Production of Surface Active Organic Material and Reduced Sulfur Species During the Growth of Marine Diatom Cylindrotheca closterium

Abstract

Electrochemical methods at the mercury electrode were used for monitoring production of surface active substances (SAS) and reduced sulfur species (RSS) during growth of marine diatom Cylindrotheca closterium isolated from the Adriatic Sea in the laboratory conditions. In the same culture samples, production of particulate and dissolved organic carbon (POC, DOC) was followed by high temperature catalytic oxidation method (HTCO). The culture growth curve obtained by microscopically counted phytoplankton cells showed an exponential growth phase that lasted 10 days, transition phase until 14 days and stationary phase until 21 days. In these time periods twofold increase of SAS and DOC was followed, while POC increased 41 times. Detail analyses of a.c. out of phase voltammetric curves recorded in original and in acidified phytoplankton culture samples indicate transformation of organic material during growth, from more anionic (negatively charged) to less anionic polymeric surface active material. In culture samples presence of non-volatile RSS were confirmed.

Voltammetric Study of Organic Matter Components in the Upper Reach of the Krka River, Croatia

“…[6] OM has an important influence on metal speciation, [7][8][9] it is a precursor in the process of fossil fuels creation, and today OM is being examined as a dynamic component of the global carbon cycle. [10] Testing and quantifying the specific components of OM such as S surface-active substances (SAS), [11,12] organic ligands that complex metal ions (metal complexing capacity, MCC), [7,13] and/or sulphur species [14] allows understanding of its properties and the cycle in natural waters. SAS, MCC, and sulphur species are important parameters in water quality monitoring that are usually measured by electroanalytical methods which are shown to be fast, non-destructive and relatively cheap.…”

Changes in organic carbon properties during intense plankton blooms and macroaggregate formation in the coastal Adriatic Sea, Croatia (case studies in 2020-2022)

“…The method is based on the measurement of the adsorption effect of SAS on the surface of a hanging mercury drop electrode as a working electrode at a potential of -0.6 V (vs. Ag|AgCl, 3 M KCl; Ćosović & Vojvodić, 1998) at initial seawater (pH around 8). Usually, SAS measurements are performed under initial and acidic conditions (by adding HCl, at pH values, pH = 2-3) when the negative charges of SAS polyelectrolytes are neutralized and more neutral and adsorbable organic substances are formed, giving a higher amount of SAS (Ciglenečki et al, 2018;Ćosović & Vojvodić, 1998).…”

“…SAS in seawater are mainly formed by biological activities, especially by phytoplankton production (Ciglenečki et al, 2018Ćosović et al, 2000;Žutić et al, 1981), bacteria (Kurata et al, 2016), and feeding of zooplankton (Croot et al, 2007;Kujawinski et al, 2002). SAS belong to the group of biosurfactants and represent the most reactive fraction of DOC with amphiphilic character, whereby they adsorbed at various natural phase boundaries such as the sea surface microlayer (Ćosović & Vojvodić, 1987;Karavoltsos et al, 2015;Plavšić et al, 2007;Sabbaghzadeh et al, 2017;Wurl et al, 2011), the halocline in stratified estuaries (Ćosović & Vojvodić, 1989;Žutić & Legović, 1988), the chemocline of a marine lake (Ciglenečki et al, 2017;Marguš et al, 2015;Simonoviće et al, 2023), and in seawater eddies (Ciglenečki et al, 2021).…”

“…Furthermore, to measure the concentration of SAS, additional insight into the type of DOC can be gained by analyzing the voltammetric curves, as shown in this study. The recorded voltammetric curves with characteristic shapes, with or without sharp and well-defined desorption peaks, may be characteristic of certain OM types (Ciglenečki et al, 2018;Ćosović et al, 2010a;Orlović-Leko et al, 2016).…”

Living Diatom Microalgae for Desiccation-Resistant Electrodes in Biophotovoltaic Devices

“…Diatoms also bear profitable features for application in BPEC solar energy conversion technologies because benthonic microalgae can generate biofilms adhering to a variety of materials, such as electrodes’ surfaces, thus allowing their spontaneous colonization. Their biofilms are also rich in bioactive molecules and proteins, , with unexplored electron-transfer potential. In principle, chemical modification of diatoms with tailored materials with conductive properties may be a powerful tool to face one of the most important challenges in BPV design i.e., favoring electrical communication between the biotic (microalgae) and abiotic (electrode) elements .…”