Gluconic and ketogluconic acid production in Pseudomonas reptilivora B-6bs

Pseudomonas reptilivora B-6bs is a promising microbial platform for the industrial production of gluconic, 2-ketogluconic, and 5-ketogluconic acids. This study optimized the production of these metabolites via response surface methodology in a 3-L bioreactor. The experimental design evaluated the effects of the glucose concentration (10-50 g/L), aeration rate (0.2-2.0 vvm), and agitation speed (250-600 rpm). Metabolite concentrations were determined via specific colorimetric-spectrophotometric methods: the glucose oxidase method for glucose, the Malaprade-Hantzsch reaction for gluconic acid, o-phenylenediamine for 2-ketogluconic acid, and the arsenomolybdate method for 5-ketogluconic acid. The optimization results distinguished between model-predicted optima and experimentally observed outcomes. While the quadratic model suggested a theoretical maximum, the highest experimental efficiency was confirmed in T2 (30 g/L glucose, 600 rpm, and 2.0 vvm), which achieved specific conversion yields (Y_P/S) of 0.54, 0.84, and 0.97 g/g for gluconic, 2-ketogluconic, and 5-ketogluconic acids, respectively, within 24 h. Statistical analysis revealed that the glucose concentration was the most significant factor. Further response surface methodology-based optimization suggested an aeration rate of 1.92 vvm at 600 rpm to maximize performance. These findings provide a quantitative baseline for the potential development of sustainable bioprocesses using P. reptilivora B-6bs. While scale-up studies are needed, the data suggest that this strain holds promise for biotechnological applications.