Oxidation of benzyl alcohol derivatives into carboxylic acids with a new Acetobacter malorum strain: boosting the productivity in a continuous flow system

The one-shot green oxidation of various benzyl alcohol derivatives into the corresponding carboxylic acids was achieved using Acetobacter malorum DSM 112354, a newly isolated strain. The oxidation of benzyl alcohol was initially optimized by considering productivity after 8 hours as the response parameter. Under optimized conditions, a set of para-substituted benzyl alcohols was tested, demonstrating the high versatility of Acetobacter malorum DSM 112354, as all substrates were oxidized, albeit at varying rates and conversions. The effect of the substituent position was subsequently investigated using 2-(hydroxymethyl)phenol, 3-(hydroxymethyl)phenol, and 4-(hydroxymethyl)phenol as starting materials, and all substrates were efficiently transformed (74–98% molar conversion in 2–24 hours). Finally, the oxidation of 1,4-phenylenedimethanol to 4-(hydroxymethyl)benzoic acid was carried out with excellent regioselectivity, with less than 3% of terephthalic acid observed. This regioselective reaction was optimized using Ba-alginate immobilized cells of Acetobacter malorum DSM 112354 in a continuous multiphasic flow reactor. Continuous operation for 24 hours was performed, yielding 0.65 g of HMBA using a 14.4 mL reactor. This intensification was associated with improved biocatalyst productivity (37.1 mmol/g dry cell weight) and space-time yield (45.1 mg/mL·day).

• Nespoli, L
• Donzella, S
• Moro, E
• Mafezoli, J
• Contente, M
• Romano, D
• Molinari, F

• Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133 Milan Italy

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