Abstract:[Objective] To study the role of napF3 in Thermoanaerobacter tengcongensis at different temperatures.[Methods]We constructed ΔnapF3 from T.tengcongensis by homologous recombination and observed the growth of ΔnapF3 at 50℃,60℃,75℃,and 80℃.Transcriptome sequencing was employed to identify the differentially expressed genes (DEGs) between ΔnapF3 and the wild type (WT) at 75℃.real-time PCR was conducted to measure the transcriptional levels of 13 genes and 3 sRNAs in WT and ΔnapF3 at 50℃,60℃,75℃,and 80℃.[Results] ΔnapF3 was successfully constructed,and it showcased suspended growth at 50℃ and 80℃ and slow growth at 60℃ and 75℃.A total of 899 DEGs between WT and ΔnapF3 at 75℃ were identified,including 363 genes with up-regulated expression and 536 genes with down-regulated expression.These DEGs were mainly involved in the biosynthesis of valine,leucine and isoleucine,ABC transporters,two-component system,fatty acid synthesis,thiamine metabolism and other pathways.The transcriptional levels of 13 genes and 3 sRNAs related to the thermophilic mechanism changed under specific temperatures.[Conclusion] napF3 plays a role in the thermophilic adaptation of T.tengcongensis.