Alien species invasion of deep-sea bacteria into mouse gut microbiota

INTRODUCTION: Deep sea has numerous bacteria which dominate in the biomass of deep-sea sediments. Some deep-sea bacteria may possess the capacity to destroy mammal health by the alteration of gut microbiota, acting as potential pathogens. OBJECTIVES: Pathogenic bacteria are great threats to human health. However, the ultimate origin of pathogenic bacteria has not been intensively explored. In this study, therefore, the influence of deep-sea bacteria on the gut microbiota was evaluated on a global scale. METHODS: The bacteria isolated from each of 106 deep-sea sediment samples were transplanted into mice in our study to assess the infectiousness of deep-sea bacteria. RESULTS: The results showed that some bacteria from deep sea, an area that has existed since the earth was formed, could proliferate in mouse gut. Based on the infectious evaluation of the bacteria from each of 106 deep-sea sediments, the bacteria isolated from 13 sediments invaded the gut bacterial communities of mice, leading to the significant alteration of mouse gut microbiota. Among the 13 deep-sea sediments, the bacteria isolated from 9 sediments could destroy mouse health by inducing glucose metabolism deterioration, liver damage and inflammatory symptom. As an example, a bacterium was isolated from deep-sea sediment DP040, which was identified to be Bacillus cereus (termed as Bacillus cereus DP040). Bacillus cereus DP040 could invade the gut microbiota of mice to change the gut microbial structure, leading to inflammatory symptom of mice. The deep-sea sediments containing the bacteria destroying the health of mice were distributed in hydrothermal vent, mid-ocean ridge and hadal trench of the Indian Ocean, the Atlantic Ocean and the Pacific Ocean. CONCLUSION: Our findings demonstrate that deep sea is an important origin of potential pathogenic bacteria and provide the first biosecurity insight into the alien species invasion of deep-sea bacteria into mammal gut microbiota.