Responses of the toxic cyanobacterium Microcystis aeruginosa to iron and humic substances

Cyanobacteria are known to be a rich source of biologically active compounds some of which can have pharmaceutical importance. In this work we present the screening results of cyanobacterial strains for their antibacterial, antifungal, and cytotoxic activity. Cyanobacterial strains were isolated from various soil types in province of Vojvodina and Central Serbia, Republic of Serbia. The screening included 9 strains of Anabaena and 9 strains of Nostoc. Both, extracellular products (from the culture liquid) and cellular crude lipophilic extracts were tested against 13 bacterial strains and 8 fungal strains. Cytotoxic activity was tested against three human cell lines. Methanol extracts were prepared according to Østensvik. Antibacterial and antifungal activities were determined measuring inhibition zone, 48 h after inoculation. The cytotoxic activity was determined by sulforhodamine B (SRB) colorimetric assay. Of all cyanobacterial strains tested, 52% showed some antifungal and 41% antibacterial activity. Two out of six tested strains possessed cytotoxic activity. The cytotoxic activity of Anabaena strain S12 was found both in culture liquid and crude cell extract. It occurred specifically between the 21st and 42nd day of cultivation against HeLa and MCF7 cells, but had no activity against cell line derived from a healthy tissue. A high percentage of the active strains among the tested strains justify the effort of screening cyanobacteria that are isolated from terrestrial environments. The most promising strains for the further study are Anabaena strain S12 which showed strong cytotoxic and antibacterial activity and Anabaena strain S20 which produces a potent antifungal compound. The future work, besides further screening and chemical identification of the active compounds, should also include the development of culture techniques that would lead to more efficient production of biologically active compounds.

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“…Recent reports suggest that metal ion-alga interaction could be of great importance in the formation of cyanobacteria blooms [38] .…”

Section: Discussionmentioning

confidence: 99%

Antibacterial, antifungal and cytotoxic activity of terrestrial cyanobacterial strains from Serbia

et al. 2008

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“…The humic substances (humic and fulvic acids) retard Fe(III) hydrolysis by complexation, and thus the precipitation of amorphous hydrous ferric oxide in seawater. In addition, humic substances stimulate the growth of coastal marine phytoplankton in laboratory cultures (Graneli & Moreira 1990, Carlsson & Graneli 1993, Kosakowska et al 2007) and contribute to phytoplankton blooms in coastal waters (Glover 1978). Therefore, the humic acid-Fe complexes supplied by riverine input also play an important role in providing biological available Fe in coastal waters.…”

Section: Uptake Of Different Fe Species By Phytoplanktonmentioning

confidence: 99%

“…Humic substances (humic and fulvic acids) contribute to iron complexation, keeping iron in a soluble form at both high pH and high concentrations of anions and cations in estuarine systems (Hering & Morel 1988). Humic substances are also able to stimulate the growth of coastal phytoplankton in laboratory cultures (Graneli & Moreira 1990, Carlsson & Graneli 1993, Kosakowska et al 2007) and contribute to the phytoplankton bloom in coastal waters (Glover 1978).…”

Section: Introductionmentioning

confidence: 99%

Accelerated uptake by phytoplankton of iron bound to humic acids

Chen¹,

Wang²

2008

Aquat. Biol.

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“…Evidence exists that growth of this organism can be limited by supply of the trace nutrient Fe (39). Additionally, Fe nutrition alters basal metabolic functions of the organism, including photosynthesis, respiration, and nutrient uptake (28,31,65), as well as potentially inducing the biosynthesis of secondary metabolites, such as the potent hepatotoxin (microcystin), possibly to prevent cellular damage from reactive oxygen species that are generated by oxidative stress (2). Recent laboratory investigations into the Fe uptake mechanisms of M. aeruginosa indicated that photoreductive dissociation of chelated Fe(III) significantly increased Fe availability for Fe-limited cells growing in EDTA-buffered culturing medium (15).…”

mentioning

confidence: 99%

Characteristics of the Freshwater Cyanobacterium Microcystis aeruginosa Grown in Iron-Limited Continuous Culture

Dang

Fujii

Rose

et al. 2012

Appl Environ Microbiol

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Responses of the toxic cyanobacterium Microcystis aeruginosa to iron and humic substances

Cited by 38 publications

References 36 publications

Antibacterial, antifungal and cytotoxic activity of terrestrial cyanobacterial strains from Serbia

Antibacterial, antifungal and cytotoxic activity of terrestrial cyanobacterial strains from Serbia

Accelerated uptake by phytoplankton of iron bound to humic acids

Characteristics of the Freshwater Cyanobacterium Microcystis aeruginosa Grown in Iron-Limited Continuous Culture

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