Submitted to: Applied and Environmental Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 2/25/2003
Publication Date: 6/20/2003
Citation: Lu, Z., Breidt, F., Plengvidhya, V., Fleming, H.P. 2003. Bacteriophage ecology in commercial sauerkraut fermentations. Applied and Environmental Microbiology. 69(6):3192-3202. Interpretive Summary: This study demonstrated for the first time that a diversity of bacterial viruses, known as bacteriophages, is present in sauerkraut fermentations. These viruses do not infect humans, but can infect some of the desirable bacteria responsible for converting the sliced cabbage into sauerkraut. The bacteriophages were discovered in samples of fermenting sauerkraut from 90-ton commercial sauerkraut fermentation tanks during a two-year study. The bacteriophages were found to attack a variety of lactic acid bacteria naturally present in the fermentations. Lactic acid bacteria convert sugars of the cabbage to acids and other flavorful compounds to give sauerkraut its characteristic flavor. This information will be useful in developing strategies for choosing lactic acid bacteria cultures to use in controlled fermentation of sauerkraut, which may allow the fermentation to occur more consistently and at lower concentrations of salt.
Technical Abstract: The ecology of bacteriophages infecting lactic acid bacteria (LAB) in commercial sauerkraut fermentations was investigated. Brine samples were taken from four commercial sauerkraut fermentation tanks over a 60- or 100-day period in 2000 and 2001. A total of 171 independent phage isolates, including at least 26 distinct phages, were obtained. In addition, 28 distinct host strains were isolated and identified as LAB by ITS restriction and 16S rRNA sequence analyses. These host strains included Leuconostoc, Weissella, and Lactobacillus species. It was found that there were two phage-host systems in the fermentations, with the dividing line occurring between day 3 and day 7 after the start of the fermentations, corresponding to the population shift from heterofermentative to homofermentative LAB. The data strongly suggested that phages may play an important role in the microbial ecology and succession of lactic acid bacterial species in vegetable fermentations. Eight phage isolates, which were independently obtained two or more times, were further characterized. They belonged to the Myoviridae or Siphoviridae family and showed distinct host ranges and DNA fingerprints. Two of phage isolates were found to be capable of infecting two Lactobacillus species. The results from this study demonstrated for the first time the complex phage ecology present in commercial sauerkraut fermentations, providing new insights into the bioprocess of vegetable fermentations. Knowledge of phage ecology in vegetable fermentations is essential for developing phage-control strategies for consistent and high quality of fermented vegetable products.