Streptomyces Strains Research Articles

Targeted inhibition of PTPN22 is a novel approach to alleviate osteogenic responses in aortic valve interstitial cells and aortic valve lesions in mice

BackgroundCalcific aortic valve disease (CAVD) is the most prevalent valvular disease and has high morbidity and mortality. CAVD is characterized by complex pathophysiological processes, including inflammation-induced osteoblastic differentiation in aortic valve interstitial cells (AVICs). Novel anti-CAVD agents are urgently needed. Protein tyrosine phosphatase nonreceptor type 22 (PTPN22), an intracellular nonreceptor-like protein tyrosine phosphatase, is involved in several chronic inflammatory diseases, including rheumatoid arthritis and diabetes. However, it is unclear whether PTPN22 is involved in the pathogenesis of CAVD.MethodsWe obtained the aortic valve tissue from human and cultured AVICs from aortic valve. We established CAVD mice model by wire injury. Transcriptome sequencing, western bolt, qPCR, and immunofluorescence were performed to elucidate the molecular mechanisms.ResultsHere, we determined that PTPN22 expression was upregulated in calcific aortic valve tissue, AVICs treated with osteogenic medium, and a mouse model of CAVD. In vitro, overexpression of PTPN22 induced osteogenic responses, whereas siRNA-mediated PTPN22 knockdown abolished osteogenic responses and mitochondrial stress in the presence of osteogenic medium. In vivo, PTPN22 ablation ameliorated aortic valve lesions in a wire injury-induced CAVD mouse model, validating the pathogenic role of PTPN22 in CAVD. Additionally, we discovered a novel compound, 13-hydroxypiericidin A 10-O-α-D-glucose (1 → 6)-β-D-glucoside (S18), in a marine-derived Streptomyces strain that bound to PTPN22 with high affinity and acted as a novel inhibitor. Incubation with S18 suppressed osteogenic responses and mitochondrial stress in human AVICs induced by osteogenic medium. In mice with aortic valve injury, S18 administration markedly alleviated aortic valve lesions.ConclusionPTPN22 plays an essential role in the progression of CAVD, and inhibition of PTPN22 with S18 is a novel option for the further development of potent anti-CAVD drugs.Graphical Therapeutic inhibition of PTPN22 retards aortic valve calcification through modulating mitochondrial dysfunction in AVICs.

Screening of Streptomyces strains helping arbuscular mycorrhizal symbiosis against pepper (Capsicum annuum L.) Phytophthora blight

Mycorrhiza helper bacteria (MHB) can promote the formation and functioning of arbuscular mycorrhizal (AM) symbiosis, but their role and application potential in coping with soil-borne diseases are still unclear. The aim of this 14-week greenhouse pot experiment was to obtain several actinomycetes strains which could help AM symbiosis in suppressing the Phytophthora blight of pepper (Capsicum annuum L.), using a soil inoculated with Phytophthora capsici after sterilization. Five Streptomyces strains, including S. pseudogriseolus, S. albogriseolus, S. griseoaurantiacus, S. tricolor and S. tendae, as well as the AM fungus (Funneliformis caledonium) were tested. The Phytophthora blight severity reached 66% at full productive stage in the control, and only F. caledonium, S. griseoaurantiacus and S. tricolor alone remarkably decreased (P < 0.05) it to 47%, 40%, and 35%, respectively. Compared to F. caledonium alone, only additional inoculation of S. tricolor and S. tendae which were isolated from the rhizosphere of a healthy individual in an infected field substantially elevated (P < 0.05) root mycorrhizal colonization, root biomass, fruit yield, and total K acquisitions of pepper, and further dramatically decreased (P < 0.05) the severity. According to the feature of enhancing disease-suppression by AM symbiosis, both S. tricolor and S. tendae were confirmed as MHB strains here. Specifically, S. tendae had a stronger performance in directly accelerating mycorrhization, while S. tricolor was also an antagonist to the pathogenic P. capsici. Furthermore, S. griseoaurantiacus with the independent disease-suppression function was not a MHB strain here. The redundancy analyses demonstrated that when AM fungus present, root mycorrhizal colonization replaced soil pH becoming the main factor impacting pepper Phytophthora blight. Thus, S. tricolor and S. tendae seemed to have the value of preparation and application in the future to help AM symbiosis against pepper Phytophthora blight.

Characterization of biologically active exopolysaccharide produced by Streptomyces sp. NRCG4 and its anti-Alzheimer efficacy: in-vitro targets

BackgroundExopolysaccharides are extremely powerful molecules with a wide range of uses in pharmaceuticals due to their structural and compositional complexity. Marine microorganisms often produce bioactive substances with novel functions and structures because of their special living conditions. Polysaccharides from marine microorganisms are of interest to new drug discovery. ResultsThe current research focused on the isolation of bacteria from Red Sea, Egypt, that have the ability to produce a new natural exopolysaccharide in order to be examined in treating Alzheimer’s illness to obviate side effects of synthetic drugs. Properties of exopolysaccharide (EPS) produced by an isolated Streptomyces strain were investigated for its capability to play as anti-Alzheimer. This strain was identified morphologically, physiologically, and biochemically and actually was confirmed by molecularly 16S rRNA analysis as Streptomyces sp. NRCG4 with accession number MK850242. The produced EPS was fractionated by precipitation 1:4 volumes of chilled ethanol and the third major fraction (1:3) listed as NRCG4, and then the functional groups, MW, and chemical evaluation have been detected via Fourier-transform infrared (FTIR), high-performance gel permeation chromatography (HPGPC), and high-performance liquid chromatography (HPLC). The findings showed that NRCG4 was an acidic EPS composed of mannuronic acid, glucose, mannose, and rhamnose in a molar ratio of 1.2:1.5:2.8:1.0, respectively. NRCG4 Mw was determined to be 4.25 × 105 gmol−1 and the Mn to be 1.97 × 105 gmol−1. Also, the NRCG4 included uronic acid (16.0%) and sulfate (0.0%), but no protein was found. In addition, antioxidant and anti-inflammation activity was measured through various methods. This study confirmed that NRCG4 exopolysaccharide exerted anti-Alzheimer’s characters via inhibition of cholinesterase and tyrosinase as well as anti-inflammatory and antioxidant abilities. Additionally, it occurred a potential role in the suppression of Alzheimer’s disease risk factors through its antioxidant (metal chelation, radical scavenging capability), anti-tyrosinase and anti-inflammatory characteristics. The anti-Alzheimer’s disease efficacy of NRCG4 exopolysaccharide may be assigned to its unique determined chemical composition. ConclusionsThe present study highlighted those exopolysaccharides could be harnessed to improve pharmaceutical industry (anti-Alzheimer, anti-tyrosinase, anti-inflammatory, and antioxidant agents).

Optimization of Culture and Sporulation for Two Plant Beneficial Streptomyces Strains

The limited effectiveness of current plant disease management treatments necessitates the development of new methods for controlling diseases using beneficial microbes. Demanding sustainable agriculture is increasingly highlighted as a biocontrol approach, particularly &lt;i&gt;Streptomyces&lt;/i&gt; species known to produce a variety of antibiotic compounds and secondary metabolites. The &lt;i&gt;Streptomyces&lt;/i&gt; globisporus SP6C4 strain and &lt;i&gt;Streptomyces&lt;/i&gt; sp. S8 have been reported as potent antifungal agents and are gaining attention for improving crop growth in sustainable agriculture. In this study, we investigated the use of &lt;i&gt;Streptomyces&lt;/i&gt; species formulations to enhance bacterial growth with nitrogen sources. Specifically, the addition of L-glutamic acid and L-cysteine resulted in earlier sporulation and bacterial growth in &lt;i&gt;Streptomyces&lt;/i&gt; strains, respectively. This approach could expand the range of fermentation techniques in agriculture and be useful for controlling plant growth-promoting bacteria.

Genome mining reveals chitin degradation potential of \(\textit{Streptomyces parvulus}\) VCCM 22513

The genus Streptomyces is not only known as a natural producer of antibiotics but also a prolific source of chitinolytic enzymes that digest recalcitrant chitin to chitooligosaccharides. However, only a few reports have used whole-genome sequencing to study chitin degradation of Streptomyces to date. In the present study, out of 22 Streptomyces strains, Streptomyces parvulus VCCM 22513 produced the highest chitinase activity. Time courses of incubation revealed that the maximum chitinase (0.91 ± 0.04 U/mL) of this strain was observed after 96 hours in the yeast extract salts medium supplemented with 10.0 g/L colloidal chitin. Additional genomic analysis of VCCM 22513 was also conducted to discover the genomic information related to chitin degradation. The VCCM 22513 genome consists of 341 CAZy genes divided into 6 families including glycoside hydrolase (134 genes), carbohydrate-binding module (88 genes), glycosyl transferase (87 genes), carbohydrate esterase (18 genes), polysaccharide lyase (7 genes), and auxiliary activity (7 genes). Further genome mining revealed the presence of 10 chitinases, 4 lytic polysaccharide monooxygenases, and 14 β-N-acetylhexosaminidases, which mainly contribute to the degradation of chitin polymers. This is the first report revealing the mechanism underlying the chitin degradation of S. parvulus. Further investigations are required to characterize chitinolytic enzymes found in this study for the bioeconomic production of high-quality chitooligosaccharides from chitin food wastes.

Exploration of Natural Product Repository by Combined Genomics and Metabolomics Profiling of Mangrove-Derived Streptomyces murinus THV12 Strain

Streptomyces, one of the largest genera belonging to the phylum Actinobacteria, contribute to more than 60% of the clinically relevant antibiotics. The present study outlined the genomics and the metabolomics of a mangrove-derived Streptomyces murinus THV12 strain. The Illumina Hiseq 2500 platform-based whole-genome sequencing of the Streptomyces strain generated a consensus sequence of 8,363,247 bp with 107 contigs and 7345 protein-coding genes, which shared significant homology with genes from Streptomyces murinus. The detection of secondary metabolite biosynthetic gene clusters (smBGCs) in the genome performed using the pipeline antiSMASH v6.1.1 revealed that the strain harbored 47 secondary metabolite clusters, which represented 17.9% of the 8.3 Mb genome. The smBGCs belonged to the metabolite categories: PKS, NRPS, ectoine, lassopeptides, lantipeptides, melanin, siderophores, terpenes and other putative products. The strain showed broad-spectrum antimicrobial activity with a inhibition zone of 30 mm against Gram-positive bacteria and Candida albicans. The secondary metabolite profiling of the crude extracts from the fermentation broth of THV12 was performed with the HPLC system coupled with an Orbitrap Exploris120 high-resolution mass spectrometer. As revealed by in silico analysis, compounds such as actinomycin D, pentamycin, desferrioxamine E and cinnabaramide A were detected with MS/MS analysis. Apart from this, compounds belonging to different chemical scaffolds, such as cyclic and linear peptides, bacterial alkaloids, linear polyketides and terpenoids, were also present in the fermentation broth of the strain when cultivated under the OSMAC (One Strain Many Compounds) approach. Thus, the combined strategy of genome mining and metabolomics of the mangrove-derived strain aided in exploring the chemical diversity of BGCs and new chemical entities, which can contribute to drug leads.

Streptomyces hilarionis sp. nov. and Streptomyces hayashii sp. nov., two new strains associated with potato scab in Brazil.

Two new actinobacteria, designated strains IBSBF 2807T and IBSBF 2953T, isolated from scab lesions on potato tubers grown in the southern Brazilian states of Rio Grande do Sul and Santa Catarina, respectively, were characterized and identified through a polyphasic approach. Phylogenetic analyses of 16S rRNA sequences revealed that these two strains belong to the genus Streptomyces. Multilocus sequence analysis using five concatenated genes, atpD, gyrB, recA, rpoB and trpB, allocated strains IBSBF 2807T and IBSBF 2953T in distinct branches of Streptomyces phytopathogenic strains. PCR-RFLP analysis of the atpD gene also confirmed that these strains differ from the type strains of Streptomyces associated with potato scab. The morphological, physiological and biochemical characterization, along with the overall genome-related index properties, indicated that these two strains could be distinguished from their closest phylogenetic relatives and each other. According to the data, IBSBF 2807T and IBSBF 2953T represent two new Streptomyces species related to potato scab. The proposed names for these strains are Streptomyces hilarionis sp. nov. (IBSBF 2807T=CBMAI 2674T=ICMP 24297T=MUM 22.66T) and Streptomyces hayashii sp. nov (IBSBF 2953T=CBMAI 2675T=ICMP 24301T=MUM 22.68T).

Co-Expression of Transcriptional Regulators and Housekeeping Genes in Streptomyces spp.: A Strategy to Optimize Metabolite Production.

The search for novel bioactive compounds to overcome resistance to current therapeutics has become of utmost importance. Streptomyces spp. are one of the main sources of bioactive compounds currently used in medicine. In this work, five different global transcriptional regulators and five housekeeping genes, known to induce the activation or overproduction of secondary metabolites in Streptomyces coelicolor, were cloned in two separated constructs and expressed in 12 different strains of Streptomyces spp. from the in-house CS collection. These recombinant plasmids were also inserted into streptomycin and rifampicin resistant Streptomyces strains (mutations known to enhance secondary metabolism in Streptomyces). Different media with diverse carbon and nitrogen sources were selected to assess the strains' metabolite production. Cultures were then extracted with different organic solvents and analysed to search for changes in their production profiles. An overproduction of metabolites already known to be produced by the biosynthesis wild-type strains was observed such as germicidin by CS113, collismycins by CS149 and CS014, or colibrimycins by CS147. Additionally, the activation of some compounds such as alteramides in CS090a pSETxkBMRRH and CS065a pSETxkDCABA or inhibition of the biosynthesis of chromomycins in CS065a in pSETxkDCABA when grown in SM10 was demonstrated. Therefore, these genetic constructs are a relatively simple tool to manipulate Streptomyces metabolism and explore their wide secondary metabolites production potential.

Resistom &lt;i&gt;Streptomyces rimosus&lt;/i&gt; - a reservoir of resistance genes to aminoglycoside antibiotics

The study of aminoglycoside acetyltransferases in actinobacteria of the genus Streptomyces is an integral part of the study of soil bacteria as the main reservoir and possible source of drug resistance genes. Previously, in the strain Streptomyces rimosus ATCC 10970 (producing oxyteteracycline), which is resistant to most natural aminoglycoside antibiotics, we have identified and biochemically characterized 3 aminoglycoside phosphotransferases, which cause resistance to kanamycin, neomycin, paromomycin, streptomycin, and hygromycin B. In the presented work, it was shown that resistance to other AGs in this strain is associated with the presence of the enzyme aminoglycoside acetyltransferase, belonging to the AAC(2′) subfamily. Induction of the expression of the gene, designated by us as aac(2′)-If, in Escherichia coli cells determines resistance to a wide range of natural aminoglycoside antibiotics (neomycin, gentamicin, tobramycin, sisomycin, and paromomycin) and to an increase in the minimum inhibitory concentrations of these antibiotics.

Activity of lactic acid-producing Streptomyces strain CSK1against Staphylococcus aureus

Activity of lactic acid-producing Streptomyces strain CSK1against Staphylococcus aureus

Resistome in Streptomyces rimosus - A Reservoir of Aminoglycoside Antibiotics Resistance Genes.

Investigation of aminoglycoside acetyltransferases in actinobacteria of the genus Streptomyces is an integral part of the study of soil bacteria as the main reservoir and possible source of drug resistance genes. Previously, we have identified and biochemically characterized three aminoglycoside phosphotransferases, which cause resistance to kanamycin, neomycin, paromomycin, streptomycin, and hygromycin B in the strain Streptomyces rimosus ATCC 10970 (producing oxytetracycline), which is resistant to most natural aminoglycoside antibiotics. In the presented work, it was shown that the resistance of this strain to other AGs is associated with the presence of the enzyme aminoglycoside acetyltransferase, belonging to the AAC(2') subfamily. Induction of the expression of the gene, designated by us as aac(2')-If, in Escherichia coli cells determines resistance to a wide range of natural aminoglycoside antibiotics (neomycin, gentamicin, tobramycin, sisomycin, and paromomycin) and increases minimum inhibitory concentrations of these antibiotics.

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 7R015T and 7R016T, 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-C16 : 0 and anteiso-C15 : 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 7R015T showed the highest similarity to that of Streptomyces pseudovenezuelae DSM 40212T (98.6 %), Streptomyces cyaneus NRRL B2296T (98.6 %) and Streptomyces curacoi DSM 40107T (98.6 %). Strain 7R016T showed the highest 16S rRNA gene sequence similarity to Streptomyces gilvifuscus NBRC 110904T (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 7R015T, 7R016T 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 7R015T and 7R016T represent novel species of the genus Streptomyces and are named herein as Streptomyces cylindrosporus sp. nov. (=NBRC 115200T = TBRC 14542T) for strain 7R015T and Streptomyces spinosisporus sp. nov. (=NBRC 115201T = TBRC 14543T) for strain 7R016T.

A Streptomyces Consortium Contributes Distinct Microbial Interactions During Arabidopsis thaliana Microbiome Assembly

Although plant microbiome assembly involves a series of both plant–microbe and microbe–microbe interactions, the latter is less often directly tested. Here, we investigate a role for Streptomyces strains to influence assembly of other bacteria into root microbiomes through the use of two synthetic communities (SynComs): a 21-member community including four Streptomyces strains and a 17-member community lacking those Streptomyces strains. Following inoculation with these SynComs on wild-type Arabidopsis thaliana Col-0, differential abundance modeling on root endosphere 16S ribosomal RNA gene amplicon sequencing data revealed altered abundance of four diverse SynCom members: Arthrobacter sp. 131, Agrobacterium sp. 33, Burkholderia sp. CL11, and Ralstonia sp. CL21. Modeling results were tested by seedling coinoculation experiments with the four Streptomyces strains and differentially abundant members, which confirmed the predicted decreased abundance for Arthrobacter sp. 131, Agrobacterium sp. 33, and Ralstonia sp. CL21 when Streptomyces strains were present. We further characterized how the phytohormone salicylic acid (SA) mediates Streptomyces strains’ influence over Agrobacterium sp. 33 and Burkholderia sp. CL11 seedling colonization. Although decreased colonization of Ralstonia sp. CL21 and Arthrobacter sp. 131 when Streptomyces spp. are present were not influenced by SA, direct antibiosis of Arthrobacter sp. 131 by Streptomyces was observed. These results highlight a role for Streptomyces-mediated microbial interactions during plant root microbiome assembly as well as distinct mechanisms that mediate them. Understanding the role of microbial interactions during microbiome assembly will inform the production of beneficial microbial treatments for use in agricultural fields.

Biological Control of Severe Fungal Phytopathogens by Streptomyces albidoflavus Strain CARA17 and Its Bioactive Crude Extracts on Lettuce Plants.

Lettuce crop is an important horticultural crop of several Mediterranean countries, including Italy. The Italian region which is a major producer of lettuce crops is Apulia, where this crop is cultivated in open fields an in greenhouses. Since several microbial pathogens are responsible for important diseases found on lettuce produced in greenhouses, in this study, the experimental activities focused on the most severe fungal soilborne pathogens, i.e., Sclerotinia sclerotiorum and Athelia rolfsii. Their control is often performed with fungicides which cause public concern over the environment and human health. The main aims of this study were to determine the biocontrol efficacy of a Streptomyces strain in vitro and in vivo conditions on lettuce seedlings against Athelia rolfsii and Sclerotinia sclerotiorum as severe fungal soilborne pathogens through the application of its vegetative propagules and putative bioactive crude extracts via filtrate culture. The results obtained confirm a significant effectiveness of CARA17 strain to control the severity of both fungal soilborne pathogens during two different experiments: when it is used as vegetative propagules and as a culture filtrate containing putative bioactive metabolites in vitro and in vivo conditions. These preliminary results demonstrated that the actinomycetes CARA17 strain is valid as a biocontrol agent (BCA) against both the severe phytopathogens used in this study. The biocontrol action performed from the CARA17 strain is clearly and mainly due to the putative bioactive crude extracts produced, but further studies are necessary to identify which metabolites (polyphenols, terpenes, fatty acids, etc.) are produced from this Streptomyces strain.

VALORIZATION OF TOMATO PLANT WASTES AND OPTIMIZATION OF GROWTH CONDITIONS FOR INDOLE-3-ACETIC ACID PRODUCTION BY Streptomyces plicatus STRAIN PT2

This study focused on the production of the phytohormone indole-3-acetic acid (IAA) using tomato plant tissues as feedstock and on highlighting its growth promotion effect on tomato seedlings. Twelve actinobacterial strains were screened for IAA production under standard growth conditions and the strain Streptomyces plicatus PT2 was selected as a promising producer. The establishment of growth conditions to increase IAA production by S. plicatus PT2 was conducted using Plackett-Burman mathematical design with seven variables. The variables L-tryptophan quantity and tomato roots-extract rate were the two significant variables influencing IAA production. The most impacting variables were optimized using the surface methodology (RSM) formulated according to the Central Composite Design (CCD). The optimized broth supplemented with 4 mg L-1 of L-tryptophan and 25% of tomato roots-extract significantly improved the IAA production from 96.3 µg mL-1 within 120h to a maximum of 110.29 µg mL-1 within 96h. The in-planta application of the produced IAA and a chemical IAA showed a significant increase in the dry weight, the shoot and root lengths of tomato seedlings. This is the first study showing the production of IAA using Streptomyces plicatus strain PT2 by exploring tomato plant tissues and its plant-growth promotion efficacy compared to a chemical marketed one. These results support a reasonable approach for the valorization of abundant worldwide tomato plant wastes in the phytohormones production bioprocesses.

Production of Diketopiperazine Derivatives by Pathway Engineering with Different Cyclodipeptide Synthases from Various Streptomyces Strains.

Cyclodipeptides from fungi and bacteria are often modified by different tailoring enzymes. They display various biological and pharmacological activities, and some derivatives are used as drugs. In a previous study, we elucidated the function of the silent guatrypmethine gene cluster from Streptomyces cinnamoneus containing a cyclodipeptide synthase (CDPS) core gene gtmA and four genes gtmB-gtmE for tailoring enzymes. The latter are used in this study for the design of modified cyclodipeptides by genetic engineering. Addition of six different cyclodipeptides to the Streptomyces albus transformant harboring gtmB-gtmE led to the detection of different pathway products. Coexpression of five CDPS genes from four Streptomyces strains with gtmB-gtmE resulted in the formation of diketopiperazine derivatives, differing in their modification stages. Our results demonstrate the potential of rational gene combination to increase structural diversity.

Endophytic actinobacteria from wild medicinal plants are a natural source of insecticide to control the African cotton leafworm (Spodoptera littoralis)

Insecticide resistance in agricultural pests has prompted the need to discover novel compounds with new modes of action. We investigated the potency of secondary metabolites from seventy endophytic actinobacteria against laboratory and field strains of Spodoptera littoralis (fourth instar), comparable to the bioinsecticide spinetoram (Radiant SC 12%). Endophytes from Artemisia herba-alba and A. judaica were highly effective. Chemical profiling of the most potent metabolite of the strain Streptomyces sp. ES2 was investigated using LC-QTOF-MS-MS technique, and the activity was validated through molecular docking studies. Metabolic extracts from actinobacteria belonging to Streptomyces, Nocardioides, and Pseudonocardia showed immediate and latent death to the Spodoptera littoralis fourth instar larvae. The metabolite from strain ES2 has shown the most promising and significant histopathological and inhibitory effects on the fourth instar larvae. ES2 metabolite caused lesions in the body wall cuticle, indicating a different mode of action than that of Radiant. Chemical profiling of ES2 showed the presence of cyromazine (molt inhibitor), 4-nitrophenol, and diazinon as key constituents. In conclusion, these findings suggest that secondary metabolites from endophytic actinobacteria inhabiting wild medicinal plants can be a sustainable source for promising natural biocontrol agents. This is the first illustration of the insecticidal activity of Artemisia spp. microbiome, and natural cyromazine synthesis by actinobacteria.

Efomycine U, a new C2 -asymmetric elaiophylin derivative from Streptomyces malaysiensis DSM 4137

Chemical examination of an actinomycete strain Streptomyces malaysiensis DSM 4137 derived from a soil sample derived isolate Streptomyces sp. DSM 3816, yielded a new C2 -asymmetric elaiophylin derivative efomycine U (1) and a known analogue halichoblelide D (2). These structures were unambiguously elucidated on the basis of extensive NMR spectroscopic and mass spectrometric analyses. All compounds isolated were subjected to antimicrobial, cytotoxic and immnosuppressive activities evaluation.

Discovery and biosynthetic assessment of 'Streptomyces ortus' sp. nov. isolated from a deep-sea sponge.

The deep sea is known to host novel bacteria with the potential to produce a diverse array of undiscovered natural products. Thus, understanding these bacteria is of broad interest in ecology and could also underpin applied drug discovery, specifically in the area of antimicrobials. Here, we isolate a new strain of Streptomyces from the tissue of the deep-sea sponge Polymastia corticata collected at a depth of 1869 m from the Gramberg Seamount in the Atlantic Ocean. This strain, which was given the initial designation A15ISP2-DRY2T, has a genome size of 9.29 Mb with a G+C content of 70.83 mol%. Phylogenomics determined that A15ISP2-DRY2T represents a novel species within the genus Streptomyces as part of the Streptomyces aurantiacus clade. The biosynthetic potential of A15ISP2-DRY2T was assessed relative to other members of the S. aurantiacus clade via comparative gene cluster family (GCF) analysis. This revealed a clear congruent relationship between phylogeny and GCF content. A15ISP2-DRY2T contains six unique GCFs absent elsewhere in the clade. Culture-based assays were used to demonstrate the antibacterial activity of A15ISP2-DRY2T against two drug-resistant human pathogens. Thus, we determine A15ISP2-DRY2T to be a novel bacterial species with considerable biosynthetic potential and propose the systematic name 'Streptomyces ortus' sp. nov.

Specific Streptomyces strain enhances the growth, defensive mechanism, and fruit quality of cucumber by minimizing its fertilizer consumption

BackgroundThe required amounts of chemical fertilizers (NPK) are determined by plant yield, and product quality is given less consideration. The use of PGPRs is an environmentally friendly approach that, in addition to increasing yield, also improves fruit quality. This study examined the role of specific Streptomyces strains in aiding cucumber plants to 1) use fewer NPK fertilizers in the same quantity 2) improve the quality of cucumber fruit, and 3) promote growth and defense system.ResultsIn this study, the effect of 17 Streptomyces strains on the vegetative traits of cucumber seedlings of the Sultan cultivar was evaluated as the first test. Four strains of Streptomyces with the highest root and shoot dry weight were selected from the strains. This experiment was performed to determine the interaction effect of selected strains and different amounts of NPK on cucumber yield, quality, physiological and biochemical responses of plants. The first experiment’s results revealed that strains IC6, Y7, SS12, and SS14 increased significantly in all traits compared to the control, while the other strains dramatically improved several characteristics. Analysis of variance (ANOVA) revealed significant differences between the effect of strains, NPK concentrations, and their interactions on plant traits. The treatments containing 75% NPK + SS12, yielded the most fruit (40% more than the inoculated control). Antioxidant enzymes assay showed that SS12 substantially increased the activity of POX, PPO, and the expression of the genes related to these two enzymes. Hormone assay utilizing HPLC analysis revealed that various strains employ a specific mechanism to improve the immune system of plants.ConclusionsTreatment with strain SS12 led to the production of cucumbers with the highest quality by reducing the amount of nitrate, and soluble sugars and increasing the amount of antioxidants and firmness compared to other treatments. A specific Streptomyces strain could reduce 25% of NPK fertilizer during the vegetative and reproductive growth period. Moreover, this strain protected plants against possible pathogens and adverse environmental factors through the ISR and SAR systems.