Four isolates (FSL S4-120 T , FSL S4-696, FSL S4-710, and FSL S4-965) of Gram-positive, motile, facultatively anaerobic, non-spore-forming bacilli that were phenotypically similar to species of the genus Listeria were isolated from soil, standing water and flowing water samples obtained from the natural environment in the Finger Lakes National Forest, New York, USA. The four isolates were closely related to one another and were determined to be the same species by whole genome DNA-DNA hybridization studies (.82 % relatedness at 55 6C and .76 % relatedness at 70 6C with 0.0-0.5 % divergence). 16S rRNA gene sequence analysis confirmed their close phylogenetic relatedness to Listeria monocytogenes and Listeria innocua and more distant relatedness to Listeria welshimeri, L. seeligeri, L. ivanovii and L. grayi. Phylogenetic analysis of partial sequences for sigB, gap, and prs showed that these isolates form a wellsupported sistergroup to L. monocytogenes. The four isolates were sufficiently different from L. monocytogenes and L. innocua by DNA-DNA hybridization to warrant their designation as a new species of the genus Listeria. The four isolates yielded positive reactions in the AccuProbe test that is purported to be specific for L. monocytogenes, did not ferment L-rhamnose, were nonhaemolytic on blood agar media, and did not contain a homologue of the L. monocytogenes virulence gene island. On the basis of their phenotypic characteristics and their genotypic distinctiveness from L. monocytogenes and L. innocua, the four isolates should be classified as a new species within the genus Listeria, for which the name Listeria marthii sp. nov. is proposed. The type strain of L. marthii is FSL S4-120 T (5ATCC BAA-1595 T 5BEIR NR 9579 T 5CCUG 56148 T ). L. marthii has not been associated with human or animal disease at this time.

Agricultural water is an important source of foodborne pathogens on produce farms. Managing water-associated risks does not lend itself to one-size-fits-all approaches due to the heterogeneous nature of freshwater environments. To improve our ability to develop location-specific risk management practices, a study was conducted in two produce-growing regions to (i) characterize the relationship between Escherichia coli levels and pathogen presence in agricultural water, and (ii) identify environmental factors associated with pathogen detection. Three AZ and six NY waterways were sampled longitudinally using 10-L grab samples (GS) and 24-h Moore swabs (MS). Regression showed that the likelihood of Salmonella detection (Odds Ratio [OR] = 2.18), and eaeA-stx codetection (OR = 6.49) was significantly greater for MS compared to GS, while the likelihood of detecting L. monocytogenes was not. Regression also showed that eaeA-stx codetection in AZ (OR = 50.2) and NY (OR = 18.4), and Salmonella detection in AZ (OR = 4.4) were significantly associated with E. coli levels, while Salmonella detection in NY was not. Random forest analysis indicated that interactions between environmental factors (e.g., rainfall, temperature, turbidity) (i) were associated with likelihood of pathogen detection and (ii) mediated the relationship between E. coli levels and likelihood of pathogen detection. Our findings suggest that (i) environmental heterogeneity, including interactions between factors, affects microbial water quality, and (ii) E. coli levels alone may not be a suitable indicator of food safety risks. Instead, targeted methods that utilize environmental and microbial data (e.g., models that use turbidity and E. coli levels to predict when there is a high or low risk of surface water being contaminated by pathogens) are needed to assess and mitigate the food safety risks associated with preharvest water use. By identifying environmental factors associated with an increased likelihood of detecting pathogens in agricultural

Sampling of agricultural and natural environments in two US states (Colorado and Florida) yielded 18 Listeria-like isolates that could not be assigned to previously described species using traditional methods. Using whole-genome sequencing and traditional phenotypic methods, we identified five novel species, each with a genome-wide average blast nucleotide identity (ANIb) of less than 85 % to currently described species. Phylogenetic analysis based on 16S rRNA gene sequences and amino acid sequences of 31 conserved loci showed the existence of four well-supported clades within the genus Listeria ; (i) a clade representing Listeria monocytogenes , L. marthii , L. innocua , L. welshimeri , L. seeligeri and L. ivanovii , which we refer to as Listeria sensu stricto, (ii) a clade consisting of Listeria fleischmannii and two newly described species, Listeria aquatica sp. nov. (type strain FSL S10-1188T = DSM 26686T = LMG 28120T = BEI NR-42633T) and Listeria floridensis sp. nov. (type strain FSL S10-1187T = DSM 26687T = LMG 28121T = BEI NR-42632T), (iii) a clade consisting of Listeria rocourtiae , L. weihenstephanensis and three novel species, Listeria cornellensis sp. nov. (type strain TTU A1-0210T = FSL F6-0969T = DSM 26689T = LMG 28123T = BEI NR-42630T), Listeria grandensis sp. nov. (type strain TTU A1-0212T = FSL F6-0971T = DSM 26688T = LMG 28122T = BEI NR-42631T) and Listeria riparia sp. nov. (type strain FSL S10-1204T = DSM 26685T = LMG 28119T = BEI NR- 42634T) and (iv) a clade containing Listeria grayi . Genomic and phenotypic data suggest that the novel species are non-pathogenic.

agricultural water (e.g., rain events were associated with L. monocytogenes isolation from samples collected downstream of dairy farms; P = 0.002). The information presented here will enable growers to comanage their operations to mitigate the produce safety risks associated with preharvest surface water use.

As our understanding of Listeria monocytogenes transmission in retail and deli operations is limited, we conducted a cross-sectional study of L. monocytogenes contamination patterns in 121 retail establishments, using testing of food and environmental samples and subtype analysis (ribotyping) of L. monocytogenes isolates. Seventy-three (60%) establishments had at least one sample that tested positive for L. monocytogenes; 5 (2.7%) of the 183 food and 151 (13.0%) of the 1,161 environmental samples tested positive for L. monocytogenes, including 125 (16.7%) and 26 (6.3%) of non-food contact and food contact surface samples, respectively. Thirty-two EcoRI ribotypes were identified among the 156 L. monocytogenes isolated. Twenty-seven establishments had two or more L. monocytogenes with the same ribotype within a given establishment, including 9 establishments where isolates from 3 to 5 samples had the same ribotype. In 5 of 7 establishments where follow-up sampling was conducted 8 to 19 months after the initial sampling, isolates with the same ribotype were obtained in both samplings; persistence of a given strain was also confirmed by pulsed-field gel electrophoresis. Our data indicate that (i) L. monocytogenes is regularly found in some retail environments; (ii) L. monocytogenes strains are often widely distributed in retail, indicating cross-contamination and dispersal; (iii) L. monocytogenes can persist in retail environments for more than 1 year; and (iv) a number of L. monocytogenes subtypes isolated at retail are common among human listeriosis cases. We also identified specific contamination patterns in retail establishments, providing critical information for the development of L. monocytogenes control strategies.