Evidence of allelochemical activity in subtropical cyanobacterial biofilms of Taiwan
Juttner, Friedrich; Wu, Jiunn-Tzong
published: Feb 11, 2000
ArtNo. ESP141014704004, Price: 29.00 €
Cyanobacterial biofilms were collected in the subtropical part of Taiwan from wet and irrigated rocks, stone and concrete walls, and drains. The biofilms developed in unpolluted freshwater and consisted of various genera, includingPhormidium, Lyngbya, Oscillatoria, Microcoleus, Aphanothece and Scytonema. Ethanolic extracts of these biofilms were used to test for growth inhibition activity against cyanobacteria (Anabaena 7120 and Anabaena P-9), grazer toxicity (acute toxicity of Thamnocephalus platyurus) and inhibition activity of extracellular and ectoenzymatic polysaccharide hydrolysis (α-glucosidase inhibition). More than 20 % of the extracts were active in the different bioassays. Most Phormidium biofilms showed growth inhibition activity; the strongest grazer toxicity was found in a Nostoc biofilm, while a Scytonema biofilm exhibited the strongest inhibitor activity against α-glucosidase. The activities shown in the different bioassays were not accumulated in a particular biofilm but were distributed over different collections and demonstrate the wide occurrence and importance of allelochemistry in cyanobacterial biofilms. The growth inhibition test for cyanobacteria was miniaturized to allow the assay of very small amounts of growth inhibitory extracts.