Triangularia manubriata sp. Nov.: A Novel Fungal Species Belonging to the Family Podosporaceae Isolated from Soil in Korea.

The fungal strain designated as KNUF-21-020, belonging to the genus Triangularia, was isolated from a soil sample collected in the Chungnam province, Korea. Phylogenetic analyses based on the concatenated nucleotide sequences of internal transcribed spacer regions and partial sequences of large subunit rRNA, beta-tubulin, and RNA polymerase II subunit genes revealed that the strain was grouped in a clade with Triangularia species. However, it occupied a distinct phylogenetic position. We also observed morphological differences between strain KNUF-21-020 and closely related species. Here, we provided detailed descriptions, illustrations, and discussions regarding the morphological and phylogenetic analyses of the closely related species to support the novelty of this isolated species. The phylogenetic analyses and morphological observations indicate that the strain KNUF-21-020 represents a novel species in the genus Triangularia (family: Podosporaceae). We have designated this species as Triangularia manubriata sp. nov.

First report of anthracnose caused by Colletotrichum grevilleae on apple in Korea.

In October 2022, typical symptoms of anthracnose were observed on apple (Malus ⅹ domestica cv. Fuji) fruits collected from Pocheon in Gyeonggi province, South Korea (N37.98074°, E127.33995°). In the surveyed orchard, the incidence rate of apple anthracnose was less than 1%. The initial symptoms were brown-to-dark brown lesions, and with disease progression, they enlarged and the pulp became soft, forming a brown band. In total 29 apple fruits were collected, and the causal agent was isolated by removing the peel, and the diseased tissues were directly transferred onto potato dextrose agar (PDA), followed by incubation for 7 days at 25°C. As the results, two isolates (GgPc22-1-11 and GgPc22-1-13) were obtained. For describing morphological and cultural characteristics, isolate GgPc22-1-11 was cultured on PDA and synthetic nutrient-poor agar (SNA) at 25°C under near-UV light with a 12-h photoperiod for 10 days. The colonies of GgPc22-1-11 on PDA were initially white and subsequently appeared light gray to olivaceous with white margins. The reverse side of the plates were dark brown and slate blue (Supplementary Fig. S1). Colonies on SNA were flat with an entire margin and short sparse white aerial mycelium. No setae were observed. Conidia on PDA were hyaline, straight, aseptate with a rounded apex, clavate to cylindrical, and measured 16.4 ± 2.4 (10.8-23.8) × 5.5 ± 0.7 (3.6-7.7) µm (n = 200). Appressoria were medium-to-dark brown, aseptate, solitary or in groups with irregular outlines, and lobate or having undulate margins (Supplementary Fig. S1). These morphological and cultural characteristics of GgPc22-1-11 were consistent with those of Colletotrichum grevilleae F. Liu, Damm, L. Cai & Crous, pathogens of Proteaceae and Punica granatum (Liu et al. 2013; Huang et al. 2023). DNA was extracted from GgPc22-1-11, PCR was performed and Phylogenetic analysis of concatenated partial sequences of the internal transcribed spacer (ITS) of rDNA, ß-tubulin (TUB2), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), chitin synthase 1 (CHS-1), and actin (ACT) genes was conducted (Weir et al. 2012). The resulting sequences were deposited in GenBank under the accession numbers LC773710-LC773714. A nucleotide BLAST search revealed that the ITS sequences of the isolates were 98.95% identical to those of C. grossum CAUG7 (KP890165.1). The TUB2, GAPDH, CHS-1, and ACT sequences of the isolates were 99.79%, 99.24%, 100%, and 100%, respectively, identical to those of C. grevilleae WP4. GgPc22-1-11 was clustered with C. grevilleae WP4 using neighbor joining analysis conducted with MEGA X software (Kumar et al. 2018) (Supplementary Fig. S2). Pathogenicity tests were conducted using GgPc22-1-11 and repeated three times. A total of 12 symptomless apples of each variety were selected, including Fuji, Hongro, Tsugaru, and RubyS. The apples were surface-sterilized with 70% ethanol and wounded using a sterile needle. Both wounded and unwounded apples were inoculated with mycelium plugs and paper disks containing a conidial suspension (1 × 106 conidia/ml) and placed in a plastic box with moist paper towels (>90% relative humidity) at 25°C in dark. At 5 days after inoculation, all artificially wounded fruits exhibited symptoms and 30% (4 out of 12) of unwounded inoculated fruits showed symptoms in each apple variety while control fruits were asymptomatic both the unwounded and wounded inoculations (Supplementary Fig. S1). To fulfill Koch's postulates, the fungi were reisolated from symptomatic tissues and were identical to GgPc22-1-11 confirmed by morphological and molecular analysis. To the best of our knowledge, C. grevilleae has been reported in Protea sp. and pomegranate (Liu et al. 2013; Huang et al. 2023) but not in apples to date, and this is the first report of C. grevilleae causing anthracnose in apple fruits. This research of the newly emerged unreported Colletotrichum species can offer valuable information for development of an effective fungicide spray program to control apple anthracnose.

The Rapid Apple Decline Phenomenon: Current Status and Expected Associated Factors in Korea.

Rapid apple decline (RAD) is a complex phenomenon affecting cultivated apple trees and particularly dwarf rootstocks on grafted young apple trees. Since its first appearance in the United States, RAD has been reported worldwide, for example in Canada, South America, Africa, and Asia. The phenomenon has also been observed in apple orchards in Korea, and it presented similar symptoms regardless of apple cultivar and cultivation period. Most previous reports have suggested that RAD may be associated with multiple factors, including plant pathogenic infections, abiotic stresses, environmental conditions, and the susceptibility of trees to cold injury during winter. However, RAD was observed to be more severe and affect more frequently apple trees on the Malling series dwarf rootstock. In this study, we reviewed the current status of RAD worldwide and surveyed biotic and abiotic factors that are potentially closely related to it in Korea.

Pectobacterium jejuense sp. nov. Isolated from Cucumber Stem Tissue.

A single Pectobacterium-like strain named 13-115T was isolated from a specimen of diseased cucumber stem tissue collected on Jeju Island, South Korea. The strain presented a rod-like shape and was negative for Gram staining. When grown on R2A medium at 25 °C, strain 13-115T formed round, convex and white colonies. This strain showed growth at temperatures ranging from 10 to 30 °C and tolerated a pH range of 6-9. The strain could also tolerate NaCl concentrations up to 5%. Analysis of the 16S rRNA gene sequence revealed that strain 13-115T exhibited similarity of over 99% with Pectobacterium brasiliense, P. carotovorum, P. polaris, and P. parvum. By conducting multilocus sequence analyses using dnaX, leuS, and recA genes, a separate phylogenetic lineage was discovered between strain 13-115T and other members of the genus Pectobacterium. Moreover, the strain showed relatively low in silico DNA-DNA hybridization (<60.6%) and average nucleotide identity (ANI) (<94.9%) values with recognized Pectobacterium species. The isolate has a genome size of 5,069,478 bp and a genomic G + C content of 52.04 mol%. Major fatty acids identified in the strain included C16:0 (28.99%), summed feature 3 (C16:1 ω7c and/or C16:1 ω6c; 28.85%), and C18:1 ω7c (19.01%). Pathogenicity assay confirmed that the novel strain induced soft rot symptoms in cucumber plants and Koch's postulates were fulfilled. Molecular analysis and phenotypic data indicated that strain 13-115T could be classified as a new species within the Pectobacterium genus, which has been named Pectobacterium jejuense. The type strain is 13-115T (= KCTC 92800T = JCM 35940T).

First report of Stagonosporopsis cucumeris causing internal fruit rot on Oriental melon (Cucumis melo L.) in Korea.

Oriental melon (Cucumis melo L.) is a popular Korean, Japanese, and Chinese fruit (Shin et al. 2017). In April 2022, abnormal fruit (n=20) that were collected in Sangju in Gyeongbuk Province (36°27'54.6"N, 128°10'49.7"E), Korea showed approximately 5% disease incidence with severity of 10-15%. Initial symptoms included shriveling, soaking, softening, dark discoloration, and sunken lesions. Internally, a rot extended to flesh, darkening from brown to black, and producing black mycelial masses. Two fungal strains (OM-rot-01 and OM-rot-02) were isolated and exhibited similar culture characteristics: aerial mycelium that was flat and pale grey to olivaceous on potato dextrose (PDA), malt extract (MEA), and oatmeal agar (OA) after seven days at 25°C and produced abundant buff-colored pycnidial ascomata on OA. Asci were bitunicate, clavate to cylindrical, 48.4 to 69.0 × 6.1 to 6.9 µm (n=10), and ascospores were biseriate, sparse, ellipsoidal, straight to slightly curved, hyaline, smooth, apex obtuse, 1-septate, 11.1 to 14.9 × 3.8 to 5.4 µm (n=20). Conidiomata were pycnidial, mostly solitary, irregular, pale brown to black, semi-immersed, 150 to 220 × 120 to 200 µm. Conidia were oblong or ovoid, smooth, thin-walled, hyaline, aseptate, 4.4 to 6.7 × 2.0 to 2.8 µm (n=35), with 1-3 guttules per conidium. The morphological characteristics corresponded to those of Stagonosporopsis cucumeris (Hou et al. 2020). For molecular identification, genomic DNA was extracted from strains (OM-rot-01 and OM-rot-02), and the ITS regions, partial 28S rDNA (LSU), beta-tubulin (TUB2), and RNA polymerase II second largest subunit (RPB2) genes were amplified and sequenced (White et al. 1990; Woudenberg et al. 2009; Vilgalys & Hester 1990; Liu et al. 1999). The obtained sequences revealed 99-100% homology with S. cucumeris accessions (MH858625, MH870265, MT005554, and MT018021). The sequences were deposited in GenBank with accession nos. for ITS regions (OP788058, OP788059), 28S rDNA (OP788094, OP788095), TUB2 (OP810568, OP810569), and RPB2 (OP810570, OP810571). Phylogenetic analysis combined with ITS, LSU, TUB2, and RPB2 concatenated sequences using neighbor-joining method revealed that the strains were S. cucumeris. To confirm pathogenicity, OM-rot-01 was inoculated onto ripe, asymptomatic Oriental melon fruit (n=6). After they were surface sterilized with 70% alcohol, fruit were wounded using a sterilized needle and corkborer, and 5-mm-diameter mycelial plugs were attached to the wound sites, followed by covering of the fruit with aluminum foil and maintenance in a plastic box (>90% relative humidity) at 25°C. Non-wounded fruit were inoculated and incubated in a similar manner, and fruit that were inoculated with PDA plugs served as controls (n=3). The aluminum foil was removed after three days of inoculation, and other conditions were kept constant. After six days, typical internal fruit rot symptoms were observed in both wounded and non-wounded fruit; brown to black rot extended into flesh, whereas control fruit remained asymptomatic. Fungi reisolated from lesions were morphologically identical to OM-rot-01; identity was confirmed by molecular analysis, fulfilling Koch's postulates, and the pathogenicity test was conducted three times. S. cucumeris was found as a canker on Cucumis sativus in the Netherlands (Hou et al. 2020), but has not been reported elsewhere as a pathogen on Cucumis spp. To our knowledge, this is the first report of S. cucumeris causing internal fruit rot on Oriental melon in Korea. This disease poses a threat to melon production, so accurate identification of the pathogen is a key starting point for development of sustainable management practices.

Neocucurbitaria chlamydospora sp. nov.: A Novel Species of the Family Cucurbitariaceae Isolated from a Stink Bug in Korea.

The fungal strain KNUF-22-18B, belonging to Cucurbitariaceae, was discovered from a stink bug (Hygia lativentris) during the investigation of insect microbiota in Chungnam Province, South Korea. The colonies of the strain KNUF-22-18B were wooly floccose, white to brown in the center on oatmeal agar (OA), and the colonies were buff, margin even, and colorless, reverse white to yellowish toward the center on malt extract agar (MEA). The strain KNUF-22-18B produced pycnidia after 60 days of culturing on potato dextrose agar, but pycnidia were not observed on OA. On the contrary, N. keratinophila CBS 121759T abundantly formed superficial pycnidia on OA and MEA after a few days. The strain KNUF-22-18B produced chlamydospores subglobose to globose, mainly in the chain, with a small diameter of 4.4-8.8 µm. At the same time, N. keratinophila CBS 121759T displayed a globose terminal with a diameter of 8-10 µm. A multilocus phylogeny using the internal transcribed spacer regions, 28S rDNA large subunit, ß-tubulin, and RNA polymerase II large subunit genes further validated the uniqueness of the strain. The detailed description and illustration of the proposed species as Neocucurbitaria chlamydospora sp. nov. from Korea was strongly supported by molecular phylogeny.

Molecular Phylogeny and Morphology of Tolypocladium globosum sp. nov. Isolated from Soil in Korea.

In this study, fungal strains designated as KNUF-22-14A and KNUF-22-15A were isolated from soil samples in Korea. These two strains were identified based on cultural and morphological characteristics as well as phylogenetic analyses and were found to be morphologically and phylogenetically identical. Upon their morphological comparison with closely related species, such as Tolypocladium album, T. amazonense, T. endophyticum, T. pustulatum, and T. tropicale, a difference in the size of short phialides [0.6-2.4(-9.3) × 0.8-1.4 µm] was observed. Meanwhile, these strains had larger conidia (1.2-3.0 × 1.2-3.0 µm) than T. album, T. amazonense, T. endophyticum, and T. tropicale and smaller conidia than T. pustulatum. Phylogenetic analyses using a multi-locus datasets based on ITS, LSU, and SSU showed that KNUF-22-14A and KNUF-22-15A formed a distinct cluster from previously identified Tolypocladium species. Thus, these fungal strains isolated from soil in Korea are proposed as a novel species according to their characteristics and are named Tolypocladium globosum sp. nov.

Morphological and Phylogenetic Analyses Reveal a New Species of Genus Monochaetia Belonging to the Family Sporocadaceae in Korea.

The fungal strain belonging to the genus Monochaetia of the family Sporocadaceae was isolated from hairy long-horned toad beetle (Moechotypa diphysis) during the screening of microfungi associated with insects from Gangwon Province, Korea. The strain KNUF-6L2F produced white, light brown to dirty black surface, and olivaceous green colonies with the higher growth, while the closest strain M. ilicis KUMCC 15-0520T were light brown to brown, and M. schimae SAUCC 212201T light brown to brown toward center. The strain KNUF-6L2F produced shorter (5.7-14.0 µm) apical appendages than M. ilicis (6.0-24.0 µm), but similar to M. schimae (7.0-12.5 µm). Three median cells of KNUF-6L2F were light brown to olivaceous green, whereas brown and olivaceous cells were observed from M. ilicis and M. schimae, respectively. And the strain KNUF-6L2F produced larger conidiogenous cells than M. ilicis and M. schimae. Additionally, phylogenetic analyses based on molecular datasets of internal transcribed spacer (ITS) regions, translation elongation factor 1-alpha (TEF1α), and ß-tubulin (TUB2) genes corroborated the strain's originality. Thus, the strain is different from other known Monochaetia species, according to molecular phylogeny and morophology, hence we suggested the new species Monochaetia mediana sp. nov. and provided a descriptive illustration.

Taxonomy of Botryotrichum luteum sp. nov. based on Morphology and Phylogeny Isolated from Soil in Korea.

In this study, a fungal strain KNUF-22-025 belonging to the genus Botryotrichum was isolated from the soil in Korea. The cultural and morphological characteristics of this strain differed from those of closely related species. On malt extract agar, strain KNUF-22-025 showed slower growth than most of the related species, except B. domesticum. The conidia size (9.6-21.1 × 9.9-18.4 µm) of strain KNUF-22-025 was larger than those of B. piluliferum, B. domesticum, and B. peruvianum but smaller than those of B. atrogriseum and B. iranicum. Conidiophores in strain KNUF-22-025 (137 µm) were longer than those in other closely related species but shorter than those in B. atrogriseum. Multi-locus analysis of molecular markers, such as ITS, 28S ribosomal DNA, RBP2, and TUB2 revealed that strain KNUF-22-025 was distinct from other Botryotrichum species. Thus, this strain is proposed as a novel species based on morphological characteristics along with molecular phylogeny and named Botryotrichum luteum sp. nov.

On-field optical imaging data for the pre-identification and estimation of leaf deformities.

Visually nonidentifiable pathological symptoms at an early stage are a major limitation in agricultural plantations. Thickness reduction in palisade parenchyma (PP) and spongy parenchyma (SP) layers is one of the most common symptoms that occur at the early stage of leaf diseases, particularly in apple and persimmon. To visualize variations in PP and SP thickness, we used optical coherence tomography (OCT)-based imaging and analyzed the acquired datasets to determine the threshold parameters for pre-identifying and estimating persimmon and apple leaf abnormalities using an intensity-based depth profiling algorithm. The algorithm identified morphological differences between healthy, apparently-healthy, and infected leaves by applying a threshold in depth profiling to classify them. The qualitative and quantitative results revealed changes and abnormalities in leaf morphology in addition to disease incubation in both apple and persimmon leaves. These can be used to examine how initial symptoms are influenced by disease growth. Thus, these datasets confirm the significance of OCT in identifying disease symptoms nondestructively and providing a benchmark dataset to the agriculture community for future reference.

Identification of entomopathogenic fungus Metarhizium rileyi infested in fall armyworm in the cornfield of Korea, and evaluation of its virulence.

The fall armyworm (FAW) Spodoptera frugiperda is an important invasive pest in Africa and Asia. It is a polyphagous pest with at least 353 recorded host plant species, including corn. Chemical control of this pest is unsuccessful because of a developed resistance and harmful effects on the environment. Entomopathogenic fungi are potential biological control agents for FAW. In this study, the native strain of Metarhizium rileyi (KNU-Ye-1), collected from a cornfield at Yeongcheon, Korea, was identified by morphological and molecular characterization. The susceptibility of the fourth-instar larvae of FAW to the native strain M. rileyi was examined in the laboratory. The results showed that the Korean strain of M. rileyi (KNU-Ye-1) was highly virulent to FAW larvae, causing 89% mortality 7 days posttreatment. Therefore, M. rileyi (KNU-Ye-1) identified in this study is highly valuable for the biological control of FAW in the field.

Isolation and Identification of Ice Nucleation Active Fusarium Strains from Rapid Apple Declined Trees in Korea.

In biological particles such as Fusarium species, ice nucleation activity (INA) has been observed. Fusarium strains isolated from apple declined trees in Korea were identified with a multilocus sequence analysis using the tef1 and rpb1 genes. Droplet-freezing and tube-freezing assays were used to determine the INA of the strains, using Pseudomonas syringae pv. syringae KACC 21200 as a positive control and resulting in seven INA+ fungal strains that were identified as F. tricinctum (KNUF- 21-F17, KNUF-21-F18, KNUF-21-F29, KNUF-21-F32, KNUF-21-F38, KNUF-21-F43, and KNUF-21-F44). The effect of Fusarium INA+ KNUF-21-F29 was compared to that of INA- strains on Chrysanthemum morifolium cv. Shinma explants. A higher callus formation and noshoot formation were observed, suggesting that fungal INA could play a role in cold injuries and be a factor to consider in rapid apple decline. To the best of our knowledge, this is the first report of INA fungal strains isolated in Korea.

Hymenobacter translucens sp. nov. and Hymenobacter pini sp. nov. isolated from soil.

Two novel bacterial strains BT175T and BT728T were isolated from soil collected in the Republic of Korea. Both strains were Gram stain negative, rod shaped, and had circular, convex, and pink-colored colonies. The 16S rRNA gene sequence similarity between the strains BT175T and BT728T was 93.6%, indicating that they represent a distinct species. 16S rRNA sequence analysis indicated that strains BT175T and BT728T belong to a distinct lineage within the genus Hymenobacter (family Hymenobacteraceae, order Cytophagales, class Cytophagia, phylum Bacteroidetes). Strain BT175T was closely related to Hymenobacter persicinus 1-3-3-3T (97.2%, 16S rRNA gene similarity), Hymenobacter knuensis 16F7C-2T (96.6%), and Hymenobacter daejeonensis PB105T (96.1%). Strain BT728T was closely related to Hymenobacter rigui KCTC 12533T (98.4%), Hymenobacter metallilatus 9PBR-2T (97.6%), and Hymenobacter perfusus LMG26000T (97.4%). Strain BT175T and BT728T were found to have the MK-7 as the major respiratory quinone. The DNA G + C content of strain BT175T was 61.6 mol% and BT728T was 59.6 mol%, respectively. Characterization based on polyphasic analysis indicated that strains BT175T and BT728T represent novel species of the genus Hymenobacter and the names Hymenobacter translucens sp. nov. and Hymenobacter pini sp. nov. are proposed. The type strain of Hymenobacter translucens is BT175T (= KCTC 72330T = NBRC 115441T) and Hymenobacter pini is BT728T (= KACC 22629T = NBRC 115444T).

Exploration of Mycobiota in Cypripedium japonicum, an Endangered Species.

Orchids live with mycorrhizal fungi in mutualism. This symbiotic relationship plays an essential role in the overall life cycle of orchids from germination, growth, settlement, and reproduction. Among the 1000 species of the orchid, the Korean lady's slipper, Cypripedium japonicum, is known as an endangered species. Currently, only five natural habitats of the Korean lady's slipper remain in South Korea, and the population of Korean lady's slipper in their natural habitat is not increasing. To prevent extinction, this study was designed to understand the fungal community interacting in the rhizosphere of the Korean lady's slipper living in the native and artificial habitats. In-depth analyses were performed to discover the vital mycorrhizal fungi contributing to habitat expansion and cultivation of the endangered orchid species. Our results suggested that Lycoperdon nigrescens contributed most to the increase in natural habitats and Russula violeipes as a characteristic of successful cultivation. And the fungi that helped L. nigrescens and R. violeipes to fit into the rhizosphere community in Korean lady's slipper native place were Paraboeremia selaginellae and Metarhizium anisopliae, respectively. The findings will contribute to restoring and maintaining the endangered orchid population in natural habitats.

Isoquercitrin isolated from newly bred Green ball apple peel in lipopolysaccharide-stimulated macrophage regulates NF-κB inflammatory pathways and cytokines.

Apple peel has several bioactive properties. The fruit is grown worldwide, and its ingredients are used medicinally. However, its anti-inflammatory activities are poorly characterized. In this study, isoquercitrin isolated from newly bred Green ball apple peel from Korea showed anti-inflammatory effects. To confirm its anti-inflammatory effects, isoquercitrin was treated with lipopolysaccharide, which induces proinflammatory factors in Raw 264.7 macrophage cells. Proinflammatory effects were measured by real-time polymerase chain reaction and Western blotting as well as enzyme-linked immunosorbent assay. Cell viability was measured using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay to define the isoquercitrin concentration nontoxic to cells. Nitric oxide (NO) production, prostaglandin E2, inducible NO synthase, cyclooxygenase-2 (COX-2), and nuclear factor-κB p65 protein expression decreased in a concentration-dependent manner by isoquercitrin. mRNA expression of tumor necrosis factor-α, interleukin (IL)-1ß, IL-6, monocyte chemoattractant protein-1, and prostaglandin E synthase 2 (PTGES2) as proinflammatory factors significantly decreased. PTGES2, which was stimulated by COX-2 and involved in PGE2 expression, was inhibited. Therefore, this study rendered isoquercitrin isolated from the newly bred Green ball apple peel as a potential pharmacological alternative to treat inflammation-related diseases.

Larkinella humicola sp. nov., a gamma radiation-resistant bacterium isolated from soil.

A Gram-negative, short rod-shaped, and pink-pigmented bacterial strain, designated MA1T, was isolated from a soil sample from Gijang-gun, Busan in Republic of Korea. The 16S rRNA gene sequence analysis showed that strain MA1T belonged to the genus Larkinella and was closely related to "Larkinella punicea" (97.5% similarity), Larkinella rosea 15J16-1T3AT (96.5%), and Larkinella knui 15J6-3T6T (96.2%). Polar lipid profile of strain MA1T contained phosphatidylethanolamine, two unidentified aminolipids, and three unidentified lipids. Menaquinone-7 was the only quinone and the main fatty acids were C16:1 ω5c (36.7%), iso-C15:0 (30.0%), iso-C17:0 3-OH (7.7%), and summed feature 3 (C16:1 ω6c and/or C16:1 ω7c and/or iso-C15:0 2-OH) (7.3%). The genomic DNA G + C content was 52.3 mol% based on the whole-genome analysis. Strain MA1T exhibited a relatively low level of ANI and in silico DDH values with "Larkinella punicea" (91.9 and 47.1%, respectively), Larkinella rosea (79.7 and 23.3%), and Larkinella knui (81.9 and 25.7%). Based on its phenotypic properties and phylogenetic distinctiveness, strain MA1T should be classified in the genus Larkinella as a representative of a novel species, for which the name Larkinella humicola sp. nov. is proposed. The type strain is MA1T (= KCTC 72629T = NBRC 114191T).

Collagen Peptide in a Combinatorial Treatment with Lactobacillus rhamnosus Inhibits the Cariogenic Properties of Streptococcus mutans: An In Vitro Study.

Dental caries is caused by the formation of cariogenic biofilm, leading to localized areas of enamel demineralization. Streptococcus mutans, a cariogenic pathogen, has long been considered as a microbial etiology of dental caries. We hypothesized that an antagonistic approach using a prebiotic collagen peptide in combination with probiotic Lactobacillus rhamnosus would modulate the virulence of this cariogenic biofilm. In vitro S. mutans biofilms were formed on saliva-coated hydroxyapatite discs, and the inhibitory effect of a combination of L. rhamnosus and collagen peptide on S. mutans biofilms were evaluated using microbiological, biochemical, confocal imaging, and transcriptomic analyses. The combination of L. rhamnosus with collagen peptide altered acid production by S. mutans, significantly increasing culture pH at an early stage of biofilm formation. Moreover, the 3D architecture of the S. mutans biofilm was greatly compromised when it was in the presence of L. rhamnosus with collagen peptide, resulting in a significant reduction in exopolysaccharide with unstructured and mixed bacterial organization. The presence of L. rhamnosus with collagen peptide modulated the virulence potential of S. mutans via down-regulation of eno, ldh, and atpD corresponding to acid production and proton transportation, whereas aguD associated with alkali production was up-regulated. Gly-Pro-Hyp, a common tripeptide unit of collagen, consistently modulated the cariogenic potential of S. mutans by inhibiting acid production, similar to the bioactivity of a collagen peptide. It also enhanced the relative abundance of commensal streptococci (S. oralis) in a mixed-species biofilm by inhibiting S. mutans colonization and dome-like microcolony formation. This work demonstrates that food-derived synbiotics may offer a useful means of disrupting cariogenic communities and maintaining microbial homeostasis.

Pedobacter segetis sp. nov., a Novel Bacterium Isolated from Soil.

A Gram-negative, motile by gliding, rod-shaped, aerobic bacterium, designated SD-bT, was isolated from a soil sample collected on Dokdo Island, South Korea. A polyphasic approach based on phenotypic, phylogenetic, and genomic analyses was used to characterize the new isolate. Phylogenetic analysis of 16S rRNA gene sequence showed that strain SD-bT belonged to the family Sphingobacteriaceae and most closely related to Pedobacter psychrophilus P4487AT (95.9% similarity). The isolate contained MK-7 as the predominant respiratory quinone; its main polar lipid was phosphatidylethanolamine; and the major fatty acids were summed feature 3 (C16:1 ω7c/C16:1 ω6c; 32.0%), C15:0 iso (19.1%), C17:0 iso 3-OH (8.3%), and C16:0 (8.2%). The draft genome had a length of 3,842,102 bp with a G+C content of 36.0 mol%, predicting 3282 coding sequences, 3 rRNA genes, 3 ncRNAs, and 36 tRNAs genes. The digital DNA-DNA hybridization and average nucleotide identity values between strain SD-bT and P. psychrophilus LMG 29436T were 22.0% and 78.9%, respectively. The results of phenotypic properties, genotypic distinctiveness, and chemotaxonomic features support the discrimination of SD-bT from its phylogenetic relatives. Pedobacter segetis sp. nov. is therefore proposed with SD-bT (= KCTC 82351T = JCM 34283T) as the type strain.

Molecular and Morphological Characteristics of a New Species Collected from an Insect (Cicindela transbaicalica) in Korea.

To exploit insect-derived fungi, insects were collected from seven different regions in Korea, including Gyeongbuk, Goryeong, and several fungi were isolated from them. A fungal strain designated 21-64-D was isolated from riparian tiger beetle (Cicindela transbaicalica) and morphologically identified as a species belonging to the genus Oidiodendron. Phylogenetic analysis using the nucleotide sequences of internal transcribed spacer (ITS) regions and the partial sequence of the large subunit of the nuclear ribosomal RNA (LSU) gene revealed the distinct phylogenetic position of the isolate among recognized Oidiodendron species including its closest neighbors O. chlamydosporicum, O. citrinum, O. maius, and O. pilicola. The hyphal and conidial morphology of the strain, particularly club-shaped hyphae, clearly differentiated it from its close relatives. Results indicated that 21-64-D is a novel species in the genus Oidiodendron, for which the name Oidiodendron clavatum sp. nov. is proposed.

Molecular and Morphological Characterization of Two Novel Species from Soil and Beetles (Dorcus titanus castanicolor) in Korea.

Two fungal strains belonging to Ascomycota were discovered in Gyeonggi-do, Korea, during this investigation of soil microfungi and microbiota of insects. The strain KNUF-20-047 produced milky white on the back and a milky creamy center to white toward the margin on the front side of colonies. Conversely, the closest Xenoacremonium falcatus displayed a pale luteous to luteous center, white toward margins on the front side, and pale luteous or luteous pigment on the back side, whereas X. recifei produced white colonies. The conidiophores of KNUF-20-047 were slightly larger than those of X. falcatus, and the conidia were distinct from X. recifei. Strain KNUF-20-NI-005 produced light brown to subhyaline conidiophores up to 56.0 µm tall, whereas Rhinocladiella anceps displayed golden to dark brown conidiophores up to 350 µm. Strain KNUF-20-NI-005 also produced larger conidia than R. anceps but smaller than R. coryli and R. fasciculata. Moreover, the molecular phylogeny strongly supports the detailed description and illustration of each proposed species to be designated as Xenoacremonium minutisporum sp. nov. and Rhinocladiella terrigenum sp. nov. in Korea.