The present study is focused on the development of a cultivation-independent molecular approach for specific detection of bioluminescent bacteria within microbial communities by direct amplification of luxA gene from environmental DNA
A new set of primers ,specifically targeting free-living bioluminescent bacteria , was designed on the base of luxA sequences available from the public database
Meso - and bathypelagic seawater samples were collected from two stations in TyrrhenianSea at the depths of 500 and 2750 m.
The same seawater samples also were used to isolate bioluminescent bacteria that were further subjected to luxA and 16S rRNA gene sequencing
PCR products obtained by amplification with designed primers were cloned , and the phylogenetic affiliation of 40 clones was determined.
All of them were clustered into three groups , only distantly related to the Photobacterium phosphoreum and Photobacterium kishitanii clades
The half of all clones formed a tight monophyletic clade , while the rest of clones were organized in ‘‘compartment’’
-specific , meso- and bathypelagic ecotypes
No matches with luxA gene sequences off our bioluminescent strains , isolated from the same seawater samples ,were observed
These findings indicate that the PCR-based approach developed in present manuscript , allowed us to detect the novel,‘‘yet to be cultivated’’ lineages of bioluminescent bacteria, which are likely specific for distinct warm bathypelagic realms of Mediterranean Sea