Insights into the bacterial and archaeal population dynamics in the deep-sea hydrothermal sediments exposed to lights with different wavelengths

The deep-sea hydrothermal environments with steep temperature and chemical gradients foster a rich microbial diversity. The presence of infrared light and bioluminescence in the hydrothermal fields has been reported. However, effects of illumination on the growth of the microorganisms in the deep-sea hydrothermal environ-ments have not been studied. In this work, metagenomic analysis of hydrothermal sediment samples was per-formed and the data showed that genes of photosensitive proteins are widely distributed, indicating that light might be a crucial environmental factor for cultivation of hydrothermal microorganisms. To further study the effects of light on enrichment and culture of hydrothermal microorganisms, sediment samples collected from deep-sea hydrothermal fields were cultured under the conditions of dark, white light, blue light, green light, red light and infrared light, respectively. Then, the V4-V5 regions of 16S rRNA genes of bacteria and archaea were sequenced through high-throughput sequencing, and the microbial community composition of bacteria and archaea in different samples was studied. The results showed that different species of microorganisms were enriched under different light conditions. Notably, there were significant differences in microbial composition under dark and other light conditions, suggesting that light is an important signal for growth and culture of hydrothermal microorganisms. Overall, this study shed light on the function of lights on the culture of hydro-thermal microorganisms.