Portal protein diversity and phage ecology

Abstract

Recent whole-genome cyanophage sequencing (Sullivan et al., 2010) has revealed that the sequences of some genes do not match those published previously as single-gene sequences derived from DNA fragments PCR-amplified from phage isolates. Specifically, the g20 gene sequences for S-SSM7 (gene GI:189397276, protein GI:189397277) and Syn33 (gene GI:189397306, protein GI:189397307) in Sullivan and colleagues (2008) were incorrect. The revised sequences do not alter g20 tree topology or the conclusions of Sullivan and colleagues (2008). The source of error for these gene sequences is not certain, but could have its origin in either a clerical error, PCR contamination and/or mixed phage stocks. On this latter point, it has recently come to light that triplicate plaque purifications do not always result in pure stocks for these cyanophages, possibly due to the fluid consistency of the agarose plates (0.28% agarose) required for growth of the host. More reliable purification procedures have subsequently been developed. However, as mixed phage stock preparations could influence host range, we recommend that published host range data (Sullivan et al., 2003) be verified before their use in further research.