microbiology02.pdf about actinomycetes .

....

1. 1
B.SC. III SEMESTER
PAPER :: BOT-231
MICROBIOLOGY
HariLoyi
Assistant Professor
[phone] | [email protected] Department of Botany
Jawaharlal Nehru College, Pasighat

2. ACTINOMYCETES
oMostly aerobic.
oGram +vebacteria.
oOccur abundantly in soil, water, mud, manure, milk & other
food products.
oMostly saprophytes. Some are parasites.
oParasitic strains cause some serious diseases in plants &
animals.
oPrimary sources of naturally synthesized antibiotics.
e.g. Straptomyces
2 Department of Botany
Jawaharlal Nehru College, Pasighat

3. DISTRIBUTION
oFound in all types of habitats.
Soil, water, decomposing organic matter, etc.
oSome are symbionts(Frankiasp.), Some are pathogenic to
humans (Dermatophylus).
3 Department of Botany
Jawaharlal Nehru College, Pasighat

4. STRUCTURE
oGreek words: Actis= ray; mykes= fungus
oFungus-like bacteria with cylindrical cells which are usually united to form
filaments, resembling the mycelium of a true fungus.
oBranched, non-septate, thin.
oIn some species, filaments break up into small coccoidcells. They are
usually non-motile.
oIn Actinoplanes, small flagella are present.
oIn young filaments, the cytoplasm is homogenous, but at maturity, many
vacuoles, fat droplets, granules and few rod-shaped bodies develop in
the cytoplasm.
oAs in other true bacteria, there is no well-defined nucleus. Instead, many
chromatin granules are present.
oAt maturity, the cell wall becomes fragile and so, the full-grown filaments
break up easily.
4 Department of Botany
Jawaharlal Nehru College, Pasighat

5. LOCOMOTION
oThey are mostly non-motile, except for Actinoplanes, which
are aquatic and swim about with the help of minute flagella.
5 Department of Botany
Jawaharlal Nehru College, Pasighat

6. REPRODUCTION
oThey generally multiply by Fragmentation (Asexual method).
oThe mycelium breaks up into small coccoidor very rarely, rod-shaped
cells, each of which grows into new filaments.
oSome species of Actinomycetesalso form asexual reproductive structures
in the form of conidia and sporangiospores.
oConidia develop on conidiophores and sporangiosporesdevelop on
sporangiophores, either singly or in long chains.
oConidia and sporangiosporesdevelop by septa formation at the tip of
aerial filaments, usually in response to nutrient deficiency.
6 Department of Botany
Jawaharlal Nehru College, Pasighat

7. CLASSIFICATION
oTaxonomic classification of Actinomyceteshas been done on the basis of
morphology, arrangement of spores, cell-wall chemistry, types of sugar
present in the cell extract and the heat resistance of the spores.
oThe single order Actinomycetaleshas 8 families.
7 Department of Botany
Jawaharlal Nehru College, Pasighat

8. OTHER SIGNIFICANT FEATURES
Symbiotic species, Frankiasp. show symbiosis with a variety of non-
leguminous plants, like Casuarina(Casuarinaceae), Rubusand Pursia
(Rosaceae).
Human Diseases ActinomycetesPathogen
oTuberculosis ……………………………… Mycobacteriumtuberculosis
oLeprosy …………………………………… Mycobacterium leprae
oDiphtheria ………………………………... Corynebacteriumdiptheriae
Animal Diseases ActinomycetesPathogen
oTB of Cattle ………………………………. Mycobacterium bovis
oTB of Domestic Fowls …………………... Mycobacterium avium(other birds also)
Plant Diseases ActinomycetesPathogen
oTondudisease of Wheat ………………… Corynebacteriumtitrici
oScab of Potato …………………………… Actinomycesscabies
8 Department of Botany
Jawaharlal Nehru College, Pasighat

9. MYCOPLASMA
oSmallest known aerobic prokaryotes without a cell wall.
oFirst discovered by Louis Pasteur (1843), while studying
Pneumonia of Cattle.
oThey were designated as PPLO (Pleuropneomonia-like Organisms).
(However, Pasteur couldn’t isolate them in pure culture on standard nutrient
media & observe them under light microscope. In 1898, two French
microbiologists –Nocard& Roux were successful in obtaining pure culture of
them in media-containing serum. They observed that these microorganisms could
produce disease when inoculated into healthy cattle.)
oGram –ve, usually non-motile, free-living, parasitic & saprophytic.
oSensitive to dessication.
oDo not grow at low pH.
oHeat sensitive (<50ºC)
9 Department of Botany
Jawaharlal Nehru College, Pasighat

10. DISTRIBUTION
oFrequent contaminants in tissue cultures rich in organic
matter.
oAbundant in unsenitizedareas rich in organic matters.
oAlso found in hot-water springs & other thermal
environments. They occur in soil, sewage water, different
substrates and in humans, animals and plants.
oMostly they are pathogens and parasites.
10 Department of Botany
Jawaharlal Nehru College, Pasighat

11. STRUCTURE
oUnicellular, prokaryotic & non-
motile. On media, forms fried-egg
shaped colonies.
oUnder microscope, they appear
small, unicellular bodies and some
of them form branched filaments.
oBecause of their particularly small
size, they can pass through
bacterial filters. They can also grow
in a medium which contains no
living tissues. Because of these two
characteristics, Mycoplasmasare
considered to be intermediate
between bacteria and viruses.
11 Department of Botany
Jawaharlal Nehru College, Pasighat

12. STRUCTURE
oA true cell wall is absent. This
makes these organisms highly
elastic and readily deformable.
Hence, Mycoplasmasdo not have
any definite regular shape. The cells
may be coccoid, granular, pear-
shaped, cluster-like, ring-like or
filamentous.
oCells are covered by a single
lipoprotein cytoplasmicmembrane.
oCytoplasm contains ribosomesand
nucleoplasm-like structures.
oResistentto antibiotics acting on cell
walls.
12 Department of Botany
Jawaharlal Nehru College, Pasighat

13. REPRODUCTION
oMostly by Budding or Binary Fission within the host cell.
oA single cell divides into very minute cells, called Elementary
Bodies, which are found in the mature cells of host plants
and animals.
oSome species forms long filaments and chain of minute
spherical conidia. These conidia are initially very small and
increase in size later after liberation.
13 Department of Botany
Jawaharlal Nehru College, Pasighat

14. CLASSIFICATION
On the basis of nutritional requirements, morphology & habitat
preferences: 4 genera
1.Mycoplasma:Require cholesterol for growth. Parasitic –infects
mucous membranes & joints of humans & animals.
2.Acholeplasma:Donotrequire cholesterol for growth. Free-living
saprophytes, heat-sensitive. Cannot grow above 45ºC.
3.Spiroplasma:Bounded by 3-layered membrane. Require
cholesterol for growth. Gram +ve, motile, facultative anaerobes.
4.Thermoplasma:Heat loving. Donotrequire cholesterol for growth.
Strictly anaerobic, acidophillic. Can grow above 60ºC temp.
14 Department of Botany
Jawaharlal Nehru College, Pasighat

15. DISEASES CAUSED BY MYCOPLASMA
Inplants,theycausediseasesinsievetubes,upsettingthe
hormonalbalance.Duetoinfection,theflowersmayassume
theshapeoffoliageleaves,becauseAnthocyaninformation
isinhibited.Itmayalsocausewiltingofleaves,forminga
conditioncalled“Witch’sBroom.”
Inhuman,theycauseadiseasecalledPAP(PrimaryAtypical
Pneumonia).PAPhasanincubationperiodof9–21daysand
thediseasemaylastupto3weeks,causingheadache,cough
etc.
Inanimals,theyinfectthemouth,pharynxandsometimes,
urogenitaltract.MostcommonspeciescausingPneumoniain
theupperrespiratorytractofanimals&humansisMycoplasma
pneumonae.
15 Department of Botany
Jawaharlal Nehru College, Pasighat

16. 16 Department of Botany
Jawaharlal Nehru College, Pasighat