publications of the research group microbial strain collection(MISG): Recent submissions
Now showing items 21-31 of 31
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Draft Genome Sequence of Streptomyces sp. Strain RFCAC02, Isolated from the Gut Microflora of the Pacific Chub Mackerel Scomber japonicus peruanus.A new strain of Streptomyces sp., strain RFCAC02, was isolated from the gut of the Pacific chub mackerel Scomber japonicus peruanus This strain produces a variety of secondary metabolites. Further bioinformatic analysis revealed the presence of biosynthetic gene clusters putatively coding for compounds related to the polycyclic tetramate macrolactams (PTMs).
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Biosynthesis of Polyketides in Streptomyces.Polyketides are a large group of secondary metabolites that have notable variety in their structure and function. Polyketides exhibit a wide range of bioactivities such as antibacterial, antifungal, anticancer, antiviral, immune-suppressing, anti-cholesterol, and anti-inflammatory activity. Naturally, they are found in bacteria, fungi, plants, protists, insects, mollusks, and sponges. Streptomyces is a genus of Gram-positive bacteria that has a filamentous form like fungi. This genus is best known as one of the polyketides producers. Some examples of polyketides produced by Streptomyces are rapamycin, oleandomycin, actinorhodin, daunorubicin, and caprazamycin. Biosynthesis of polyketides involves a group of enzyme activities called polyketide synthases (PKSs). There are three types of PKSs (type I, type II, and type III) in Streptomyces responsible for producing polyketides. This paper focuses on the biosynthesis of polyketides in Streptomyces with three structurally-different types of PKSs.
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Streptomyces ciscaucasicus Sveshnikova et al. 1983 is a later subjective synonym of Streptomyces canus Heinemann et al. 1953.he respiratory tract is constantly exposed to the environment and displays a favorable niche for colonizing microorganisms. However, the effects of respiratory bacterial carriage on the immune system and its implications for secondary responses remain largely unclear. We have employed respiratory carriage with Bordetella bronchiseptica as the underlying model to comprehensively address effects on subsequent immune responses. Carriage was associated with the stimulation of Bordetella-specific CD4(+), CD8(+), and CD4(+)CD25(+)Foxp3(+) T cell responses, and broad transcriptional activation was observed in CD4(+)CD25(+) T cells. Importantly, transfer of leukocytes from carriers to acutely B. bronchiseptica infected mice, resulted in a significantly increased bacterial burden in the recipient's upper respiratory tract. In contrast, we found that respiratory B. bronchiseptica carriage resulted in a significant benefit for the host in systemic infection with Listeria monocytogenes. Adaptive responses to vaccination and influenza A virus infection, were unaffected by B. bronchiseptica carriage. These data showed that there were significant immune modulatory processes triggered by B. bronchiseptica carriage, that differentially affect subsequent immune responses. Therefore, our results demonstrated the complexity of immune regulation induced by respiratory bacterial carriage, which can be beneficial or detrimental to the host, depending on the pathogen and the considered compartment.
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Ala-geninthiocin, a new broad spectrum thiopeptide antibiotic, produced by a marine Streptomyces sp. ICN19.Bioassay-guided screening of antibacterial compounds from the cultured marine Streptomyces sp. ICN19 provided Ala-geninthiocin (1), along with its known analogs geninthiocin (2) and Val-geninthiocin (3) and the indolocarbazole staurosporine (4). The structure of 1 was determined on the basis of 1D and 2D NMR spectra and ESI-HRMS. The absolute configurations of the amino acid residues were determined by enantioselective GC-MS analysis. Compound 1 exhibited potent activity against Gram-positive bacteria including Staphylococcus aureus, Bacillus subtilis, Mycobacterium smegmatis, and Micrococcus luteus, as well as cytotoxicity against A549 human lung carcinoma cells with an IC50 value of 6 nM
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Two New Cyathane Diterpenoids from Mycelial Cultures of the Medicinal Mushroom Hericium erinaceus and the Rare Species, Hericium flagellum.Basidiomycetes of the genusHericiumare among the most praised medicinal and edible mushrooms, which are known to produce secondary metabolites with the potential to treat neurodegenerative diseases. This activity has been attributed to the discovery of various terpenoids that can stimulate the production of nerve growth factor (NGF) or (as established more recently) brain-derived neurotrophic factor (BDNF) in cell-based bioassays. The present study reports on the metabolite profiles of a Lion's Mane mushroom (Hericium erinaceus) strain and a strain of the rare species,Hericium flagellum(synonymH. alpestre). While we observed highly similar metabolite profiles between the two strains that were examined, we isolated two previously undescribed metabolites, given the trivial names erinacines Z1 and Z2. Their chemical structures were elucidated by means of nuclear magnetic resonance (NMR) spectroscopy and high resolution mass spectrometry. Along with six further, previously identified cyathane diterpenes, the novel erinacines were tested for neurotrophin inducing effects. We found that erinacines act onBDNF, which is a neurotrophic factor that has been reported recently by us to be induced by the corallocins, but as well onNGFexpression, which is consistent with the literature.
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Six Heterocyclic Metabolites from the Myxobacterium Labilithrix luteola.Two new secondary metabolites, labindole A [2-methyl-3-(2-nitroethyl)-3H-indole] (1) and labindole B [2-methyl-3-(2-nitrovinyl)-3H-indole] (2), were isolated from the myxobacteriumLabilithrixluteola(DSM 27648T). Additionally, four metabolites3,4,5and6already known from other sources were obtained. Their structures were elucidated from high resolution electrospray ionisation mass spectrometry (HRESIMS) and 1D and 2D nuclear magnetic resonance (NMR) spectroscopy data and their relative configuration was assigned based on nuclear Overhauser effect (NOE) and vicinal ¹H-NMR coupling data. The compounds where tested for biological activities; labindoles A (1) and B (2) exhibited significant activity against Hepatitis C Virus, 9H-carbazole (3), 3-chloro-9H-carbazole (4) and 4-hydroxymethyl-quinoline (5) showed antifungal activities. Moreover, compound3had weak to moderate antibacterial activities, while labindoles A (1) and B (2) were devoid of significant antifungal and antibacterial effects.
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Taxonomic analyses of members of the Streptomyces cinnabarinus cluster, description of Streptomyces cinnabarigriseus sp. nov. and Streptomyces davaonensis sp. nov.Roseoflavin is the only known riboflavin (vitamin B2) analog with antibiotic properties. It is actively taken up by many micro-organisms and targets flavinmononucleotide riboswitches and flavoproteins. It is described as the product of the tentatively named 'Streptomyces davawensis' JCM 4913. Taxonomic analysis of this strain with a polyphasic approach showed that it is very closely related to Streptomyces cinnabarinus (DSM 40467). The two Streptomyces isolates were obtained from different geographical locations (the Philippines and the Kamchatka Peninsula, respectively), their genomes have been sequenced and the question was whether or not the two isolates were representatives of the same species. As we also worked with another isolate of Streptomyces cinnabarinus JS 360, the producer of the cinnabaramides, we wanted to clarify the taxonomic position of the three isolates by using a polyphasic approach. After analysis of the 16S rRNA gene sequence, we found in total 23 species of the genus Streptomyces that showed a similarity higher than 98.5 % to the three strains. We showed that 'S. davawensis' JCM 4913 and S. cinnabarinus DSM 40467 were very closely related but belong to two different species. Hence, we validate 'S. davawensis' as Streptomyces davaonensis sp. nov. with the type strain JCM 4913T (=DSM 101723T). In addition, the cinnabaramide producer can be clearly differentiated from S. davaonensis and this isolate is described as Streptomyces cinnabarigriseus sp. nov. with strain JS360T (=NCCB 100590T=DSM 101724T) as the type strain.
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Soil myxobacteria as a potential source of polyketide-peptide substances.Myxobacteria, a group of antimicrobial producing bacteria, have been successfully cultured and characterized from ten soil samples collected from different parts of Slovakia. A total of 79 myxobacteria belonging to four genera (Myxococcus, Corallococcus, Sorangium, and Polyangium) were isolated based on aspects of their life cycle. Twenty-five of them were purified, fermented, and screened for antimicrobial activities against 11 test microorganisms. Results indicated that crude extracts showed more significant activities against Gram-positive than against Gram-negative bacteria or fungi. Based on a higher degree and broader range of antimicrobial production, the two most potential extracts (K9-5, V3-1) were selected for HPLC fractionation against Micrococcus luteus and Staphylococcus aureus and LC/MS analysis of potential antibiotic metabolites. The analysis resulted in the identification of polyketide-peptide antibiotics, namely corallopyronin A and B (K9-5) and myxalamid B and C (V3-1), which were responsible for important Gram-positive activity in the observed strains. A sequence similarity search through BLAST revealed that these strains showed the highest sequence similarity to Corallococcus coralloides (K9-5, NCBI accession number KX256198) and Myxococcus xanthus (V3-1, NCBI accession number KX256197). Although screening of myxobacteria is laborious, due to difficulties in isolating cultures, this research represented the first report covering the isolation and cultivation of this challenging bacterial group from Slovakian soils as well as the screening of their antimicrobial activity, cultural identification, and secondary metabolite identification.
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Actinobacteria and Myxobacteria-Two of the Most Important Bacterial Resources for Novel Antibiotics.Bacteria have been by far the most promising resource for antibiotics in the past decades and will in all undoubtedly remain an important resource of innovative bioactive natural products in the future. Actinobacteria have been screened for many years, whereas the Myxobacteria have been underestimated in the past. Even though Actinobacteria belong to the Gram-positive and Myxobacteria to the Gram-negative bacteria both groups have a number of similar characters, as they both have huge genomes with in some cases more than 10kB and a high GC content and they both can differentiate and have often cell cycles including the formation of spores. Actinobacteria have been used for the antibiotic research for many years, hence it is often discussed whether this resource has now been exhaustively exploited but most of the screening programs from pharmaceutical companies were basing on the cultivation mainly of members of the genus Streptomyces or Streptomyces like strains (e.g., some Saccharopolyspora, Amycolatopsis or Actinomadura species) by use of standard methods so that many of the so called "neglected" Actinobacteria were overlooked the whole time. The present review gives an overview on the state of the art regarding new bioactive compounds with a focus on the marine habitats. Furthermore, the evaluation of Myxobacteria in our ongoing search for novel anti-infectives is highlighted.
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Actinobacteria from Arid and Desert Habitats: Diversity and Biological Activity.The lack of new antibiotics in the pharmaceutical pipeline guides more and more researchers to leave the classical isolation procedures and to look in special niches and ecosystems. Bioprospecting of extremophilic Actinobacteria through mining untapped strains and avoiding resiolation of known biomolecules is among the most promising strategies for this purpose. With this approach, members of acidtolerant, alkalitolerant, psychrotolerant, thermotolerant, halotolerant and xerotolerant Actinobacteria have been obtained from respective habitats. Among these, little survey exists on the diversity of Actinobacteria in arid areas, which are often adapted to relatively high temperatures, salt concentrations, and radiation. Therefore, arid and desert habitats are special ecosystems which can be recruited for the isolation of uncommon Actinobacteria with new metabolic capability. At the time of this writing, members of Streptomyces, Micromonospora, Saccharothrix, Streptosporangium, Cellulomonas, Amycolatopsis, Geodermatophilus, Lechevalieria, Nocardia, and Actinomadura are reported from arid habitats. However, metagenomic data present dominant members of the communities in desiccating condition of areas with limited water availability that are not yet isolated. Furthermore, significant diverse types of polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) genes are detected in xerophilic and xerotolerant Actinobacteria and some bioactive compounds are reported from them. Rather than pharmaceutically active metabolites, molecules with protection activity against drying such as Ectoin and Hydroxyectoin with potential application in industry and agriculture have also been identified from xerophilic Actinobacteria. In addition, numerous biologically active small molecules are expected to be discovered from arid adapted Actinobacteria in the future. In the current survey, the diversity and biotechnological potential of Actinobacteria obtained from arid ecosystems, along with the recent work trend on Iranian arid soils, are reported.
