|
KMID : 0545120030130010050
|
|
Journal of Microbiology and Biotechnology
2003 Volume.13 No. 1 p.50 ~ p.56
|
|
|
Biotoxic Cyanobacterial Metabolites Exhibiting Pesticidal and Mosquito Larvicidal Activities
|
|
SINGH, DHANANJAYA P.
KUMAR, ASHOK/TYAGI, M.B.
|
|
|
Abstract
|
|
|
|
A freshwater bloom-forming cyanobacterium, Microcystis aeruginosa, and local soil isolate Scytonema sp. strain BT 23 were demonstrated to contain biotoxic secondary metabolites with pesticidal and mosquito larvicidal activities. A purified toxic constiuent from M. aeruginosa showed an absorption maximum at 230 nm and its toxicity symptoms, Rf value on TLC, and retention time observed in an HPLC analysis were similar to thoses of the hepatotoxic heptapeptide microcystin-LR. The bioactive constituent of the Scytonema sp. was less polar in nature and exhibited two peaks at 240 and 285 nm. When applied to two cruciferous pests, Pieris brassicae and Plutella xylostella, the crude extracts and toxic principles from the two cyanobacteria showed significant antifeedant activity in a no-choice bioassay, and at higher concentrations exhibited contact toxicity to the insect larvae. The purified toxin from M. aeruginosa was found to be more effective and produced 97.5 and 92.8% larval mortality in the two pets, following 2 h of toxin treatment at a concentration of 25 ㎍ per leaf disc (2.5 cm dia.). Meanwhile, similar treatment with the purified toxin from Scytonema sp. strain BT 23 only produced 73 and 78% mortality in the two pests. The cyanobacteria constituents also showed significant activity against Cluex and Anopheles larvae. The M. aeruginosa toxin (20 ㎍ ml^-1) caused 98.2 and 88.1% mortality in the Cluex and Anopheles larvae, respectively, while the purified toxin from the Scytonema sp. was less toxin and only produced a 96.3 and 91.2% mortality, respectively, at a much higher concentration (40 ㎍ ml^-1). Accordingly, the current results point to certain hitherto unknown biological properties of cyanobacterial biotoxins.
|
|
|
KEYWORD
|
|
|
|
|
|
FullTexts / Linksout information
|
|
|
|
|
|
Listed journal information
|
|
  
|
|