Maltooligosaccharides in the northwestern Adriatic Sea

The aim of this study was to monitor for the first time the oligosaccharide pattern in the northwestern Adriatic Sea. Oligosaccharides are components of the low-molecular-weight fraction of dissolved organic matter (DOM). They perform an important ecological function in the microbial loop prompting substrates for bacterial degradation. In particular, our investigation focused on maltooligosaccharides (glucose a 1-4 linked). The analyses were carried out using a dialysis-charcoal column sorption pre-concentration method, followed by liquid chromatography-tandem mass spectrometry analyses with a triple quadrupole mass spectrometer operating in multiple reaction monitoring mode. During the study period, the concentration of maltooligosaccharides with a low degree of polymerisation (ranging from maltose to maltotetraose) was higher than other maltooligosaccharides (maltopentaose and maltoeptaose) and all together they reached their highest concentration in June. This concentration was temporally shifted from a long period of diatom bloom (from January to April). Furthermore, the annual maltooligosaccharide trend was monitored together with several chemical, physical and biological parameters to investigate their potential role on the maltooligosaccharide accumulation. Our results suggested that the maltooligosaccharide accumulation could be related to the water column stratification.