Pseudomonas fluorescensHYK0210-SK09 offers species-specific biological control of winter algal blooms caused by freshwater diatomStephanodiscus hantzschii

Abstract

Aims: The study of an algicidal activity and mechanism of the isolated Pseudomonas fluorescens HYK0210‐SK09 (SK09) against a winter bloomed harmful diatom, Stephanodiscus hantzschii. Methods and Results: SK09 was isolated from the Paldang reservoir, Korea and used to biological control of S. hantzschii. The inoculation of SK09 at the final density of 5 × 106 cells ml−1 caused degradation of >90% of S. hantzschii cells within 5 days. The algal cell lysis was achieved by a direct attack of the bacteria to the diatom cells, and the algicidal compound was located in the cytoplasm of the cell. As SK09 did not suppress Microcystis aeruginosa, Anabaena cylindrica, Coelastrum astroideum or Cyclotella meneghiniana, it appeared to attack S. hantzschii in a species‐specific manner. Testing in an indoor mesocosms confirmed that SK09 effectively reduced S. hantzschii cells by 88% within 9 days. Conclusions: This bacterium is useful in regulating blooms of S. hantzschii. However, it should be studied in the future that their impact in shaping phytoplankton community and their activity in natural environments. Significance and Impact of the Study: The bacterium enabled us to develop a new strategy, to understand the interaction for anthropogenic control of harmful algal blooms in nature.

Algicidal activity of the bacterium, Pseudomonas fluorescens SK09, to mitigate Stephanodiscus hantzschii (Bacillariophyceae) blooms using field mesocosms

“…Therefore, the ability to function at a low temperature is an essential requirement for SK09 to express its algicidal activity. The previous study confirmed that SK09 grows well between 10 C and 30 C (Jung et al 2008) and showed the powerful algicidal activity between 5 C and 15 C in the wild (Jung et al 2010(Jung et al , 2013. Thus, it is possible to apply this bacterium to naturally occurring Stephanodiscus blooms.…”

“…To answer this question, we implemented two mesocosm experiments and studied direct application of immobilized SK09 cells in extremely low temperatures and analyzed the results. Some of the experimental data referred to in this work were obtained in our previous studies (Jung et al 2008(Jung et al , 2009a(Jung et al , 2010(Jung et al , 2013.…”

“…Isolation and culture of algicidal bacterium SK09 was isolated using the algal lawn method by Jung et al (2008). To obtain a high density of the algicidal bacteria, SK09 cells were incubated with 40 L of nutrient broth (NB) medium (30 rpm at 28 C) and grown to a density of 5.2 § 0.8 £ 10 6 cells/mL.…”

“…As such, CONTACT Seung Won Jung diatoms@kiost.ac.kr in our previous studies, we evaluated SK09 as a biocontrol agent against natural S. hantzschii blooms. In indoor and outdoor mesocosm studies (Jung et al 2008(Jung et al , 2010, SK09 was found to markedly inhibit the proliferation of this diatom. However, its application is associated with several environmental effects, such as changing inorganic nutrient concentrations and the consequent succession of phytoplankton species.…”

“…Algicidal bacteria are of particular interest in this context in marine and freshwater environments. For example, we have isolated an algicidal bacterium, Pseudomonas fluorescens HYK0210-SK09 (SK09) that can control S. hantzschii (Jung et al 2008). The ecological responses of aquatic organisms to bacterial treatments must be considered if the bacterium to be developed as a biocontrol agent is a potential disturbance to the natural environment.…”