Cyanobacteria from benthic mats of Antarctic lakes as a source of new bioactivities.
OBJECTIVE
To exploit the cyanobacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes for the discovery of novel antibiotic and antitumour activities.


RESULTS
In all, 51 Antarctic cyanobacteria isolated from benthic mats were cultivated in the laboratory by optimizing temperature, irradiance and mixing. Productivity was generally very low (</=60 mg l(-1) d(-1)) with growth rates (mu) in the range of 0.02-0.44 d(-1). Growth rates were limited by photosensitivity, sensitivity to air bubbling, polysaccharide production or cell aggregation. Despite this, 126 extracts were prepared from 48 strains and screened for antimicrobial and cytotoxic activities. Seventeen cyanobacteria showed antimicrobial activity (against the Gram-positive Staphylococcus aureus, the filamentous fungus Aspergillus fumigatus or the yeast Cryptococcus neoformans), and 25 were cytotoxic. The bioactivities were not in accordance with the phylogenetic grouping, but rather strain-specific. One active strain was cultivated in a 10-l photobioreactor.


CONCLUSIONS
Isolation and mass cultivation of Antarctic cyanobacteria and LC-MS (liquid chromatography/mass spectrometry) fractionation of extracts from a subset of those strains (hits) that exhibited relatively potent antibacterial and/or antifungal activities, evidenced a chemical novelty worthy of further investigation.


CONCLUSIONS
Development of isolation, cultivation and screening methods for Antarctic cyanobacteria has led to the discovery of strains endowed with interesting antimicrobial and antitumour activities.
Biondi
N
N
Dipartimento di Biotecnologie Agrarie, Universita' degli Studi di Firenze, Firenze, Italy.
Tredici
M R
MR
Taton
A
A
Wilmotte
A
A
Hodgson
D A
DA
Losi
D
D
Marinelli
F
F
D000864:Antarctic Regions; D000900:Anti-Bacterial Agents / Q000302:isolation & purification*; D000935:Antifungal Agents / Q000302:isolation & purification*; D001232:Aspergillus fumigatus / Q000187:drug effects; D001431:Bacteriological Techniques; D003455:Cryptococcus neoformans / Q000187:drug effects; D000458:Cyanobacteria / Q000254:growth & development / Q000378:metabolism*; D008826:Microbial Sensitivity Tests; D010788:Photosynthesis; D010933:Plankton; D013211:Staphylococcus aureus / Q000187:drug effects; D018675:Toxicity Tests; D014871:Water Microbiology
D000900:Anti-Bacterial Agents; D000935:Antifungal Agents