N. Pérez-Rodríguez

Erratum to: Optimization of Xylanase Production by Filamentous Fungi in Solid-State Fermentation and Scale-up to Horizontal Tube Bioreactor

The original version of this article unfortunately contained a mistake in the pictures depicted in the right column of Fig. 4 regarding the SEM photographs showing the morphology of lignocellulosic surface of a) raw corncob, b) destarched corncob, c) destarched corncob followed by NaOH treatment, d) destarched corncob followed by NH4OH treatment, e) destarched corncob treated by autoclave, and f) destarched corncob treated by autoclave and microwave. The correct Figure should be the following: Appl Biochem Biotechnol (2015) 176:317–319 DOI 10.1007/s12010-015-1534-1

Effects of enzymatic hydrolysis and ultrasounds pretreatments on corn cob and vine trimming shoots for biogas production

Due to their lignocellulosic nature, corn cob and vine trimming shoots (VTS) could be valorized by anaerobic digestion for biogas production. To enhance the digestibility of substrates, pretreatments of lignocellulosic materials are recommended. The effect of enzymatic hydrolysis, ultrasounds pretreatments (US) and the combination of both was assayed in lignocellulosic composition, methane, and biogas yields. The pretreatments leaded to a reduction in lignin and an increase in neutral detergent soluble compounds making corn cob and VTS more amendable for biogas conversion. The US were negative for biogas production from both substrates and in particular strongly detrimental for VTS. On the opposite side, the enzymatic hydrolysis was certainly beneficial increasing 59.8% and 14.6% the methane production from VTS and corn cob, respectively. The prior application of US did not potentiate (or not sufficiently) the improvement in the methane production reflected by the enzymatic hydrolysis pretreatment of VTS and corn cob.

Feruloyl esterase production by Aspergillus terreus CECT 2808 and subsequent application to enzymatic hydrolysis

Ferulic acid esterases (FAE) were produced by Aspergillus terreus CECT 2808 from vine trimming shoots (VTS) and corn cob. Later, the fungal extracts thus obtained were used to enzymatically release ferulic acid (FA) from both substrates. Our findings showed a higher FAE activity in the enzymatic extracts produced on corn cob (0.070±0.004U/mL). Nevertheless, the enzymatic extracts produced on VTS demonstrated a better performance for FA release from both corn cob (2.05±0.01mg/g) and VTS (0.19±0.003mg/g). This result was probably because of the higher xylanase/FAE ratio determined in VTS extract. Therefore, an additional assay was carried out by supplementing corn cob extract with a commercial xylanase to test the influence of FAE/xylanase ratio in FA release. The results revealed the relevance of the FAE/xylanase ratio for an optimal FA release.

Ferulic acid transformation into the main vanilla aroma compounds by Amycolatopsis sp. ATCC 39116

The wild strain Amycolatopsis sp. ATCC 39116 was explored in ferulic acid-based media to produce naturally the aroma components of the cured vanilla pod, namely vanillin, vanillic acid, and vanillyl alcohol. Other phenolic compounds (4-vinyl guaiacol, guaiacol, and protocatechuic acid) were also evaluated. The influence of medium composition, fermentation technology (batch or fed-batch), supplementation with vanillic acid, and inoculum concentration on ferulic acid biotransformation were evaluated. The results postulate the initial concentration of cell mass as the variable with the strongest impact on ferulic acid metabolization under the studied conditions. The highest amounts of vanillin and vanillic acid were achieved at intermediate values of cell mass. Vanillyl alcohol and protocatechuic acid were more closely linked to high cell mass concentrations. Conversely, 4-vinyl guaiacol reached its highest amount at the lowest amount of cell mass. Guaiacol was not detected in any case. Therefore, the initial cell concentration must be considered a critical parameter when using Amycolaptosis sp. ATCC 39116 for the production of vanillin and related compounds.

Use of Aspergillus niger Extracts Obtained by Solid-State Fermentation

Abstract Agroindustrial wastes are both an environmental and economic problem that industries must strive to solve. However, these residues represent an inexpensive alternative source for microbial growth and biomass or enzyme production, mainly using solid-state fermentation (SSF). Corn cob, a worldwide by-product obtained from maize processing, has a lignocellulosic structure made up of cellulose, hemicelluloses, and lignin. Aspergillus niger is one of the most frequently employed filamentous fungi in the production of enzymes by SSF. This fungal species can grow on corn cob to produce xylanases, which catalyze the hydrolysis of xylan, a heterogeneous polysaccharide consisting mainly of a backbone chain of β-1,4-linked β- d -xylopyranose units. Fungal xylanases have several applications in the paper manufacturing, animal feed, bread making, juice, and wine industries. Xylanases are also interesting for the production of xylooligosaccharides, used as functional food ingredients, and xylose for bioconversion into xylitol.