Identification and characterization of a new Halomicronema species (Cyanobacteria) isolated from the Mediterranean marine sponge Petrosia ficiformis (Porifera).

A filamentous cyanobacterium (strain ITAC101) isolated from a Mediterranean sponge (Petrosia ficiformis) was characterized by a combined phenotypic and genetic approach. Morphological and ultrastructural observations were performed along with growth measurements and pigment characterization. The molecular phylogenetic analyses were based on the sequencing of the 16S rRNA gene. In culture conditions, strain ITAC101 is moderately halophilic and grew in the range 0.3-7.6% (w/v) salinity with the optimum at 3.6%. Cell dimensions, thylakoid arrangement and pigment composition of this cyanobacterium fit the Halomicronema genus description, and phylogenetic analyses evidenced 99.9% similarity with another strain endolithic in tropical corals. The new Halomicronema metazoicum species was established including the two cyanobacteria associated to marine animals.