A new actinomycin complex produced by a Micromonospora species: fermentation, isolation, and characterization

Antifungal activity of compounds from Gordonia sp. WA8-44 isolated from the gut of Periplaneta americana and molecular docking studies

Invasive fungal infections are on the rise, leading to a continuous demand for antifungal antibiotics. Rare actinomycetes have been shown to contain a variety of interesting compounds worth exploring. In this study, 15 strains of rare actinobacterium Gordonia were isolated from the gut of Periplaneta americana and screened for their anti-fungal activity against four human pathogenic fungi. Strain WA8-44 was found to exhibit significant anti-fungal activity and was selected for bioactive compound production, separation, purification, and characterization. Three anti-fungal compounds, Collismycin A, Actinomycin D, and Actinomycin X2, were isolated from the fermentation broth of Gordonia strain WA8-44. Of these, Collismycin A was isolated and purified from the secondary metabolites of Gordonia for the first time, and its anti-filamentous fungi activity was firstly identified in this study. Molecular docking was carried out to determine their hypothetical binding affinities against nine target proteins of Candida albicans. Chitin Synthase 2 was found to be the most preferred antimicrobial protein target for Collismycin A, while 1,3-Beta-Glucanase was the most preferred anti-fungal protein target for Actinomycin D and Actinomycin X2. ADMET prediction revealed that Collismycin A has favorable oral bioavailability and little toxicity, making it a potential candidate for development as an orally active medication.

Identification and characterization of Streptomyces flavogriseus NJ-4 as a novel producer of actinomycin D and holomycin

This paper is the first public report that Streptomyces flavogriseus can produce both actinomycin D and holomycin. The actinomycete strain NJ-4 isolated from the soil of Nanjing Agricultural University was identified as S. flavogriseus. This S. flavogriseus strain was found for the first time to produce two antimicrobial compounds that were identified as actinomycin D and holomycin. GS medium, CS medium and GSS medium were used for the production experiments. All three media supported the production of actinomycin D, while holomycin was detected only in GS medium and was undetectable by HPLC in the CS and GSS media. The antimicrobial activity against B. pumilus, S. aureus, Escherichia coli, F. moniliforme, F. graminearum and A. niger was tested using the agar well diffusion method. Actinomycin D exhibited strong antagonistic activities against all the indicator strains. Holomycin exhibited strong antagonistic activities against B. pumilus, S. aureus and E. coli and had antifungal activity against F. moniliforme and F. graminearum but had no antifungal activity against A. niger. The cell viability was determined using an MTT assay. Holomycin exhibited cytotoxic activity against A549 lung cancer cells, BGC823 gastric cancer cells and HepG2 hepatocellular carcinoma cells. The yield of actinomycin D from S. flavogriseus NJ-4 was 960 mg/l. S. flavogriseus NJ-4 exhibits a distinct capability and has the industrial potential to produce considerable yields of actinomycin D under unoptimized conditions.

Micromonospora maritima sp. nov., isolated from mangrove soil

Strain D10-9-5(T) was isolated from mangrove soil in Samut Sakhon province, Thailand. A polyphasic approach was used to determine the taxonomic position of the strain. The strain presented single rough spores on substrate mycelium and no aerial mycelium. Chemotaxonomic data supported the assignment of strain D10-9-5(T) to the genus Micromonospora based on the presence of meso-diaminopimelic acid and glycolyl muramic acid in the peptidoglycan, ribose, mannose, galactose, xylose and glucose as whole-cell sugars, MK-10(H(4)) (14.8 %), MK-10(H(6)) (46.7 %) and MK-10(H(8)) (27.5 %) as the predominant isoprenoid quinones, iso-C(15 : 0) (17.9 %), anteiso-C(17 : 0) (14.6 %), iso-C(17 : 0) (9.6 %), C(17 : 0) (8.0 %), iso-C(16 : 0) (7.7 %) and C(17 : 1)ω8c (7.0 %) as the major cellular fatty acids, and diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidylinositol mannosides and phosphatidylethanolamine as the predominant phospholipids in the cell wall. The 16S rRNA gene sequence and phylogenetic analysis showed that strain D10-9-5 was closely related to Micromonospora marina JCM 12870(T) (99.6 %), Micromonospora coxensis JCM 13248 (T) (99.4 %), Micromonospora aurantiaca JCM 10878(T) (99.3 %), Micromonospora humi JCM15292(T) (99.3 %), Micromonospora halophytica JCM 3125(T) (99.1%) and Micromonospora chalcea JCM 3031(T) (99.1 %). Strain D10-9-5(T) could be clearly distinguished from related members of the genus Micromonospora by its physiological and biochemical characteristics as well as its phylogenetic position and level of DNA-DNA relatedness. Therefore, the strain represents a novel species for which the name Micromonospora maritima sp. nov. is proposed; the type strain is D10-9-5(T) ( = JCM 17013(T) = NBRC 108767(T) = PCU 322(T) = TISTR 2000(T)).