
We collect this discharged pus and use it as a specimen for laboratory
diagnosis.

8. STREPTOMYCES
 They form long, branched aerial mycelia consisting of non-fragmenting
filaments.
 These hyphae are septate & produce spores[conidia] in long spore
chain[straight, curved/ coiled].
CHARACTERISTIC FEATURES:
 The nature of spore surface which when observed under microscope
appear smooth, spiny or hairy.
 The pigmentation of mycelium may be white, yellow, violet, red, blue,
green/ grey.
 The color of pigment exuded by mycelium.
 Physiological characteristics such as utilization of various carbon
source, organic acids, reduction of nitrate & hydrolysis of urea.
 The conidia of this group are not endospores & not as heat resistant as
the endospores of true bacteria.
 A temp of 65⁰C for 30mins is enough to kill the spores.
 These colonies are tiny & bright coloured and grow best at 25⁰C at ph

9.  Most of these species are saprophytes in soil & some are pathogenic
to animals and plants.
ANTIBIOTICS
 A large number of species and sub species of this group can produce
Antibiotics.
E.g.- tetracycline's, Oxytetracycline & erythromycin.
St. griseus – streptomycin
St. fradiae – neomycin
St. aureofaciens - aureofacin
ECONOMIC IMPROTANCE