Effects of sponge-derived Ageladine A on the photosynthesis of different microalgal species and strains

Carolin Peter,Ulf Bickmeyer,Silke Thoms,Franz Josef Sartoris,Florian Koch,Joseph Selvin

doi:10.1371/journal.pone.0244095

Abstract

Fluorescent natural compounds have been identified in several marine hosts of microalgae. Their prevalence, and the energy the host is expending on their synthesis, suggests an important, yet poorly understood ecological role. It has been suggested that some of these natural products may enhance the photosynthesis of microbial symbionts. In this study, the effect of Ageladine A (Ag A), a pH-dependent fluorophore found in sponges of the genus Agelas, on the photosynthesis of nine microalgal species and strains was examined. The data showed that the variety of effects of Ag A additions differed between species, and even strains within a species. While in one strain of Synechococcus sp., the presence of Ag A increased gross photosynthesis under UV light exposure, it decreased in another. And while in the chlorophyte T. chuii overall metabolic activity was greatly reduced under all forms of lighting, photosynthesis in T. lutea was positively affected by the addition of Ag A. The variety of effects of Ag A on photosynthesis observed in this study indicate a complex interaction of Ag A with microalgal cells and suggests that a host may be able to shape its own symbiotic microbiome with self-produced natural products.

Highlights

The pH-dependent fluorophore Ageladine A (Ag A) was discovered in 2003 in lipophilic extracts of the marine sponge Agelas nakamurai [1]
RCC539 showed no effect of Ag A at any UV radiation intensity, RCC1084 exhibited highly significant positive effects under all intensities (Fig 2)
RCC791 and S. bacillaris CCMP1333, the effect on oxygen evolution depended on radiation intensity

Summary

Introduction

The pH-dependent fluorophore Ageladine A (Ag A) was discovered in 2003 in lipophilic extracts of the marine sponge Agelas nakamurai [1]. While at neutral and alkaline pH the uncharged species dominates, single and double protonated states of Ag A are formed when the pH decreases. This shift in molecular composition corresponds to an increase in fluorescence, which peaks at pH 3–4. The peak in excitation wavelength in water at 370 nm corresponds to an emission ranging from 415 nm to 500 nm with a maximum at 415 nm [2], these excitation/emission profiles can change with chnaging environments [3]. Its specific function within the sponge holobiont has not yet been identified

Methods

Results

Discussion

Conclusion