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Author: search.filters.author.Chamroensaksri, NitchaStart date: 2022

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    Genomic Characterization and Hydrolysis Enzyme of Piscibacillus salipiscarius RBU1-1ᵀ and Allobacillus salarius SKP4-8ᵀ Isolated from Fermented Fish Products
    (2026-01-01)
    Namwong, Sirilak
    ;
    Chaimongkol, Apichai
    ;
    Kingkaew, Engkarat
    ;
    Phongsopitanun, Wongsakorn
    ;
    Chamroensaksri, Nitcha
    Two halophilic bacterial strains, Piscibacillus salipiscarius RBU1-1ᵀ and Allobacillus salarius SKP4-8ᵀ, were isolated from traditional Thai fermented foods, namely pla-ra from Ratchaburi, Thailand, and ka-pi from Samut Sakhon, Thailand, respectively. Comparative genomics confirmed their taxonomic distinctiveness, with RBU1-1ᵀ representing a novel species and SKP4-8ᵀ showing clear genomic separation from its closest relatives. The draft genomes were 2.99 Mb (36.7 mol% G+C) for RBU1-1ᵀ and 2.59 Mb (38.8 mol% G+C) for SKP4-8ᵀ. Both strains encoded hydrolytic enzymes and secondary metabolite pathways, with SKP4-8ᵀ displaying higher protease activity and RBU1-1ᵀ harboring ectoine biosynthetic and stress-response genes. RBU1-1ᵀ encoded the biosynthesis pathways for ectoine, tryptophan, and thiamine, while SKP4-8ᵀ encoded thiamine, riboflavin, coenzyme A, and menaquinone, indicating their potential contributions to postbiotic and nutritional value. Safety assessment revealed the absence of biogenic amine, antibiotic biosynthesis, and major virulence genes in both strains. Although antimicrobial resistance-associated genes were detected, no complete clusters were identified, suggesting low phenotypic risk. Computational pathogenicity prediction indicated a low probability for RBU1-1ᵀ (0.242) and a higher probability for SKP4-8ᵀ (0.945), though these require cautious interpretation. Overall, genomic evidence and enzymatic activity support RBU1-1ᵀ and SKP4-8ᵀ as safe, functional starter culture candidates, with RBU1-1ᵀ showing strong potential through postbiotic biosynthesis and SKP4-8ᵀ through proteolytic activity.
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    Lentilactobacillus terminaliae sp. nov., isolated from tree bark (Terminalia ivorensis Chev.) and its antioxidant activity
    (2025-01-01)
    Phuengjayaem, Sukanya
    ;
    Kingkaew, Engkarat
    ;
    Chamroensaksri, Nitcha
    ;
    Phongsopitanun, Wongsakorn
    ;
    Tanasupawat, Somboon
    A Gram-stain-positive, facultatively anaerobic, rod-shaped strain, designated SPB1-3<sup>T</sup>, was isolated from tree bark. This strain exhibited heterofermentative production of dl-lactic acid from glucose. Optimal growth was observed at 25–40 °C, pH 4.0–7.0, and in the presence of 3% (w/v) NaCl. The cell wall peptidoglycan contained lysine and aspartic acid. The predominant fatty acids identified were C<inf>16:0</inf> and the Summed feature 7 (C<inf>19:1</inf> ω7c/C<inf>19:1</inf> ω6c and/or C<inf>19:1</inf> ω6c/ω7c/19cy). The polar lipid profile included phosphatidylglycerol, diphosphatidylglycerol and phosphatidylinositol, along with two unidentified phospholipids, two unidentified amino lipids and two unidentified lipids. Phylogenetic analysis based on 16S rRNA gene sequences positioned strain SPB1-3<sup>T</sup> within the genus Lentilactobacillus, showing a close relation to Lentilactobacillus kosonis NBRC 111893<sup>T</sup> (99.86%) and Lentilactobacillus curieae CCTCC M 2011381<sup>T</sup> (98.65%). The whole genome of strain SPB1-3<sup>T</sup> comprised 1 932 998 base pairs with 1955 coding genes and a DNA G+C content of 37.8%. Digital DNA–DNA hybridization between strain SPB1-3<sup>T</sup> and closely related type strains ranged from 19.50 to 27.20%. The average nucleotide identity ranged from 84.21 to 85.56%, and the average amino acid identity ranged from 57.25 to 85.99%, both falling below the established thresholds for species delineation. Strain SPB1-3<sup>T</sup> was clearly distinguishable from related Lentilactobacillus species based on its phenotypic and chemotaxonomic char-acteristics, 16S rRNA gene sequence similarity and whole genome analysis. Additionally, the strain exhibited radical scavenging activity at 66.92% and demonstrated 82.32% inhibition in the tyrosinase inhibitory assay. These findings support the classification of strain SPB1-3<sup>T</sup> as a novel species within the genus Lentilactobacillus, for which the name Lentilactobacillus terminaliae sp. nov. is proposed. The type strain is SPB1-3<sup>T</sup> (=JCM 35081<sup>T</sup>=TISTR 10005<sup>T</sup>).
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    Glycomyces amatae sp. nov., isolated from a yellow-ringed grass moth (Amata sperbius)
    (2022-01-01)
    Suriyachadkun, Chanwit
    ;
    Ngaemthao, Wipaporn
    ;
    Pujchakarn, Tawanmol
    ;
    Chamroensaksri, Nitcha
    ;
    Niemhom, Nantawan
    A novel mycelium-forming actinomycete strain, designated A-F 0318<sup>T</sup>, was isolated from a yellow-ringed grass moth (Amata sperbius) collected from Phitsanulok Province, Thailand. Long chains of non-motile cylindrical spores with a smooth surface developed on aerial mycelia. The polyphasic taxonomic study suggested that strain A-F 0318<sup>T</sup> belonged to the genus Glyco-myces. The 16S rRNA gene sequence analysis indicated that strain A-F 0318<sup>T</sup> was closely related to Glycomyces harbinensis LL-DO5139<sup>T</sup> with 97.94 % sequence similarity. The average nucleotide identity (ANI) based on blast, ANI based on the MUMmer algorithm and average amino acid identity values of strain A-F 0318<sup>T</sup> with G. harbinensis LL-DO5139<sup>T</sup> were 86.9, 89.1 and 84.24 %, respectively. The digital DNA–DNA hybridization value between A-F 0318<sup>T</sup> and its closest relative, G. harbinensis LL-DO5139<sup>T</sup> was 33.8 %. The digital G+C content of the genomic DNA was 71.7 mol%. The cell-wall peptidoglycan contained meso-diaminopimelic acid. The whole-cell sugars contained ribose, xylose, glucose and galactose. The predominant menaquinone was MK-10(H<inf>4</inf> ). The predominant fatty acids were iso-C<inf>16: 0</inf>, anteiso-C<inf>15: 0</inf>, anteiso-C<inf>17: 0</inf> and iso-C<inf>16: 1</inf> G. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, two unknown phosphoglycolipids and one unknown phospholipid. Based on comparative analysis of genotypic, phenotypic and chemotaxo-nomic data, the novel actinomycete strain A-F 0318<sup>T</sup> (=TBRC 13612<sup>T</sup>=NBRC 115417<sup>T</sup>) represents the type strain of a novel species, for which the name Glycomyces amatae sp. nov. is proposed.