Influence of salinity on fungal communities in a submerged fixed bed bioreactor for wastewater treatment

Salinity is known to influence the performance of biological wastewater treatment plants. While its impact on bacterial communities has been thoroughly studied, its influence on fungal communities has been largely overlooked. To address this knowledge gap, we assessed the effect of saline influents (0, 3.7, 24.1 and 44.1 g NaCl/L) on the community structure and diversity of fungi in a submerged fixed bed bioreactor (SFBBR). For this purpose, denaturing gradient gel electrophoresis (DGGE) and 454-pyrosequencing of PCR-amplified fungal 18S rRNA gene fragments and ITS regions, respectively, were used. Significant differences in the fungal community structure were found in relation to the NaCl concentration. Fungal diversity increased as salinity increased to a concentration up to 24.1 g NaCl/L, but was significantly reduced at 44.1 g NaCl/L. Basidiomycota dominated the fungal community in the absence of NaCl but decreased in relative abundance with increasing salinity, being replaced progressively by Ascomycota.