Benzaldehyde

Ultrapure 18.3 MΩ⋅cm water used for these experiments was produced from a Zeneer Power III TOC system (Human Corp., Seoul, Korea). All the following reagents were purchased from Sigma Aldrich, unless stated otherwise, and were standard grade: butyl acetate, hexanal (Alfa Aesar, Haverhill, MA, USA), butanol, 3-methyl-1-butanol (Alfa Aesar), (E)-hex-2-enal (Alfa Aesar), hexanol, (Z)-hex-3-en-1-ol (Alfa Aesar), nonanal, 2-ethyl-1-hexanol, acetophenone, α-terpineol, benzyl alcohol, 2-phenylethanol, ethyl tetradecanoate, ethyl dodecanoate, methyl 2-hydroxybenzoate (Alfa Aesar), citronellol, ethyl decanoate, benzaldehyde (Alfa Aesar), ethyl octanoate, ethyl heptanoate, isoamyl acetate, limonene, 2-methyl-1-butanol, ethyl hexanoate, ethyl acetate, ethyl butanoate, Saccharomyces cerevisiae (Franke, Italy), (NH₄)₂HPO₄ (Franke, Italy), K₂S₂O₅ (Franke, Italy), tartaric acid, polyvinylpolypyrrolidone (Alfa Aesar), sodium azide (Alfa Aesar), NaOH, Na₂PO₄(H₂O)₂, citric acid, HCl, 3-octanol, MeOH, CH₂Cl₂, β-glucosidase enzyme (Ecozim AROM, CRC Biotek, Roma, Italy), hydrocarbon mixture from C8–C23 (Sigma-Aldrich, St. Louis, MO, USA).

The conversions of the aldehyde benzaldehyde (from Fisher Scientific, Thermo Fisher Scientific Inc, Waltham, MA, USA), and of the ketones 2-acetylpyridine, α-tetralone, 4′-(trifluoromethyl)acetophenone, isobutyrophenone, 1-indanone, 2-acetylpyraine, cyclohexyl phenyl ketone, 4′-methoxyacetophenone, and benzophenone (all from Sigma-Aldrich, St. Louis, MO, USA) were performed in triplicate. The reaction medium had a final volume of 1.2 mL and contained 10% (v/v) of dimethyl sulfoxide (DMSO), whole G. arilaitensis 232 cells at 10.42 mg mL⁻¹ of dry cell weight (DCW), and 5 mM of the respective ketone or aldehyde tested in 100 mM Tris-HCl pH 7.5 buffer. The medium was stirred at 800 rpm. Samples collected at the start (0 h) and after 24 h of reaction were collected and processed for gas chromatography-mass spectrometry (GC-MS) analysis for determination of substrate conversion and product formation.

VUAA1 (N-(4-ethylphenyl)-2-((4-ethyl-5-(3-pyridinyl)-4H-1,2,4-triazol-3-yl)thio)acetamide) was synthesized by the group “Mass Spectrometry/Proteomics” of the Max Planck Institute for Chemical Ecology (Jena, Germany). Ethyl hexanoate (99%, Sigma-Aldrich), L-Cysteine hydrochloride (Cat. Nr. C1276, Sigma-Aldrich), Papain (Cat. Nr. 5125, Calbiochem, San Diego, CA, United States), cOmplete protease inhibitor cocktail (Cat. Nr. 04693116001, Roche, Basel, Switzerland), methanol (≥99.5%, Roth) HCl (≥32%, Sigma-Aldrich), H₂SO₄ (95∼97%, Sigma-Aldrich), sodium metasilicate solution (Cat. Nr. 13729, Sigma-Aldrich), low Ca²⁺-Schneider’s medium (Cat. Nr. S9895, Sigma-Aldrich), Benzaldehyde (Acros Organics, NJ, United States) were used in following experiments.

Acetonitrile (HPLC grade) and manganese(IV) oxide (99%) were purchased from Fisher Scientific. Sodium sulfite, manganese(II) chloride, copper(II) chloride, and iron(III) chloride (all analysis grade) were purchased from Prolabo. Benzyl alcohol (99%), benzaldehyde (98%), iron powder 352 mesh (99%), sulfuric acid (96% in water), and potassium permanganate (98%) were procured from Acros. Iron(III) oxide (99.998%), iron(II, III) oxide (97%), iron(II) oxide (99.5%), manganese(II) oxide (99%), and manganese(II) titanium oxide (99.9%) were procured from Alfa Aesar. Copper(II) chloride (≥98%) and copper(II) sulfate (≥98%) came from Roth. Cobalt iron oxide (99%) was obtained from Aldrich. Benzoic acid (>99.5%), copper powder (grain size > 63 µm), and soda lime (both analysis grade) were obtained from Merck. Ultra-high-quality (UHQ) water obtained from Elga Maxima system was used for the experiments.