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The nixtamalized maize pericarp (NMP) is a plentiful by-product of the tortilla industry and an important source of fermentable sugars. The aim of this study was to describe the degradation profile of NMP by the action of a consortium (PM-06) obtained from the native microbial community of this residue. The degradation was analyzed in terms of the changes in the community dynamics, production of enzymes (endo-xylanase and endo-cellulase), physicochemical parameters, and substrate chemical and microstructural characteristics, to understand the mechanisms behind the process. The consortium PM-06 degraded 86.8 ± 3.3% of NMP after 192 h of growth. Scanning electron microscopy images, and the composition and weight of the residual solids, showed that degradation was sequential starting with the consumption of hemicellulose. Xylanase was the highest enzyme activity produced, with a maximum value of 12.45 ± 0.03 U mL −1 . There were fluctuations in the pH during the NMP degradation, starting with the acidification of the culture media and finishing with a pH close to 8.5. The most abundant species in the consortium, at the moment of maximum degradation activity, were Aneurinibacillus migulanus, Paenibacillus macerans, Bacillus coagulans, Microbacterium sp . LCT - H2 , and Bacillus thuringiensis. The diversity of PM-06 provided metabolic abilities that in combination helped to produce an efficient process. The consortium PM-06 generated a set of different tools that worked coordinated to increase the substrate availability through the solubilization of components and elimination of structural diffusion barriers. This is the first report about the degradation of NMP using a microbial consortium. Electronic supplementary material The online version of this article (10.1186/s13568-019-0812-7) contains supplementary material, which is available to authorized users.

Aims In this study, the ability of the consortium MR‐01 to degrade phenol was determined. The effects of this chemical on the taxonomy and the metabolic behaviour were analysed through metagenomics. Methods and Results Consortium MR‐01 was acclimated in a sublethal concentration of phenol. After this process, the capacity to degrade this molecule was analysed. Results showed that degradation increased with the increment of the initial phenol concentration. Metagenomic analysis indicates that the consortium metabolized phenol under aerobic conditions using phenol 2‐monooxygenase and the meta‐cleavage pathway. Sequence of the enzymes involved in the phenol degradation was ascribed to the Actinomycetales and Chloroflexales orders, with relative abundances <1%. The most abundant genera were part of the Sphingomonadales order; however, the role of these species in the consortium is not clear. Conclusions Consortium MR‐01 degrades efficiently high concentrations of phenol. The participation of extremophiles in the degradation process and the emergence of beneficial metabolic dependencies between the community members are some of the strategies used by the consortium to survive and develop under harsh environmental conditions. Significance and Impact of the Study This is one of the few studies describing the taxonomy and metabolic profile of a phenol degrading consortium.

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