The remaining clusters were analyzed for occurrence of bacterial SECIS elements, located immediately downstream of the in-frame TGA codons, using bSECISearch program . The final clusters were manually analyzed and divided into three groups: known selenoproteins, new selenoproteins (clusters containing at least two different sequences with conserved in-frame TGA codons) and selenoprotein candidates (clusters containing only one sequence). It should be noted that sequencing errors that generate in-frame UGA codons could not be excluded for selenoprotein candidates.