Antibiotics–Producing Microorganisms

Question

• Which 4 organisms make the most antibiotics?

• Chemotherapeutic agents: antimicrobial agents of synthetic origin useful in the treatment of microbial or viral disease. Examples: sulfonilamides, isoniazid, ethambutol, AZT, chloramphenicol. Note that the microbiologist's definition of a chemotherapeutic agent requires that the agent be used for antimicrobial purposes and so excludes synthetic agents used for therapy against diseases that are not of microbial origin.

• Antibiotics are low molecular-weight (non-protein) molecules produced as secondary metabolites, mainly by microorganisms that live in the soil.

• Among the molds, the notable antibiotic producers are Penicillium and Cephalosporium , which are the main source of the beta-lactam antibiotics (penicillin and its relatives).

• In the Bacteria, the Actinomycetes, notably Streptomyces species, produce a variety of types of antibiotics including the aminoglycosides (e.g. streptomycin), macrolides (e.g. erythromycin), and the tetracyclines. Endospore-forming Bacillus species produce polypeptide antibiotics such as polymyxin and bacitracin.

Representative Sources of Antibiotics

Microorganisms AntibioticsFungi

Penicillium notatum Penicillin G

Cephalosporium species Cephalothin

Penicillium gryseofulvum Griseofulvin

Gram-Positive Rods

Bacillus polymyxa Polymyxin

Bacillus subtilis Bacitracin

Actinomycetes

Streptomyces griseus Streptomycin

Micromonospora species Gentamicin

Streptomyces orientales Vancomycin

Streptomyces lincolnensis Clindamycin

Streptomyces erythreus Erythromycin

Streptomyces cattleya Imipenem

Streptomyces mediterranei Rifampicin

Streptomycesspecies Tetracycline

Streptomyces venezuelae Chloramphenicol

Streptomyces fradiae Neomycin

Streptomyces nodosus Amphotericin

Streptomyces noursei Nystatin

Penicillium• Penicillium is one of the most commonly found molds. It is common

in soil, food, cellulose and grains. Often found growing indoors on water damaged building materials (chipboard/OSB, plywood, wallpaper, glue, carpet, wall paper) as well as on food items (dried foods, cheeses, fruits, herbs, spices, cereals). Penicillium mold is used to make the antibiotic penicillin and even an antifungal drug called griseofulvin.

The organization of the phialides at the tips of the conidiophores is very typical. They form brush-like clusters which are also referred to as "penicilli"

Light microscopeSEM

In the center of the plate is a colony of Penicillium notatum, a mold that produces penicillin. After appearance of the mold colony, the plate was overlaid with a bacterial culture of Micrococcus luteus which forms a yellow "lawn" of growth. A zone of inhibition of bacterial growth surrounds the fungal colony where penicillin has diffused into the medium.

Penicillium chrysogenum

• The first member of the newer series of beta-lactams was isolated in 1956 from extracts of Cephalosporium acremonium, a sewer fungus.

Streptomycin discovered by Selman Waksman and Albert Schatz in the 1940s

Two Strains of Streptomyces griseus• I isolated two strains of Streptomyces griseus from two separate

sources. Both strains produced streptomycin. And streptomycin was effective against both gram-negative bacteria and the tubercle bacillus. I called one strain of S.griseus 18-16 because it was the 16th actinomycete I isolated from a heavily manured field soil. That was the 18th soil from which I obtained actinomycetes to test for antibiotic activity (Schatz, 1945).

• I isolated another strain of S.griseus from a petri dish which my fellow graduate student Doris Jones, now Doris Ralston, had streaked with a swab from a healthy chicken's throat.  I called that second isolate D-1 because it was the first (No. I) actinomycete I isolated from the plates that Doris (D) gave me. ------ S.griseus is an actinomycete that is widely distributed in soils.Its spores can be blown around in the air and inhaled by people and animals.

Streptomyces - a promising source of drugs.

This strain produces an aminoglycoside antibioticC streptomycinC which is clinically used as a broad-spectrum antibacterial (tuberculostatic) agentD Aerial mass color is yellow and straight spore chains with a smooth surface are developed.

Streptomyces griseus

From a single spore a vegetative mycelium germinates, this is followed by aerial growth with the production of aerial hyphae. These hyphae in turn will undergo synchronous septation to produce unigenomic spore compartments, which will disperse and thus commence a new cycle 

• Medically useful antibiotics are produced by B. subtilis (bacitracin) and B. polymyxa(polymyxin B).

• In addition, strains of B. amyloliquefaciens bacteria, which occur in association with certain plants, are known to synthesize several different antibiotic substances, including bacillaene, macrolactin, and difficidin. These substances serve to protect the host...

Morphology colony: Bacillus subtilis

Bacillus subtilis.  These gram positive, sporeforming rods produce colonies which are dry, flat, and irregular, with lobate margins.

Antimicrobial activity of B.subtilis at 0, 8, 12 and 16

hours of incubation,against M. luteus, as shown

by clear zone ofinhibition (mm) [A: 0, B: 8,

C: 12, D: 16 hours]. Zone of inhibition directly

related to the amount of antibiotic produced is

decreasing with thepassage of incubation time

Answer 

1. Penicillium (e.g. Penicillium chrysogenum/notatum),

2. Cephalosporium (e.g. Cephalosporium acremonium ),

3. Streptomyces (e.g. Streptomyces antibioticus) and

4. some Bacillus species (e.g. Bacillus polymyxa and Bacillus subtilis )

Tugas:

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