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Diversity of actinomycetes habitats. Actinomycetes are predominantly found in various ecological habitats e.g., marine ecosystems (of water bodies, coral reefs, seawater, mangrove forest), and terrestrial ecosystems (soil and plants, and insects).
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Actinomycetes inhabit both terrestrial and marine ecosystems and are highly proficient in producing a wide range of natural products with diverse biological functions, including antitumor, immunosuppressive, antimicrobial, and antiviral activities. In this review, we delve into the life cycle, ecology, taxonomy, and classification of actinomycetes,...
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... are widely distributed in various ecosystems and habitats including soil and marine habitats, freshwater, animals, plants, insects, and fertilizer ( Figure 2) [8,9]. They are free-living, saprophytes in an environment such as soil pore [8] or living as endophytes in plants [10]. ...
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... are widely distributed in various ecosystems and habitats including soil and marine habitats, freshwater, animals, plants, insects, and fertilizer ( Figure 2) [8,9]. They are free-living, saprophytes in an environment such as soil pore [8] or living as endophytes in plants [10]. ...
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... strains have been isolated from diverse plants, such as crop plants, medicinal plants, halophytes, and some woody tree species [10,25]. Examples of endophytic actinomycetes include Actinoallomurus, Actinoplanes, Allonocardiopsis, Amycolatopsis, Blastococcus, Glycomyces, Kibdelosporangium, Micrococcus, Micromonospora, Figure 2. Diversity of actinomycetes habitats. ...
Citations
... Actually, it was found that Actinobacteria were abundant in the rhizosphere of T. aestivum [50]. Actinobacteria are the main source of bioactive compounds, such as secondary metabolites, antibiotics, and enzymes with agriculture importance known to date [51,52]. A very important genus of this phylum, such as Streptomyces, was isolated from agricultural soil sources [53]. ...
The use of rhizospheric SynComs can be a new and sustainable strategy in the agrobiotechnology sector. The objective of this study was to create the most appropriate SynCom composition; examine the ability to dissolve natural rock phosphate (RP) from Morocco in liquid-modified NBRIP medium; determine organic acids, and phytohormones; and verify plant growth promoting and nutrition uptake effect in the pot experiments of winter wheat (Triticum aestivum). A total of nine different microorganisms were isolated, which belonged to three different genera: Bacillus, Pseudomonas, and Streptomyces. Out of the 21 treatments tested, four SynComs had the best phosphate-dissolving properties: IJAK-27+44+91 (129.17 mg L−1), IIBEI-32+40 (90.95 µg mL−1), IIIDEG-45+41 (122.78 mg L−1), and IIIDEG-45+41+72 (120.78 mg L−1). We demonstrate that these SynComs are capable of producing lactic, acetic, gluconic, malic, oxalic, citric acids, and phytohormones such as indole-3-acetic acid, zeatin, gibberellic acid, and abscisic acid. In pot experiments with winter wheat, we also demonstrated that the designed SynComs were able to effectively colonize the plant root rhizosphere and contributed to more abundant plant growth characteristics and nutrient uptake as uninoculated treatment or uninoculated treatment with superphosphate (NPK 0-19-0). The obtained results show that the SynCom compositions of IJAK-27+44+91, IIBEI-32+40, IIIDEG-45+41, and IIIDEG-45+41+72 can be considered as promising candidates for developing biofertilizers to facilitate P absorption and increase plant nutrition.
... Researchers are progressively directing their focus towards bacterial QS systems to screen for QSIs from metabolites of marine microorganisms, with the aim of developing novel antibacterial drugs [10-13]. Marine actinomycetes, known for their valuable contributions, serve as abundant sources of novel secondary metabolites characterized by complex structures and unique activities, making them exceptional candidates for the screening of potential QSIs [14][15][16]. ...
An ethyl acetate extract of a marine actinomycete strain, Nocardiopsis mentallicus SCSIO 53858, isolated from a deep-sea sediment sample in the South China Sea, exhibited anti-quorum-sensing (QS) activity against Chromobacterium violaceum CV026. Guided by the anti-QS activity, a novel active compound was isolated and purified from the extract and was identified as 2,3-dimethoxycinnamic acid (2,3-DCA) through spectral data analysis. At a concentration of 150 μg/mL, 2,3-DCA exhibited robust inhibitory effects on three QS-regulated traits of C. violaceum CV026: violacein production, swarming motility, and biofilm formation, with inhibition rates of 73.9%, 65.9%, and 37.8%, respectively. The quantitative reverse transcription polymerase chain reaction results indicated that 2,3-DCA can disrupt the QS system in C. violaceum CV026 by effectively suppressing the expression of QS-related genes, including cviR, vioA, vioB, and vioE. Molecular docking analysis revealed that 2,3-DCA hinders the QS system by competitively binding to the same binding pocket on the CviR receptor as the natural signal molecule N-hexanoyl-L-homoserine lactone. Collectively, these findings suggest that 2,3-DCA exhibits promising potential as an inhibitor of QS systems, providing a potential solution to the emerging problem of bacterial resistance.
... For this reason, natural sources, mainly novel microorganisms, are being investigated to combat developing resistance to antibiotics [1]. Among microorganisms, Actinobacteria represent an outstanding group of bacteria that synthesize different bioactive metabolites [2]. They are responsible for producing over 50% of the bioactive secondary metabolites that have been discovered, most notably antibiotics, anticancer medicines, anti-inflammatory drugs, and enzymes [3]. ...
With the alarming rise of drug resistant pathogens, the quest for new bioactive compounds from natural habitats has increased. Actinobacteria are Gram-positive bacteria, considered prominent natural antibiotic synthesizers. This study aimed at isolating Actinobacteria from agricultural soil samples of Tamnine El Tahta and Haddatha, with an emphasis on the physicochemical soil characteristics. It also aimed at screening and identifying the antibacterial-producing Actinobacteria, with a determination of the chemical composition of the extract. Forty-six Actinobacteria were isolated from six soil samples. Actinobacteria load exhibited a positive correlation with moisture content, and a negative correlation with pH, salinity, and organic matter content. Primary screening for antibacterial activity was performed against various Gram-positive and Gram-negative bacteria by cross-streak method. Fourteen Actinobacteria isolates were potent against the test microorganisms, and the most effective isolate (T25) was selected for identification, and extract preparation. The antibacterial activity of the extract was tested using secondary screening, in addition to minimal inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) determination. T25 isolate exhibited a 92% similarity with Micrococcus luteus/lylae. MIC recorded was 12.5 mg/ml and the MBC was higher than 100 mg/ml against all test microorganisms. Total phenol content was estimated to be 18.5 ± 0.0015 mg GAE/g dry weight using Folin-Ciocalteu method, and total flavonoid content recorded 2.3 ± 0.02 mg RE/g dry weight using aluminum nitrate colorimetric method. This study revealed that the physicochemical parameters in soils impact the distribution of Actinobacteria. Moreover, it focuses on Micrococcus luteus/lylae strain, considered a promising antibacterial resource for further potential clinical investigations.
... Actinomycetes are one of the largest phyla of bacterial groups and are ubiquitous in both terrestrial and marine ecosystems [5]. Their biosynthetic gene clusters (BGCs) have well-known talents in the metabolization of complex natural products [6]. Streptomyces, as the most numerous and advanced genus of actinomycetes, is the source of 60% natural antibiotics, and classic examples widely are used in clinical practice including erythromycin, streptomycin and rifamycin [7,8]. ...
... The tirandamycins are a class of bacterial RNA polymerases (RNAPs) inhibitors containing dienoyl tetramic acid and 2,4-pyrrolidinedione structures [41]. Two new tirandamycin analogues tirandamycin K and isotirandamycin B (58 and 59, Figure 5), together with two known derivatives (60 and 61, Figure 5) 6 were produced from marine Streptomyces strains [42,43]. Compound 58 was the first linear tirandamycin derivative which avoided bicyclic ketal ring formation due to the inability of the C-9S hydroxyl group to be nucleophilic attacked by C-13. ...
Natural alkaloids of actinomycetes origin and synthetic derivatives have always been among the important suppliers of small-molecule drugs. Among their biological sources, Streptomyces is the highest and most extensively researched genus. Marine-derived Streptomyces strains harbor unconventional metabolic pathways and have been demonstrated to be efficient producers of biologically active alkaloids since more than 60% of these compounds exhibit valuable activity such as antibacterial, antitumor, anti-inflammatory activity, etc. This review comprehensively summarizes novel alkaloids produced by marine Streptomyces discovered in the past decade, focusing on their structural features, biological activity and pharmacological mechanisms. Future perspectives on the discovery and development of novel alkaloids from marine Streptomyces are also provided.
... The study of the biological activity of low-molecular-weight substances of marine origin, in particular with accent on antimicrobial and antitumor activity, is one of the main trends in applied biological research in recent years (Malve, 2016). Various compounds with antimicrobial and cytotoxic activity have recently been found in representatives of a wide range of taxonomic groups of marine prokaryotes, primarily Actinomycetota, Bacillota, and Cyanobacteriota, which indicates that the genetic potential of the marine microbial community is understudied and underused (Ruiz-Torres et al., 2017;Potapenko et al., 2021;Ngamcharungchit et al., 2023). Many new compounds and chemical scaffolds of marine microbial origin are already undergoing clinical trials, e.g. ...
The Black Sea is a unique water basin consisting of a thin superficial oxygenic layer with moderate salinity, and a deep anoxic water mass. The microbiota of the Black Sea remains relatively understudied, which makes it interesting first of all from the most practical point of view of the search for producers of new biologically active compounds. A strain of actinobacteria Streptomyces sp. ONU 561 was isolated from the surface of mussel shells collected in the coastal zone of Odesa. It demonstrated a wide range of antagonistic activity, inhibiting the growth of a set of opportunistic pathogens, including representatives of Staphylococcus aureus, Escherichia coli, Proteus vulgaris, and Klebsiella pneumoniae. In addition, bacteria of this strain were able to inhibit the growth of all tested strains of mycelial fungi, including representatives of Aspergillus niger, A. flavus and Fusarium oxysporum species, and Candida albicans yeast. A significant cytotoxic effect was revealed in the cell cultures of human malignant cells – human rhabdomyosarcoma (RD) and human laryngeal adenocarcinoma (Hep-2). Analysis of the exometabolome of the strain did not explain these effects.The strain was comprehensively characterized, including physiological, biochemical, and morphological traits. The complete genome of the strain was sequenced using Illumina HiSeq 4000 (2x150) and ONT and annotated using NCBI PGAP. Its genome has a size of 8 359 197 bp. GC content – 71.59%. Using antiSMASH 7.0, 35 biosynthetic clusters were revealed. The indices of digital DNA-DNA hybridization and orthoANI for all of the type strains with Streptomyces sp. ONU 561 are much lower than threshold values for the species separation. The obtained results, including a comparative analysis of the genome, indicate the possible affiliation of the strain Streptomyces sp. ONU 561 to a new species and the potential ability of these actinobacteria to synthesize previously unknown antibiotic compounds.
... These microorganisms (viruses, bacteria, archaea...) play an important role in the biogeochemical cycles of basic elements. They exist not only in a planktonic state, but also in the association with other marine organisms such as animals, plants, algae, etc. (Pita et al 2018;Chananan et al, 2023). Many studies are focused on secondary substances produced by marine microorganisms has achieved remarkable achievements. ...
... Marine micro-organism resources have the potential as source of natural products with diverse biological functions (Chananan et al, 2023). ...
The marine environment has been known as a resource containing a lot of compounds with antibiotic, anti-tuberculosis and antiviral activities. Many of the marine microorganisms have been found to live in sediment, sand, surface or within the body of other living organisms such as sponges, soft coral, mollusk, algae… Natural products from marine actinomyces and fungi are considered an important source for the discovery of novel compounds, of their rich secondary metabolites. From 38 samples collected at 22 coordinates and different depths in the sea from Bach Long Vy island - Hai Phong to Ly Son island - Quang Ngai on the marine research vessel “Oparin Academik”, 40 actinomycetes and 20 fungal strains were isolated. The crude extracts of 60 isolates were primary screened for their antimicrobial activity against 7 pathogenic microorganisms by the Bioassay method in a 96-well tray. As a result, 53/60 strains were resistant at least 1 tested microorganisms, 22/60 isolates against 3 or more the test microorganisms, respectively. In particular, there were 4 isolates (three actinomyces G817, G819, G824 and fungus OM01) with the strongest resistance to four or more tested strains, which were then studied further. The results of phenotypic and molecular identification by 16S rRNA sequences for G817, G819, G824 and 18S rRNA sequence for OM01 showed that OM01 was Penicillium citrinum; G817, G819 strains belonged to Salinispora arenicola, while G824 was identified as Pseudonocardia carboxydivorans. The promising candidate isolates were analyzed in a phylogenetic tree based on MegaX software.
Indolizidines have long been recognized for their valuable bioactivities, their common feature being a bicyclic structure connected via a nitrogen atom. Traditionally, plants have been identified as the primary producers. However, recent discoveries have revealed that certain bacterial strains belonging to the genus of actinomycetes also possess the ability to synthesize various indolizidine-based compounds. Among these strains, Streptomyces sp. HNA39, Saccharopolyspora sp. RL78, and Streptomyces NCIB 11649 have been identified as producers of cyclizidines, characterized by their distinctive cyclopropyl moiety. Additionally, Streptomyces griseus OS-3601 synthesizes a unique class of indolizidine derivatives known as iminimycines, distinguished by their rare imine-cation structure. Protoplast fusion of a Streptomyces griseus strain with Streptomyces tenjimariensis resulted in a new indolizidine named in-dolizomycin. This review aims to provide an overview of known bacterial indolizidine producers, summarize current knowledge regarding the biosynthesis of cyclizidines and iminimycines, and assess their bioactivities.
Tobacco (Nicotiana tabacum L.) is a major cash crop, and soil quality played a significant role in the yield and quality of tobacco. Most farmers cultivate tobacco in rotation with other crops to improve the soil characteristics. However, the effects of different previous crops on the soil’s nutrient status and bacterial community for tobacco cultivation still need to be determined. Three treatments were assessed in this study, i.e., tobacco-planting soil without treatment (CK), soil with barley previously cultivated (T1), and soil with rapeseed previously cultivated (T2). The soil physical and chemical properties and the 16S rRNA gene sequence diversity of the bacterial community were analyzed. The effects of different crops on the physical and chemical properties of tobacco-planting soil and the diversity and richness of the bacterial community were comprehensively discussed. The results of this study showed that different previously cultivated crops altered the nutrient status of the soil, with changes in the ratio of NH4⁺-N to NO3⁻-N having the most significant impact on tobacco. In CK, the ratio of NH4⁺-N to NO3⁻-N was 1:24.2, T1–1:9.59, and T2–1:11.10. The composition of the bacterial community in tobacco-planting soil varied significantly depending on the previously cultivated crops. The richness and diversity of the bacterial community with different crops were considerably higher than without prior cultivation of different crops. The dominant bacteria in different treatments were Actinobacteriota, Proteobacteria, and Chloroflexi with their relative abundance differed. In conclusion, our study revealed significant differences in nutrient status, bacterial community diversity, and the richness of tobacco-planting soil after the preceding cultivation of different crops. Suitable crops should be selected to be previously cultivated in tobacco crop rotations in near future for sustainable agriculture.
Among the actinomycetes in the rare genera, Micromonospora is of great interest since it has been shown to produce novel therapeutic compounds. Particular emphasis is now on its isolation from plants since its population from soil has been extensively explored. The strain CR3 was isolated as an endophyte from the roots of Hieracium canadense, and it was identified as Micromonospora chokoriensis through 16S gene sequencing and phylogenetic analysis. The in-vitro analysis of its extract revealed it to be active against the clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA) and Candida tropicalis (15 mm). No bioactivity was observed against Gram-negative bacteria, Escherichia coli ATCC 25922, and Klebsiella pneumoniae ATCC 706003. The Micromonospora chokoriensis CR3 extract was also analyzed through the HPLC-DAD-UV–VIS resident database, and it gave a maximum match factor of 997.334 with the specialized metabolite BagremycinA (BagA). The in-silico analysis indicated that BagA strongly interacted with the active site residues of the sterol 14-α demethylase and thymidylate kinase enzymes, with the lowest binding energies of − 9.7 and − 8.3 kcal/mol, respectively. Furthermore, the normal mode analysis indicated that the interaction between these proteins and BagA was stable. The DFT quantum chemical properties depicted BagA to be reasonably reactive with a HOMO-LUMO gap of (ΔE) of 4.390 eV. BagA also passed the drug-likeness test with a synthetic accessibility score of 2.06, whereas Protox-II classified it as a class V toxicity compound with high LD50 of 2644 mg/kg. The current study reports an endophytic actinomycete, M. chokoriensis, associated with H. canadense producing the bioactive metabolite BagA with promising antimicrobial activity, which can be further modified and developed into a safe antimicrobial drug.
