Selective Algicidal Action of Peptides against Harmful Algal Bloom Species

Seong-Cheol Park,Yoonkyung Park,Jong-Kook Lee,Si Wouk Kim,Terence Evens

doi:10.1371/journal.pone.0026733

Abstract

Recently, harmful algal bloom (HAB), also termed “red tide”, has been recognized as a serious problem in marine environments according to climate changes worldwide. Many novel materials or methods to prevent HAB have not yet been employed except for clay dispersion, in which can the resulting sedimentation on the seafloor can also cause alteration in marine ecology or secondary environmental pollution. In the current study, we investigated that antimicrobial peptide have a potential in controlling HAB without cytotoxicity to harmless marine organisms. Here, antimicrobial peptides are proposed as new algicidal compounds in combating HAB cells. HPA3 and HPA3NT3 peptides which exert potent antimicrobial activity via pore forming action in plasma membrane showed that HPA3NT3 reduced the motility of algal cells, disrupted their plasma membrane, and induced the efflux of intracellular components. Against raphidoflagellate such as Heterosigma akashiwo, Chattonella sp., and C. marina, it displayed a rapid lysing action in cell membranes at 1∼4 µM within 2 min. Comparatively, its lysing effects occurred at 8 µM within 1 h in dinoflagellate such as Cochlodium polykrikoides, Prorocentrum micans, and P. minimum. Moreover, its lysing action induced the lysis of chloroplasts and loss of chlorophyll a. In the contrary, this peptide was not effective against Skeletonema costatum, harmless algal cell, even at 256 µM, moreover, it killed only H. akashiwo or C. marina in co-cultivation with S. costatum, indicating to its selective algicidal activity between harmful and harmless algal cells. The peptide was non-hemolytic against red blood cells of Sebastes schlegeli, the black rockfish, at 120 µM. HAB cells were quickly and selectively lysed following treatment of antimicrobial peptides without cytotoxicity to harmless marine organisms. Thus, the antibiotic peptides examined in our study appear to have much potential in effectively controlling HAB with minimal impact on marine ecology.

Highlights

Harmful algal bloom (HAB), commonly called ‘‘red tide’’ and caused by massive and exceptional overgrowth of microalgae and cyanobacteria around the coasts, has increased globally with serious implications for the aquaculture industry and human health [1]
The anti-algal activity of HPA3 and HPA3NT3 peptides was evaluated by the observation of decreased motility and bursting of harmful algal species, Cochlodinium polykrikoides, Prorocentrum minimum and micans, Chattonella marina and sp., and Heterosigma akashiwo under light microscopy (Table 1)
Problems with HABs have significantly increased due to factors such as extensive costal eutrophication and global climate change [23,24,25]

Summary

Introduction

Harmful algal bloom (HAB), commonly called ‘‘red tide’’ and caused by massive and exceptional overgrowth of microalgae and cyanobacteria around the coasts, has increased globally with serious implications for the aquaculture industry and human health [1]. HAB leads to huge economic loss and contributes to pollution of the coastal areas. This phenomenon often causes damage such as mass mortalities of fish, marine mammals, shellfish, and other oceanic life due to toxins and depletion of oxygen [2]. Secondary pollution of the marine environment is caused by imprudent treatments for preventing HABs. For example, clay or yellow loess was used to remove HAB organisms by sedimentation in Korea, Japan, and other countries; this method occasionally creates secondary effects on the bottom-dwelling organisms or ecological and environmental problems through dispersal of a large amount of clay to sea [11,12,13]. Alternative methods or materials are needed to minimize such problems

Objectives

Methods

Results

Conclusion