Fernández González, NuriaPedizzi, ChiaraLema Rodicio, Juan ManuelCarballa Arcos, Marta2020-05-062020-05-062019Nuria Fernandez‐Gonzalez et al. (2019). Air‐side ammonia stripping coupled to anaerobic digestion indirectly impacts anaerobic microbiome. "Microbial biotechnology", vol. 12, n. 6 p. 1403-1416http://hdl.handle.net/10347/22052Air‐side stripping without a prior solid–liquid phase separation step is a feasible and promising process to control ammonia concentration in thermophilic digesters. During the process, part of the anaerobic biomass is exposed to high temperature, high pH and aerobic conditions. However, there are no studies assessing the effects of those harsh conditions on the microbial communities of thermophilic digesters. To fill this knowledge gap, the microbiomes of two thermophilic digesters (55°C), fed with a mixture of pig manure and nitrogen‐rich co‐substrates, were investigated under different organic loading rates (OLR: 1.1–5.2 g COD l−1 day−1), ammonia concentrations (0.2–1.5 g free ammonia nitrogen l−1) and stripping frequencies (3–5 times per week). The bacterial communities were dominated by Firmicutes and Bacteroidetes phyla, while the predominant methanogens were Methanosarcina sp archaea. Increasing co‐substrate fraction, OLR and free ammonia nitrogen (FAN) favoured the presence of genera Ruminiclostridium, Clostridium and Tepidimicrobium and of hydrogenotrophic methanogens, mainly Methanoculleus archaea. The data indicated that the use of air‐side stripping did not adversely affect thermophilic microbial communities, but indirectly modulated them by controlling FAN concentrations in the digester. These results demonstrate the viability at microbial community level of air side‐stream stripping process as an adequate technology for the ammonia control during anaerobic co‐digestion of nitrogen‐rich substrateseng© 2019 The Authors. Microbial Biotechnology published by John Wiley & Sons Ltd and Society for Applied Microbiology. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly citedhttps://creativecommons.org/licenses/by/4.0/Anaerobic microbiomeAir-sidejournal article10.1111/1751-7915.134821751-7915open access