scholarly journals Discovery of a polybrominated aromatic secondary metabolite from a planctomycete points at an ambivalent interaction with its macroalgae host

2019 ◽  
Author(s):  
Fabian Panter ◽  
Ronald Garcia ◽  
Angela Thewes ◽  
Nestor Zaburannyi ◽  
Boyke Bunk ◽  
...  

AbstractThe roles of the majority of bacterial secondary metabolites, especially those from uncommon sources are yet elusive even though many of these compounds show striking biological activities. To further investigate the secondary metabolite repertoire of underexploited bacterial families, we chose to analyze a novel representative of the yet untapped bacterial phylum Planctomycetes for the production of secondary metabolites under laboratory culture conditions. Development of a planctomycetal high density cultivation technique in combination with high resolution mass spectrometric analysis revealed Planctomycetales strain 10988 to produce the plant toxin 3,5 dibromo p-anisic acid. This molecule represents the first secondary metabolite reported from any planctomycete. Genome mining revealed the biosynthetic origin of this doubly brominated secondary metabolite and a biosynthesis model for the com-pound was devised. Comparison of the biosynthetic route to biosynthetic gene clusters responsible for formation of polybrominated small aromatic compounds reveals evidence for an evolutionary link, while the compound’s herbicidal activity points towards an ambivalent role of the metabolite in the planctomycetal ecosystem.

2020 ◽  
Author(s):  
Zhenhe Su ◽  
Xiuye Chen ◽  
Xiaomeng Liu ◽  
Qinggang Guo ◽  
Shezeng Li ◽  
...  

Abstract Background Bacillus subtilisstrain NCD-2 is anexcellent biocontrol agent against plant soil-borne diseases and shows broad-spectrum antifungal activities. This study aimed to explore all the secondary metabolite synthetic gene clusters and related bioactive compounds in NCD-2. An integrative approach, which coupled genome mining with structural identification technologies using ultra-high-performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-MS/MS), was conducted to interpret the chemical origins of the significant biological activities in NCD-2. Results Genome mining revealed that NCD-2 contained nine gene clustershaving predicted functionsinvolving secondary metabolites with bioactive abilities. They encoded six known products-fengycin, surfactin, bacillaene, subtilosin, bacillibactin, and bacilysin-as well as three unknown products.Interestingly, the synthetic gene clusters for surfactin and fengycin showed 83% and 92% amino acid sequence similarity levels with the corresponding productsin Bacillus velezensisstrain FZB42. A further comparison of gene clusters encoding fengycin and surfactinrevealed that strain NCD-2 had lost thefenC and fenDgenes in the fengycinbiosynthetic operon, and that the surfactin synthetic enzyme-related gene srfAB was divided into two parts.Abioinformatics analysis showed that fenEAmay function as fenCD in synthesizing fengycinand that the structure of thisfengycin synthetic gene clusteris likely unique to NCD-2.Five kinds of fengycin,with 26 homologs, and surfactin,with 4 homologs,were detectedfrom strain NCD-2, which indicated the non-typical and unique nature of this fengycin biosynthetic gene cluster.To the best of our knowledge, this is the first report of a non-typical gene cluster related to fengycin synthesis. Conclusions The data provide the genetic characteristics of secondary metabolite synthetic gene clusters for fengycinand surfactin in B. subtilis NCD-2, including the unique synthetic mechanism for fengycin, and suggest that bioactive secondary metabolites explain the biological activities of NCD-2.


2020 ◽  
Vol 7 (1) ◽  
Author(s):  
Yongjae Lee ◽  
Namil Lee ◽  
Soonkyu Hwang ◽  
Woori Kim ◽  
Yujin Jeong ◽  
...  

AbstractStreptomyces species are gram-positive bacteria with GC-rich linear genomes and they serve as dominant reservoirs for producing clinically and industrially important secondary metabolites. Genome mining of Streptomyces revealed that each Streptomyces species typically encodes 20–50 secondary metabolite biosynthetic gene clusters (smBGCs), emphasizing their potential for novel compound discovery. Unfortunately, most of smBGCs are uncharacterized in terms of their products and regulation since they are silent under laboratory culture conditions. To translate the genomic potential of Streptomyces to practical applications, it is essential to understand the complex regulation of smBGC expression and to identify the underlying regulatory elements. To progress towards these goals, we applied two Next-Generation Sequencing methods, dRNA-Seq and Term-Seq, to industrially relevant Streptomyces species to reveal the 5´ and 3´ boundaries of RNA transcripts on a genome scale. This data provides a fundamental resource to aid our understanding of Streptomyces’ regulation of smBGC expression and to enhance their potential for secondary metabolite synthesis.


Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 673
Author(s):  
Kattia Núñez-Montero ◽  
Damián Quezada-Solís ◽  
Zeinab G. Khalil ◽  
Robert J. Capon ◽  
Fernando D. Andreote ◽  
...  

Concern about finding new antibiotics against drug-resistant pathogens is increasing every year. Antarctic bacteria have been proposed as an unexplored source of bioactive metabolites; however, most biosynthetic gene clusters (BGCs) producing secondary metabolites remain silent under common culture conditions. Our work aimed to characterize elicitation conditions for the production of antibacterial secondary metabolites from 34 Antarctic bacterial strains based on MS/MS metabolomics and genome mining approaches. Bacterial strains were cultivated under different nutrient and elicitation conditions, including the addition of lipopolysaccharide (LPS), sodium nitroprusside (SNP), and coculture. Metabolomes were obtained by HPLC-QTOF-MS/MS and analyzed through molecular networking. Antibacterial activity was determined, and seven strains were selected for genome sequencing and analysis. Biosynthesis pathways were activated by all the elicitation treatments, which varies among strains and dependents of culture media. Increased antibacterial activity was observed for a few strains and addition of LPS was related with inhibition of Gram-negative pathogens. Antibiotic BGCs were found for all selected strains and the expressions of putative actinomycin, carotenoids, and bacillibactin were characterized by comparison of genomic and metabolomic data. This work established the use of promising new elicitors for bioprospection of Antarctic bacteria and highlights the importance of new “-omics” comparative approaches for drug discovery.


2008 ◽  
Vol 74 (24) ◽  
pp. 7607-7612 ◽  
Author(s):  
Edyta Szewczyk ◽  
Yi-Ming Chiang ◽  
C. Elizabeth Oakley ◽  
Ashley D. Davidson ◽  
Clay C. C. Wang ◽  
...  

ABSTRACT The sequencing of Aspergillus genomes has revealed that the products of a large number of secondary metabolism pathways have not yet been identified. This is probably because many secondary metabolite gene clusters are not expressed under normal laboratory culture conditions. It is, therefore, important to discover conditions or regulatory factors that can induce the expression of these genes. We report that the deletion of sumO, the gene that encodes the small ubiquitin-like protein SUMO in A. nidulans, caused a dramatic increase in the production of the secondary metabolite asperthecin and a decrease in the synthesis of austinol/dehydroaustinol and sterigmatocystin. The overproduction of asperthecin in the sumO deletion mutant has allowed us, through a series of targeted deletions, to identify the genes required for asperthecin synthesis. The asperthecin biosynthesis genes are clustered and include genes encoding an iterative type I polyketide synthase, a hydrolase, and a monooxygenase. The identification of these genes allows us to propose a biosynthetic pathway for asperthecin.


2021 ◽  
Vol 18 (4) ◽  
pp. 709-721
Author(s):  
Le Ngoc Giang ◽  
Le Thi Hong Minh ◽  
Vu Thi Quyen ◽  
Nguyen Mai Anh ◽  
Nguyen Thi Kim Cuc ◽  
...  

The streptomyces is one of the best characterized ubiquitous filamentous bacteria from the actinobacteriaclass. They are known to produce thousands of specialized metabolite biosynthesis gene clusters (SMBG). Their SMBG clusters have multiple activities ranging from antimicrobial, antitumor, antiviral and probiotic. Streptomyces strain and their isolates with interesting biological activities against gram-positive and gram-negative indicator strains was recently characterised. Currently, they are employed in more than half of all antibiotics used in human and veterinary medicine. With the increase in drug resistance bacteria, it is important to mine for new natural chemicals.In this study, screening via disk-diffusion agar method revealed that Streptomyces sp. PDH23 isolated from the Rhabdastrellaglobostellata marine sponge sample from Da Nang, Vietnam produce antimicrobial agents with a wide spectrum of activities. This species can produce highly active enzymes, which breakdown celluloses, amyloses and proteins. On top of that they are shown to restrict the grow of the gram positive Bacillus cereus ATCC14579 (BC), Staphylococcus aureus ATCC25923 (SA), the gram-negativeVibrio parahaemolyticus ATCC17802 (VP) and the Candida albicans ATCC10231 fungus (CA). They are antimethicillin-resistant S. aureus(MRSA) ATCC33591 andmethicillin-resistantS. epidermidis (MRSE) ATCC35984. The taxonomy of PDH23 was characterized using 16S rRNA analysis. Whole genome sequencing of PDH23 showed 8594820 base pairs with GC content of 72.03%. Mining of secondary metabolites reveals gene clusters responsible for the biosynthesis of known and/or novel secondary metabolites, including different types of terpene, NRPS-like , PKS, PKS-like, hglE-KS, betalactone, melanin, t1pks, t2pks, t3pks, nrps, indole, siderophore, bacteriocin, ectoine, butyrolactone, phenazine.


Author(s):  
Jérôme Collemare ◽  
Michael F Seidl

ABSTRACTFungal secondary metabolites are small molecules that exhibit diverse biological activities exploited in medicine, industry and agriculture. Their biosynthesis is governed by co-expressed genes that often co-localize in gene clusters. Most of these secondary metabolite gene clusters are inactive under laboratory conditions, which is due to a tight transcriptional regulation. Modifications of chromatin, the complex of DNA and histone proteins influencing DNA accessibility, play an important role in this regulation. However, tinkering with well-characterised chemical and genetic modifications that affect chromatin alters the expression of only few biosynthetic gene clusters, and thus the regulation of the vast majority of biosynthetic pathways remains enigmatic. In the past, attempts to activate silent gene clusters in fungi mainly focused on histone acetylation and methylation, while in other eukaryotes many other post-translational modifications are involved in transcription regulation. Thus, how chromatin regulates the expression of gene clusters remains a largely unexplored research field. In this review, we argue that focusing on only few well-characterised chromatin modifications is significantly hampering our understanding of the chromatin-based regulation of biosynthetic gene clusters. Research on underexplored chromatin modifications and on the interplay between different modifications is timely to fully explore the largely untapped reservoir of fungal secondary metabolites.


Marine Drugs ◽  
2021 ◽  
Vol 19 (6) ◽  
pp. 332
Author(s):  
Dini Hu ◽  
Simon Ming-Yuen Lee ◽  
Kai Li ◽  
Kai Meng Mok

Mangroves are intertidal extreme environments with rich microbial communities. Actinobacteria are well known for producing antibiotics. The search for biosynthetic potential of Actinobacteria from mangrove environments could provide more possibilities for useful secondary metabolites. In this study, whole genome sequencing and MS/MS analysis were used to explore the secondary metabolite production potential of one actinobacterial strain of Streptomyces olivaceus sp., isolated from a mangrove in Macau, China. The results showed that a total of 105 gene clusters were found in the genome of S. olivaceus sp., and 53 known secondary metabolites, including bioactive compounds, peptides, and other products, were predicted by genome mining. There were 28 secondary metabolites classified as antibiotics, which were not previously known from S. olivaceus. ISP medium 2 was then used to ferment the S. olivaceus sp. to determine which predicted secondary metabolite could be truly produced. The chemical analysis revealed that ectoine, melanin, and the antibiotic of validamycin A could be observed in the fermentation broth. This was the first observation that these three compounds can be produced by a strain of S. olivaceus. Therefore, it can be concluded that Actinobacteria isolated from the mangrove environment have unknown potential to produce bioactive secondary metabolites.


Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 193
Author(s):  
Jenny Schwarz ◽  
Georg Hubmann ◽  
Katrin Rosenthal ◽  
Stephan Lütz

Over the past decade, the one strain many compounds (OSMAC) approach has been established for the activation of biosynthetic gene clusters (BGCs), which mainly encode the enzymes of secondary metabolite (SM) biosynthesis pathways. These BGCs were successfully activated by altering various culture conditions, such as aeration rate, temperature, and nutrient composition. Here, we determined the biosynthetic potential of 43 bacteria using the genome mining tool antiSMASH. Based on the number of BGCs, biological safety, availability of deposited cultures, and literature coverage, we selected five promising candidates: Bacillus amyloliquefaciens DSM7, Corallococcus coralloides DSM2259, Pyxidicoccus fallax HKI727, Rhodococcus jostii DSM44719, and Streptomyces griseochromogenes DSM40499. The bacteria were cultivated under a broad range of OSMAC conditions (nutrient-rich media, minimal media, nutrient-limited media, addition of organic solvents, addition of biotic additives, and type of culture vessel) to fully assess the biosynthetic potential. In particular, we investigated so far scarcely applied OSMAC conditions to enhance the diversity of SMs. We detected the four predicted compounds bacillibactin, desferrioxamine B, myxochelin A, and surfactin. In total, 590 novel mass features were detected in a broad range of investigated OSMAC conditions, which outnumber the predicted gene clusters for all investigated bacteria by far. Interestingly, we detected mass features of the bioactive compounds cyclo-(Tyr-Pro) and nocardamin in extracts of DSM7 and DSM2259. Both compounds were so far not reported for these strains, indicating that our broad OSMAC screening approach was successful. Remarkably, the infrequently applied OSMAC conditions in defined medium with and without nutrient limitation were demonstrated to be very effective for BGC activation and for SM discovery.


2021 ◽  
Vol 12 ◽  
Author(s):  
Chunmiao Jiang ◽  
Gongbo Lv ◽  
Yayi Tu ◽  
Xiaojie Cheng ◽  
Yitian Duan ◽  
...  

Filamentous fungi possess the capacity to produce a wide array of secondary metabolites with diverse biological activities and structures, such as lovastatin and swainsonine. With the advent of the post-genomic era, increasing amounts of cryptic or uncharacterized secondary metabolite biosynthetic gene clusters are continually being discovered. However, owing to the longstanding lack of versatile, comparatively simple, and highly efficient genetic manipulation techniques, the broader exploration of industrially important secondary metabolites has been hampered thus far. With the emergence of CRISPR/Cas9-based genome editing technology, this dilemma may be alleviated, as this advanced technique has revolutionized genetic research and enabled the exploitation and discovery of new bioactive compounds from filamentous fungi. In this review, we introduce the CRISPR/Cas9 system in detail and summarize the latest applications of CRISPR/Cas9-mediated genome editing in filamentous fungi. We also briefly introduce the specific applications of the CRISPR/Cas9 system and CRISPRa in the improvement of secondary metabolite contents and discovery of novel biologically active compounds in filamentous fungi, with specific examples noted. Additionally, we highlight and discuss some of the challenges and deficiencies of using the CRISPR/Cas9-based genome editing technology in research on the biosynthesis of secondary metabolites as well as future application of CRISPR/Cas9 strategy in filamentous fungi are highlighted and discussed.


Author(s):  
Jenny Schwarz ◽  
Stephan Lütz

Over the past decade, the One Strain Many Compounds (OSMAC) approach has been established for silent gene cluster activation and elicitation of secondary metabolite production, but so far the full secondary metabolome of a biosynthetically promising bacterium has not been elucidated yet. Here, we investigate the ability of seven categories of OSMAC conditions to elicit new mass features from bacterial strains with little literature coverage but high biosynthetic potential. The strains B. amyloliquefaciens DSM7, C. coralloides DSM2259, P. fallax HKI727, R. jostii DSM44719 and S. griseochromogenes DSM40499 were selected after genome mining with antiSMASH. After cultivation under OSMAC conditions, the generated extracts were subjected to LC/MS and MZmine analysis to determine new mass features, expressed gene clusters and evaluate the tested culture conditions. 4 predicted compounds, bacillibactin, desferrioxamine B, myxochelin A and surfactin, were identified and up to 147 new mass features were detected in the generated extracts, which greatly surpasses the number of predicted gene clusters. Among the new mass features are bioactive compounds which were so far unreported for the strains such as cyclo-(Tyr-Pro) from DSM7 and nocardamin from DSM2259. Furthermore, the tested culture conditions were evaluated regarding their suitability for the generation of new mass features from the selected strains and promising new starting points for further screenings are postulated. Especially culture conditions with little prior literature coverage are responsible for the activation of secondary metabolite production.


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