Gluconic acid sodium salt

2,3-Butanediol (2,3-BD), AC, gluconic acid sodium salt, and sodium acetate-1-¹³C were purchased from Sigma (USA). N-acetylglucosamine (GlcNAc) was purchased from Aladdin (Shanghai, China). Restriction enzymes were purchased from TaKaRa Bio Inc. (China). Polymerase chain reaction (PCR) primers were provided by Sangon (Shanghai, China). FastPfu DNA polymerase and T4 DNA ligase were purchased from Transgen Biotech (China) and ThermoFisher (America), respectively. NAD⁺/NADH Quantification Colorimetric Kit was purchased from Biovision (K337-100, USA). EasyPure RNA Kit (used for RNA extraction) and TransStart Top Green qPCR SuperMix (used for qPCR) were purchased from Transgen (Beijing, China). HiScript II Q RT SuperMix for qPCR (+gDNA wiper, used for RNA reverse transcription) was purchased from Vazyme (R223-01, Nanjing, China). BacTiter-Glo™ Microbial Cell Viability Assay used for ATP detection was purchased from Promega (America). All other chemicals were of analytical grade and commercially available.

Commercial glucose (dextrose monohydrate, Dextropam 100 kindly supplied by Copam-Portugal) was used as the substrate in bioreactor cultivation; D (+) glucose anhydrous 99.5% (Fisher Chemicals), gluconic acid sodium salt 99% (Sigma), and 2-oxoglutaric acid for biochemistry (Merck) were used as standards in the analyses by HPLC. For the identification of metabolites by LC-MS, the aqueous solutions and the mobile phases were prepared with water, acetonitrile, and formic acid, grade LC-MS Optima (Fisher Scientific).The Gelidium corneum residues were supplied by Iberagar–Sociedade Luso-Espanhola de Colóides Marinhos S.A., and its composition (expressed in g/100 g of raw material in oven-dry basis ±standard deviation based on three replicate determinations) was 35.26 ± 0.87 of ash, 16.00 ± 0.94 of crude protein, 19.24 ± 0.88 of glucan, and 5.24 ± 0.06 of galactan.
The hydrolysates from the Gelidium residues were prepared and delivered by the Centre of Biological Engineering (CBE), University of Minho, Portugal (project partners in PTDC/BII-BIO/29242/2017).