Valorization of agro-industrial wastes by producing 2-phenylethanol via solid-state fermentation: Influence of substrate selection on the process

2-phenylethanol (2-PE) is a value-added compound widely used in industry due to its rose-like odor and antibacterial properties that can be bioproduced using wastes as raw materials. This study presents the valorization of nine agro-industrial wastes as potential substrates for 2-PE production using an isolated 2-PE producer Pichia kudriavzevii, and the solid-state fermentation (SSF) technology as an alternative approach. The assessed substrates comprised wastes of varied traits such that each of them provided different characteristics to the fermentation. Thus, by using a principal component analysis (PCA), it was possible to identify the most significant characteristics associated with the substrates affecting the 2-PE production. Results show that L-phenylalanine biotransformation was more efficient than de novo synthesis for producing 2-PE. Besides, from the evaluated set, the maximum 2-PE production was achieved with red apple pomace, reaching 1.7 and 25.2 mg(2PE) per gram of used waste through de novo and Lphenylalanine biotransformation, respectively. In that scenario, volumetric productivity and precursor yield were 39.6 mg(2)PE L(-1)h(-1) and 0.69 g(2PE) per gram of L-phenylalanine added, respectively. From the PCA, it was identified that the reducing sugars content of the substrate, the air-filled porosity of the bed and the L-phenylalanine availability were the most critical parameters (associated with the substrates) influencing the microbial activity and 2-PE production. These results suggest that the desirable traits a solid media needs for promoting 2-PE production via SSF could be reached by using a combination of wastes in a synergistic approach. (c) 2021 Elsevier Ltd. All rights reserved.

Automated summary

2-phenylethanol (2-PE), a compound with rose-like odor and antibacterial properties, can be produced using agro-industrial wastes. This study evaluated nine different wastes as potential substrates for 2-PE production and identified red apple pomace as the most effective waste. It was found that the reducing sugars content, air-filled porosity, and availability of L-phenylalanine in the substrates were key parameters influencing microbial activity and 2-PE production.