title: Fungal Laccase-Catalyzed Oxidation of Naturally Occurring Phenols for Enhanced Germination and Salt Tolerance of Arabidopsis thaliana: A Green Route for Synthesizing Humic-like Fertilizers.
abstract: Fungal laccases have been highlighted as a catalytic tool for transforming phenols. Here we demonstrate that fungal laccase-catalyzed oxidations can transform naturally occurring phenols into plant fertilizers with properties very similar to those of commercial humic acids. Treatments of Arabidopsis thaliana with highly cross-linked polyphenolic products obtained from a mixture of catechol and vanillic acid were able to enhance the germination and salt tolerance of this plant. These results revealed that humic-like organic fertilizers can be produced via in vitro enzymatic oxidation reactions. In particular, the root elongation pattern resulting from the laccase products was comparable to that resulting from an auxin-like compound. A detailed structural comparison of the phenol variants and commercial humic acids revealed their similarities and differences. Analyses based on SEM, EFM, ERP, and zeta-potential measurement showed that they both formed globular granules bearing various hydrophilic/polar groups in aqueous and solid conditions. Solid-phase13C NMR, FT-IR-ATR, and elemental analyses showed that more nitrogen-based functional and aliphatic groups were present in the commercial humic acids. Significant differences were also identifiable with respect to particle size and specific surface area. High-resolution (15 T) FT-ICR mass spectrometry-based van Krevelen diagrams showed the compositional features of the variants to be a subset of those of the humic acids. Overall, our study unraveled essential structural features of polyaromatics that affect the growth of plants, and also provided novel bottom-up ecofriendly and finely tunable pathways for synthesizing humic-like fertilizers.
authors.forename: Joon-Yung
authors.initials: JY
authors.lastname: Cha
authors.forename: Tae-Wan
authors.initials: TW
authors.lastname: Kim
authors.affiliation: Biomedical Omics Group, Korea Basic Science Institute , Cheongju 28119, Republic of Korea.|Department of Biotechnology and Bioinformatics, Korea University , Sejong 30019, Republic of Korea.
authors.forename: Jung Hoon
authors.initials: JH
authors.lastname: Choi
authors.affiliation: Biomedical Omics Group, Korea Basic Science Institute , Cheongju 28119, Republic of Korea.
authors.forename: Kyoung-Soon
authors.initials: KS
authors.lastname: Jang
authors.forename: Laila
authors.initials: L
authors.lastname: Khaleda
authors.forename: Woe-Yeon
authors.initials: WY
authors.lastname: Kim
authors.forename: Jong-Rok
authors.identifier: http://orcid.org/0000-0002-5815-7815
authors.initials: JR
authors.lastname: Jeon
mesh_terms: D017360:Arabidopsis / Q000187:drug effects* / Q000502:physiology; D002396:Catechols / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D005308:Fertilizers; D005656:Fungal Proteins / Q000737:chemistry / Q000378:metabolism; D018525:Germination / Q000187:drug effects*; D055772:Green Chemistry Technology / Q000379:methods; D006812:Humic Substances; D042845:Laccase / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D010636:Phenols / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D055049:Salt Tolerance; D017550:Spectroscopy, Fourier Transform Infrared; D055454:Trametes / Q000201:enzymology; D014641:Vanillic Acid / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology
chemical_list: D002396:Catechols; D005308:Fertilizers; D005656:Fungal Proteins; D006812:Humic Substances; D010636:Phenols; D042845:Laccase; D014641:Vanillic Acid; C034221:catechol
keywords: fungal laccases; germination; humic acids; naturally occurring phenols; salt tolerance