Exploring the potential for oxygen production by cable bacteria in the deep sediment through the investigation of amoA gene expression

This thesis aims to investigate the potential for oxygen production by cable bacteria in the deep sediment. To accomplish this, an indirect approach was used, specifically studying the expression of the amoA gene, belonging to the Nitrosomonas genus, in the RNA extracted from the sediment samples taken at different depths and time-points. The amoA gene encodes for ammonia monooxygenase, which catalyzes the initial step of ammonia oxidation by converting ammonia to hydroxylamine. As this enzyme requires the presence of molecular oxygen to function, we hypothesize that an increase in the transcript abundance of the Nitrosomonas amoA gene in the deep sediment, is indicative of cable bacteria producing oxygen. Along with the amoA gene, the aprA gene is taken into consideration as well, as an indicator of cable bacteria being present. From this study it was observed that the amoA gene is present in the deep sediment, supporting the notion that cable bacteria are promoting Nitrosomonas growth and highlighting the need for further investigations.