purification-identification-antimicrobial-protein-from-green-alga

Purification and Identification of Antimicrobial Protein from the Green Alga <em>Tetraspora</em> Sp. CU2551

Antimicrobial resistance (AMR) is an escalating global health threat, necessitating the discovery of novel antimicrobial agents. Algae-derived proteins ...

King Mongkut's Institute of Technology Ladkrabang

An actinomycete, designated strain HSS6-12, 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 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(H), MK-9(H), and MK-10(H) were major menaquinones. Major cellular fatty acids were iso-C, iso-C, and iso-C. Phospholipid profile was composed of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol, and phosphatidylinositolmannosides. 16S rRNA gene analysis revealed that HSS6-12 shared the highest 16S rRNA gene sequence similarity with Micromonospora inositola DSM 43819 (99.3%). In contrast, the genome analysis showed that HSS6-12 formed a tight taxonomic position in a phylogenomic tree with Micromonospora endolithica DSM 44398. Moreover, the average nucleotide identity-blast, the digital DNA-DNA hybridization, and the average amino acid identity values between HSS6-12 and M. inositola DSM 43819 and M. endolithica DSM 44398 were 83.1-84.0%, 27.5-28.7%, and 80.4-82.2%, respectively, indicating that HSS6-12 was different species with both closely related Micromonospora-type strains. In addition, HSS6-12 could be discriminated from its closely related type strains by many physiological and biochemical characteristics. Thus, HSS6-12 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 (= BCC 41915 = JCM 17127).

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

An actinobacterium strain, SW21, 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). -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(H) and MK-7(H). The major cellular fatty acids were C, C 9, C and C10-methyl (TBSA). The 16S rRNA gene sequence data supported the assignment of strain SW21 to the genus  and showed that  KCTC 49383 (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 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 is representative of novel species of the genus . The name  sp. nov. is proposed for strain SW21. The type strain is SW21 (=TBRC 15691=NBRC 115558).

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

An actinobacterium strain, PPF5-17, 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 . Colonies of PPF5-17 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 was found to have -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(H), MK-9(H), MK-10(H) and MK-9(H) were the major menaquinones. The predominant cellular fatty acids were iso-C, iso-C, anteiso-C and iso-C. PPF5-17 shared the highest 16S rRNA gene sequence similarity with  LMG 30467 (99.3 %). A genome-based taxonomic study revealed that PPF5-17 was closely related to  DSM 44815 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 could be distinguished from its closest neighbours,  LMG 30467 and  DSM 44815, with respect to a broad range of phenotypic properties. Thus, PPF5-17 represents a novel species, for which the name  sp. nov. is proposed. The type strain is PPF5-17 (= TBRC 8478 = NBRC 113441).

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

An endophytic actinobacterium, designated strain PLAI 1-29, was isolated from the root tissue of  collected from Pathum Thani province, Thailand. Strain PLAI 1-29 was characterized using a polyphasic taxonomic approach. It typically exhibited morphological and chemotaxonomic properties of the genus . Strain PLAI 1-29 produced a spiral spore chain on aerial mycelium and grew at 15-40 °C, pH 6-10 on International  Project 2 agar. The maximum NaCl concentration for growth was 9 % (w/v). Cells of strain PLAI 1-29 presented -diaminopimelic acid, arabinose, galactose and ribose. The detected phospholipids were diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylinositol and phosphatidylinositol mannoside. The major menaquinones were MK-9(H) and MK-9(H). The major cellular fatty acids were -C, -C and -C. The genome-based taxonomic details revealed the assignment of strain PLAI 1-29 to the genus  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,  S187. Furthermore, several differential physiological and biochemical characteristics were detected between strain PLAI 1-29 and the closest type strain. Based on the combined phenotypic and genomic features, strain PLAI 1-29 (=TBRC 7645=NBRC 113170) is considered to represent a new  species, for which we propose the name  sp. nov.

 sp. nov., an endophytic actinobacterium isolated from the root tissue of .

Thiolutin and 2,2-dioxidothiolutin are sulfur-containing antibiotics discovered through a targeted high-throughput screening strategy designed to identify compounds with antimicrobial activity. The producing strain, JHD1, is an actinomycete isolated from marine sediment collected in Chonburi Province, Thailand. Chemotaxonomic characteristics and 16S rRNA gene sequence analysis indicated that strain JHD1 belongs to the genus Streptomyces. Taxonomic analysis using a polyphasic approach further supported its placement within the genus Streptomyces. The strain exhibited low similarity to its closest known relatives, Streptomyces alkaliterrae OF1 and Streptomyces chumphonensis KK1-2, with average nucleotide identity based on MuMmer ultra-rapid aligning tool (ANIm) values of 85.7-86.2%, average amino acid identity (AAI) values of 71.8-78.1%, and digital DNA-DNA hybridization (dDDH) values of 23.4-25.0%, all well below the established thresholds for species delineation. These results reveal that strain JHD1 represents a novel species within the genus Streptomyces, for which the name Streptomyces marinisediminis sp. nov. is proposed. The crude extract obtained from the culture broth of strain JHD1 exhibited strong antimicrobial activity against Gram-positive bacteria and led to the discovery of two promising secondary metabolites, thiolutin and 2,2-dioxidothiolutin, along with 8-amino-2H-benz[e][1,3]oxazine-2,4(3H)-dione, benadrostin, 2,3-dihydroxybenzamide, and 2-hydroxy-3-methoxybenzamide. In this study, 2,2-dioxidothiolutin was structurally confirmed for the first time by X-ray crystallographic analysis. Interestingly, thiolutin demonstrated strong anti-human small cell lung cancer (NCI-H187) activity, with an IC₅₀ value of 0.35 µg/mL, and also showed cytotoxicity against human breast cancer (MCF-7) cells, with an IC₅₀ value of 5.61 µg/mL.

Article	Year
Micromonospora thermarum sp. nov., an actinobacterium isolated from hot spring soil. Archives of microbiology\| PubMed ID: 36939906	2023
sp. nov., a novel marine actinobacterium isolated from seawater in the upper gulf of Thailand. International journal of systematic and evolutionary microbiology\| PubMed ID: 36961870	2023
sp. nov., an actinobacterium isolated from hot spring soil. International journal of systematic and evolutionary microbiology\| PubMed ID: 37141114	2023
sp. nov., an endophytic actinobacterium isolated from the root tissue of . International journal of systematic and evolutionary microbiology\| PubMed ID: 37288648	2023
Discovery of Streptomyces marinisediminis sp. nov., a new thiolutin producing actinomycete isolated from Thai marine sediment. Scientific reports\| PubMed ID: 40790075	2025

Rawirat Pansomsuay

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