Bacteriophages have been suggested as natural food preservatives as well as rapid detection materials for food-borne pathogens in various foods. Since Listeria monocytogenes-targeting phage cocktail (ListShield) was approved for applications in foods, numerous phages have been screened and experimentally characterized for phage applications in foods. A single phage and phage cocktail treatments to various foods contaminated with food-borne pathogens including E. coli O157:H7, Salmonella enterica, Campylobacter jejuni, Listeria monocytogenes, Staphylococcus aureus, Cronobacter sakazakii, and Vibrio spp. revealed that they have great potential to control various food-borne pathogens and may be alternative for conventional food preservatives. In addition, phage-derived endolysins with high host specificity and host lysis activities may be preferred to food applications rather than phages. For rapid detection of food-borne pathogens, cell-wall binding domains (CBDs) from endolysins have been suggested due to their high host-specific binding. Fluorescence-tagged CBDs have been successfully evaluated and suggested to be alternative materials of expensive antibodies for various detection applications. Most recently, reporter phage systems have been developed and tested to confirm their usability and accuracy for specific detection. These systems revealed some advantages like rapid detection of only viable pathogenic cells without interference by food components in a very short reaction time, suggesting that these systems may be suitable for monitoring of pathogens in foods. Consequently, phage is the next-generation biocontrol agent as well as rapid detection tool to confirm and even identify the food-borne pathogens present in various foods.

BackgroundEscherichia coli O157:H7 and Shigella flexneri are well-known food-borne pathogens causing severe food poisoning at low infectious doses. Bacteriophages have been approved for food applications by the US Food and Drug Administration (FDA) and have been suggested as natural food preservatives to control specific food-borne pathogens. To develop a novel natural food preservative against E. coli O157:H7 and S. flexneri, a new bacteriophage needs to be isolated and characterized.Methodology/Principal FindingsBacteriophage HY01 infecting both E. coli O157:H7 and S. flexneri was isolated from a swine fecal sample. HY01 belongs to the family Myoviridae and is stable under various temperature and pH conditions. One-step growth curve analysis showed relatively short eclipse and latent periods as well as large burst size. The 167-kb genome sequence of HY01 was sequenced, and a comparative genome analysis with T4 for non-O157:H7 E. coli suggests that the receptor recognition protein of HY01 plays an important role in determination of host recognition and specificity. In addition, food applications using edible cabbage were conducted with two E. coli O157:H7 strains (ATCC 43890 and ATCC 43895), showing that treatment with HY01 inhibits these clinical and food isolates with >2 log reductions in bacterial load during the first 2 h of incubation.Conclusions/SignificanceHY01 can inhibit both E. coli O157:H7 and S. flexneri with large burst size and stability under stress conditions. The ability of HY01 to infect both E. coli O157:H7 and S. flexneri may be derived from the presence of two different host specificity-associated tail genes in the genome. Food applications revealed the specific ability of HY01 to inhibit both pathogens in food, suggesting its potential as a novel biocontrol agent or novel natural food preservative against E. coli O157:H7 and potentially S. flexneri.

Strain PFL01 was isolated from traditional Korean fermented clam, jogae-jeotgal, and characterized. The strain was a facultative anaerobic, Gram-stain-negative bacterium that was rod-shaped, motile and beige-pigmented. The phylogenetic sequence analysis based on the 16S rRNA gene from PFL01 revealed that it was closely related to Lelliottia nimipressuralis LMG 10245 and Lelliottia amnigena LMG 2784 with 99.3 and 99.3 % sequence identities, respectively. Multilocus sequence type analysis of concatenated partial aptD, gyrB, infB and rpoB gene sequences showed a clear distinction of strain PFL01 from its closest related type strains. The discrimination was also supported by unique repetitive extragenic palindromic PCR (Rep-PCR, ERIC-PCR) fingerprint patterns. In addition, results from average nucleotide identity analyses with other species were less than 85 %. vitek and API analyses revealed distinct characteristics from other species of Lelliottia. The cellular fatty acid profile of the strain consisted of C16 : 0, cyclo-C17 : 0, C16 : 1ω7c/C16 : 1ω6c and C18 : 1ω7c/C18 : 1ω6c as major components. The whole genome of PFL01 was 4.6 Mb with a G+C content of 55.3 mol%. Based on these results, strain PFL01 was classified as a novel species of the genus Lelliottia, for which the name Lelliottia jeotgali sp. nov. is proposed. The type strain in PFL01 (=KCCM 43247=JCM 31901).

A hyperthermophilic methanogen, strain JH146T , was isolated from 26 6C hydrothermal vent fluid emanating from a crack in basaltic rock at Marker 113 vent, Axial Seamount in the northeastern Pacific Ocean. It was identified as an obligate anaerobe that uses only H 2 and CO 2 for growth. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain is more than 97 % similar to other species of the genus Methanocaldococcus. Therefore, overall genome relatedness index analyses were performed to establish that strain JH146 T represents a novel species. For each analysis, strain JH146 T was most similar to Methanocaldococcus sp. FS406-22, which can fix N 2 and also comes from Marker 113 vent. However, strain JH146 T differs from strain FS406-22 in that it cannot fix N 2 . The average nucleotide identity score for strain JH146 T was 87 %, the genome-to-genome direct comparison score was 33-55 % and the species identification score was 93 %. For each analysis, strain JH146 T was below the species delineation cut-off. Full-genome gene synteny analysis showed that strain JH146 T and strain FS406-22 have 97 % genome synteny, but strain JH146 T was missing the operons necessary for N 2 fixation and assimilatory nitrate reduction that are present in strain FS406-22. Based on its whole genome sequence, strain JH146 T is suggested to represent a novel species of the genus Methanocaldococcus for which the name Methanocaldococcus bathoardescens is proposed. The type strain is JH146 T (5DSM 27223 T 5KACC 18232 T ).The genus Methanocaldococcus was proposed when the order Methanococcales was reclassified to reduce the diversity of each genus within the order (Boone et al., 1993). It consists of strictly hyperthermophilic, hydrogenotrophic methanogens that are obligately anaerobic and coccoidal (Boone et al., 1993;Whitman & Jeanthon, 2006). In this study, the complete genome sequence of a strain of the genus Methanocaldococcus, strain JH146 T , was used to establish the novelty of the strain. The strain was isolated from 26 u C hydrothermal fluid that was flowing from a crack in basaltic rock at Marker 113 vent at Axial Seamount on the Juan de Fuca Ridge in the northeastern Pacific Ocean (Ver Eecke et al., 2012, 2013). The strain used only H 2 as its electron donor and CO 2 as its sole electron acceptor and carbon source (Ver Eecke et al., 2013). Strain JH146 T grew within the temperature range of 48-90 u C with an optimum temperature of 82 u C, within the pH range of 4.5-9.0 with an optimum pH of 7.0 and within the chlorinity range of 127-974 mM chloride with an optimum chlorinity of 358 mM (Ver Eecke et al., 2013). Its phenotypic characteristics were very similar to all other species of the genus Methanocaldococcus (Table 1).The phylogenetic relatedness of strain JH146T to other species of the genus Methanocaldococcus was determined using 16S rRNA gene sequences obtained from the Ribosomal Database Project (Cole et al., 2007) and comparing them via MEGABLAST (McGinnis & Madden, 2004). Strain JH146T showed 99.7 % s...

Foodborne illness represents a major threat to public health and is frequently attributed to pathogenic microorganisms on fresh produce. Recurrent outbreaks often come from vegetables that are grown close to or within the ground. Therefore, the first step to understanding the public health risk of microorganisms on fresh vegetables is to identify and describe microbial communities. We investigated the phyllospheres on Chinese cabbage ( subsp. , = 54). 16S rRNA gene amplicon sequencing targeting the V5-V6 region of 16S rRNA genes was conducted by employing the Illumina MiSeq system. Sequence quality was assessed, and phylogenetic assessments were performed using the RDP classifier implemented in QIIME with a bootstrap cutoff of 80%. Principal coordinate analysis was performed using a weighted Fast UniFrac matrix. The average number of sequence reads generated per sample was 34,584. At the phylum level, bacterial communities were composed primarily of Proteobacteria and Bacteroidetes. The most abundant genera on Chinese cabbages were , and. Diverse potential pathogens, such as , and were also detected from the samples. Although further epidemiological studies will be required to determine whether the detected potential pathogens are associated with foodborne illness, our results imply that a metagenomic approach can be used to detect pathogenic bacteria on fresh vegetables.