Soil collected in the Great Smoky Mountains National Park yielded a novel Listeria species, L. swaminathanii, effectively expanding the sensu stricto clade to ten species

Soil samples collected in the Great Smoky Mountains National Park yielded a Listeria isolate that could not be classified to the species level. Whole-genome sequence-based average nucleotide identity BLAST and in silico DNA-DNA Hybridization analyses confirmed this isolate to be a novel Listeria sensu stricto species with the highest similarity to L. marthii (ANI=93.9%, isDDH=55.9%). Additional whole-genome-based analysis using the Genome Taxonomy Database Toolkit, an automated program for classifying bacterial genomes, further supported delineation as a novel Listeria sensu stricto species, as this tool failed to assign a species identification but identified L. marthii as the closest match. Phenotypic and genotypic characterization results indicate that this species is nonpathogenic. Specifically, the novel Listeria species described here is phenotypically (i) non-hemolytic and (ii) negative for phosphatidylinositol-specific phospholipase C activity; the draft genome lacks all virulence genes found in the Listeria pathogenicity island 1 (LIPI-1), as well as the internalin genes inlA and inlB. While the type strain for the new species is phenotypically catalase-negative (an unusual characteristic for Listeria sensu stricto species), its genome contained an apparently intact catalase gene (kat); hence assessment of this phenotype with future isolates will be important. Rapid species identification systems (Listeria API, VITEK 2, VITEK MS) misidentified this novel species as either L. monocytogenes, L. innocua, or L. marthii. We propose the name L. swaminathanii, and the type strain is FSL L7-0020T (=ATCC TSD-239T).

Listeria spp. Isolated from Soil Samples Collected in the Great Smoky Mountains

Listeria monocytogenes, a foodborne pathogen, and other Listeria spp. are present in natural environments. Isolating and characterizing strains from natural reservoirs can provide insight into the prevalence and diversity of Listeria spp. in these environments, elucidate their contribution to contamination of agricultural and food processing environments and food products, and lead to the discovery of novel species. In this study, we evaluated the diversity of Listeria spp. isolated from soil samples in a small region of the Great Smoky Mountains National Park (GSMNP), which is the most biodiverse national park in the United States National Park system. Of the 17 Listeria isolates that were recovered, whole-genome sequencing revealed that 14 were unique strains. The unique strains were shown to represent a diversity of Listeria spp., including L. monocytogenes (n=9), L. cossartiae subsp. cossartiae (n=1), L. marthii (n=1), L. booriae (n=1), and a novel Listeria sp. (n=2). The Listeria isolated in this study were collected from high elevation sites near a creek that drains into a series of rivers ultimately leading to the Mississippi River; thus, the Listeria present in this natural environment could potentially travel downstream to a large region that includes portions of nine southeastern and midwestern states in the U.S. The Listeria spp. isolated and described in this study provide insight into the diversity of Listeria spp. found in the Great Smoky Mountains and indicate that this environment is a reservoir of novel Listeria spp.

An updated species list for “Smoky Bears”: Tardigrades of the Great Smoky Mountains National Park, USA

One of the largest inventories of tardigrades ever conducted occurred from 2000–2010 in the Great Smoky Mountains National Park, USA. Over 16,000 specimens were catalogued, 85 species were identified, 11 species new to science were described, and 16 other possible new species await further study. More than 20 papers have resulted from the GSMNP tardigrade inventory, making the Smokies the most thoroughly studied area in North America for tardigrades. Several species lists have been published over this 20-year period, but many taxonomic revisions and new identifications have led to significant changes to the list. Biogeographical studies citing species records from earlier studies could yield serious errors. Here we update the species list from the Smokies to accommodate the many recent changes in tardigrade taxonomy, we re-analyze some species in light of delineations of cryptic species groups that have occurred recently via integrative taxonomy, and we provide a table of all synonyms that have been used in previous publications. We also make available, for the first time, the Smokies tardigrade database, complete with all locations, elevations, and substrates.

Lightning Occurrence and Casualties in U.S. National Parks

National park visitors travel primarily to view natural features while outdoors, however visits often occur in warmer months when lightning is present. This study uses cloud-to-ground flashes from 1999-2018 and cloud-to-ground strokes from 2009-2018 from the National Lightning Detection Network to identify lightning at the 46 contiguous United States national parks larger than 100 km2. The largest density is 6.10 flashes km-2 y-1 within Florida’s Everglades, and the smallest is near zero in Pinnacles National Park.The six most-visited parks are Great Smoky Mountains, Grand Canyon, Rocky Mountain, Zion, Yosemite, and Yellowstone. For these parks, lightning data are described by frequency, location and time of year and day. The four parks west of the Continental Divide have most lightning from 01 July to 15 September, and 1100 to 1900 LST. Each park has its own spatial lightning pattern dependent on local topography.Deaths and injuries from lightning within national parks have the same summer afternoon dominance shown by lightning data. Most casualties occur to people visiting from outside the parks’ states. The most common activities and locations are mountain climbing, hiking, and viewing canyons from overlooks.Lightning Fatality Risk, the product of areal visitor and CG flash densities, shows that many casualties are not in parks with high Risk, while very small Risk indicates parks where lightning awareness efforts can be minimized. As a result, safety advice should focus on specific locations where lightning-vulnerable activities are engaged by many visitors such as canyon rims, mountains and exposed high-altitude roads.

Rhododendron smokianum, a New Species from the Great Smoky Mountains

Abstract—Species delimitation in Rhododendron subsect. Caroliniana (Ericaceae) has been disputed in the past with one or three species accepted. Here we report a fourth species, R. smokianum, a narrow endemic from the Great Smoky Mountains (Tennessee/North Carolina, USA). It is characterized by short-tubed corollas and small, compact growth. We support our conclusion by phylogenetic analyses of ITS and plastid trnL-F sequence data. The new species is a specialist of open mafic rock slopes and maintains morphological and phenological differences to the related species even in cultivation.

Assemblages of myxomycetes associated with three different substrates affected by forest wildfires

Background and aims – In late November and early December of 2016, forest wildfires occurred over portions of the Great Smoky Mountains National Park (USA) and more than 4 000 ha were affected. Previous studies have shown that myxomycete assemblages can be greatly impacted as a result of this type of disturbance; after which, the recovery of the forest determines the availability of substrates for new colonisation. The objective of the project reported herein was to assess the impact of wildfires on the recovery of the assemblages of myxomycetes associated with three different substrates (forest floor leaf litter, the bark of living trees, and woody twigs) in two areas with different fire intensity.Material and methods – Two study areas subjected to different fire intensity were selected and sampled 30 months after the wildfires. Myxomycetes were studied using the moist chamber culture technique as it applies to these organisms. Satellite imagery was used to determine forest recovery and similarity indices were used to compare experimental myxomycete assemblages among study areas and substrates. Historical data were used as a reference to contextualise the results.Key results – A total of 38 species of myxomycetes representing 17 different genera were recorded from the two study areas. Samples from the lower intensity burn area yielded more myxomycetes than samples from the higher intensity burn area, with values of 84% and 59%, respectively. This same pattern was also observed for the number of recorded specimens (133 and 93, respectively). The comparison of experimental assemblages with previous data suggested that ground litter assemblages were still in early stages of recovery, whereas the assemblages associated with bark and twigs had recovered much faster.Conclusion – The relatively higher intensity fire had more of an effect on myxomycetes than the relatively lower intensity fire. Myxomycete assemblages are resilient to wildfires and they recover differentially depending on the substrate they grow on.