The  in situ  incubation sites and layout diagram of the deep-sea in situ microbial incubator (DIMI) in the deep sea. (A) the locations of the three in situ incubations. IO, Indian Ocean; SCS, South China Sea; PO, Pacific Ocean. (B) the layout diagram of DIMIs at three sites in the deep sea. The DIMIs were located in three different habitats, including the seafloor of the SCS (①), the seafloor of the Indian Ocean (②), and the top of a seamount in the Pacific Ocean (③). Site SCS is located in a deep-sea basin with a water depth of 3758 m in the northern SCS. Site IO is located in the deep-sea basin near the southwest Indian ridge at a water depth of 4434 m in the Indian Ocean. Site PO is located at the top of a flat-topped seamount with a water depth of 1622 m in the West Pacific Ocean. (C) DIMI recycling diagram. DIMI is dropped freely on the surface and lands on the deep-sea bottom, and once it reaches the seafloor, in situ enrichment in the deep sea is triggered. The lid of each incubation chamber (IC) was kept open to ensure that substrates were accessible to the surroundings during enrichment. After months of incubation, the DIMI was released by an acoustic signal and up the sea surface. During the process of going up, the lid of each chamber was closed tightly.