Veillonella faecalis sp. nov., a propionic acid-producing bacterium isolated from the faeces of an infant.

A strictly anaerobic, Gram-stain-negative, catalase-negative, cocci-shaped, and propionate-producing bacterial strain, named Ds1651T was isolated from the fecal sample collected from a South Korean infant. Through a comparison of 16S rRNA gene sequences, it was revealed that Ds1651T had the highest phylogenetic affinity with Veillonella nakazawae KCTC 25297 T (99.86%), followed by Veillonella infantium KCTC 25370 T (99.80%), and Veillonella dispar KCTC 25309 T (99.73%) in the family Veillonellaceae. Average nucleotide identity values between Ds1651T and three reference species were 95.48% for Veillonella nakazawae KCTC 25297 T, 94.46% for Veillonella infantium KCTC 25370 T, and 92.81% for Veillonella dispar KCTC 25309 T. The G + C content of Ds1651T was 38.58 mol%. Major fermentation end-products were acetic and propionic acids in Trypticase peptone glucose yeast extract broth with 1% (v/v) sodium lactate. The predominant cellular fatty acids that account for more than 10% were summed in Feature 8 (C17:1 ω8c and/or C17:2) and C13:0. Based on the findings from phylogenetic, genomic, phenotypic, and chemotaxonomic studies, we propose that the type strain Ds1651T (= KCTC 25477 T = GDMCC 1.3707 T) represents a novel bacterial species within the genus Veillonella, with the proposed name Veillonella faecalis sp. nov.

Sphingomonas cremea sp. nov., isolated from ginseng soil.

A novel Gram-stain-negative, aerobic, rod-shaped, non-motile, cream-coloured strain (G124T) was isolated from ginseng soil collected in Yeongju, Republic of Korea. Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain G124T belongs to a distinct lineage within the genus Sphingomonas (family Sphingomonadaceae, order Sphingomonadales and class Alphaproteobacteria). Strain G124T was closely related to Sphingomonas rhizophila THG-T61T (98.5 % 16S rRNA gene sequence similarity), Sphingomonas mesophila SYSUP0001T (98.3 %), Sphingomonas edaphi DAC4T (97.6 %) and Sphingomonas jaspsi TDMA-16T (97.6 %). The strain contained ubiquinone 10 as the major respiratory quinone. The major polar lipid profile of strain G124T comprised phosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and sphingoglycolipids. The predominant cellular fatty acids of strain G124T were summed feature 8 (C18 : 1 ω7c/C18 : 1 ω6c; 33.4 %), summed feature 3 (C16 : 1 ω6c/C16 : 1 ω7c; 27.2 %) and C16 : 0 (18.3 %). The genome size of strain G124T was 2 549 305 bp. The genomic DNA G+C content is 62.0 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain G124T and other Sphingomonas species were in the range of 71.2-75.9 % and 18.7-19.9 %, respectively. Based on the polyphasic analysis such as biochemical, phylogenetic and chemotaxonomic characteristics, strain G124T represents a novel species of the genus Sphingomonas, for which the name Sphingomonas cremea sp. nov. is proposed. The type strain is G124T (=KACC 21691T=LMG 31729T).

Parabacteroides faecalis sp. nov. Isolated from Swine Faeces.

A Gram-negative, obligate anaerobic, non-motile, non-spore-forming, rod-shaped bacterial strain designated AGMB00274T was isolated from swine faeces. An 16S rRNA gene analysis indicated that strain AGMB00274T belonged to the genus Parabacteroides, with the highest similarity to Parabacteroides johnsonii (P. johnsonii) DSM 18315T (sequence similarity of 94.9%). The genome size of strain AGMB00274T was 4,308,683 bp, with a DNA G+C content of 42.5 mol%. The biochemical analysis of strain AGMB00274T showed that it was positive for gelatin hydrolysis and α-fucosidase, but negative for the acid production from D-glucose, D-mannitol, D-maltose, salicin, glycerol, D-cellobiose, D-mannose, D-melezitose, D-sorbitol, D-trehalose, and negative for α-arabinosidase, glutamic acid decarboxylase, and pyroglutamic acid arylamidase. The dominant cellular fatty acids (> 10%) of the isolate were anteiso-C15: 0 (23.2%), iso-C15: 0 (16.6%), C18: 1 ω9c (16.4%), summed feature 11 (iso-C17: 0 3-OH and/or C18: 2 DMA) (12.5%), and C16: 0 (11.3%). The major respiratory quinones of strain AGMB00274T were MK-9 (55.4%) and MK-10 (44.6%). The major polar lipid was phosphatidylethanolamine. Based on phylogenetic, genetic, physiological, and chemotaxonomic analyses, as a novel species of the genus Parabacteroides, strain AGMB00274T was proposed with the name Parabacteroides faecalis sp. nov. The type strain used was AGMB00274T (= KCTC 25286T = GDMCC 1.2742T).

Chryseobacterium panacisoli sp. nov., isolated from ginseng-cultivation soil with ginsenoside-converting activity.

A Gram-stain-negative, non-motile, non-spore-forming, aerobic, rod-shaped and yellow-pigmented bacterium, designated strain Gsoil 183T, was isolated from ginseng-cultivation soil sampled in Pocheon Province, Republic of Korea. This bacterium was characterized to determine its taxonomic position by using a polyphasic approach. Strain Gsoil 183T grew at 10-37 °C and at pH 5.0-9.0 on tryptic soy agar. Strain Gsoil 183T had ß-glucosidase activity, which was responsible for its ability to convert ginsenoside Rb1 (one of the dominant active components of ginseng) to F2. Based on 16S rRNA gene sequencing, strain Gsoil 183T clustered with species of the genus Chryseobacterium and appeared to be closely related to Chryseobacterium sediminis LMG 28695T (99.1 % sequence similarity), Chryseobacterium lactis NCTC 11390T (98.6%), Chryseobacterium rhizoplanae LMG 28481T (98.6%), Chryseobacterium oncorhynchi CCUG 60105T (98.5%), Chryseobacterium viscerum CCUG 60103T (98.4%) and Chryseobacterium joostei DSM 16927T (98.3%). Menaquinone MK-6 was the predominant respiratory quinone and the major fatty acids were iso-C15 : 0, iso-C17 : 0-3OH and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c). The polar lipids were phosphatidylethanolamine, six unidentified glycolipids, five unidentified aminolipids and three unidentified lipids. The G+C content of the genomic DNA was 36.6 mol%. Digital DNA-DNA hybridization between strain Gsoil 183T and the type strains of C. sediminis, C. lactis, C. rhizoplanae, C. oncorhynchi, C. viscerum and C. joostei resulted in values below 70 %. Strain Gsoil 183T could be differentiated genotypically and phenotypically from the recognized species of the genus Chryseobacterium. The isolate therefore represents a novel species, for which the name Chryseobacterium panacisoli sp. nov. is proposed, with the type strain Gsoil 183T (=KACC 15033T=LMG 23397T).

Ochrobactrum soli sp. nov., Isolated from a Korean Cattle Farm.

A Gram stain negative, motile, non-spore-forming, rod-shaped, strictly aerobic, beige-pigmented bacterium, designated strain BO-7T, was isolated from soil of cattle farm, in Seosan, Republic of Korea. On the basis of 16S rRNA gene sequencing, strain BO-7T clustered with species of the genus Ochrobactrum and appeared closely related to O. haematophilum CCUG 38531T (98.9%), O. daejeonense KCTC 22458T (98.1%), O. rhizosphaerae DSM 19824T (98.1%), O. pituitosum DSM 22207T (98.0%), and O. pecoris DSM 23868T (98.0%). The digital DNA-DNA hybridization and average nucleotide identity between strain BO-7T and the closely related strains were 21.9-39.1%, 78.5-89.5%, respectively, indicating that BO-7T is a novel species of the genus Ochrobactrum. The DNA G + C content of the genomic DNA was 57.1 mol%, and ubiquinone Q-10 was the predominant respiratory quinone. The polar lipids consisted of phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, phosphatidylmonomethyl-ethanolamine, di-phosphatidylglycerol, the major polyamines were spermidine, putrescine, and sym-homospermidine. The major cellular fatty acids (> 5%) were C16:0, C19:0 cycle ω7c, and C18:1ω7c and/or C18:1ω6c (summed feature 8). ANI calculation, digital DNA-DNA hybridization, physiological and biochemical characteristics indicated that strain BO-7T represents a novel species of the genus Ochrobactrum, for which the name Ochrobactrum soli sp. nov. is proposed. The type strain is BO-7T (= KACC 19676T = LMG 30809T).

Species-Specific Interactions between Plant Metabolites and Insect Juvenile Hormone Receptors.

Because juvenile hormone (JH) controls insect development and its analogs are used as insecticides, juvenile hormone disruptors (JHDs) represent potential sources from which novel pesticides can be developed. Many plant species harbor JHD activity, which has previously been attributed plant secondary metabolites (i.e., diterpenes) that disrupt insect development by interfering with the JH-mediated heterodimer formation of insect juvenile receptor complexes. The results of the present study indicate that plant JHD activity is also concentrated in certain plant groups and families and that plant metabolites have insect group-specific activity. These findings suggest that reciprocal diversification has occurred between plants and insects through the evolution of the plant metabolites and JH receptors, respectively, and that plant metabolites could be developed into insect group-specific pesticides with limited effects on non-target species.

Conifer Diterpene Resin Acids Disrupt Juvenile Hormone-Mediated Endocrine Regulation in the Indian Meal Moth Plodia interpunctella.

Diterpene resin acids (DRAs) are important components of oleoresin and greatly contribute to the defense strategies of conifers against herbivorous insects. In the present study, we determined that DRAs function as insect juvenile hormone (JH) antagonists that interfere with the juvenile hormone-mediated binding of the JH receptor Methoprene-tolerant (Met) and steroid receptor coactivator (SRC). Using a yeast two-hybrid system transformed with Met and SRC from the Indian meal moth Plodia interpunctella, we tested the interfering activity of 3704 plant extracts against JH III-mediated Met-SRC binding. Plant extracts from conifers, especially members of the Pinaceae, exhibited strong interfering activity, and four active interfering DRAs (7α-dehydroabietic acid, 7-oxodehydroabietic acid, dehydroabietic acid, and sandaracopimaric acid) were isolated from roots of the Japanese pine Pinus densiflora. The four isolated DRAs, along with abietic acid, disrupted the juvenile hormone-mediated binding of P. interpunctella Met and SRC, although only 7-oxodehydroabietic acid disrupted larval development. These results demonstrate that DRAs may play a defensive role against herbivorous insects via insect endocrine-disrupting activity.

Comparison of Plasmid Curing Efficiency across Five Lactic Acid Bacterial Species.

With the recent stringent criteria for antibiotic susceptibility in probiotics, the presence of antibiotic resistance genes and plasmids associated with their transfer has become a limiting factor in the approval of probiotics. The need to remove genes related to antibiotic resistance and virulence through plasmid curing for the authorization of probiotics is increasing. In this study, we investigated the curing efficiency of ethidium bromide, acridine orange, and novobiocin at different concentrations and durations in five strains of plasmid-bearing lactic acid bacteria and examined the curing characteristics in each strain. Limosibacillus reuteri and Lacticaseibacillus paracasei exhibited curing efficiencies ranging from 5% to 44% following treatment with ethidium bromide (10-50 µg/ml) for 24-72 h, while Lactobacillus gasseri showed the highest efficiency at 14% following treatment with 10 µg/ml novobiocin for 24 h. Lactiplantibacillus plantarum, which harbors two or more plasmids, demonstrated curing efficiencies ranging from 1% to 8% after an additional 72-h treatment of partially cured strains with 10 µg/ml novobiocin. Plasmid curing in strains with larger plasmids exhibited lower efficiencies and required longer durations. In strains harboring two or more plasmids, a relatively low curing efficiency with a single treatment and a high frequency of false positives, wherein recovery occurred after curing, were observed. Although certain strains exhibited altered susceptibilities to specific antibiotics after curing, these outcomes could not be attributed to the loss of antibiotic resistance genes. Furthermore, the genomic data from the cured strains revealed minimal changes throughout the genome that did not lead to gene mutations.

Limosilactobacillus reuteri DS0384 promotes intestinal epithelial maturation via the postbiotic effect in human intestinal organoids and infant mice.

Little is known about the modulatory capacity of the microbiota in early intestinal development. We examined various intestinal models that respond to gut microbial metabolites based on human pluripotent stem cell-derived human intestinal organoids (hIOs): physiologically relevant in vitro fetal-like intestine, intestinal stem cell, and intestinal disease models. We found that a newly isolated Limosilactobacillus reuteri strain DS0384 accelerated maturation of the fetal intestine using 3D hIO with immature fetal characteristics. Comparative metabolomic profiling analysis revealed that the secreted metabolite N-carbamyl glutamic acid (NCG) is involved in the beneficial effect of DS0384 cell-free supernatants on the intestinal maturation of hIOs. Experiments in an intestinal stem cell spheroid model and hIO-based intestinal inflamed model revealed that the cell-free supernatant from DS0384 comprising NCG promoted intestinal stem cell proliferation and was important for intestinal protection against cytokine-induced intestinal epithelial injury. The probiotic properties of DS0384 were also evaluated, including acid and bile tolerance and ability to adhere to human intestinal cells. Seven-day oral administration of DS0384 and cell-free supernatant promoted the intestinal development of newborn mice. Moreover, NCG exerted a protective effect on experimental colitis in mice. These results suggest that DS0384 is a useful agent for probiotic applications and therapeutic treatment for disorders of early gut development and for preventing intestinal barrier dysfunction.