Bacteriophage Ecology in Commercial Sauerkraut Fermentations

Abstract

Knowledge of bacteriophage ecology in vegetable fermentations is essential for developing phage control strategies for consistent and high quality of fermented vegetable products. The ecology of phages 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 phage isolates, including at least 26 distinct phages, were obtained. In addition, 28 distinct host strains were isolated and identified as LAB by restriction analysis of the intergenic transcribed spacer region and 16S rRNA sequence analysis. These host strains included Leuconostoc, Weissella, and Lactobacillus species. It was found that there were two phage-host systems in the fermentations corresponding to the population shift from heterofermentative to homofermentative LAB between 3 and 7 days after the start of the fermentations. The data suggested that phages may play an important role in the microbial ecology and succession of LAB species in vegetable fermentations. Eight phage isolates, which were independently obtained two or more times, were further characterized. They belonged to the family Myoviridae or Siphoviridae and showed distinct host ranges and DNA fingerprints. Two of the 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.Like most vegetable fermentations, sauerkraut fermentation is spontaneous and relies on a very small population of lactic acid bacteria (LAB), which are naturally present on fresh vegetables, for preservation. It is known that a succession of various LAB species and their metabolic activities are responsible for the quality and safety of these products (25). The process is characterized by an initial heterofermentative stage, followed by a homofermentative stage. Heterofermentative Leuconostoc mesenteroides initiates the fermentation and quickly predominates the early stage of the fermentation because it is present at an initially higher number (approximately 10 3 CFU/ml) and has a shorter generation time at 18°C (the typical temperature of sauerkraut fermentation) than most other epiphytic LAB (22,23,24,25,27). The quality characteristics of sauerkraut are largely dependent upon the growth of this species (25). Between 3 and 7 days after the start of the fermentation, heterofermentative Leuconostoc species are usually succeeded by the more acid-tolerant homofermentative Lactobacillus species, due to the accumulation of lactic acid to 1% (wt/vol) or more and the decrease in pH below 4.5 (21, 25). Lactobacillus plantarum completes the fermentation, with a final pH of approximately 3.5 (25, 29).The correct sequence of LAB species is essential in achieving a stable product with the typical flavor and aroma of sauerkraut. It ...

Characterization and lytic activity of Pseudomonas fluorescens phages from sewage

“…The results are in concordance with an earlier study wherein the phages of Pseudomonas were successfully isolated only from water samples, while in soil and feces no Pseudomonas specific phages were detected (22).Earlier studies attribute similar results to relatively low viable counts of phage capable of infecting specific bacteria (6), relatively low rates of phage diffusion within soil, particularly under drier conditions (18) and relatively high rates of free-phage inactivation within soil (27). There have been a number of reports of phage presence, in various environments (14,2).…”

Bacteriophage cocktail and multi-strain probiotics in the feed for weanling pigs: effects on intestine morphology and targeted intestinal coliforms and Clostridium

“…Phages probably pass gastro-intestinal tract safely because they are able to survive in an acidic environment, however, pH = 6 to 7 is the optimum range for most of them to show the highest efficiency. Lu et al (2003) reported that 24 phage isolates were obtained in fermentation tanks with sauerkraut (pH < 3.5) after 60 days. Yan et al (2012) reported that growing pigs fed diets supplemented with anti-Salmonella bacteriophage had greater digestibility of DM, which is in agreement with our results (Experiment 1, phase 3).…”

Evaluation of different conditions to enhance the performances of Lactobacillus pentosus OM13 during industrial production of Spanish-style table olives

“…Furthermore, the use of starter cultures may improve the food shelf-life by inhibition of spoilage microorganisms based on nutrient competition (Fernandez-Díez et al, 1985;Garrido-Fernandez et al, 1997;Duran Quintana et al, 1999;Holzapfel, 2002;Devlieghere et al, 2004;Silvestri et al, 2009), and should improve aroma and flavor of final products not only by inhibition of the spoilage microorganisms that interfere with the process of aroma generation, but also directly through their metabolism (Aponte et al, 2010). Until now, Lactobacillus plantarum (Lu et al, 2003) and Lactobacillus pentosus (Rodríguez-Gomez et al, 2013) have been the primary LAB species commonly applied to produce fermented table olives (Hurtado et al, 2012). However, some yeasts, such as Wickerhamomyces anomalus, Saccharomyces cerevisiae and Pichia membranifaciens have been selected as starters for this kind of production (Garrido-Fernandez et al, 1997;Bautista-Gallego et al, 2011;Arroyo-Lopez et al, 2012).…”