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Applied and Environmental Microbiology Feb 2022New antimicrobial agents are urgently needed to combat the emergence and spread of multidrug-resistant bacteria. Activating the cryptic biosynthetic gene clusters for...
New antimicrobial agents are urgently needed to combat the emergence and spread of multidrug-resistant bacteria. Activating the cryptic biosynthetic gene clusters for actinomycete secondary metabolites can provide essential clues for research into new antimicrobial agents. An effective method for this purpose is based on drug resistance selection. This report describes interesting results for drug resistance selection using antibiotics that target DNA replication and can effectively potentiate secondary metabolite production by actinomycetes. Ofloxacin-resistant mutants were isolated from five different streptomycetes. Ofloxacin is an antibiotic that binds to DNA complexes and type II topoisomerase, causing double-stranded breaks in bacterial chromosomes. Physiological and genetic characterization of the mutants revealed that the development of ofloxacin resistance in streptomycetes leads to the emergence of various types of secondary metabolite-overproducing strains. In Streptomyces coelicolor A3(2), ofloxacin-resistant mutants that overproduced actinorhodin, undecylprodigiosin, or carotenoid were identified. An ofloxacin-resistant mutant that overproduces methylenomycin A, whose biosynthetic gene cluster is located on the endogenous plasmid, SCP1, also was isolated. These observations indicate that ofloxacin resistance activates biosynthetic genes on both chromosomes and endogenous plasmids. We also identified the mutations that are probably involved in the phenotype of ofloxacin resistance and secondary metabolite overproduction in S. coelicolor A3(2). Furthermore, we observed an interesting phenomenon in which several ofloxacin-resistant mutants overproduced antibiotics in the presence of ofloxacin. Based on these results, we present the unique physiological and genetic characteristics of ofloxacin-resistant mutants and discuss the importance and potential development of the new findings. The abuse or overuse of antibacterial agents for therapy and animal husbandry has caused an increased population of antimicrobial-resistant bacteria in the environment. Consequently, fewer effective antimicrobials are now available. Due to the depleted antibiotic pipeline, pandemic outbreaks caused by antimicrobial-resistant bacteria are deeply concerning, and the development of new antibiotics is now an urgent issue. Promising sources of antimicrobial agents include cryptic biosynthetic gene clusters for secondary metabolites in streptomycetes and rare actinomycetes. This study's significance is the development of an unprecedented activation method to accelerate drug discovery research on a global scale. The technique developed in this study could allow for simultaneous drug discovery in different countries, maximizing the world's microbial resources.
Topics: Anti-Bacterial Agents; Drug Resistance, Bacterial; Multigene Family; Ofloxacin; Streptomyces; Streptomyces coelicolor
PubMed: 34936843
DOI: 10.1128/aem.02327-21 -
International Journal of Environmental... Nov 2020The purpose of this study was to investigate streptomycete populations in desert and savanna ecozones in Sudan and to identify species based on 16S rRNA gene sequences....
The purpose of this study was to investigate streptomycete populations in desert and savanna ecozones in Sudan and to identify species based on 16S rRNA gene sequences. A total of 49 different phenotypes (22 from sites representing the desert and semi-desert ecozone; 27 representing the savanna ecozone) have been included in the study. The isolates were characterized phenotypically and confirmed using 16S rRNA gene sequence analysis. The two ecozones showed both similarities and uniqueness in the types of isolates. The shared species were in cluster 1 (, cluster 2 ( sp.), cluster 3 (-like), and cluster 7 (. The desert ecozone revealed unique species in cluster 9 ( sp.) and cluster 10 (). Whereas, the savanna ecozone revealed unique species in cluster 4 ( sp.), cluster 5 (), cluster 6 (), and cluster 8 ( sp.). Streptomycetes are widely distributed in both desert and the savanna ecozones and many of these require full descriptions. Extending knowledge on communities and their dynamics in different ecological zones and their potential antibiotic production is needed.
Topics: Cluster Analysis; Desert Climate; Genetic Variation; Grassland; Phylogeny; RNA, Ribosomal, 16S; Soil Microbiology; Streptomyces; Sudan
PubMed: 33255614
DOI: 10.3390/ijerph17238749 -
Journal of Visualized Experiments : JoVE Sep 2018Streptomycetes are filamentous soil bacteria belonging to the phylum Actinobacteria that are found throughout the world and produce a wide array of antibiotics and other...
Streptomycetes are filamentous soil bacteria belonging to the phylum Actinobacteria that are found throughout the world and produce a wide array of antibiotics and other secondary metabolites. Streptomyces coelicolor is a well-characterized, non-pathogenic species that is amenable to a variety of analyses in the lab. The phenotyping methods described here use S. coelicolor as a model streptomycete; however, the methods are applicable to all members of this large genus as well as some closely related actinomycetes. Phenotyping is necessary to characterize new species of Streptomyces identified in the environment, and it is also a vital first step in characterizing newly isolated mutant strains of Streptomyces. Proficiency in phenotyping is important for the many new researchers who are entering the field of Streptomyces research, which includes the study of bacterial development, cell division, chromosome segregation, and second messenger signaling. The recent crowdsourcing of antibiotic discovery through the isolation of new soil microbes has resulted in an increased need for training in phenotyping for instructors new to the field of Streptomyces research and their college or high school students. This manuscript describes methods for bacterial strain propagation, storage, and characterization through visual and microscopic examination. After reading this article, new researchers (microbiology education laboratories and citizen scientists) should be able to manipulate Streptomyces strains and begin visual characterization experiments.
Topics: Streptomyces
PubMed: 30272646
DOI: 10.3791/57373 -
Nature Communications Jan 2022Filamentous actinobacteria such as Streptomyces undergo two distinct modes of cell division, leading to partitioning of growing hyphae into multicellular compartments...
Filamentous actinobacteria such as Streptomyces undergo two distinct modes of cell division, leading to partitioning of growing hyphae into multicellular compartments via cross-walls, and to septation and release of unicellular spores. Specific determinants for cross-wall formation and the importance of hyphal compartmentalization for Streptomyces development are largely unknown. Here we show that SepX, an actinobacterial-specific protein, is crucial for both cell division modes in Streptomyces venezuelae. Importantly, we find that sepX-deficient mutants grow without cross-walls and that this substantially impairs the fitness of colonies and the coordinated progression through the developmental life cycle. Protein interaction studies and live-cell imaging suggest that SepX contributes to the stabilization of the divisome, a mechanism that also requires the dynamin-like protein DynB. Thus, our work identifies an important determinant for cell division in Streptomyces that is required for cellular development and sporulation.
Topics: Bacterial Proteins; Biological Phenomena; Cell Division; Cell Wall; Hyphae; Life Cycle Stages; Spores, Bacterial; Streptomyces
PubMed: 35013186
DOI: 10.1038/s41467-021-27638-1 -
Microbiology (Reading, England) Aug 2020The actinomycetes are Gram-positive bacteria belonging to the order within the phylum . They include members with significant economic and medical importance, for... (Review)
Review
The actinomycetes are Gram-positive bacteria belonging to the order within the phylum . They include members with significant economic and medical importance, for example filamentous actinomycetes such as species, which have a propensity to produce a plethora of bioactive secondary metabolites and form symbioses with higher organisms, such as plants and insects. Studying these bacteria is challenging, but also fascinating and very rewarding. As a Microbiology Society initiative, members of the actinomycete research community have been developing a Wikipedia-style resource, called ActinoBase, the purpose of which is to aid in the study of these filamentous bacteria. This review will highlight 10 publications from 2019 that have been of special interest to the ActinoBase community, covering 4 major components of actinomycete research: (i) development and regulation; (ii) specialized metabolites; (iii) ecology and host interactions; and (iv) technology and methodology.
Topics: Actinobacteria; Animals; Bacteriological Techniques; Biological Products; Biomedical Research; Databases, Factual; Environmental Microbiology; Gene Expression Regulation, Bacterial; Streptomyces; Symbiosis
PubMed: 32558638
DOI: 10.1099/mic.0.000944 -
Applied and Environmental Microbiology Nov 2021The production of specialized metabolites by bacteria is usually temporally regulated. This regulation is complex and frequently involves both global and...
The production of specialized metabolites by bacteria is usually temporally regulated. This regulation is complex and frequently involves both global and pathway-specific mechanisms. Streptomyces ambofaciens ATCC23877 produces several specialized metabolites, including spiramycins, stambomycins, kinamycins and congocidine. The production of the first three molecules has been shown to be controlled by one or several cluster-situated transcriptional regulators. However, nothing is known regarding the regulation of congocidine biosynthesis. Congocidine (netropsin) belongs to the family of pyrrolamide metabolites, which also includes distamycin and anthelvencins. Most pyrrolamides bind into the minor groove of DNA, specifically in A/T-rich regions, which gives them numerous biological activities, such as antimicrobial and antitumoral activities. We previously reported the characterization of the pyrrolamide biosynthetic gene clusters of congocidine () in S. ambofaciens ATCC23877, distamycin () in Streptomyces netropsis DSM40846, and anthelvencins () in Streptomyces venezuelae ATCC14583. The three gene clusters contain a gene encoding a putative transcriptional regulator, , , and respectively. Cgc1, Dst1, and Ant1 present a high percentage of amino acid sequence similarity. We demonstrate here that Cgc1, an atypical orphan response regulator, activates the transcription of all genes in the stationary phase of S. ambofaciens growth. We also show that the cluster is constituted of eight main transcriptional units. Finally, we show that congocidine induces the expression of the transcriptional regulator Cgc1 and of the operon containing the resistance genes ( and , coding for an ABC transporter), and propose a model for the transcriptional regulation of the gene cluster. Understanding the mechanisms of regulation of specialized metabolite production can have important implications both at the level of specialized metabolism study (expression of silent gene clusters) and at the biotechnological level (increase of the production of a metabolite of interest). We report here a study on the regulation of the biosynthesis of a metabolite from the pyrrolamide family, congocidine. We show that congocidine biosynthesis and resistance are controlled by Cgc1, a cluster-situated regulator. As the gene clusters directing the biosynthesis of the pyrrolamides distamycin and anthelvencin encode a homolog of Cgc1, our findings may be relevant for the biosynthesis of other pyrrolamides. In addition, our results reveal a new type of feed-forward induction mechanism, in which congocidine induces its own biosynthesis through the induction of the transcription of .
Topics: Distamycins; Gene Expression Regulation, Bacterial; Genes, Bacterial; Multigene Family; Netropsin; Streptomyces
PubMed: 34586912
DOI: 10.1128/AEM.01380-21 -
Nature May 2024Streptomyces are a genus of ubiquitous soil bacteria from which the majority of clinically utilized antibiotics derive. The production of these antibacterial molecules...
Streptomyces are a genus of ubiquitous soil bacteria from which the majority of clinically utilized antibiotics derive. The production of these antibacterial molecules reflects the relentless competition Streptomyces engage in with other bacteria, including other Streptomyces species. Here we show that in addition to small-molecule antibiotics, Streptomyces produce and secrete antibacterial protein complexes that feature a large, degenerate repeat-containing polymorphic toxin protein. A cryo-electron microscopy structure of these particles reveals an extended stalk topped by a ringed crown comprising the toxin repeats scaffolding five lectin-tipped spokes, which led us to name them umbrella particles. Streptomyces coelicolor encodes three umbrella particles with distinct toxin and lectin composition. Notably, supernatant containing these toxins specifically and potently inhibits the growth of select Streptomyces species from among a diverse collection of bacteria screened. For one target, Streptomyces griseus, inhibition relies on a single toxin and that intoxication manifests as rapid cessation of vegetative hyphal growth. Our data show that Streptomyces umbrella particles mediate competition among vegetative mycelia of related species, a function distinct from small-molecule antibiotics, which are produced at the onset of reproductive growth and act broadly. Sequence analyses suggest that this role of umbrella particles extends beyond Streptomyces, as we identified umbrella loci in nearly 1,000 species across Actinobacteria.
Topics: Anti-Bacterial Agents; Antibiosis; Bacterial Proteins; Bacterial Toxins; Cryoelectron Microscopy; Lectins; Microbial Sensitivity Tests; Models, Molecular; Streptomyces; Streptomyces coelicolor; Streptomyces griseus
PubMed: 38632398
DOI: 10.1038/s41586-024-07298-z -
Applied Microbiology Feb 1972A simplified technique to detect polyphenol oxidase and melanin formation by Streptomyces culture filtrates was developed. The procedure involves the direct assay of...
A simplified technique to detect polyphenol oxidase and melanin formation by Streptomyces culture filtrates was developed. The procedure involves the direct assay of pigment formation by the culture filtrate with 3-(3,4-dihydroxyphenyl)-L-alanine (L-dopa) as a substrate. Among cultures of the International Streptomyces Project, 34 failed to produce a diffusible dark brown pigment on peptone-yeast extract-iron-agar and synthetic tyrosine-agar and gave a negative reaction to the melanin formation test. Sixteen cultures produced a diffusible dark brown pigment on both peptone-yeast extract-iron-agar and synthetic tyrosine-agar and gave positive reactions to the test with either L-tyrosine or L-dopa as substrate. Twenty-one cultures produced a diffusible dark brown pigment on peptone-yeast extract-iron-agar, but failed to do so on synthetic tyrosine-agar. Most of these cultures gave a positive reaction to the test when L-dopa was used as the substrate. The correlation between chromogenicity on complex organic media and melanin formation was more clearly established with L-dopa as substrate than with synthetic tyrosine-agar in the present test. The melanin formation test by the present technique, instead of chromogenicity on complex organic media, is recommended as a key feature for the classification of Streptomyces.
Topics: Agar; Amino Acids; Bacteriological Techniques; Carbohydrate Metabolism; Catechol Oxidase; Culture Media; Dihydroxyphenylalanine; Glutamates; Iron; Melanins; Peptones; Plant Extracts; Saccharomyces; Species Specificity; Spectrophotometry; Streptomyces; Tyrosine
PubMed: 4622831
DOI: 10.1128/am.23.2.402-406.1972 -
Bioscience, Biotechnology, and... Feb 2007The complex morphogenesis of the bacterial genus Streptomyces has made this genus a model prokaryote for study of multicellular differentiation, and its ability to... (Review)
Review
The complex morphogenesis of the bacterial genus Streptomyces has made this genus a model prokaryote for study of multicellular differentiation, and its ability to produce a wide variety of secondary metabolites has made it an excellent supplier of biologically active substances, including antibiotics. This review summarizes our study of these two characteristics of Streptomyces, focusing on the A-factor regulatory cascade and work derived from the A-factor study. A microbial hormone, A-factor (2-isocapryloyl-3R-hydroxymethyl-gamma-butyrolactone), triggers morphological differentiation and secondary metabolism in Streptomyces griseus. The key steps in the A-factor regulatory cascade, including afsA, encoding the key enzyme for A-factor biosynthesis, arpA, encoding the A-factor receptor, and adpA, encoding a transcriptional activator, are elucidated. The target genes of the regulatory cascade include genes of various functions required for morphological development and secondary metabolite formation. The biosynthesis gene clusters for grixazone and hexahydroxyperylenequinone are examples. The former contains the enzymes for novel benzene ring formation and phenoxazinone formation, and the latter contains enzymes belonging to a type III polyketide synthase and a cytochrome P-450. Enzymes of various catalytic functions in Streptomyces are useful as members of an artificial gene cluster constructed in Escherichia coli for fermentative production of plant-specific flavonoids, including isoflavones and unnatural compounds.
Topics: Anti-Bacterial Agents; Catalysis; Combinatorial Chemistry Techniques; DNA, Bacterial; Gene Expression Regulation, Bacterial; Models, Molecular; Streptomyces
PubMed: 17284841
DOI: 10.1271/bbb.60627 -
Brazilian Journal of Microbiology :... 2018Fifty seven soil-borne actinomycete strains were assessed for the antibiotic production. Two of the most active isolates, designed as Streptomyces ST-13 and DK-15...
Fifty seven soil-borne actinomycete strains were assessed for the antibiotic production. Two of the most active isolates, designed as Streptomyces ST-13 and DK-15 exhibited a broad range of antimicrobial activity and therefore they were selected for HPLC fractionation against the most suppressed bacteria Staphylococcus aureus (ST-13) and Chromobacterium violaceum (DK-15). LC/MS analysis of extracts showed the presence of polyketides factumycin (DK15) and tetrangomycin (ST13). The taxonomic position of the antibiotic-producing actinomycetes was determined using a polyphasic approach. Phenotypic characterization and 16S rRNA gene sequence analysis of the isolates matched those described for members of the genus Streptomyces. DK-15 strain exhibited the highest 16S rRNA gene sequence similarity to Streptomyces globosus DSM-40815 (T) and Streptomyces toxytricini DSM-40178 (T) and ST-13 strain to Streptomyces ederensis DSM-40741 (T) and Streptomyces phaeochromogenes DSM-40073 (T). For the proper identification, MALDI-TOF/MS profile of whole-cell proteins led to the identification of S. globosus DK-15 (accession number: KX527570) and S. ederensis ST13 (accession number: KX527568). To our knowledge, there is no report about the production of these antibiotics by S.globosus and S. ederensis, thus isolates DK15 and ST13 identified as S. globosus DK-15 and S.ederensis ST-13 can be considered as new sources of these unique antibacterial metabolites.
Topics: Anti-Bacterial Agents; Bacterial Typing Techniques; Benz(a)Anthracenes; DNA, Bacterial; Phylogeny; Pyridones; Soil Microbiology; Streptomyces
PubMed: 29705162
DOI: 10.1016/j.bjm.2017.12.007