The bacterial flora of vacuum-packed cold-smoked salmon stored at 7 degrees C, identified by direct 16S rRNA gene analysis and pure culture technique.
OBJECTIVE
The indigenous flora of freshly chilled cold-smoked salmon just after the vacuum packaging, and the spoilage flora after storage, in vacuum package at 7 degrees C for 19 days, were to be investigated with two different sampling strategies.


RESULTS
Identification was performed using 16S rRNA sequencing of both isolated bacteria and bacterial DNA from tissue extract. The indigenous flora of fresh cold-smoked vacuum-packed salmon was dominated by, in order, Brochothrix thermosphacta, Yersinia ruckeri, Photobacterium and Carnobacterium, whereas the spoilage flora of the same product stored at 7 degrees C for 19 days was dominated by Lactobacillus and Photobacterium. The two sampling strategies showed similar results on the fish flora. Several new types of Photobacterium sequences, closely related to Photobacterium iliopiscarium and Photobacterium phosphoreum, were found from both the freshly processed and the stored salmon, indicating that smoked salmon harbours at least three different, as yet unknown, Photobacterium species.


CONCLUSIONS
Ten per cent of the bacterial flora multiplying on chilled, vacuum-packed, cold-smoked salmon comprised unknown species. The two sampling strategies complement each other.


CONCLUSIONS
As cold-smoked salmon is consumed without heat-treatment, the presence of undefined bacteria in high numbers should be considered in public health assessments.
Olofsson
T C
TC
Laboratory of Food Hygiene, Department of Food Technology, Engineering and Nutrition, Lund University, Lund, Sweden.
Ahrné
S
S
Molin
G
G
D000818:Animals; D001419:Bacteria / Q000145:classification / Q000302:isolation & purification*; D015373:Bacterial Typing Techniques / Q000379:methods; D003080:Cold Temperature; D005511:Food Handling / Q000379:methods; D005516:Food Microbiology; D018857:Food Packaging / Q000379:methods*; D005519:Food Preservation / Q000379:methods; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012474:Salmon / Q000382:microbiology*; D017747:Seafood / Q000382:microbiology*; D014618:Vacuum
D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S