Abstract
Harmful algal blooms caused by Karenia mikimotoi frequently occur worldwide and severely threaten the marine environment. In this study, the biochemical and physiological responses of K. mikimotoi to the algicidal bacterium Paracoccus homiensis O-4 were investigated, and the effects on the levels of reactive oxygen species (ROS), malondialdehyde content, multiple antioxidant systems and metabolites, photosynthetic pigments, and photosynthetic index were examined. The cell-free supernatant in strain O-4 significantly inhibited K. mikimotoi cell growth. The bacterium caused the K. mikimotoi cells to activate their antioxidant defenses to mitigate ROS, and this effect was accompanied by the upregulation of intracellular antioxidant enzymes and non-enzyme systems. However, the overproduction of ROS induced lipid peroxidation and oxidative damage within K. mikimotoi cells, ultimately leading to algal death. In addition, the photosynthetic efficiency of the algal cells was significantly inhibited by O-4 and was accompanied by a reduction in photosynthetic pigments. This study indicates that O-4 inhibits K. mikimotoi through excessive oxidative stress and impaired photosynthesis. This research into the biochemical and physiological responses of K. mikimotoi to algicidal bacteria provides insights into the prophylaxis and control of harmful algal blooms via interactions between harmful algae and algicidal bacteria.
Highlights
Harmful algal blooms (HABs) are typically related to the discharge of nitrogen and phosphorus nutrients from industry and agriculture and cause considerable threats to fisheries and public health worldwide (Zhang et al, 2014; Berdalet et al, 2016)
The study objective was to elucidate the biochemical and physiological responses of the algal cells to the algicidal activity of the bacterium and guide the potential application of P. homiensis O-4 in controlling HABs dominated by K. mikimotoi
The results indicate that the algicidal activity by strain O-4 against K. mikimotoi cells was concentration-dependent
Summary
Harmful algal blooms (HABs) are typically related to the discharge of nitrogen and phosphorus nutrients from industry and agriculture and cause considerable threats to fisheries and public health worldwide (Zhang et al, 2014; Berdalet et al, 2016). Algicidal bacteria can inhibit algal growth or lyse algae by attacking the cells directly or indirectly by secreting extracellular substances, including proteins, polypeptides, biosurfactants, amino acids, and antibiotics (Zhuang et al, 2018). The physiological and biochemical responses of the alga to the algicidal substances from P. homiensis O-4 were further investigated from the following aspects: (1) the algicidal mode of P. homiensis O-4 against K. mikimotoi; (2) the extent of oxidative damage and antioxidant systems activity of algal cells; and (3) the effects of strain O-4 on the algal photosystem in K. mikimotoi. The study objective was to elucidate the biochemical and physiological responses of the algal cells to the algicidal activity of the bacterium and guide the potential application of P. homiensis O-4 in controlling HABs dominated by K. mikimotoi
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
