Algicidal bacteria in phycosphere regulate free-living Symbiodinium fate via triggering oxidative stress and photosynthetic system damage

Yang Jia; Jiazhan Lu; Min Wang; Wenli Qin; Binbin Chen; Hanqing Xu; Zengling Ma

doi:10.1016/j.ecoenv.2023.115369

Algicidal bacteria in phycosphere regulate free-living Symbiodinium fate via triggering oxidative stress and photosynthetic system damage

Ecotoxicol Environ Saf. 2023 Sep 15:263:115369. doi: 10.1016/j.ecoenv.2023.115369. Epub 2023 Aug 14.

Authors

Yang Jia¹, Jiazhan Lu¹, Min Wang¹, Wenli Qin¹, Binbin Chen¹, Hanqing Xu², Zengling Ma³

Affiliations

¹ National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Wenzhou University, Wenzhou 325035, China; Zhejiang Provincial Key Lab for Subtropical Water Environment and Marine Biological Resources Protection, Wenzhou University, Wenzhou 325035, China.
² National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Wenzhou University, Wenzhou 325035, China; Zhejiang Provincial Key Lab for Subtropical Water Environment and Marine Biological Resources Protection, Wenzhou University, Wenzhou 325035, China. Electronic address: hqxu@wzu.edu.cn.
³ National and Local Joint Engineering Research Center of Ecological Treatment Technology for Urban Water Pollution, Wenzhou University, Wenzhou 325035, China; Zhejiang Provincial Key Lab for Subtropical Water Environment and Marine Biological Resources Protection, Wenzhou University, Wenzhou 325035, China. Electronic address: mazengling@wzu.edu.cn.

PMID: 37586194
DOI: 10.1016/j.ecoenv.2023.115369

Abstract

Free-living Symbiodinium, which forms symbiotic relationships with many marine invertebrates, plays an important role in the vast ocean. Nutrient levels have been shown to significantly impact microbial community structure and regulate algal communities. In this study, the bacterial community structure within the phycosphere of free-living Symbiodinium underwent significant changes in response to nutrient stimulation. Alteromonas exhibited dominance in Zobell 2216E broth nutrient stimulation concomitant with the demise of algal cells. Alteromonas abrolhosensis JY-JZ1, a marine bacterium isolated from the phycosphere of Symbiodinium, demonstrated an algicidal effect on Symbiodinium cells. Optical and scanning electron microscopy revealed that the algal cell membrane structure was disrupted, leading to intracellular leakage. Strain JY-JZ1 exerted its cytotoxicity by producing and secreting bioactive compounds into the supernatant. The marked declines in the chlorophyll a content, photosynthetic efficiency (Fv/Fm) and the electron transport rate (rETR) indicated that the photosynthetic system of Symbiodinium was damaged by JY-JZ1 supernatant. The observed elevation in levels of malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) content suggested that the algal cells experienced oxidative stress. Moreover, the supernatant exhibited remarkable adaptability to temperature and pH. Additionally, it displayed exceptional algicidal efficacy against various harmful algae species. To the best of our knowledge, this study represents the first successful isolation of an algicidal bacterial strain from the phycosphere of free-living Symbiodinium and subsequent investigation into its mechanism for controlling Symbiodinium growth, thereby providing novel insights into algae-bacteria interactions. The remarkable algicidal efficacy exhibited by strain JY-JZ1 against other harmful algae species suggests its significant potential for harmful algal blooms (HABs) control.

Keywords: Algae-bacteria interaction; Algicidal bacteria; Alteromonas; Free-living Symbiodinium; Phycosphere bacterial community.

MeSH terms

Bacteria / metabolism
Chlorophyll A / metabolism
Dinoflagellida* / physiology
Harmful Algal Bloom
Oxidative Stress / physiology

Substances

Chlorophyll A