Accelerated growth and hydrogen production induced by laboratory adaptation to CO in a hyperthermophilic archaeon: Deciphering based on next generation sequencing

Abstract

Due to global warming caused by fossil fuel consumption, finding renewable and clean energy sources is an urgent problem of the whole world. Hydrogen gas is considered to be a candidate for future clean energy sources. Thermococcus onnurineus NA1 was reported to have a strong hydrogen producing activity from one carbon compounds such as formate or carbon monoxide. In this study we attempted adaptive evolution to enhance the hydrogen productivity of this strain from CO. Wild type cells were successively transferred 156 times in CO-containing media. During the laboratory evolution the growth rate, hydrogen productivity and final cell density were increased dramatically. The culture which was transferred 156 times (156T), showed final cell density and hydrogen productivity more than 4 times higher than wild type. To understand the molecular mechanisms which drove the phenotypical changes, the transcription profiles of intermediate and final cultures were monitored by next generation sequencing. Generally the transcription patterns of whole cells moved to the direction supporting faster growth. Expectedly CODH cluster and ATP synthase genes generating electrochemical gradient and ATP from CO consumption were dramatically increased by adaptation to CO-containing media. The transcription of ribosomal proteins, RNA polymerase, DNA polymerase and S-layer protein which seemed necessary for fast growth, also increased gradus NA1 was reported to have a strong hydrogen producing activity from one carbon compounds such as formate or carbon monoxide. In this study we attempted adaptive evolution to enhance the hydrogen productivity of this strain from CO. Wild type cells were successively transferred 156 times in CO-containing media. During the laboratory evolution the growth rate, hydrogen productivity and final cell density were increased dramatically. The culture which was transferred 156 times (156T), showed final cell density and hydrogen productivity more than 4 times higher than wild type. To understand the molecular mechanisms which drove the phenotypical changes, the transcription profiles of intermediate and final cultures were monitored by next generation sequencing. Generally the transcription patterns of whole cells moved to the direction supporting faster growth. Expectedly CODH cluster and ATP synthase genes generating electrochemical gradient and ATP from CO consumption were dramatically increased by adaptation to CO-containing media. The transcription of ribosomal proteins, RNA polymerase, DNA polymerase and S-layer protein which seemed necessary for fast growth, also increased grad