Growth Inhibition of Microcystis Cyanobacteria by L-Lysine and Disappearance of Natural Microcystis Blooms with Spraying

Abstract

Low concentrations of L-lysine and L-lysine-containing-peptides strongly inhibited the growth of axenic strains of 4 species belonging to the genus Microcystis (cyanobacteria). Inhibitory activities decreased in theThe addition of 50 mM of L-lysine to growing cells of axenic strains of M. novacekii TAC20-1 and M. viridis NIES102 resulted in a loss of buoyancy, a decrease in chlorophyll a content and consequent cell lysis. The cells took up most of the L-lysine added to the culture medium of M. viridis NIES-102 in one day. However, the amino acid was released back into the medium with cell lysis 3 days after the addition. Laboratory results were confirmed in experimental ponds outdoors by spraying L-lysine onto natural Microcystis blooms in the summer of 1999 and 2000. The spraying of 50 mM L-lysine caused Microcystis colonies to vanish from the surface water within two days; there was a dramatic change in the color and transparency of the pond surface water. After the immediate disappearance of Microcystis sp., both Euglena sp. and/or Phormidium tenue appeared, the latter becoming the dominant species in the phytoplankton community of the pond. In the experiment in summer 2000, the L-lysine provided to the pond was assayed. The level decreased gradually and L-lysine was not detected in the pond water after 6 days. The mechanisms of growth inhibition by L-lysine and a possible mitigation of Microcystis blooms by the amino acid are discussed.

Existing and emerging cyanocidal compounds: new perspectives for cyanobacterial bloom mitigation

“…In lake treatments with HP, this has been inspected and judged as a lesser problem than anticipated. Like the observations in the application of the cyanocide lysine by Takamura et al (2004), debris of dead cells sank rapidly from the water surface in the water column and onwards to the sediment with clear water emerging in\48 h after the treatment (unpublished results Weenink et al). Furthermore, while HP application is advised against in case the rate of HP degradation is too high, this naturally limits the applicability in lake mitigation of denser blooms.…”

“…To ponds with a water volume of 20 m 3 and natural Microcystis blooms, 7.3 mg L -1 (final concentration of L-lysin) was added and also applied on the water surface to affect floating cyanobacteria directly (Takamura et al 2004). The Microcystis removal was rapid, already after 2 days Microcystis colonies vanished from the water surface.…”

Effect of Selected Plant Extracts and D- and L-Lysine on the Cyanobacterium Microcystis aeruginosa

“…In addition, potential effects of organic carbon and nitrogen enrichment (adding L-lysine at 5 mg L ) on ecosystem functioning should be studied first. This is further corroborated by [23], who observed in a repetition of their pond experiment an almost complete absence of Microcystis for almost two weeks, but after a short ) led oxygen drop to about 70% of that in the control [50]. Also lysis of the M. aeruginosa cells could enhance decomposition and reduce oxygen concentrations.…”

“…Hence, it remains to be seen if treatment with L-lysine delivers immediate improve of the water quality. Repeated additions of L-lysine are expected to influence water quality, while the replacement with other cyanobacteria [23,39] illustrates that the earlier mentioned among strain and species variability in sensitivity to L-lysine might present a major drawback in its applicability in cyanobacterial control.…”

“…In such testing, extracts from Fructus mume [19], Salvia miltiorrhiza (Chinese Danshen) [20] and extracts from seeds of the pan tropical tree Moringa oleifera [21] are observed to express anti-cyanobacterial activity against M. aeruginosa. In addition, the amino acid L-lysine is reported as active against cyanobacteria [22][23][24]. However, with respect to D-Lysine reports are less conclusive; while Kaya and Sano [22] reported that D-Lysine was equally suppressive to Microcystis as L-Lysine, others found no effect of D-Lysine on Microcystis [25].…”