Impact of glucose concentration on productivity and yield of hydrogen production by the new isolate Clostridium beijerinckii Br21

Abstract

AbstractThis paper presents a detailed analysis of the batch kinetic fermentative assays data used to evaluate how glucose concentration influences fermentative H2 production, including the non‐dissociated acid concentration threshold, with the new isolate Clostridium beijerinckii Br21. Fermentative batch assays for hydrogen (H2) production were conducted with initial glucose concentrations of 5.2, 27.2, 54.4, 97.2, or 154.4 mmol/L without pH control. The dry cell mass (X), glucose (S), and product (H2) concentrations and the pH were monitored for 60 h. Increasing initial glucose concentration raised the maximum specific H2 production rate to values as high as 1.19 mmol H2/mg X · h. However, the H2 production yield (YH2/S) decreased from 2.23 to 0.2 mmol H2/mmol glucose. The initial glucose concentration that provided the best compromise between YH2/S and H2 productivity was 37 mmol/L (6.7 g/L). The lactic acid, acetic acid, and butyric acid concentrations enhanced at higher initial glucose concentrations, leading to the largest pH decrease. Lower pH favoured non‐dissociated acids, which switched the Clostridium metabolism to solventogenesis. The threshold acid concentrations for C. beijerinckii Br21 solventogenesis were non‐dissociated butyric acid at 8 mmol/L and total non‐dissociated acetic and butyric acids at 13 mmol/L. Glucose supply and pH control in continuous or fed‐batch biorreactors could culminate in higher H2 productivity and yield by C. beijerinckii Br21.