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Anaerobic digestion (AD) is a process that can efficiently degrade organic waste into renewable energies. AD failure is however common as the underpinning microbial mechanisms are highly vulnerable to a wide range of inhibitory compounds. Sequencing technologies enable the identification of microbial indicators of digesters inhibition, but existing studies are limited. They used different inocula, substrates, sites and types of reactors and reported different or contradictory indicators. Our aim was to identify a robust signature of microbial indicators of phenol and ammonia inhibitions across four independent AD microbial studies. To identify such signature, we applied an original multivariate integrative method on two in-house studies, then validated our approach by predicting the inhibitory status of samples from two other studies with more than 90% accuracy. Our approach shows how we can efficiently leverage on existing studies to extract reproducible microbial community patterns and predict AD inhibition to improve AD microbial management., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

This study aimed at providing a better understanding of the influence of support media (10g/L of zeolites, 10g/L of activated carbons, and 1g/L of chitosan) on key phylotypes steering anaerobic digestion (AD) performance in presence of 19g/L of Total Ammonia Nitrogen (TAN) within batch digesters. Support media did not influence TAN concentration. However, both zeolites and activated carbon 1 reduced methanization lag phase by 47% and 25%, respectively. By contrast, activated carbon 2 and chitosan led to an increase of methanization lag phase by 51% and 32%, respectively. 16S rRNA gene sequencing revealed that zeolites preserved Methanosarcina and enhanced Methanobacterium. In presence of activated carbon 1, Methanoculleus, became predominant earlier than without support while chitosan and activated carbon 2 limited its implantation. This study highlighted potentialities to use supports to enhance AD stability under extreme TAN concentration and evidenced their specific influence on the microbiota composition., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

A wide variety of inhibitory substances can induce anaerobic digester upset or failure. In this work the possibility to improve the resistance of an anaerobic microbiota to a common pollutant, the phenol, was evaluated in a lab-scale semi-continuous bioreactor. An acclimation strategy, consisting in a regular step-wise adaptation of the microbiota to stressful condition was employed. Degradation performances were monitored and molecular tools (16S sequencing and ARISA fingerprinting technique) were used to track changes in the microbial community. The acclimation strategy progressively minimized the effect of phenol on degradation performances. After 3 successive disturbance episodes, microbiota resistance was considerably developed and total inhibition threshold increased from 895 to 1942mg/L of phenol. Microbiota adaptation was characterized by the selection of the most resistant Archaea OTU from Methanobacterium genus and an important elasticity of Bacteria, especially within Clostridiales and Bacteroidales orders, that probably enabled the adaptation to more and more stressful conditions., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Ammonia inhibition represents a major operational issue for anaerobic digestion (AD). In order to get more insights into AD microbiota resistance, anaerobic batch reactors performances were investigated under a wide range of Total Ammonia Nitrogen (TAN) concentrations up to 50.0g/L at 35°C. The half maximal inhibitory concentration (IC50) value was determined to be 19.0g/L. Microbial community dynamics revealed that above a TAN concentration of 10.0g/L, remarkable modifications within archaeal and bacterial communities occurred. 16S rRNA gene sequencing analysis showed a gradual methanogenic shift between two OTUs from genus Methanosarcina when TAN concentration increased up to 25.0g/L. Proportion of potential syntrophic microorganisms such as Methanoculleus and Treponema progressively raised with increasing TAN up to 10.0 and 25.0g/L respectively, while Syntrophomonas and Ruminococcus groups declined. In 25.0g/L assays, Caldicoprobacter were dominant. This study highlights the emergence of AD key phylotypes at extreme ammonia concentrations., (Copyright © 2016 Elsevier Ltd. All rights reserved.)