Degradation profile of nixtamalized maize pericarp by the action of the microbial consortium PM-06

José Germán Serrano-Gamboa,Jorge Luis Folch-Mallol,Diego Javier Jiménez,Araceli González-Burgos,Rafael Antonio Rojas-Herrera,Mónica Noel Sánchez-González

doi:10.1186/s13568-019-0812-7

José Germán Serrano-Gamboa, Jorge Luis Folch-Mallol + Show 4 more

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https://doi.org/10.1186/s13568-019-0812-7

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Abstract

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.

Highlights

Agro-industrial residues are important sources of fermentable sugars useful for the production of biofuels, biomaterials and biocatalysts (Bhatia et al 2012)
Origin and selection of the native microbial consortium PM‐06 Consortium PM-06 was enriched from the endogenous microbiota in nixtamalized maize pericarp (NMP) by the dilution-to-stimulation approach (Lee et al 2013)
PH and NMP degradation profiles The consortium PM-06 was obtained after the enrichment and stabilization of the native microbiota present in NMP

Summary

Introduction

Agro-industrial residues are important sources of fermentable sugars useful for the production of biofuels, biomaterials and biocatalysts (Bhatia et al 2012). The structural complexity makes the sustainable use of these residues a technological challenge. In Mexico and Central America, maize is nixtamalized before consumption (Serna-Saldivar 2016). Serrano‐Gamboa et al AMB Expr (2019) 9:85. (Gutiérrez-Cortez et al 2010). Industrial NMP is a residue rich in hemicellulose (~ 45%), followed by cellulose (~ 19%), starch (~ 13%) and lignin (~ 5%) (Rostro-Alanís et al 2014). Like other recalcitrant lignocellulosic structures, NMP requires the use thermochemical (207 °C) or harsh alkaline treatments to recover high valuable components such as hemicellulose (López-Martínez et al 2011; Rostro-Alanís et al 2014)

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