Relationship between HSF
colony phenotype and presence/absence of the yraS gene in different Y . ruckeri isolates. (A) Aliquots of 5 μl of early stationary phase cultures of isolates of Y. ruckeri from different hosts and geographic origins were spotted onto TSA-SDS medium. After 48 h of incubation at 28°C, colonies were photographed. (B). Aliquots from the same cultures were used for an yraS gene fragment amplification using PCR reactions according the protocol described in Experimental Procedures. PCR-generated amplicons were separated in agarose gel and photographed. Lane ʎ100 shows DNA molecular mass markers from 100 to 1000 bp. All the isolates showing HSF+ phenotype (creamy white colonies) were positive for the PCR reaction, whereas the isolates with HSF- phenotype (transparent colonies) did not present the amplicon.