Cyanobactericidal Effect of Streptomyces sp. HJC-D1 on Microcystis auruginosa

Yun Kong,Liang Zhu,Xiangyang Xu,Paul Jaak Janssen

doi:10.1371/journal.pone.0057654

Abstract

An isolated strain Streptomyces sp. HJC-D1 was applied to inhibit the growth of cyanobacterium Microcystis aeruginosa FACHB-905. The effect of Streptomyces sp. HJC-D1 culture broth on the cell integrity and physiological characteristics of M. aeruginosa FACHB-905 was investigated using the ﬂow cytometry (FCM), enzyme activity and transmission electron microscopy (TEM) methods. Results showed that the growth of M. aeruginosa FACHB-905 was significantly inhibited, and the percentage of live cells depended on the culture broth concentration and exposure time. The activities of antioxidant enzymes including superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) increased with exposure concentration and exposure time, and the significant increase of reactive oxygen species (ROS) led to the disruption of the subcellular structure of M. aeruginosa FACHB-905, and caused the increase of malondialdehyde (MDA). Furthermore, TEM observation suggested the presence of three stages (cell breakage, organelle release and cell death) for the cyanobactericidal process of Streptomyces sp. HJC-D1. Therefore, Streptomyces sp. HJC-D1 not only affected antioxidant enzyme activities and ROS level, but also destroyed the subcellular structure of M. aeruginosa FACHB-905, demonstrating excellent cyanobactericidal properties.

Highlights

Up to now, the increasingly frequent outbreak of cyanobacterial blooms in lakes, reservoirs and rivers has drawn great attention in China [1]
The growth of M. aeruginosa FACHB905 cells were effectively inhibited by the culture broth with a concentration range of 3%–10% (v/v) after 4 d exposure
The analysis by means of ow cytometry showed that the different concentration of culture broth in the culture medium inhibited the growth of M. aeruginosa FACHB-905, and cyanobacterium cultures with culture broth concentrations of greater than or equal to 5% (v/v) showed a good inhibition performance compared to the control group

Summary

Introduction

The increasingly frequent outbreak of cyanobacterial blooms in lakes, reservoirs and rivers has drawn great attention in China [1]. Environmental and health problems caused by cyanobacterial blooms have been documented in many regions, and many eutrophication control methods such as chemical algaecides, oxidants, allelochemicals and cyanobactericidal microorganisms, have been applied for cyanobacteria and algae suppression [2,3]. Previous studies indicated that the inhibition of harmful algal or cyanobacterial growth might be the result of extracellular secretions from microorganisms [4,5,6]. These cyanobactericidal microorganisms including Bacillus, Dietzia, Janibacter, Micrococcus [5], Streptomyces sp. Research on the enzymatic response of bloom cyanobacteria by cyanobactericidal microorganisms may be helpful to explain the cyanobactericidal mechanism and promote the application of cyanobactericidal microbial technology

Methods

Results

Discussion

Conclusion