Application of in situ Solid-Phase Microextraction on Mediterranean Sponges for Untargeted Exometabolome Screening and Environmental Monitoring

Barbara Bojko,Janusz Pawliszyn,Bora Onat,Ezel Boyaci,Thanos Dailianis,Eleftheria Psillakis

doi:10.3389/fmars.2019.00632

Abstract

In marine ecosystems, sponges are ubiquitous sessile organisms that contain a wide range of specialized metabolites. These metabolites point to a diverse range of biochemical pathways. Some of these compounds are biomarkers that indicate the presence of bacteria that form symbiotic relationships with a host sponge (microsymbionts). Sponges hold considerable promise as bioindicators for seawater quality monitoring, as they are exposed to, and accumulate, significant levels of anthropogenic contamination in coastal areas. Solid-phase microextraction (SPME) is a low-invasive and non-exhaustive technique that combines sampling and extraction into a single step and offers the added benefit of biocompatible extraction phases. We used different types of SPME devices to extract exometabolites from sponges (genus: Sarcotragus) in situ. Following extraction, the samples were analyzed via GC- and LC-MS in order to verify the presence of compounds associated with quorum sensing, as well as to examine the metabolism of organic pollutants, such as monocyclic aromatic hydrocarbons (MAHs), polycyclic aromatic hydrocarbons (PAHs), pesticides, and other bioactive compounds in an untargeted format. As the results demonstrate, when the extracted metabolites are compared with the background controls, SPME offers a non-exhaustive approach that can be used in the field to discover novel metabolites deriving from complex holobionts such as marine sponges.

Highlights

Sponges are sessile filter feeders that are capable of turning over liters of water per day (Hentschel et al, 2006)
These bacteria develop a symbiotic relationship with the sponge host, forming an ecological unit known as a “sponge holobiont” (Oulhen et al, 2016; Pita et al, 2018)
A detailed analysis of these symbionts’ defense systems against foreign genetic material, such as those related to viral defense, revealed that the sponge microbiome features enhanced Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) and Restriction Modification Systems (RMS) (Horn et al, 2016). These findings suggest that sponge microbiomes form defense systems against foreign DNA as a by-product of circulating water to maintain the symbiotic relationship between bacteria and the sponge host

Summary

INTRODUCTION

Sponges are sessile filter feeders that are capable of turning over liters of water per day (Hentschel et al, 2006). In addition to constituting an important part of a sponge’s diet, prokaryotic microorganisms are found in their mesohyl matrix (Webster et al, 2001; Montalvo et al, 2005) These bacteria develop a symbiotic relationship with the sponge host, forming an ecological unit known as a “sponge holobiont” (Oulhen et al, 2016; Pita et al, 2018). The development of a minimally invasive in situ and in vivo extraction method is of great interest, as it would eliminate the need to remove marine organisms from their habitat, and allow the elusive portion of the metabolome to be captured during its interactions with the living and non-living components of its ecosystem This would be especially important when the analytical study of endangered marine species is aimed. Chromatographic separation was performed by 30 m, HP-5 5% phenyl–methyl siloxane column (Agilent 19091J-433) with an I.D and thickness of 0.25 mm (Agilent Technologies Inc., Santa Clara, CA, United States)

METHODS

RESULTS AND DISCUSSION

DATA AVAILABILITY STATEMENT