Allelopathic control of cyanobacterial blooms by periphyton biofilms

Abstract

SummaryPeriphyton biofilms are natural mixtures comprised of photoautotrophic and heterotrophic complex microorganisms. In this work, the inhibition effects of periphyton biofilms on cyanobacterial blooms were studied in pilot and field trials. Results show that the cyanobacterial species responsible for the blooms had an upper nutrient concentration threshold, below which it could not effectively compete with other organisms in the periphyton. The disappearance of the cyanobacterial blooms was due to the allelopathy between the cyanobacteria and periphyton biofilm. In particular, it was found that the periphyton biofilm could produce water-soluble allelochemicals such as indole and 3-oxo-a-ionone to significantly inhibit the growth of the cyanobacteria. These allelochemicals are able to damage the thylakoid membranes of the cyanobacteria, interrupt the electron transport in photosystem II, decrease effective quantum yields, and eventually lead to the failure of photosynthesis. A comprehensive discussion on the ecological consequences of these findings is also presented. This work demonstrates the potential of periphyton biofilm to be used as an environmentally friendly ecological engineering solution for (i) the control of cyanobacterial blooms and (ii) a transitional means for the construction of beneficial conditions for ecosystem restoration. In addition, this work provides significant insights into the competitive relationships between algae and biofilms.

Macrophyte Species Drive the Variation of Bacterioplankton Community Composition in a Shallow Freshwater Lake

“…In the present field study, the presence of macrophytes may exert a suppressing effect on Cyanobacteria at macrophyte-dominated zones (14,32,38). Previous studies indicated that the presence of macrophytes influences nutrient cycling and phytoplankton biomass (30), and phytoplankton may affect bacterioplankton diversity due to differences in their chemical compositions (37).…”

“…Betaproteobacteria are abundant in freshwater lakes (4,10,12,32,44) and have been shown to degrade a variety of organic molecules (3). Wu et al (38) demonstrated that large numbers of Gammaproteobacteria were observed in turbid waters, and Actinobacteria and Betaproteobacteria were revealed to be highly important in clear waters. Furthermore, a few phylotypes related to OD1 and TM7 were found only in the N. peltata tank in the microcosm experiment (see Table S2 in the supplemental material), which needs further investigation.…”

First report on the allelopathic effect of Tychonema bourrellyi (Cyanobacteria) against Microcystis aeruginosa (Cyanobacteria)

“…Chlorophyll a is firstly excited by the photons, and then produces electrons. Electrons are transported from the PQ pool to the cytochrome bf complex and then transferred to photosystem I and generate NADPH (Wu et al 2011). ETR max is the measure of the capacity of PS II to utilize the absorbed light energy (Marshall et al 2000).…”

“…The dramatic differences of the inhibitory effects between the treatments of static culture and shaking culture suggest that the allelopathic substances excreted by T. bourrellyi may be volatile substances. Recently, some volatile substances, such as β-cyclocitral (Ozaki et al 2008), β-ionone (Ozaki et al 2008;Shao et al 2011), and α-ionone (Wu et al 2011), have been reported to exhibit inhibitory effects on M. aeruginosa. β-Ionone was identified as the major ingredient in the volatile substances in the cultures of T. bourrellyi CHAB663.…”

The Studies of Periphyton: From Waters to Soils

“…Many contaminants such as Cu, Cd and Hg can be removed by periphyton and their mechanisms involve in adsorption, degradation and both [5][6][7][8][9]. While the appearance of some new contaminants such as TiO 2 nanoparticle and hormone, the traditional periphyton-technologies might be difficult to effectively work.…”