Identification and first insights into the structure of chitin from the endemic freshwater demosponge Ochridaspongia rotunda (Arndt, 1937).

Studies on the identification, properties and function of chitin in sponges (Porifera), which are recognized as the first multicellular organisms on Earth, continue to be of fundamental scientific interest. The occurrence of chitin has so far been reported in 21 marine sponge species and only in two inhabiting fresh water. In this study, we present the discovery of α-chitin in the endemic demosponge Ochridaspongia rotunda, found in Lake Ohrid, which dates from the Tertiary. The presence of chitin in this species was confirmed using special staining, a chitinase test, FTIR, Raman and NEXAFS spectroscopy, and electrospray ionization mass spectrometry (ESI-MS). In contrast to the case of marine sponges, chitin in O. rotunda has been found only within its holdfast, suggesting a role of chitin in the attachment of the sponge to the hard substratum. Isolated fibrous matter strongly resemble the shape and size of the sponge holdfast with membrane-like structure.

The Alburnus benthopelagic fish species of the Western Balkan Peninsula: An assessment of their sustainable use.

In this study, we aimed to assess the population status of bleak (Alburnus spp.) over the Western Balkan Peninsula in terms of its sustainable use. A second objective was to determine key factors important for fishery management planning. Two different basins, continental (the Danube Basin and the Sava River sub-basin) and marine (the Adriatic and the Aegean Sea Basins) were examined. A sustainability assessment and factor analysis were conducted using the adjusted ESHIPPOfishing model, extended with additional socio-economic sub-elements, and the categorical principal components analysis (CATPCA), respectively. The results of the assessment revealed the bleak populations in the Danube Basin and the Sava River sub-basin to be highly sustainable. The population characteristics with abiotic and biotic factors were responsible for this status, while the influence of socio-economic factors was insignificant. The sustainability status of the bleak populations of the Mediterranean basin varied, with the populations from Ohrid and Skadar Lakes showing a high and those from Prespa and Dojran Lakes a medium status. Socio-economic factors with traditional fishing were the most important for the Mediterranean bleak populations.

Anti-quorum sensing activity of selected sponge extracts: a case study of Pseudomonas aeruginosa.

The anti-quorum sensing activities towards the bacterium Pseudomonas aeruginosa PA01 (pyocyanin production, biofilm formation and twitching and flagella motility) of two crude extracts (methanol and acetone) of the freshwater sponge Ochridaspongia rotunda (Arndt, 1937) were evaluated in vitro for the first time. Both extracts demonstrated P. aeruginosa pyocyanin inhibitory activity, reducing its production for 49.90% and 42.44%, respectively. In addition, they both showed higher anti-biofilm activity (48.29% and 53.99%, respectively) than ampicillin (30.84%). Finally, O. rotunda extracts effectively reduced twitching and flagella motility of P. aeruginosa. Taken all together, these results suggest that endemic sponge species from the oldest lake in Europe may offer novel bioactive natural products with promising medicinal potential towards P. aeruginosa infections.

In vitro evaluation of antimicrobial activity of the freshwater sponge Ochridaspongia rotunda (Arndt, 1937).

The antimicrobial activity of five crude extracts (aqueous, methanol, ethyl acetate, acetone and methylene chloride) of the freshwater sponge Ochridaspongia rotunda (Arndt, 1937) was evaluated in vitro by using microdilution method against eight bacterial and eight fungal strains for the first time. The extracts were proven to be active in varying degrees against all the bacteria and fungi tested. O. rotunda methanol extract exhibited the highest antibacterial activity (minimum inhibitory concentration (MIC) 7.5-15.0 µg/mL and minimum bactericidal concentration 15-30 µg/mL), while its acetone extract exhibited the most promising antifungal activity (MIC 7.5-45.0 µg/mL and minimum fungicidal concentration 15-60 µg/mL). The extracts were more effective against the bacteria and fungi screened compared with the positive controls (streptomycin and ampicillin for bacteria and bifonazole and ketoconazole for fungi, respectively). According to the experimental data obtained, this deepwater sponge species may be considered as a gold mine of new antimicrobial substances with significant and broad-range activity.