Diatom and Bacterial Communities in Saline Habitats (Vojvodina, Serbia)

Current knowledge of the microbiota of soda pans of the Carpathian Basin focuses mainly on diatoms. In studying six soda pans in Vojvodina (Serbia), we aimed to gain deeper insights into the diatom community by using not only traditional microscopic analysis but also high-throughput sequencing of the 18S rRNA gene. In addition, this study aimed to evaluate bacterial communities in these soda pans for the first time using the 16S rRNA gene marker. Although similar numbers of diatom taxa were found using both approaches, a significant discrepancy in species composition was found. The genus Nitzschia was one of the most represented and numerous genera according to the morphological and molecular analyses, but with lower diversity according to the molecular data, with the sequences mostly unassigned. Another major discrepancy was noticed with taxon Halamphora veneta, the results of metabarcoding showed high abundance in almost all soda pans, while microscopy detected it as very low. Diverse communities of aerobic and anaerobic bacteria were detected in the studied soda pans, such as Proteobacteria, Bacteroidota, Actinobacteria, Bacillaceae, and Peptoclostridium. According to current knowledge, harsh environmental conditions and habitat homogeneity regulate diatom and bacteria community composition and enable the survival of taxa with predominantly high ecophysiological plasticity. Finally, uncovering the structure of the microbial community as the first phase in developing an efficient tool to assess the ecological status of these fragile ecosystems is an essential step towards their conservation.