Biobutanol production from apple pomace: The importance of pretreatment methods on the fermentability of lignocellulosic agro-food wastes

This document is a pre-print version of the manuscript that was subsequently peer-reviewed and accepted for publication by the journal Applied Microbiology and Biotechnology (Vol. 101, pages 8041-8052, year 2017). The final publication is available at Springer via http://dx.doi.org/10.1007/s00253-017-8522-z

Cell Immobilization for Erythritol Production

Nowadays, commercial erythritol synthesis is performed by free-cell fermentation with fungi in liquid media containing high concentrations of pure carbon sources. Alternative fermentation techniques, such as cell immobilization, could imply an economic and energetic improvement for erythritol-producing factories. The present work describes, for the first time, the feasibility of achieving cell immobilization during erythritol production. Cells of the fungus Moniliella pollinis were successfully immobilized on a cotton cloth which was placed inside a 2-L bioreactor, where they were fed with red grape must supplemented with yeast extract. They produced 47.03 ± 6.16 g/L erythritol in 96 h (yield 0.18 ± 0.04 g/g) over four consecutive fermentation batches. The immobilized cells remained stable and operative during a 456 h period. The erythritol concentration attained was similar (p > 0.05; Tukey HSD test) to the reference value obtained with the use of free cells (41.88 ± 5.18 g/L erythritol) under the same fermentation conditions. The comparable results observed for free and immobilized cells evidences the efficiency of the immobilization system. Therefore, the proposed method for erythritol bioproduction eliminates the need for the continuous preparation of fungal inocula before each fermentation batch, thus reducing the costs of the reagents and energy

Development and validation of a HPLC-DAD method for simultaneous determination of main potential ABE fermentation inhibitors identified in agro-food waste hydrolysates

Producción CientíficaLignocellulosic agro-food wastes are regarded as interesting carbohydrate sources for acetone-butanol-ethanol (ABE) fermentation. However, the physicochemical and enzymatic pretreatments applied to release their sugars generate inhibitory compounds that hinder the fermentation. The release of inhibitory compounds in the hydrolysates of four agro-food industrial wastes [apple pomace (AP), potato peel (PP), brewers' spent grain (BSG) and coffee silverskin (CS)] obtained after various chemical pretreatments (acid, alkali, organic solvents and surfactant pretreatments) was analyzed. Sixty-seven potential inhibitors were identified by gas chromatography–mass spectrometry (GC–MS) and were classified into non-aromatic compounds (aliphatic acids, nitrogen-containing compounds, furans and fatty acids) and aromatic compounds (phenolics and non-phenolics). Then, a high performance liquid chromatography method with diode array detection (HPLC-DAD) was developed and validated for the quantification of the main potential inhibitors identified in the hydrolysates (i.e. gallic, 3,4-dihydroxybenzoic, 2,5-dihydroxibenzoic, 4-hydroxybenzoic, 3-hydroxybenzoic, vanillic, caffeic, syringic, p-coumaric, and ferulic acids, vanillin, syringaldehyde and caffeine). The proposed HPLC-DAD method was simple, fast and robust and allowed the direct injection of samples without previous treatment, enabling the simultaneous quantification of the abovementioned compounds for the first time. The method was successfully applied to the analysis of AP, PP, BSG and CS hydrolysates.Instituto Nacional de Investigaciones Agronómicas (INIA) (DOC-INIA, grant number DOC 2013-010)H2020-LCE-2015 Waste2Fuels project (Sustainable production of next generation biofuels from waste streams - Waste2Fuels. GA - 654623

Yeast screening and cell immobilization on inert supports for ethanol production from cheese whey permeate with high lactose loads.

Eight yeast strains of the genera Saccharomyces and Kluyveromyces were screened to ferment high lactose-load cheese whey permeate (CWP) (>130 g/L lactose) without nutrient supplementation. The fermentation conditions (temperature, pH and time) were optimized to maximize the fermentation performance (ethanol titer, ethanol yield and lactose consumption) for the two preselected strains, K. marxianus DSM 5422 and S. cerevisiae Ethanol Red, using a response surface methodology (RSM). Under optimized conditions, K. marxianus DSM 5422 attained ethanol titers of 6% (v/v) in only 44 h. Moreover, the feasibility of immobilizing this strain on four different inorganic supports (plastic, glass and Tygon silicone Raschig rings and alumina beads) was assessed. Glass Raschig rings and alumina beads showed a more stable performance over time, yielding ethanol titers of 60 g/L during 1,000 hours, which remarkably reduces yeast cultivation costs. Results demonstrate the feasibility of using CWP for successful ethanol production in a simple and economical process, which represents an attractive alternative for waste treatment in dairy industries

Decontamination of waterborne chemical pollutants by using atmospheric pressure nonthermal plasma: a review

<div><p>Water pollution abatement is a topic of growing interest worldwide, mainly due to the large number of contaminants that continental waters may contain and the need for a safe wastewater reclamation and reuse in many sectors (agriculture, industry, aquifer recharge, and landscape restoration) and industrial recycling to reduce the end-of-pipe treatment. In this review, different advanced oxidation processes based on atmospheric pressure nonthermal plasma treatment for the removal of organic contaminants from waters are critically reviewed. Factors affecting the removal efficiency and energy yield are reviewed for specific organic contaminants (e.g. VOC, phenols, organic dyes, pharmaceuticals and personal care products, surfactants) and also for conventional water quality parameters (e.g. BOD, COD, TOC, , turbidity). Moreover, effects of operational modes (e.g. type of discharge, reactor configuration, plasma gas), catalytic processes (heterogeneous: TiO₂, NiO, and homogeneous: Cu²⁺, Fe²⁺, ), post-treatment reactions and external oxidant addition (O₃, H₂O₂) are also presented.</p></div