Quantitative real-time PCR monitoring dynamics of Thermotoga neapolitana in synthetic co-culture for biohydrogen production

This study demonstrates the potential for biohydrogen production in a co-culture of two ecologically distant species, Thermatoga neapolitana and Caldicellulosiruptor saccharolyticus, and the development of a quantitative real-time PCR (qPCR) method for quantifying the hyperthermophilic bacterium of the genus Thermotoga. Substrate utilization and H-2 production performance was compared to those of their individual cultures. The highest H-2 yields obtained were 2.7 +/- 0.05, 2.5 +/- 0.07 and 2.8 +/- 0.09 mol H-2/mol glucose for C. saccharolyticus, T. neapolitana, and their co-culture respectively. Statistical analysis comparing the H-2 production rate of the co-culture to either C. saccahrolyticus or T. neapolitana pure cultures indicated a significant difference in the H-2 production rate (p < 0.05: t-test), with the highest rate of H-2 production (36.02 mL L-1 h(-1)) observed from the co-culture fermentations. In order to monitor the presence of T. neapolitana in the bioprocess, we developed a qPCR method using 16S rRNA gene and hydrogenase (hydA) gene targets. The qPCR data using hydA primers specific to T. neapolitana showed an increase in hydA gene copies from 3.32 x 10(7) to 4.4 x 10(8) hydA gene copies per mL confirming the influence of T. neapolitana in the synthetic consortium. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.