Process conditions affect microbial diversity and activity in a haloalkaline biodesulfurization system.

Biodesulfurization (BD) systems that treat sour gas employ mixtures of haloalkaliphilic sulfur-oxidizing bacteria to convert sulfide to elemental sulfur. In the past years, these systems have seen major technical innovations that have led to changes in microbial community composition. Different studies have identified and discussed the microbial communities in both traditional and improved systems. However, these studies do not identify metabolically active community members and merely focus on members' presence/absence. Therefore, their results cannot confirm the activity and role of certain bacteria in the BD system. To investigate the active community members, we determined the microbial communities of six different runs of a pilot-scale BD system. 16S rRNA gene-based amplicon sequencing was performed using both DNA and RNA. A comparison of the DNA- and RNA-based sequencing results identified the active microbes in the BD system. Statistical analyses indicated that not all the existing microbes were actively involved in the system and that microbial communities continuously evolved during the operation. At the end of the run, strains affiliated with