high-rate anaerobic digestion fungi and bacteria

This study investigated the emergence of fungal-bacterial-methanogenic consortia within two lab-scale high-rate anaerobic digestion reactors fed with saline synthetic wastewater (5g Na + /L) and saline-acclimated biomass. In Trail 1, UASB reactors were operated under conditions of reduction of hydraulic retention time (HRT) from 24 to 18 h. In Trial 2, the organic load rate was increased from 10.7 to 15.4 g COD/d using hybrid UASB. In trial 3, biomass with fungal growth was transferred to a UASB reactor to assess the influence of the reactor configuration. The fungal emergence did not have a negative effect on the reactors' performance, with no significant difference in the biogas, CH 4 production or soluble chemical oxygen demand (COD) removal in Trials 1 and 2. Fungal consortia showed a higher salinity tolerance (up to 15 g Na + /L) compared to the conventional bacterial-archaeal consortia, and increased protein degradation, making it a promising strategy to overcome salinity stress. The main fungi identified in the systems were facultative ascomycetes and basidiomycetes fungi, with the halotolerant Pseudallescheria/Scedosporium complex as the dominant fungi in both biomasses, which is recognized for their salinity tolerance and ability to degrade recalcitrant pollutants. Application of multi-omic integrative framework (DIABLO) showed a strong positive correlation between fungi and methanogenic acetoclastic (Methanothrix), which was proposed as the determining factor governing fungi emergence in high-rate systems. These results shed new light on the potential of filamentous fungi in anaerobic digestion systems for the treatment of saline effluents.