78F-8

R. BARRANGOU¹, S. S. Yoon, F. Breidt, Jr., T. R. Klaenhammer, and H. P. Fleming. (1) U.S. Department of Agriculture, ARS, Department of Food Science, NC State University, Raleigh, NC 27695-7624

Sauerkraut fermentation relies on naturally occurring lactic acid bacteria present on the raw cabbage. Leuconostoc species, including Leuconostoc mesenteroides and Leuconostoc fallax, are known to be present during the early stage of sauerkraut fermentation. It was previously shown that L. mesenteroides bacteriophages are present in sauerkraut fermentations.

The objective of this study was to investigate the occurrence and characteristics of bacteriophages active against L. fallax.

Six distinct bacteriophages active against L. fallax strains were isolated from fermenting sauerkraut brines during the first seven days of an industrial fermentation. The phages were characterized as to morphology, one step growth kinetics, DNA and SDS-PAGE profiles, and lytic activity against six Leuconostoc species.

All six phages were lytic against L. fallax, but showed variable reactions in seven different L. fallax strains. The phages did not attack other Leuconostoc species. Morphologically, three phages with isometric heads and long noncontractile tails were assigned to the Siphoviridae family. Three bacteriophages with isometric heads and short contractile tails were assigned to the Myoviridae family. The major capsid proteins detected by electrophoresis were distinct in each family, with either 50, 33 and 24 kDa proteins or 30 and 25 kDa proteins for Siphoviridae phages, and 63 and 53 kDa proteins for Myoviridae phages. RFLP analysis of Myoviridae phage R03 showed that its DNA was over 70 kb in length. Also, the one step growth kinetics of this bacteriophage indicated a burst size of 80 pfu cell^-1, a latent period of 65 minutes, and an eclipse phase of 30 minutes.

These results revealed for the first time the existence of bacteriophages against L. fallax. Moreover, this study confirms the presence of phages in fermenting sauerkraut. Bacteriophage activity against Leuconostoc strains, either naturally occurring or starter cultures, may be a potential cause for fermentation variability.