Draft genome sequence of an ubiquinone-10 producing Methylobacterium durans LRY1-08 isolated from lichen in Thailand

A ubiquitous and pink-pigmented facultatively methylotrophic bacterium, designated LRY1-08 (=JCM 33120), was isolated from a lichen in Thailand. Strain LRY1-08 and Methylobacterium durans NBRC 112876T shared 99.92 % similarity based on the 16S rRNA gene sequence. The draft genome of LRY1-08 was 5.26 Mbp with 4,952 protein-coding sequences and an average G + C content of 70.0 mol%. Comparing strain LRY1-08 to M. durans NBRC 112876T, the ANIb, ANIm, AAI, and digital DNA-DNA hybridization values were 96.29 %, 97.10 %, 96.7 %, and 82.29 %, respectively. Based on the phenotypic characteristics and genome analysis, it was identified as M. durans. Its genomic sequence data revealed the PHB and CoQ10 biosynthesis genes. Therefore, the results offer suggestions for further investigation into possible applications of this bacterium in biotechnology. The draft genome was deposited at DDBJ/EMBL/GenBank (DNA Databank of Japan/European Molecular Biology Laboratory/Genbank) (JAYEEX000000000).

Pradimicin U, a promising antimicrobial agent isolated from a newly found Nonomuraea composti sp. nov

Pradimicin U is a new dihydrobenzo[a]naphthacenequinone compound found to be active on a screen designed to investigate compounds with antimicrobial activity, produced by the actinomycete designated strain FMUSA5-5T. The strain was isolated from a bio-fertilizer of Musa spp. collected from Suphanburi province, Thailand. The chemotaxonomic characteristics and 16S rRNA gene analysis revealed that strain FMUSA5-5T is a member of the genus Nonomuraea. Low genome-based taxonomic criteria, average nucleotide identity (ANI) (82.8-88.3%), average amino-acid identity (AAI) (79.4-87.3%), and digital DNA-DNA hybridization (dDDH) (29.5-38.5%) values and several phenotypic differences between strain FMUSA5-5T and its closest type strains of the genus Nonomuraea indicated that strain FMUSA5-5T represents a novel species of the genus Nonomuraea and the name Nonomuraea composti sp. nov. is proposed for the strain. The crude extract from the culture broth of strain FMUSA5-5T displayed promising antimicrobial activity against several pathogens and led to the isolation of a novel secondary metabolite, pradimicin U. Interestingly, this compound displayed a broad spectrum of biological activities such as antimalarial activity against Plasmodium falciparum K1 (IC50 value = 3.65 µg/mL), anti-Mycobacterium tuberculosis H37Ra (MIC value = 25.0 µg/mL), anti-Alternaria brassicicola BCC 42724 (MIC value = 25.0 µg/mL), anti-Bacillus cereus ATCC 11778 and anti-Staphylococcus aureus ATCC 29213 (MIC values = 6.25 and 1.56 µg/mL, respectively). Moreover, the compound possessed strong anti-human small cell lung cancer (NCI-H187) activity with IC50 value of 5.69 µg/mL, while cytotoxicity against human breast cancer (MCF-7) and Vero cells was very weak (IC50 values of 52.49 and 21.84 µg/mL, respectively).

Association between organic nitrogen substrates and the optical purity of D-lactic acid during the fermentation by Sporolactobacillus terrae SBT-1

The development of biotechnological lactic acid production has attracted attention to the potential production of an optically pure isomer of lactic acid, although the relationship between fermentation and the biosynthesis of highly optically pure D-lactic acid remains poorly understood. Sporolactobacillus terrae SBT-1 is an excellent D-lactic acid producer that depends on cultivation conditions. Herein, three enzymes responsible for synthesizing optically pure D-lactic acid, including D-lactate dehydrogenase (D-LDH; encoded by ldhDs), L-lactate dehydrogenase (L-LDH; encoded by ldhLs), and lactate racemase (Lar; encoded by larA), were quantified under different organic nitrogen sources and concentration to study the relationship between fermentation conditions and synthesis pathway of optically pure lactic acid. Different organic nitrogen sources and concentrations significantly affected the quantity and quality of D-lactic acid produced by strain SBT-1 as well as the synthetic optically pure lactic acid pathway. Yeast extract is a preferred organic nitrogen source for achieving high catalytic efficiency of D-lactate dehydrogenase and increasing the transcription level of ldhA2, indicating that this enzyme plays a major role in D-lactic acid formation in S. terrae SBT-1. Furthermore, lactate racemization activity could be regulated by the presence of D-lactic acid. The results of this study suggest that specific nutrient requirements are necessary to achieve a stable and highly productive fermentation process for the D-lactic acid of an individual strain.

Streptomyces pyxinae sp. nov. and Streptomyces pyxinicus sp. nov. isolated from lichen Pyxine cocoes (Sw.) Nyl

Two novel actinobacteria, designated as LP05-1T and LP11T, were isolated from the lichen Pyxine cocoes (Sw.) Nyl. collected in Bangkok, Thailand. Genotypic and phenotypic analyses revealed that both strains represented members of the genus Streptomyces. The 16S rRNA gene of LP05-1T showed the highest similarity to the genome of Streptomyces gelaticus (98.41 %), while the 16S rRNA gene of LP11T was most similar to that of Streptomyces cinerochromogenes (98.93 %). The major menaquinones in LP05-1T were MK-9(H8), MK-9(H6), MK-9(H4) and MK-9(H2), and in LP11T, they were MK-9(H8) and MK-9(H6). Both strains exhibited the major fatty acids iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0, with LP05-1T also possessing iso-C17 : 0. The polar lipids of LP05-1T included phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside and an unidentified lipid, while those of LP11T consisted of phosphatidylethanolamine, lyso-phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, an unidentified aminolipid and an unidentified glycolipid. The digital DNA-DNA hybridisation (dDDH) and average nucleotide identity (ANI) values indicated that both strains are distinct from each other with values below 70 and 95 %, respectively. dDDH, ANI by blast (ANIb) and ANI by MUMmer (ANIm) values between LP05-1T and its closely related type strains were 26.07-26.80 %, 81.24-82.01 % and 86.82-86.96 %, respectively, while those for LP11T and its closely related type strains were 30.70-31.70 %, 84.09-85.31 % and 88.02-88.39 %, respectively. The results of the taxonomic investigation, including dDDH and ANI values, indicate that LP05-1T and LP11T are novel type strains of two novel species within the genus Streptomyces. The names proposed are Streptomyces pyxinae sp. nov. for strain LP05-1T (=TBRC 15494T, =NBRC 115434T) and Streptomyces pyxinicus sp. nov. for strain LP11T (=TBRC 15493T, =NBRC 115421T).

Actinomycetospora termitidis sp. nov., an insect-derived actinomycete isolated from termite (Odontotermes formosanus)

Strain Odt1-22T, an insect-derived actinomycete was isolated from a termite (Odontotermes formosanus) that was collected from Chanthaburi province, Thailand. Strain Odt1-22T was aerobic, Gram-stain-positive, and produced bud-like spore chain on the substrate hypha. According to chemotaxonomic analysis, strain Odt1-22T contained meso-diaminopimelic acid in peptidoglycan and the whole-cell hydrolysates contained arabinose, galactose, glucose, and ribose. The major menaquinone was MK-8(H4). The diagnostic phospholipids were diphosphatidylglycerol, hydroxyphosphatidylethanolamine, phosphatidylethanolamine and phosphatidylglycerol. Phylogenetic analysis based on 16 S rRNA gene sequence revealed that strain Odt1-22T was identified to the genus Actinomycetospora and showed high similarity values with A. chiangmaiensis DSM 45062 T (99.24%), A. soli SF1T (99.24%) and A. corticicola 014-5 T (98.17%). The genomic size of strain Odt1-22T was 6.6 Mbp with 73.8% G + C content and 6355 coding sequences (CDSs). The genomic analysis, strain Odt1-22T and closely related species A. chiangmaiensis DSM 45062 T, A. soli SF1T and A. corticicola DSM 45772 T displayed the values of average nucleotide identity-blast (ANIb) at 83.7-84.1% and MUMmer (ANIm) at 86.6-87.0%. Moreover, the results of digital DNA-DNA hybridization values between strain Odt1-22T and related Actinomycetospora species were 45.8-50.5% that lower than the threshold value of commonly used to delineate separated species level. On the basis of phenotypic, chemotaxonomic, and genotypic data, strain Odt1-22T represented a novel species within the genus Actinomycetospora, for which the name Actinomycetospora termitidis sp. nov. is proposed. The type strain of the species is Odt1-22T (= TBRC 16192 T = NBRC 115965 T).

Comparative genomics reveals insight into the phylogeny and habitat adaptation of novel Amycolatopsis species, an endophytic actinomycete associated with scab lesions on potato tubers

A novel endophytic actinomycete, strain MEP2-6T, was isolated from scab tissues of potato tubers collected from Mae Fag Mai Sub-district, San Sai District, Chiang Mai Province, Thailand. Strain MEP2-6T is a gram-positive filamentous bacteria characterized by meso-diaminopimelic acid in cell wall peptidoglycan and arabinose, galactose, glucose, and ribose in whole-cell hydrolysates. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and hydroxy-phosphatidylethanolamine were the major phospholipids, of which MK-9(H6) was the predominant menaquinone, whereas iso-C16:0 and iso-C15:0 were the major cellular fatty acids. The genome of the strain was 10,277,369 bp in size with a G + C content of 71.7%. The 16S rRNA gene phylogenetic and core phylogenomic analyses revealed that strain MEP2-6T was closely related to Amycolatopsis lexingtonensis NRRL B-24131T (99.4%), A. pretoriensis DSM 44654T (99.3%), and A. eburnea GLM-1T (98.9%). Notably, strain MEP2-6T displayed 91.7%, 91.8%, and 87% ANIb and 49%, 48.8%, and 35.4% dDDH to A. lexingtonensis DSM 44653T (=NRRL B-24131T), A. eburnea GLM-1T, and A. pretoriensis DSM 44654T, respectively. Based on phenotypic, chemotaxonomic, and genomic data, strain MEP2-6T could be officially assigned to a novel species within the genus Amycolatopsis, for which the name Amycolatopsis solani sp. nov. has been proposed. The type of strain is MEP2-6T (=JCM 36309T = TBRC 17632T = NBRC 116395T). Amycolatopsis solani MEP2-6T was strongly proven to be a non-phytopathogen of potato scab disease because stunting of seedlings and necrotic lesions on potato tuber slices were not observed, and there were no core biosynthetic genes associated with the BGCs of phytotoxin-inducing scab lesions. Furthermore, comparative genomics can provide a better understanding of the genetic mechanisms that enable A. solani MEP2-6T to adapt to the plant endosphere. Importantly, the strain smBGCs accommodated 33 smBGCs encoded for several bioactive compounds, which could be beneficially applied in the fields of agriculture and medicine. Consequently, strain MEP2-6T is a promising candidate as a novel biocontrol agent and antibiotic producer.

Anaerobic flora, Selenomonas ruminis sp. nov., and the bacteriocinogenic Ligilactobacillus salivarius strain MP3 from crossbred-lactating goats

This study aimed to examine the distribution of anaerobic bacteria in the rumen fluid of Thai crossbred goats and to screen potential probiotic strains capable of producing antimicrobial compounds and inhibiting bacteria that cause milk fat depression. Thirty-four strains of bacteria from the rumen fluid were divided into 13 groups within 12 genera based on 16S rRNA gene sequences. The RF1-5 and RF5-12 were identified as Streptococcus luteliensis and Bacillus licheniformis, respectively, and demonstrated non-ropy exopolysaccharide. Furthermore, mPRGC5T was closely related to Selenomonas caprae JCM 33725 T (97.8% similarity) based on 16S rRNA gene sequences. It exhibited low average nucleotide identity, digital DNA-DNA hybridization, and average amino acid identity values with related type strains ranging from 84.9 to 86.0%, 21.3 to 21.8%, and 73.8 to 76.1%, respectively. The genotypic and phenotypic characteristics of mPRGC5T strongly support this strain as a new species of the genus Selenomonas for which the name Selenomonas ruminis mPRGC5T was proposed. The type strain is mPRGC5T (= JCM 33724 T = KCTC 25177 T). Ligilactobacillus salivarius MP3 showed antibacterial activity against Cutibacterium acnes subsp. acnes DSM 1897 T and Kocuria rhizophila MIII. The enterolysin A cluster gene was identified in its genome. The auto-aggregation of L. salivarius MP3 was 93.6 ± 0.2%. Additionally, co-aggregation of L. salivarius MP3 with C. acnes DSM 1897 T and K. rhizophila MIII had 92.2 ± 3.4% and 87.3 ± 4.5%, respectively. The adhesion capacity of strain MP3 was 76.11 ± 2.2%. Probiogenomic analysis revealed that L. salivarius MP3 was nonhazardous to animal supplementation and included acid- and bile-tolerant ability. However, strain MP3 contained three antibiotic resistance genes. Thus, the supplementation of L. salivarius MP3 could increase the milk fat content by suppressing C. acnes DSM 1897 T with antibiotic resistance gene horizontal transfer awareness.

Bacterial diversity, community structure and function in association of potato scabby tubers during storage in northern Thailand

Potato scab is a common potato tuber disease that affects quality and cost in the marketplace, shortening storage, and increasing the chance for secondary infection. The tubers with disease severity of 1 to 4 are accepted and stored in potato storage for cheap selling in Thailand. However, there are few studies of the bacterial community of the scabby tuber during storage. Thus, we aim to elucidate the diversity, structure, and function of the bacterial community of 30-day storage potato scabby tubers stored in different temperatures using 16S amplicon metagenomic sequencing. Bacterial communities of storage potato scabby tubers (Spunta cultivar) collected from different storage temperatures, 4 °C (MEP1) and 6 °C (MEP2), were characterized using 16S rRNA amplicon metagenomic sequencing. The alpha-diversity abundance in the bacteriome of the scabby tubers stored at 6 °C was higher than in those stored at 4 °C. Actinobacteria (34.7%) was a dominant phylum in MEP1, while Proteobacteria (39.9%) was predominant in MEP2. The top 10 genera of both communities were Rhizobium group, Streptomyces, Pectobacterium, Ruminococcus, Cellulomonas, Promicromonospora, Prevotella, Enterobacter, Pedobacter, and Paenarthrobacter. Moreover, functional profile prediction of both communities reveals essential genes in the pathosystem: nos, bglA, and cebEFG-msiK for potato scab disease and phc and peh operons for rot disease. Our findings are the first study to explore details of the bacteriome of the accepted potato scabby tubers for selling during storage in Thailand and strongly indicate that although potatoes were stored at low temperatures, diseases still occur by secondary pathogens.

Diversity and antimicrobial activity of the tropical ant-derived actinomycetes isolated from Thailand

Antibiotic resistance is one of the most important global healthcare challenges and is responsible for the mortality of millions of people worldwide every year. It is a crisis attributed to misuse of antibiotics and a lack of new drug development. Actinomycetes constitute a group of Gram-positive bacteria known for their distinctive high guanine-cytosine (G+C) content in their genomic DNA. These microorganisms are widely recognized for their capability to generate a wide range of secondary metabolites with diverse biological activities. These versatile microorganisms are ubiquitous in diverse ecosystems, including soil, freshwater, marine sediments, and within the bodies of insects. A recent study has demonstrated that social insects, such as ants, host a diverse array of these bacteria. In this study, we involved the isolation and characterization of a total of 72 actinomycete strains obtained from 18 distinct ant species collected from various regions across Thailand. Utilizing 16S rRNA gene analysis, these isolated actinomycetes were classified into four distinct genera: Amycolatopsis (2 isolates), Micromonospora (1 isolate), Nocardia (8 isolates), and Streptomyces (61 isolates). Among the Streptomyces strains, 23 isolates exhibited antimicrobial activity against a panel of Gram-positive bacteria, including Bacillus subtilis ATCC 6633, Staphylococcus epidermidis ATCC 12228, Staphylococcus aureus ATCC 25923, Kocuria rhizophila ATCC 9341, and Methicillin-resistant Staphylococcus aureus (MRSA) DMST 20646. Additionally, two isolates displayed antifungal activity against Candida albicans TISTR 5554. Based on 16S rRNA gene sequence similarity studies, these two isolates, ODS25 and ODS28, were demonstrated to be closely related to Streptomyces lusitanus NBRC 13464T (98.07%) and Streptomyces haliclonae DSM 41970T (97.28%), respectively. The level of 16S rRNA gene sequence similarity below 98.65% cutoff indicates its potential as a novel actinomycete species. These findings underscore the potential of actinomycetes sourced from ants as a valuable reservoir of novel antimicrobials.

Actinoplanes pyxinae sp. nov., a new lichen-derived rare actinobacterium exhibiting antimicrobial and anticancer activity

A novel lichen-derived actinobacterium, designated Pm04-4T, was isolated from Pyxine cocoes (Sw.) Nyl. lichen collected from Chaiyaphum, Thailand. A polyphasic approach was used to describe the taxonomic position of the strain. The strain had morphological and chemotaxonomic properties similar to members of the genus Actinoplanes. It produced sporangia on the substrate mycelia. Meso-diaminopimelic acid, galactose, glucose and mannose were detected in the whole-cell hydrolysate of the strain. The major menaquinone was MK-9(H4). The polar lipids were phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The predominant cellular fatty acids were iso-C15 : 0, anteiso-C15 : 0, iso-C16 : 0 and anteiso-C17 : 0. Strain Pm04-4T showed the highest 16S rRNA gene sequence similarity to Actinoplanes akusuensis TRM 8003T (99.0 %). In the phylogenomic tree, strain Pm04-4T was positioned close to A. aksuensis TRM88003T, A. maris M416T, A. polyasparticus TRM66264T, A. hotanensis TRM88002T, A. abujensis DSM 45518T, A. bogorensis NBRC 110975T, A. brasiliensis DSM 43805T, A. lichenicola LDG1-01T and A. ovalisporus LDG1-06T. The average nucleotide identity and digital DNA-DNA hybridization values between strain Pm04-4T and its closely related neighbours were below the threshold values for describing new species. Moreover, the strain could be distinguished from its closely related type strains by phenotypic properties. Based on genotypic and phenotypic evidence, it can be concluded that strain Pm04-4T is a representative of a new Actinoplanes species for which the name Actinoplanes pyxinae sp. nov. is proposed. The type strain is Pm04-4T (=TBRC 16207T=NBRC 115836T). The type strain exhibited activity against Staphylococcus aureus ATCC 25923 as well as four yeast strains, namely Candida albicans TISTR 5554, Candida glabrata TISTR 5006, Candida krusei TISTR 5351 and Candida parapsilosis TISTR 5007. It also showed cytotoxicity against Caco-2, MNT-1 and MCF-7 cancer cells.

Functional genome analysis and anti-Helicobacter pylori activity of a novel bacteriocinogenic Lactococcus sp. NH2-7C from Thai fermented pork (Nham)

Helicobacter pylori, linked to gastric diseases, is targeted for probiotic treatment through bacteriocin production. Bacteriocins have gained recognition for their non-toxic effects on host cells and their ability to combat a wide range of pathogens. This study aimed to taxonomically characterize and evaluate the safety and probiotic properties of the novel species of Lactococcus sp. NH2-7C isolated from fermented pork, as well as its bacteriocin NH2-7C, both in vitro and in silico. Comparative genotypic analysis revealed an average nucleotide identity of 94.96%, an average amino acid identity of 94.29%, and a digital DNA-DNA hybridization value of 63.80% when compared to Lactococcus lactis subsp. lactis JCM 5805T. These findings suggest that strain NH2-7C represents a novel species within the genus Lactococcus. In silico assessments confirmed the non-pathogenic nature of strain NH2-7C and the absence of genes associated with virulence and biogenic amine formation. Whole-genome analysis revealed the presence of the nisA gene responsible for nisin A production, indicating its potential as a beneficial compound with anti-Helicobacter pylori activity and non-toxic characteristics. Probiotic assessments indicated bile salt hydrolase and cholesterol assimilation activities, along with the modulation of interleukin-6 and tumour necrosis factor-α secretion. Strain NH2-7C demonstrated gastrointestinal tolerance and the ability to adhere to Caco-2 cells, affirming its safety and probiotic potential. Additionally, its ability to produce bacteriocins supports its suitability as a functional probiotic strain with therapeutic potential. However, further in vitro and in vivo investigations are crucial to ensure its safety and explore potential applications for Lactococcus sp. NH2-7C as a probiotic agent.

Frenolicins H and I from the caterpillar-associated Streptomyces sp. TBRC17107

Two undescribed frenolicins H and I (1 and 2) along with six previously described frenolicin analogues [frenolicins A (3), B (4), UCF76-B (5), E - G (6 - 8)] and two anthraquinones [3,8-dihydroxy-1-propylanthraquinone-2-carboxylic acid (9) and 3,8-dihydroxy-1-propylanthraquinone (10)] were isolated from a longkong bark eating caterpillar-derived Streptomyces sp. TBRC17107. The chemical structures were determined by NMR spectroscopic information and HRESIMS data. Frenolicins H (1) and I (2) showed weak cytotoxicity against malignant and non-malignant cells. Frenolicins A (3) and B (4) showed antimalarial activity against Plasmodium falciparum (IC50 17.4 and 1.37 μM), antibacterial activity against Bacillus cereus and Staphylococcus aureus (MIC 50.0 and 0.20 μg/mL). Only frenolicin B had anti-plant pathogenic fungal activity against Collectotrichum acutatum and Alternaria brassicicola with MIC values of MIC 1.56 and 6.25 μg/mL, respectively. Frenolicins A and G possessed anti-Mycobacterium tuberculosis with equal MICs of 25.0 μg/mL.

Probiogenomic Analysis of Lactiplantibacillus sp. LM14-2 from Fermented Mussel (Hoi-dong), and Evaluation of its Cholesterol-lowering and Immunomodulation Effects

Lactiplantibacillus sp. LM14-2, isolated from Thai-fermented mussel (Hoi-dong), showed attractive probiotic properties. This strain was identified as Lactiplantibacillus plantarum based on its phenotypic, chemotaxonomic, and genetic characteristics including whole-genome sequencing (WGS). The draft genome sequence was analyzed and annotated for the molecular mechanisms involved in the safety assessment, the adaptation and adhesion of L. plantarum LM14-2 to the gastrointestinal tract (GIT), and the beneficial genes involved in bacteria-host interactions. The L. plantarum LM14-2 exhibited bile salt hydrolase (BSH) activity, assimilated cholesterol at 86.07 ± 5.03%, stimulated the secretion of interleukin-12, interferon-gamma, and human beta defensin-2, and induced nitric oxide production. In addition, L. plantarum LM14-2 showed excellent gastrointestinal tolerance and adhesion ability to Caco-2 cells. Furthermore, the in silico analysis showed that L. plantarum LM14-2 was a non-human pathogen and did not contain antibiotic resistance genes or plasmids. L. plantarum LM14-2 also contained potential genes associated with various probiotic characteristics and health-promoting effects. Consequently, this study suggested that L. plantarum LM14-2 could be considered safe, with potential probiotic properties and health-promoting impacts, which could facilitate its probiotic application.

Streptomyces rugosispiralis sp. nov., a Novel Actinobacterium Isolated from Peat Swamp Forest Soil That Produces Ansamycin Derivatives and Nocardamines

Actinomycetes, especially the genus Streptomyces, are one of the most promising sources of bioactive natural products. In this study, a novel Streptomyces strain, RCU-064T, was isolated from a soil sample collected from a peat swamp forest in Thailand. Strain RCU-064T showed the highest 16S rRNA gene sequence similarity (99.06%) with Streptomyces malaysiensis NBRC 16446T. Based on a polyphasic approach, strain RCU-064T represents a novel species of the genus Streptomyces, for which the name Streptomyces rugosispiralis sp. nov. is proposed. The chemical isolation of the crude ethyl acetate extracts of the strain led to the isolation of six compounds: (1) geldanamycin, (2) 17-O-demethylgeldanamycin, (3) reblastatin, (4) 17-demethoxyreblastatin, (5) nocardamine, and (6) dehydroxynocardamine. These compounds were evaluated for their biological activities. All compounds showed no antimicrobial activity against tested microorganisms used in this study. Compounds (1)-(4) displayed cytotoxic activity against the NCI-H187 cell line, with IC50 values ranging from 0.045-4.250 µg/mL. Cytotoxicity against the MCF-7 cell line was found in compounds (1) and (3) with IC50 values of 3.51 and 1.27 µg/mL, respectively. Compounds (5) and (6) exhibited cytotoxicity only against Vero cells (IC50 of 16.57 µg/mL) and NCI-H187 cells (IC50 of 13.96 µg/mL), respectively. These results indicate that peat swamp forest soil remains a promising reservoir of novel actinomycetes capable of producing bioactive natural products.

Diversity, astaxanthin production, and genomic analysis of Rhodotorula paludigena SP9-15

Astaxanthin is a carotenoid known for its powerful antioxidant properties. This study focused on isolating yeast strains capable of producing astaxanthin from flower and fruit samples collected in Thailand. Out of 115 isolates, 11 strains were identified that produced astaxanthin. Molecular identification techniques revealed that these isolates belonged to two species: Rhodotorula paludigena (5 isolates) and Rhodosporidiobolus ruineniae (6 isolates). Whole-genome analysis of one representative strain, R. paludigena SP9-15, identified putative candidate astaxanthin synthesis-associated genes, such as CrtE, CrtYB, CrtI, CrtS, CrtR, CrtW, CrtO, and CrtZ. High-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LC-MS) confirmed astaxanthin production. Further optimization of astaxanthin production was carried out by investigating the effects of various factors on the growth rate and astaxanthin production. The optimal conditions were 40 g/L glucose as a carbon source, pH 7.5, and cultivation at 25 °C with 200 rpm for 3 days. Under these conditions, R. paludigena SP9-15 synthesized biomass of 11.771 ± 0.003 g/L, resulting in astaxanthin with a content of 0.558 ± 0.018 mg/g DCW (dry cell weight), an astaxanthin yield of 6.565 ± 0.238 mg/L, and astaxanthin productivity of 2.188 ± 0.069 g/L/day. These findings provide insights into astaxanthin production using red yeast strains from Thailand and highlight the potential of R. paludigena SP9-15 for further application.

Sporolactobacillus mangiferae sp. nov., a spore-forming lactic acid bacterium isolated from tree bark in Thailand

A Gram-stain-positive, facultatively anaerobic and endospore-forming rod-shaped bacterium, designed strain CPB3-1^T, was isolated from tree bark. This homofermentative strain produced dl-lactic acid from glucose. It grew at 20-45 °C, pH 4.0-9.5 and in 0-3.0 % (w/v) NaCl. It contained meso-diaminopimelic acid in cell-wall peptidoglycan and had menaquinone with seven isoprene units (MK-7) as the predominant component. The major fatty acid was anteiso-C_17 : 0. The polar lipids were phosphatidylglycerol, diphosphatidylglycerol, an unknown phospholipid and an unknown lipid. Based on the results of 16S rRNA gene sequence analysis, strain CPB3-1^T belonged to the genus Sporolactobacillus and was closely related to Sporolactobacillus kofuensis DSM 11701^T and Sporolactobacillus spathodeae BK117-1^T (both 96.7 % similarity), Sporolactobacillus inulinus NRIC 1133^T and Sporolactobacillus terrae DSM 11697^T (both 96.6 % similarity), and Sporolactobacillus shoreicorticis MK21-7^T, Sporolactobacillus laevolacticus DSM 442^T, Sporolactobacillus shoreae BK92^T and Sporolactobacillus pectinivorans GD201205^T (all 95.8-96.5 % similarity). The draft genome of strain CPB3-1^T contained 2 930 919 bps with 3117 coding genes. The DNA G+C content was 45.1 mol%. The digital DNA-DNA hybridization values between strain CPB3-1^T and closely related type strains were 19.2-24.0 %. The average nucleotide identity (84.0-87.6 %) and average amino acid identity (66.5-76.3 %) values were lower than the cut-off values for species delineation. Strain CPB3-1^T was clearly distinguished from related Sporolactobacillus species based on its phenotypic and chemotaxonomic characteristics, 16S rRNA gene sequence similarity and the results of draft genome analysis. Therefore, the strain represents a novel species of the genus Sporolactobacillus, for which the name Sporolactobacillus mangiferae sp. nov. is proposed. The type strain is CPB3-1^T (=JCM 35082^T=TISTR 10004^T).

Selenomonas caprae sp. nov., an obligately anaerobic and volatile fatty acid producing bacterium from ruminal fluid of domestic goat (Capra hircus L.)

A novel Gram-stain-negative, motile, obligately anaerobic bacterium strain mPRGC8^T was isolated from the ruminal fluid of a domestic goat (Capra hircus L.) in Nakhon Pathom province, Thailand. The strain grew at 20-45 °C (optimum, 37 °C), pH 6.0-9.0 (optimum, pH 7.5) and 3 % (w/v) NaCl. It produced acetate, propionate, valerate, caproate and heptanoate from glucose. The 16S rRNA gene sequence analysis indicated that strain mPRGC8^T belonged to the genus Selenomonas and was closely related to Selenomonas ruminantium subsp. ruminantium DSM 2150^T (98.0 %) and Selenomonas ruminantium subsp. lactilytica JCM 6582^T (97.9 %). The in silico DNA G+C content was 53.0 mol %. Strain mPRGC8^T showed average nucleotide identity, digital DNA-DNA hybridization and average animo acid identity values with Selenomonas montiformis JCM 34373^T, S. ruminantium subsp. lactilytica JCM 6582^T and S. ruminantium subsp. ruminantium DSM 2150^T ranging from 84.9 to 86.0 %, 21.3 to 21.8 % and 73.8 to 76.1 %, respectively. The predominant cellular fatty acids were C_16 : 1  ω9c and C_18 : 1  ω9c. Phosphatidylethanolamine, three unidentified aminophospholipids, two unidentified ninhydrin positive glycolipids, an unidentified phospholipid and an unidentified lipid were detected as polar lipids. The genomic and phenotypic characteristics of strain mPRGC8^T strongly support its classification as representative of new species of the genus Selenomonas for which the name Selenomonas caprae sp. nov. is proposed. The type strain is mPRGC8^T (=JCM 33725^T=KCTC 25178^T).

Streptomyces zingiberis sp. nov., an endophytic actinobacterium isolated from the root tissue of Zingiber montanum

An endophytic actinobacterium, designated strain PLAI 1-29^T, was isolated from the root tissue of Zingiber montanum collected from Pathum Thani province, Thailand. Strain PLAI 1-29^T was characterized using a polyphasic taxonomic approach. It typically exhibited morphological and chemotaxonomic properties of the genus Streptomyces. Strain PLAI 1-29^T produced a spiral spore chain on aerial mycelium and grew at 15-40 °C, pH 6-10 on International Streptomyces Project 2 agar. The maximum NaCl concentration for growth was 9 % (w/v). Cells of strain PLAI 1-29^T presented ll-diaminopimelic acid, arabinose, galactose and ribose. The detected phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The major menaquinones were MK-9(H₆) and MK-9(H₈). The major cellular fatty acids were iso-C_16 : 0, anteiso-C_15 : 0 and anteiso-C_17 : 0. The genome-based taxonomic details revealed the assignment of strain PLAI 1-29^T to the genus Streptomyces and exhibited low threshold values for the delineation of a novel species by average nucleotide identity-blast (84.0%), average amino acid identity (80.0%) and digital DNA-DNA hybridization (27.6%) with its closest type strain, Streptomyces xinghaiensis S187^T. Furthermore, several differential physiological and biochemical characteristics were detected between strain PLAI 1-29^T and the closest type strain. Based on the combined phenotypic and genomic features, strain PLAI 1-29^T (=TBRC 7645^T=NBRC 113170^T) is considered to represent a new Streptomyces species, for which we propose the name Streptomyces zingiberis sp. nov.

Streptomyces telluris sp. nov., a promising terrestrial actinobacterium with antioxidative potentials

An actinomycete strain, AA8^T, which produced a long straight chain of spores (verticillati type), was isolated from the rhizosphere soil of Mangifera indica in Bangkok, Thailand. A polyphasic taxonomic study was carried out to establish the taxonomic position of the strain. Strain AA8^T formed a tight taxonomic position in the 16S rRNA gene tree with Streptomyces roseifaciens MBT76^T. In contrast, the genome-based taxonomic analysis showed that strain AA8^T shared low average nucleotide identity-BLAST (94.1%), the digital DNA-DNA hybridization (58.2%), and the average amino acid identity (93.6%) values with S. roseifaciens MBT76^T. Moreover, a combination of physiological and biochemical properties indicated that strain AA8^T was distinguished from all Streptomyces species with effectively published names. Strain AA8^T, therefore, represents a novel species of Streptomyces, and the name Streptomyces telluris is proposed for the strain. The type strain is AA8^T (= TBRC 8483^T = NBRC 113461^T). The chemical investigation led to the isolation of nine known compounds (compounds 1-9). Among these compounds, compound 7 (3,4-dihydroxybenzaldehyde) possesses strong antioxidant activity equal to ascorbic acid, a powerful antioxidative agent.

Genome sequences and functional analysis of Levilactobacillus brevis LSF9-1 and Pediococcus acidilactici LSF1-1 from fermented fish cake (Som-fak) with gamma-aminobutyric acid (GABA) production

Gamma-aminobutyric acid (GABA) is a crucial inhibitory neurotransmitter in the sympathetic nervous system that exerts regulatory effects on the blood, immune, and nervous systems. GABA production in som-fak, a traditional fermented fish of Thailand, has been attributed to the activity of lactic acid bacteria (LAB). The present study aims to characterize the LAB isolates and compare the genomes and GABA synthesis genes of selected isolates capable of GABA production. Thirteen isolates demonstrating GABA synthesis capability were identified based on their phenotypic and genotypic characteristics. Seven isolates (group I: LSF3-3, LSF8-3, LSF9-1, LSF9-3, LSF9-6, LSF9-7, and LSF10-14) were identified as Levilactobacillus brevis with 99.78-100% similarity. LSF2-1, LSF3-2, LSF5-4, and LSF6-5 (group II) were identified as Lactiplantibacillus pentosus with 99.86-100% similarity. Strain LSF1-1 (group III) was identified as Pediococcus acidilactici (99.47%), and LSF10-4 (group IV) was identified as Pediococcus pentosaceus with 99.93% similarity. The GABA production of isolates ranged from 0.087 to 16.935 g/L. The maximum production of 16.935 g/L from 3% monosodium glutamate was obtained from strain LSF9-1. Gene and genome analysis revealed that L. brevis LSF9-1 has multiple gad genes in the genome, such as gadB1, gadB2, gadC1, and gadC2, making it the potential strain for GABA production. Additionally, the genome analysis of P. acidilactici LSF1-1 consists of gadA, gadB, and gadC, which respond to controlling GABA production and export. Furthermore, strain LSF1-1 was considered safe, containing no virulence factors. Thus, Levilactobacillus brevis LSF9-1 and Pediococcus acidilactici LSF1-1 have the potential for GABA production and probiotic use in future studies.

Micromonospora solifontis sp. nov., an actinobacterium isolated from hot spring soil

An actinobacterium strain, PPF5-17^T, was isolated from hot spring soil collected from Chiang Rai province, Thailand. The strain exhibited morphological and chemotaxonomic properties similar to those of members of the genus Micromonospora. Colonies of PPF5-17^T were strong pinkish red and turned black after sporulation in ISP 2 agar medium. Cells formed single spores directly on the substrate mycelium. Growth was observed from 15 to 45 °C and at pH 5-8. Maximum NaCl concentration for growth was 3 % (w/v). PPF5-17^T was found to have meso-diaminopimelic acid, xylose, mannose and glucose in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositolmannosides were observed as the membrane phospholipids. MK-10(H₆), MK-9(H₆), MK-10(H₄) and MK-9(H₄) were the major menaquinones. The predominant cellular fatty acids were iso-C_15 : 0, iso-C_17 : 0, anteiso-C_17 : 0 and iso-C_16 : 0. PPF5-17^T shared the highest 16S rRNA gene sequence similarity with Micromonospora fluminis LMG 30467^T (99.3 %). A genome-based taxonomic study revealed that PPF5-17^T was closely related to Micromonospora aurantinigra DSM 44815^T in the phylogenomic tree with an average nucleotide identity by blast (ANIb) of 87.7 % and a digital DNA-DNA hybridization (dDDH) value of, 36.1 % which were below the threshold values for delineation of a novel species. Moreover, PPF5-17^T could be distinguished from its closest neighbours, M. fluminis LMG 30467^T and M. aurantinigra DSM 44815^T, with respect to a broad range of phenotypic properties. Thus, PPF5-17^T represents a novel species, for which the name Micromonospora solifontis sp. nov. is proposed. The type strain is PPF5-17^T (= TBRC 8478^T = NBRC 113441^T).

Streptomyces cylindrosporus sp. nov. and Streptomyces spinosisporus sp. nov.: two new endophytic actinobacteria isolated from the roots of Barleria lupulina Lindl

Two endophytic actinobacteria, designated as strains 7R015^T and 7R016^T, were isolated from the roots of Barleria lupulina collected in Thailand. The morphological characteristics and results of chemotaxonomic studies and 16S rRNA gene analysis indicated that both strains represented members of the genus Streptomyces. They contained ll-diaminopimelic acid in the peptidoglycan. Ribose and glucose were detected as the whole-cell sugars. MK-9(H₄), MK-9(H₆) and MK-9(H₈), were found as the membrane menaquinone. The predominant cellular fatty acids detected were iso-C_16 : 0 and anteiso-C_15 : 0. The genomes of both strains harboured biosynthetic gene clusters for melanin, terpene, lanthipeptide, polyketides, non-ribosomal peptide synthetase, siderophore and ectoine. The 16S rRNA gene sequence of 7R015^T showed the highest similarity to that of Streptomyces pseudovenezuelae DSM 40212^T (98.6 %), Streptomyces cyaneus NRRL B2296^T (98.6 %) and Streptomyces curacoi DSM 40107^T (98.6 %). Strain 7R016^T showed the highest 16S rRNA gene sequence similarity to Streptomyces gilvifuscus NBRC 110904^T (98.2 %), which is lower than the threshold value for 16S rRNA gene sequence similarity for differentiation at the species level (98.65 %). Comparative genome analysis revealed that the genomes of 7R015^T, 7R016^T and the closely related type strains had an average nucleotide identity (ANI) of less than 95 % and a digital DNA-DNA hybridisation (dDDH) of less than 70 %, the thresholds for species demarcation. On the basis of the results of the polyphasic study, strains 7R015^T and 7R016^T represent novel species of the genus Streptomyces and are named herein as Streptomyces cylindrosporus sp. nov. (=NBRC 115200^T = TBRC 14542^T) for strain 7R015^T and Streptomyces spinosisporus sp. nov. (=NBRC 115201^T = TBRC 14543^T) for strain 7R016^T.

Bacterial microbiome in tropical lichens and the effect of the isolation method on culturable lichen-derived actinobacteria

Ten samples of tropical lichens collected from Doi Inthanon, Thailand, were explored for the diversity of their bacterial microbiomes through 16S rRNA-based metagenomics analysis. The five predominant lichen-associated bacteria belonged to the phyla Proteobacteria (31.84%), Planctomycetota (17.08%), Actinobacteriota (15.37%), Verrucomicrobiota (12.17%), and Acidobacteriota (7.87%). The diversity analysis metric showed that Heterodermia contained the highest bacterial species richness. Within the lichens, Ramalina conduplicans and Cladonia rappii showed a distinct bacterial community from the other lichen species. The community of lichen-associated actinobacteria was investigated as a potential source of synthesized biologically active compounds. From the total Operational Taxonomic Units (OTUs) found across the ten different lichen samples, 13.21% were identified as actinobacteria, including the rare actinobacterial genera that are not commonly found, such as Pseudonocardia, Kineosporia, Dactylosporangium, Amycolatopsis, Actinoplanes, and Streptosporangium. Evaluation of the pretreatment method (heat, air-drying, phenol, and flooding) and isolation media used for the culture-dependent actinobacterial isolation revealed that the different pretreatments combined with different isolation media were effective in obtaining several species of actinobacteria. However, metagenomics analyses revealed that there were still several strains, including rare actinobacterial species, that were not isolated. This research strongly suggests that lichens appear to be a promising source for obtaining actinobacteria.

New insights into the neuroprotective and beta-secretase1 inhibitor profiles of tirandamycin B isolated from a newly found Streptomyces composti sp. nov

Tirandamycin (TAM B) is a tetramic acid antibiotic discovered to be active on a screen designed to find compounds with neuroprotective activity. The producing strain, SBST2-5^T, is an actinobacterium that was isolated from wastewater treatment bio-sludge compost collected from Suphanburi province, Thailand. Taxonomic characterization based on a polyphasic approach indicates that strain SBST2-5^T is a member of the genus Streptomyces and shows low average nucleotide identity (ANI) (81.7%), average amino-acid identity (AAI) (78.5%), and digital DNA-DNA hybridization (dDDH) (25.9%) values to its closest relative, Streptomyces thermoviolaceus NBRC 13905^T, values that are significantly below the suggested cut-off values for the species delineation, indicating that strain SBST2-5^T could be considered to represent a novel species of the genus Streptomyces. The analysis of secondary metabolites biosynthetic gene clusters (smBGCs) in its genome and chemical investigation led to the isolation of TAM B. Interestingly, TAM B at 20 µg/mL displayed a suppressive effect on beta-secretase 1 (BACE1) with 68.69 ± 8.84% inhibition. Molecular docking simulation reveals the interaction mechanism between TAM B and BACE1 that TAM B was buried in the pocket of BACE-1 by interacting with amino acids Thr231, Asp 228, Gln73, Lys 107 via hydrogen bond and Leu30, Tyr71, Phe108, Ile118 via hydrophobic interaction, indicating that TAM B represents a potential active BACE1 inhibitor. Moreover, TAM B can protect the neuron cells significantly (% neuron viability = 83.10 ± 9.83% and 112.72 ± 6.83%) from oxidative stress induced by serum deprivation and Aβ_1-42 administration models at 1 ng/mL, respectively, without neurotoxicity on murine P19-derived neuron cells nor cytotoxicity against Vero cells. This study was reportedly the first study to show the neuroprotective and BACE1 inhibitory activities of TAM B.

Micromonospora thermarum sp. nov., an actinobacterium isolated from hot spring soil

An actinomycete, designated strain HSS6-12^T, was isolated from hot spring sediment collected from Ranong province, Thailand. The strain showed taxonomic characteristics consistent with those of members of the genus Micromonospora. HSS6-12^T produced a single spore directly on the substrate mycelium, and no aerial mycelium was detected. The isomer of diamino acid presented in cell wall peptidoglycan was meso-diaminopimelic acid. Arabinose, xylose, glucose, and ribose were detected in whole-cell hydrolysates. MK-10(H₄), MK-9(H₄), and MK-10(H₆) were major menaquinones. Major cellular fatty acids were iso-C_16:0, iso-C_15:0, and iso-C_17:0. Phospholipid profile was composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylinositolmannosides. 16S rRNA gene analysis revealed that HSS6-12^T shared the highest 16S rRNA gene sequence similarity with Micromonospora inositola DSM 43819^T (99.3%). In contrast, the genome analysis showed that HSS6-12^T formed a tight taxonomic position in a phylogenomic tree with Micromonospora endolithica DSM 44398^T. Moreover, the average nucleotide identity-blast, the digital DNA-DNA hybridization, and the average amino acid identity values between HSS6-12^T and M. inositola DSM 43819^T and M. endolithica DSM 44398^T were 83.1-84.0%, 27.5-28.7%, and 80.4-82.2%, respectively, indicating that HSS6-12^T was different species with both closely related Micromonospora-type strains. In addition, HSS6-12^T could be discriminated from its closely related type strains by many physiological and biochemical characteristics. Thus, HSS6-12^T could be considered a novel species of the genus Micromonospora, and the name Micromonospora thermarum is proposed for the strain. The type strain is HSS6-12^T (= BCC 41915^T = JCM 17127^T).

Gordonia aquimaris sp. nov., a novel marine actinobacterium isolated from seawater in the upper gulf of Thailand

An actinobacterium strain, SW21^T, was isolated from seawater collected in the upper Gulf of Thailand. Cells were Gram-stain-positive, aerobic and rod-shaped. Growth was observed from 15 to 37 °C and at pH 6-8. Maximum NaCl for growth was 14 % (w/v). meso-Diaminopimelic acid, arabinose, galactose, glucose, rhamnose and ribose were detected in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol and phosphatidylinositol mannoside were detected as the phospholipids in the cells. The major menaquinones were MK-9(H₂) and MK-7(H₂). The major cellular fatty acids were C_16 : 0, C_18 : 1  ω9c, C_18 : 0 and C_18 : 010-methyl (TBSA). The 16S rRNA gene sequence data supported the assignment of strain SW21^T to the genus Gordonia and showed that Gordonia mangrovi KCTC 49383^T (98.7 %) was the closest relative. Moreover, the average nucleotide identity-blast (85.5 %) and digital DNA-DNA hybridization (30.7 %) values between strain SW21^T and its closest neighbour were below the threshold values for delineation of a novel species. The combination of genotypic and phenotypic data indicated that strain SW21^T is representative of novel species of the genus Gordonia. The name Gordonia aquimaris sp. nov. is proposed for strain SW21^T. The type strain is SW21^T (=TBRC 15691^T=NBRC 115558^T).

Novosphingobium kaempferiae sp. nov., a phosphate-solubilizing bacterium isolated from stem of Kaempferia marginata Carey

A Gram-stain-negative, aerobic, rod-shaped, non-spore-forming and yellow-pigment-producing bacterium, designated as Sx8-5^T, was isolated from stem tissue of Kaempferia marginata Carey in Kanchanaburi Province, Thailand. The strain exhibited tricalcium phosphate solubilizing activity. Its taxonomic position was investigated using a polyphasic approach. Sx8-5^T grew at 25-37 °C (optimum 30 °C), pH 6-9 (optimum 7) and with 0 and 1% NaCl (optimum 0 %). According to the 16S rRNA gene phylogeny, Sx8-5^T represents a member of genus Novosphingobium and shared the highest sequence similarities to Novosphingobium barchaimii LL02^T of 99.4 % and shared sequence similarities with other species of the genus Novosphingobium of less than 99.4 %. The whole-genome size was 5.7 Mb, comprised of one contig, with a DNA G+C content of 66 %. The average nucleotide identity using BLASTn (ANIb) or MUMMER (ANIm) values for whole genome comparisons between Sx8-5^T and Novosphingobium barchaimii LL02^T and six closely related type strains were 72.33-82.14 % and 83.82-87.38 %, respectively, and the digital DNA-DNA hybridization (dDDH) values ranged from 21.0 to 28.6% when compared with the type strains of the members of the genus Novosphingobium. Major fatty acids were summed feature 8 (C_18 : 1 ω7c and/or C_18 : 1  ω6c), C_16 : 0 and summed feature 3 (C_16 : 1 ω7c and/or C_16 : 1 ω6c), respectively. Polar lipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylmonomethylethanolamine, phosphatidylglycerol, unidentified phospholipids and unidentified polar lipids. The major isoprenoid quinone was Q-10. According to results obtained using a polyphasic approach, Sx8-5^T represents a novel species of the genus Novosphingobium, the name Novosphingobium kaempferiae sp. nov. is proposed. The type strain is Sx8-5^T (=JCM 35076^T =TBRC 15600^T).

Identification and Optimisation of Indole-3-Acetic Acid Production of Endophytic Bacteria and Their Effects on Plant Growth

Indole-3-acetic acid (IAA) is one of the most physiologically active auxins produced by rhizobacteria and is potentially applied for agriculture. Two endophytic bacteria, VR2 and MG9, isolated from the root of Chrysopogon zizanioides (L.) collected at Cha-Am, and the leaf of Bruguiera cylindrica (L.) Blume collected from a mangrove forest at Ban Laem, Phetchaburi Province, Thailand, were taxonomic characterised based on their phenotypic characteristics and 16S rRNA gene analysis. Strain VR2 was closely related to Enterobacter hormaechei CIP 103441^T (99.6% similarity), while strain MG9 was closely related to Bacillus aryabhattai B8W22^T (99.9% similarity). Consequently, they were identified as Enterobacter hormaechei and Bacillus aryabhattai, respectively. The IAA production of VR2 and MG9 strains are determined and applied to rice seeds for their root and shoot germination. Strains VR2 and MG9 greatly produced a yield of IAA, 246.00 and 195.55 μg/mL in 1,000 μg/mL of L-tryptophan at pH 6 for 48 h. They showed no significant differences in IAA to root and shoot development. However, the bacterial IAA exhibited potential nearby synthetic IAA, which had a significant effect compared to the control. IAA produced from these two strains might preferably trim down the use of synthetic IAA and could contribute to sustainable agriculture.

Antimalarial and antimicrobial substances isolated from the endophytic actinomycete, Streptomyces aculeolatus MS1-6

Seven undescribed compounds, including four naphthoquinone terpenoids (aculeolatins A - D), one rare 2-nitropyrrole terpenoid (nitropyrrolin F), and two hydroxamate siderophores (aculeolamides A and B) and one further undescribed compound (2,5,7-trihydroxy-3,6-dimethylnaphthalene-1,4-dione), together with eleven known compounds (arromycin, phenaziterpene A, nitropyrrolin A, heronapyrroles A and B, salaceyin A, 5,7-dihydroxy-2-isopropylchromone, 1-hydroxyphenazine, 1-methoxyphenazine, 1-acetyl-β-carboline, and N-(2-phenylethyl) acetamide), were isolated from the cultures of the endophytic Streptomyces aculeolatus MS1-6. The structures of the isolated compounds were determined using NMR spectroscopy and corroborated using chemical modification. These compounds exhibited a broad spectrum of biological activities, including antimalarial (IC₅₀ 6.03-9.84 μg/mL), antitubercular (MIC 3.13-6.25 μg/mL), anti-plant pathogenic fungal (MIC 25.0-50.0 μg/mL), and antibacterial (MIC 3.03-50 μg/mL) activities; however, they displayed unremarkable cytotoxicity against cancerous (MCF-7 and NCI-H187) and non-cancerous (Vero) cell lines.

Lactiplantibacillus argentoratensis and Candida tropicalis Isolated from the Gastrointestinal Tract of Fish Exhibited Inhibitory Effects against Pathogenic Bacteria of Nile Tilapia

Nile tilapia is one of the most consumed farmed fish in the world. The outbreak of pathogenic bacterial diseases causes high mortality rates and economic losses in Nile tilapia farming. Antibiotic administrations are commonly utilized to inhibit and prevent bacterial infections. However, antibiotics are expensive and cause serious concerns for antibiotic resistance in fish that can be potentially transferred to humans. As an alternative solution, probiotics can be used to prevent infection of pathogenic bacteria in fish. In this work, both bacteria and yeast were isolated from fish gastrointestinal tracts and their inhibitory activity against Nile tilapia pathogenic bacteria was evaluated, as well as other probiotic properties. In this study, 66 bacteria and 176 acid tolerant yeasts were isolated from fish gastrointestinal tracts. Of all isolated microorganisms, 39 bacterial and 15 yeast isolates with inhibitory effect against pathogens were then examined for their probiotic properties (acidic and bile salt resistance, adhesion potential, and biofilm formation), formation of antibacterial factor survival rate under simulated gastrointestinal fluid, and safety evaluation. AT8/5 bacterial isolate demonstrated probiotic properties and the highest inhibition against all 54 tested pathogens while YON3/2 yeast isolate outperformed the inhibitory effect among all yeast isolates. These two probiotic isolates were further identified by 16S rDNA and the D1/D2 domain of 26S rDNA sequence analysis for bacterial and yeast identification, respectively. AT8/5 and YON3/2 showed the highest similarity to Lactiplantibacillus argentoratensis and Candida tropicalis, respectively. This is the first report on isolated L. argentoratensis and C. tropicalis with antipathogenic bacteria of Nile tilapia properties. Collectively, AT8/5 and YON3/2 could be potentially used as promising alternatives to existing antibiotic methods to prevent pathogenic bacteria infection in Nile tilapia farming.

1-(6-Methylsalicyloyl)glycerol from stony coral-derived Micromonospora sp

A new natural product, 1-(6-methylsalicyloyl)glycerol (1) was isolated from the culture extract of the stony coral-derived Micromonospora sp. C029. The structure of 1 was determined by extensive analysis of 1D and 2D NMR spectroscopic data. The absolute configuration was determined to be S by comparison of specific rotation with synthetic (R)- and (S)-1. Compound 1 showed weak antimicrobial activity against Kocuria rizhophila. Structurally related benzoyl glycerol is not reported from actinomycetes, suggesting that isolation of actinomycetes from little studied environments should be important for the discovery of novel natural products.

Streptomyces macrolidinus sp. nov., a novel soil actinobacterium with potential anticancer and antimalarial activity

A novel actinomycete, strain RY43-2^T, belonging to the genus Streptomyces, was isolated from a peat swamp forest soil collected from Rayong Province, Thailand. The strain was characterized by using a polyphasic approach. The cell-wall peptidoglycan contained ll-diaminopimelic. Ribose and glucose were detected in its whole-cell hydrolysates. The strain contained anteiso-C_15:0, iso-C_14:0 and iso-C_16:0 as the predominant fatty acids, and MK-9(H₄), MK-9(H₆) and MK-9(H₈) as the major menaquinones. The phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, three unidentified ninhydrin-positive phospholipids and two unidentified phospholipids. Strain RY43-2^T showed the highest 16S rRNA gene similarity to Streptomyces misionensis JCM 4497^T (98.9 %) and Streptomyces lichenis LCR6-01^T (98.9 %). The draft genome of RY43-2^T was 6.7 Mb with 6078 coding sequences with an average G+C content of 70.8 mol%. Genomic analysis revealed that the average nucleotide identity (ANI) values based on blast (ANIb) and MUMmer (ANIm) between strain RY43-2^T and S. misionensis JCM 4497^T were 80.1 and 86.1%, respectively. The ANIb and ANIm values between strain RY43-2^T and S. lichenis LCR6-01^T were 77.0 and 85.5%, respectively. The digital DNA-DNA hybridization values were 25.2 and 23.0% in comparison with the draft genomes of S. misionensis JCM 4497^T and S. lichenis LCR6-01^T, respectively. The results of taxonomic analysis suggested that strain RY43-2^T represented a novel species of the genus Streptomyces for which the name Streptomyces macrolidinus sp. nov. is proposed. The type strain is RY43-2^T (=TBRC 7286^T=NBRC 115640^T). Strain RY43-2^T exhibited antimicrobial activity against Enterococcus faecium ATCC 51559, Colletotrichum capsici BMGC 106 and Colletotrichum gloeosporioides BMGC 107 with the minimum inhibitory concentration values of 25.0, 12.5, and 6.25 µg ml^-1. It also exhibited potent antimalarial activity against Plasmodium falciparum K1 with IC₅₀ of 0.0031 µg ml^-1. In addition, it showed cytotoxicity against Vero, KB, MCF-7 and NCI-H187 with IC₅₀ values of 0.0347, 6.15, 3.36 and 0.0352 µg ml^-1, respectively.

Characterization of Lactic Acid Bacteria from Fermented Fish (pla-paeng-daeng) and Their Cholesterol-lowering and Immunomodulatory Effects

The cholesterol-lowering and immunomodulatory effects and probiotic properties of 25 lactic acid bacteria (LAB) isolated from fermented fish (pla-paeng-daeng) in Thailand were examined in the present study. Based on their phenotypic and genetic characteristics, LAB were identified as Lactiplantibacillus pentosus (Group I, 6 isolates), Lactiplantibacillus argentoratensis (Group II, 1 isolate), Limosilactobacillus fermentum (Group III, 2 isolates), Companilactobacillus pabuli (Group IV, 4 isolates), Companilactobacillus farciminis (Group V, 5 isolates), Companilactobacillus futsaii (Group VI, 6 isolates), and Enterococcus lactis (Group VII, 1 isolate). Lactiplantibacillus pentosus PD3-1 and PD9-2 and Enterococcus lactis PD3-2 exhibited bile salt hydrolase (BSH) activities. The percentage of cholesterol assimilated by all isolates ranged between 21.40 and 54.07%. Bile salt hydrolase-producing isolates tolerated acidic and bile conditions and possessed adhesion properties. They also exerted immunomodulatory effects that affected the production of interleukin-12 (IL-12), interferon-γ (IFN-γ), human β-defensin-2 (hBD-2), and nitric oxide (NO). These isolates meet standard probiotic requirements and exert beneficial effects.

Weizmannia acidilactici sp. nov., a lactic acid producing bacterium isolated from soils

The strains designed PP-18^T, JC-4 and JC-7 isolated from soils, were Gram-stain-positive rods, facultative anaerobe, endospore-forming bacteria. The strains produced l-lactic acid from glucose. They showed positive for catalase but negative for oxidase, nitrate reduction and arginine hydrolysis. Strains P-18^T, JC-4 and JC-7 were closely related to Weizmannia coagulans LMG 6326^T (97.27-97.64%) and W. acidiproducens KCTC 13078^T (96.46-96.74%) based on 16S rRNA gene sequence similarity, respectively. They contained meso-diaminopimelic acid in cell wall peptidoglycan and had seven isoprene units (MK-7) as the predominant menaquinone. The major cellular fatty acids of strain PP-18^T were iso-C_15:0, anteiso-C_17:0, iso-C_16:0 and anteiso-C_15:0. The ANIb and ANIm values among the genomes of strains PP-18^T, JC-4 and JC-7 are above 99.4% while their ANIb and ANIm values among them and W. coagulans LMG 6326^T and W. acidiproducens KCTC 13078^T were ranged from 76.61 to 79.59%. These 3 strains showed the digital DNA-DNA hybridization (dDDH) values of 20.7-23.6% when compared with W. coagulans LMG 6326^T and W. acidiproducens DSM 23148^T. The DNA G + C contents of strains PP-18^T, JC-4 and JC-7 were 45.82%, 45.86% and 45.86%, respectively. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphoglycolipids. The results of phenotypic and chemotaxonomic characteristics and whole-genome analysis indicated that the strains PP-18^T, JC-4 and JC-7 should be represented as a novel species within the genus Weizmannia for which the name Weizmannia acidilactici sp. nov. is proposed. The type strain is PP-18^T (=KCTC 33974^T = NBRC 113028^T = TISTR 2515^T).

Distribution, cholesterol-lowering and immunomodulation effects of lactic acid bacteria from fermented mussel (Hoi-dong)

Forty-eight lactic acid bacteria (LAB) isolated from fermented mussels in Thailand were evaluated for their probiotic properties, bile salt hydrolase (BSH), cholesterol assimilation and immunomodulatory effects. They were identified as Companilactobacillus formosensis (Group I, 10 isolates), Lentilactobacillus buchneri (Group II, 8 isolates), Lactiplantibacillus plantarum subsp. plantarum (Group III, 16 isolates), Lacticaseibacillus rhamnosus (Group IV, 1 isolate), Pediococcus pentosaceus (Group V, 5 isolates) and P. acidilactici (Group V, 1 isolate), Enterococcus thailandicus (Group VI, 2 isolates), En. hirae (Group VII, 1 isolate), En. durans (Group VI, 1 isolate), Lactococcus lactis subsp. lactis (Group VII, 1 isolate), Lc. lactis subsp. hordinae (Group VII, 1 isolate), and Leuconostoc lactis (Group VIII, 1 isolate), based on their phenotypic and genetic characteristics. Seven isolates, L. plantarum subsp. plantarum LM6-1, LM6-2, LM7-2-2B, LM12-1, LM14-1, LM15-1P and LM15-2 expressed bile salt hydrolase activity. All isolates assimilated cholesterol ranging from 20.73 to 79.40%. BSH-producing isolates were tolerant to acidic and bile conditions and showed the adhesion ability to Caco-2 cells. The BSH-producing and selected isolates showed the immunomodulatory effects to stimulate interleukin-12 (IL-12), interferon-gamma (IFN-γ), human beta defensin-2 (hBD-2) and nitric oxide (NO) production at various levels. Therefore, these results indicated that the isolates meet the standard probiotic criteria and beneficial effects.

Streptomyces acidipaludis sp. nov., an actinobacterium isolated from peat swamp forest soil

An actinobacterium strain PLK6-54^T was isolated from Lankwai peat swamp forest soil collected from Yala province, Thailand. Strain PLK6-54^T exhibited morphological and chemotaxonomic properties described for the genus Streptomyces. It formed a spiral spore chain directly on aerial mycelium. Growth was observed between 20 and 40 °C and at pH 5-8. The maximum NaCl for growth was 2 % (w/v). ll-Diaminopimelic acid, arabinose and ribose were detected in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositolmannoside were detected as the phospholipids. The major menaquinones were MK-10(H₂) and MK-9(H₆). The major cellular fatty acids were iso-C_16 : 0, anteiso-C_15 : 0 and iso-C_14 : 0. 16S rRNA gene sequence data supported the assignment of strain PLK6-54^T to the genus Streptomyces and showed that Streptomyces rubidus NBRC 102073^T (99.0 %) was the closest relative. Moreover, the average nucleotide identity-blast (85.5 %) and digital DNA-DNA hybridization (30.7 %) values reported between strain PLK6-54^T and its closest neighbour were below the threshold values for delineation of a novel species. Strain PLK6-54^T could be distinguished from related validly described Streptomyces species by several phenotypic properties. The combination of genotypic and phenotypic data indicated that strain PLK6-54^T is representative of a novel species of the genus Streptomyces. The name Streptomyces acidipaludis sp. nov. is proposed for strain PLK6-54^T. The type strain is PLK6-54^T (=TBRC 11250^T=NBRC 114297^T).

Draft genome sequencing data of the moderately halophilic bacterium, Allobacillus halotolerans SKP2-8 from shrimp paste (ka-pi)

A moderately halophilic, Gram-stain-positive, spore-forming rod-shaped bacterium, designated SKP2-8 was isolated from a traditional fermented shrimp paste (Ka-pi) collected from the market in Samut Sakhon province, Thailand. This isolate SKP2-8 was closely related to Allobacillus halotolerans LMG 24826^T with 99.56% similarity based on 16S rRNA gene sequence. The draft genome of SKP2-8 was 2.53 Mb with 2,515 coding sequences with an average G+C content of 39.5 mol%. The ANIb, ANIm, AAI and the digital DNA-DNA hybridization values of isolate SKP2-8 were 97.22%, 97.64%, 97.75% and 78.0%, respectively, compared with A. halotolerans LMG 24826^T. Based on the phenotypic characteristics, DNA-DNA relatedness and phylogenomic analysis, it was identified as Allobacillus halotolerans. The genome sequence data of this isolate provide information for further analysis of the potential biotechnological use of this microorganism and guide the characterization. The draft genome was deposited at DDBJ/ EMBL/GenBank (DNA Databank of Japan/European Molecular Biology Laboratory/Genbank) (VMHF00000000).

Saccharothrix obliqua sp. nov., isolated from soil of Sichang Island, Thailand

During an investigation of rare actinobacteria, isolate SC076T was isolated from a soil sample collected from Sichang Island, Chonburi Province, Thailand. The strain showed the highest 16S rRNA gene similarity to Saccharothrix australiensis DSM 43800T (98.6%) and Saccharothrix espanaensis DSM 44229T (98.6%). The zigzag morphology of the spore chain was observed on the aerial mycelia. meso-Diaminopimelic acid was detected in the peptidoglycan. Whole-cell sugars contained rhamnose, ribose, mannose glucose and galactose. Polar lipids were phosphatidylethanolamine, hydroxyphosphatidylethanolamine, diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol mannoside, phosphatidylinositol, unidentified ninhydrin-positive glycolipid, unidentified glycolipid and four unidentified lipids. The menaquinones were MK-9(H8), MK-9(H4), MK-9(H2) and MK-9(H0). The predominant fatty acids were iso-C16 : 0, iso-C15 : 0 and anteiso-C17 : 0. The draft genome of SC076T was 8040245 bp with a G+C content of 72.5 mol%. The results of genomic analysis between strain SC076T and the related type strains showed that the digital DNA–DNA hybridization and average nucleotide identity values among the strains were 23.6-32.8% and 77.7–86.8 %, respectively, which are lower than the thresholds used to distinguish strains from others of the same species. Based on the taxonomic evidence, strain SC076T represents a novel species of the genus Saccharothrix for which the name Saccharothrix obliqua sp. nov. is proposed. The type strain is SC076T (=TBRC 14540T=NBRC 115117T).

Neokomagataea anthophila sp. nov., an osmotolerant acetic acid bacterium isolated in Thailand and emended description of the genus Neokomagataea

A novel Gram-stain-negative, rod-shaped, non-motile, aerobic bacterium isolated from a sea bean flower [Canavalia rosea (Sw.) DC.] collected in Surat Thani Province, Thailand, and designated as AH18T was characterized on the basis of polyphasic taxonomy. The phylogenetic analysis of 16S rRNA gene revealed that strain AH18T represented a member of the genus Neokomagataea . In the 16S rRNA gene sequence analysis, the strain's closest phylogenetic neighbour was Neokomagataea thailandica TBRC 376T. The draft genome size of strain AH18T was 2613495 bp, and its DNA G+C content was 52.0 mol%. The strain showed 90.3 and 76.3% pairwise-determined whole-genome average nucleotide identity and 39.8 and 19.6% digital DNA–DNA hybridization values with N. thailandica TBRC 376T and N. tanensis TBRC 7768T, respectively. The 16S rRNA gene sequences and phylogenomic analysis revealed that the strain clustered with the members of the genus Neokomagataea but was located in a distinct branch closely related to N. thailandica TBRC 376T. The predominant cellular fatty acids of the strain were summed feature 8 (C18:1 ω6c and/or C18:1 ω7c), C16:0 and C18:1 2OH (>5%). The major respiratory ubiquinone was Q-10. In addition, strain AH18T was substantiated by differences in several physiological characteristics and by MALDI-TOF profiling. On the basis of the results obtained from phenotypic, chemotaxonomic, phylogenetic and genomic analyses, the strain clearly represented a novel species within the genus Neokomagataea , for which the name Neokomagataea anthophila sp. nov. (AH18T=TBRC 2177T=NBRC 115156T) is proposed. An emended description of the genus Neokomagataea is also given.

Streptomyces corallincola and Kineosporia corallincola sp. nov., two new coral-derived marine actinobacteria

Two new marine actinobacteria, designated as J2-1^T and J2-2^T, were isolated from a coral, Favites pentagona, collected from Rayong Province, Thailand. The taxonomic positions of the two strains were identified based on polyphasic taxonomy. Based on morphological characteristics and chemotaxonomy, strains J2-1^T and J2-2^T were identified as members of the genus Streptomyces and Kineosporia, respectively. Strains J2-1^T and J2-2^T showed the highest 16S rRNA gene sequence similarity to Streptomyces broussonetiae T44^T (98.62 %) and Kineosporia babensis VN05A0415^T (98.08 %), respectively. Strain J2-1^T had chemotaxonomic properties resembling members of the genus Streptomyces. ll-Diaminopimelic acid, glucose and ribose were detected in the whole-cell hydrolysate. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, phosphatidylinositolmannoside, unidentified aminolipid and five unidentified phospholipids were detected as the polar lipids. The major cellular fatty acids were C_16 : 0 iso, C_15 : 0 anteiso, C_15 : 0 iso, C_16 : 0, C_17 : 0 anteiso, C_14 : 0 iso and C_17 : 0 iso. Strain J2-2^T a showed similar cell composition to members of the genus Kineosporia. Both isomers of ll- and meso-diaminopimelic acid were detected in the peptidoglycan. Arabinose, galactose, madurose and xylose were observed in the whole-cell hydrolysate. The polar lipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannoside, phosphatidylcholine, an unidentified phospholipid and an unidentified glycolipid. The major cellular fatty acids were C_16 : 0, C_18 : 1 ω9c, C_18 : 0 10-methyl, tuberculostearic acid, C_18 : 0 and C_17 : 0. Both strains could be distinguished from their closely related type strains according to their phenotypic characteristics. Comparative genome analysis indicated the delineation of two novel species based on digital DNA-DNA hybridization and average nucleotide identity values, which were below 70 and 95 %, respectively. The names proposed are Streptomyces corallincola sp. nov. (J2-1^T=TBRC 13503^T=NBRC 115066^T) and Kineosporia corallincola sp. nov. (J2-2^T=TBRC 13504^T=NBRC 114885^T).

Nocardia coffeae sp. nov., an endophytic actinobacterium isolated from the root of Coffea arabica (L.)

The polyphasic taxonomic study of a novel endophytic actinobacterium strain (CA2R105T) was carried out. The strain formed fragmented substrate mycelium and showed chemotaxonomic properties typical of members of the genus Nocardia, i.e. the presence of mycolic acid and MK-8 (H4ω-cycl) in its cells. Strain CA2R105T exhibited the highest 16S rRNA gene sequence similarity to Nocardia jiangxiensis NBRC 101359T (99.2%). The genome-based taxonomic analysis revealed low average nucleotide identity-blast and digital DNA–DNA hybridization values (<93.7, and <65.2%, respectively) to its closest relative. Moreover, many different phenotypic characteristics were observed between strain CA2R105T and all related Nocardia -type strains. This taxonomic evidence suggested that strain CA2R105T should be judged as representing a novel species of the genus Nocardia and the name, Nocardia coffeae sp. nov. is proposed. The type strain is CA2R105T (=TBRC 11247T=NBRC 114292T).