Complete genome of Mycetocola spongiae MSC19 isolated from deep-sea sponge Cacospongia mycofijiensis indicates the adaptation to deep-sea environment and sponge-microbe symbioses.

Genome of Mycetocola spongiae MSC19, a novel marine sponge-associated Actinobacteria isolated from the Mariana Trench sponge Cacospongia mycofijiensis, was sequenced. The genome has one circular chromosome of 3,196,754 bp, with an average GC content of 66.43 mol%, and 2887 coding sequences. Gene annotation shows that M. spongiae MSC19 possesses series of genes related to adaptation to deep-sea environmental stresses including cold shock, heat shock, osmotic stress and oxidative stress. Genes encoding for heavy metal resistance, multidrug resistance and multiple natural product biosynthesis which are crucial for survival in the extreme environment are also detected in the genome. The potentials to synthesize kinds of vitamins and eukaryotic-like proteins indicates the possible nutrient exchange and mutual recognization between M. spongiae MSC19 and its sponge host. The genome provides insights into the stress resistance and ecological fitness of bacterial symbionts in the deep-sea sponge holobionts.