Efficient nonenzymatic cyclization and domain shuffling drive pyrrolopyrazine diversity from truncated variants of a fungal NRPS

Nonribosomal peptide synthetases (NRPSs) generate the core peptide scaffolds of many natural products. These include small cyclic dipeptides such as the insect feeding deterrent peramine, which is a pyrrolopyrazine (PPZ) produced by grass-endophyticEpichloëfungi. Biosynthesis of peramine is catalyzed by the 2-module NRPS, PpzA-1, which has a C-terminal reductase (R) domain that is required for reductive release and cyclization of the NRPS-tethered dipeptidyl-thioester intermediate. However, some PpzA variants lack this R domain due to insertion of a transposable element into the 3′ end ofppzA. We demonstrate here that these truncated PpzA variants utilize nonenzymatic cyclization of the dipeptidyl thioester to a 2,5-diketopiperazine (DKP) to synthesize a range of novel PPZ products. Truncation of the R domain is sufficient to subfunctionalize PpzA-1 into a dedicated DKP synthetase, exemplified by the truncated variant, PpzA-2, which has also evolved altered substrate specificity and reducedN-methyltransferase activity relative to PpzA-1. Further allelic diversity has been generated by recombination-mediated domain shuffling betweenppzA-1andppzA-2, resulting in theppzA-3andppzA-4alleles, each of which encodes synthesis of a unique PPZ metabolite. This research establishes that efficient NRPS-catalyzed DKP biosynthesis can occur in vivo through nonenzymatic dipeptidyl cyclization and presents a remarkably clean example of NRPS evolution through recombinant exchange of functionally divergent domains. This work highlights that allelic variants of a single NRPS can result in a surprising level of secondary metabolite diversity comparable to that observed for some gene clusters.

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An Orphan MbtH-Like Protein Interacts with Multiple Nonribosomal Peptide Synthetases inMyxococcus xanthusDK1622

Journal of Bacteriology ◽

10.1128/jb.00346-18 ◽

2018 ◽

Vol 200 (21) ◽

Cited By ~ 8

Author(s):

Karla J. Esquilín-Lebrón ◽

Tye O. Boynton ◽

Lawrence J. Shimkets ◽

Michael G. Thomas

Keyword(s):

Myxococcus Xanthus ◽

Gene Clusters ◽

Biosynthetic Gene ◽

Biosynthetic Gene Clusters ◽

Nonribosomal Peptide ◽

Content Type ◽

Nonribosomal Peptide Synthetases ◽

Peptide Synthetases

ABSTRACTOne mechanism by which bacteria and fungi produce bioactive natural products is the use of nonribosomal peptide synthetases (NRPSs). Many NRPSs in bacteria require members of the MbtH-like protein (MLP) superfamily for their solubility or function. Although MLPs are known to interact with the adenylation domains of NRPSs, the role MLPs play in NRPS enzymology has yet to be elucidated. MLPs are nearly always encoded within the biosynthetic gene clusters (BGCs) that also code for the NRPSs that interact with the MLP. Here, we identify 50 orphan MLPs from diverse bacteria. An orphan MLP is one that is encoded by a gene that is not directly adjacent to genes predicted to be involved in nonribosomal peptide biosynthesis. We targeted the orphan MLP MXAN_3118 fromMyxococcus xanthusDK1622 for characterization. TheM. xanthusDK1622 genome contains 15 NRPS-encoding BGCs but only one MLP-encoding gene (MXAN_3118). We tested the hypothesis that MXAN_3118 interacts with one or more NRPS using a combination ofin vivoandin vitroassays. We determined that MXAN_3118 interacts with at least seven NRPSs from distinct BGCs. We show that one of these BGCs codes for NRPS enzymology that likely produces a valine-rich natural product that inhibits the clumping ofM. xanthusDK1622 in liquid culture. MXAN_3118 is the first MLP to be identified that naturally interacts with multiple NRPS systems in a single organism. The finding of an MLP that naturally interacts with multiple NRPS systems suggests it may be harnessed as a “universal” MLP for generating functional hybrid NRPSs.IMPORTANCEMbtH-like proteins (MLPs) are essential accessory proteins for the function of many nonribosomal peptide synthetases (NRPSs). We identified 50 MLPs from diverse bacteria that are coded by genes that are not located near any NRPS-encoding biosynthetic gene clusters (BGCs). We define these as orphan MLPs because their NRPS partner(s) is unknown. Investigations into the orphan MLP fromMyxococcus xanthusDK1622 determined that it interacts with NRPSs from at least seven distinct BGCs. Support for these MLP-NRPS interactions came from the use of a bacterial two-hybrid assay and copurification of the MLP with various NRPSs. The flexibility of this MLP to naturally interact with multiple NRPSs led us to hypothesize that this MLP may be used as a “universal” MLP during the construction of functional hybrid NRPSs.

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A plant endophyte Staphylococcus hominis strain MBL_AB63 produces a novel lantibiotic, homicorcin and a position one variant

Scientific Reports ◽

10.1038/s41598-021-90613-9 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

M. Aftab Uddin ◽

Shammi Akter ◽

Mahbuba Ferdous ◽

Badrul Haidar ◽

Al Amin ◽

...

Keyword(s):

Gene Clusters ◽

Antimicrobial Activities ◽

Whole Genome Sequence ◽

Antimicrobial Substances ◽

The Core ◽

Rp Hplc ◽

Ring Structures ◽

Core Peptide ◽

Staphylococcus Hominis ◽

Epilancin 15X

AbstractHere we report a jute endophyte Staphylococcus hominis strain MBL_AB63 isolated from jute seeds which showed promising antimicrobial activity against Staphylococcus aureus SG511 when screening for antimicrobial substances. The whole genome sequence of this strain, annotated using BAGEL4 and antiSMASH 5.0 to predict the gene clusters for antimicrobial substances identified a novel antimicrobial peptide cluster that belongs to the class I lantibiotic group. The predicted lantibiotic (homicorcin) was found to be 82% similar to a reported peptide epicidin 280 having a difference of seven amino acids at several positions of the core peptide. Two distinct peaks obtained at close retention times from a RP-HPLC purified fraction have comparable antimicrobial activities and LC–MS revealed the molecular mass of these peaks to be 3046.5 and 3043.2 Da. The presence of an oxidoreductase (homO) similar to that of epicidin 280- associated eciO or epilancin 15X- associated elxO in the homicorcin gene cluster is predicted to be responsible for the reduction of the first dehydrated residue dehydroalanine (Dha) to 2-hydroxypropionate that causes an increase of 3 Da mass of homicorcin 1. Trypsin digestion of the core peptide and its variant followed by ESI–MS analysis suggests the presence of three ring structures, one in the N-terminal and other two interlocking rings at the C-terminal region that remain undigested. Homicorcin exerts bactericidal activity against susceptible cells by disrupting the integrity of the cytoplasmic membrane through pore formation as observed under FE-SEM.

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Pseudomonas syringae Phytotoxins: Mode of Action, Regulation, and Biosynthesis by Peptide and Polyketide Synthetases

Microbiology and Molecular Biology Reviews ◽

10.1128/mmbr.63.2.266-292.1999 ◽

1999 ◽

Vol 63 (2) ◽

pp. 266-292 ◽

Cited By ~ 515

Author(s):

Carol L. Bender ◽

Francisco Alarcón-Chaidez ◽

Dennis C. Gross

Keyword(s):

Pseudomonas Syringae ◽

Plasma Membranes ◽

Antimicrobial Agents ◽

Gene Clusters ◽

Regulatory Genes ◽

Signal Molecules ◽

Peptide Synthetases ◽

Biological Stress ◽

Regulatory Circuits ◽

And Function

SUMMARY Coronatine, syringomycin, syringopeptin, tabtoxin, and phaseolotoxin are the most intensively studied phytotoxins of Pseudomonas syringae, and each contributes significantly to bacterial virulence in plants. Coronatine functions partly as a mimic of methyl jasmonate, a hormone synthesized by plants undergoing biological stress. Syringomycin and syringopeptin form pores in plasma membranes, a process that leads to electrolyte leakage. Tabtoxin and phaseolotoxin are strongly antimicrobial and function by inhibiting glutamine synthetase and ornithine carbamoyltransferase, respectively. Genetic analysis has revealed the mechanisms responsible for toxin biosynthesis. Coronatine biosynthesis requires the cooperation of polyketide and peptide synthetases for the assembly of the coronafacic and coronamic acid moieties, respectively. Tabtoxin is derived from the lysine biosynthetic pathway, whereas syringomycin, syringopeptin, and phaseolotoxin biosynthesis requires peptide synthetases. Activation of phytotoxin synthesis is controlled by diverse environmental factors including plant signal molecules and temperature. Genes involved in the regulation of phytotoxin synthesis have been located within the coronatine and syringomycin gene clusters; however, additional regulatory genes are required for the synthesis of these and other phytotoxins. Global regulatory genes such as gacS modulate phytotoxin production in certain pathovars, indicating the complexity of the regulatory circuits controlling phytotoxin synthesis. The coronatine and syringomycin gene clusters have been intensively characterized and show potential for constructing modified polyketides and peptides. Genetic reprogramming of peptide and polyketide synthetases has been successful, and portions of the coronatine and syringomycin gene clusters could be valuable resources in developing new antimicrobial agents.

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T1000: A reduced toxicogenomics gene set for improved decision making

10.7287/peerj.preprints.27839 ◽

2019 ◽

Author(s):

Othman Soufan ◽

Jessica Ewald ◽

Charles Viau ◽

Doug Crump ◽

Markus Hecker ◽

...

Keyword(s):

Dose Response ◽

Gene Clusters ◽

Gene Set ◽

Chemical Hazards ◽

Gene Sets ◽

Toxicological Research ◽

Multiple Species ◽

Response Modeling

There is growing interest within regulatory agencies and toxicological research communities to develop, test, and apply new approaches, such as toxicogenomics, to more efficiently evaluate chemical hazards. Given the complexity of analyzing thousands of genes simultaneously, there is a need to identify reduced gene sets.Though several gene sets have been defined for toxicological applications, few of these were purposefully derived using toxicogenomics data. Here, we developed and applied a systematic approach to identify 1000 genes (called Toxicogenomics-1000 or T1000) highly responsive to chemical exposures. First, a co-expression network of 11,210genes was built by leveraging microarray data from the Open TG-GATEs program. This network was then re-weighted based on prior knowledge of their biological (KEGG, MSigDB) and toxicological (CTD) relevance. Finally, weighted correlation network analysis was applied to identify 258 gene clusters. T1000 was defined by selecting genes from each cluster that were most associated with outcome measures. For model evaluation, we compared the performance of T1000 to that of other gene sets (L1000, S1500, Genes selected by Limma, and random set) using two external datasets. Additionally, a smaller (T384) and a larger version (T1500) of T1000 were used for dose-response modeling to test the effect of gene set size. Our findings demonstrated that the T1000 gene set is predictive of apical outcomes across a range of conditions (e.g.,in vitroand in vivo, dose-response, multiple species, tissues, and chemicals), and generally performs as well, or better than other gene sets available.

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Refactoring the formicamycin biosynthetic gene cluster to make high-level producing strains and new molecules

10.1101/2020.09.15.275776 ◽

2020 ◽

Cited By ~ 1

Author(s):

Rebecca Devine ◽

Hannah McDonald ◽

Zhiwei Qin ◽

Corinne Arnold ◽

Katie Noble ◽

...

Keyword(s):

Gene Cluster ◽

Large Scale ◽

Liquid Culture ◽

Gene Clusters ◽

Biosynthetic Gene Cluster ◽

Resistant Bacteria ◽

Drug Resistant ◽

Biosynthetic Gene ◽

Biosynthetic Genes

AbstractThe formicamycins are promising antibiotics with potent activity against Gram-positive pathogens including VRE and MRSA and display a high barrier to selection of resistant isolates. They were first identified in Streptomyces formicae KY5, which produces the formicamycins at low levels on solid agar but not in liquid culture, thus hindering further investigation of these promising antibacterial compounds. We hypothesised that by understanding the organisation and regulation of the for biosynthetic gene cluster, we could rationally refactor the cluster to increase production levels. Here we report that the for biosynthetic gene cluster consists of 24 genes expressed on nine transcripts. Seven of these transcripts, including those containing all the major biosynthetic genes, are repressed by the MarR-regulator ForJ which also controls the expression of the ForGF two-component system that initiates biosynthesis. A third cluster-situated regulator, ForZ, autoregulates and controls production of the putative MFS transporter ForAA. Consistent with these findings, deletion of forJ increased formicamycin biosynthesis 5-fold, while over-expression of forGF in the ΔforJ background increased production 10-fold compared to the wild-type. De-repression by deleting forJ also switched on biosynthesis in liquid-culture and induced the production of two novel formicamycin congeners. By combining mutations in regulatory and biosynthetic genes, six new biosynthetic precursors with antibacterial activity were also isolated. This work demonstrates the power of synthetic biology for the rational redesign of antibiotic biosynthetic gene clusters both to engineer strains suitable for fermentation in large scale bioreactors and to generate new molecules.ImportanceAntimicrobial resistance is a growing threat as existing antibiotics become increasingly ineffective against drug resistant pathogens. Here we determine the transcriptional organisation and regulation of the gene cluster encoding biosynthesis of the formicamycins, promising new antibiotics with activity against drug resistant bacteria. By exploiting this knowledge, we construct stable mutant strains which over-produce these molecules in both liquid and solid culture whilst also making some new compound variants. This will facilitate large scale purification of these molecules for further study including in vivo experiments and the elucidation of their mechanism of action. Our work demonstrates that understanding the regulation of natural product biosynthetic pathways can enable rational improvement of the producing strains.

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Abstract 18587: Downregulation of Pulmonary Artery Endothelial Catechol-o-methyltransferase Activity by Aldosterone Increases Norepinephrine Levels in Pulmonary Arterial Hypertension

Circulation ◽

10.1161/circ.130.suppl_2.18587 ◽

2014 ◽

Vol 130 (suppl_2) ◽

Author(s):

Samantha Torquato ◽

Kiyotake Ishikawa ◽

Jaume Aguerro ◽

Bradley A Maron ◽

Joseph Loscalzo ◽

...

Keyword(s):

Pulmonary Arterial Hypertension ◽

Pulmonary Artery ◽

Arterial Hypertension ◽

Right Heart Failure ◽

Therapeutic Interventions ◽

Pulmonary Vasculature ◽

Methyltransferase Activity ◽

Comt Activity ◽

Pulmonary Arterial

Elevated levels of norepinephrine (NE) occur in pulmonary arterial hypertension (PAH) and are determined, in part, by the activity of catechol- O -methyltransferase (COMT). COMT degrades catecholamines, is negatively regulated by calcium, and is expressed by pulmonary artery endothelial cells (PAEC). As hyperaldosteronism occurs in PAH and aldosterone (ALDO) influences calcium levels, we hypothesized that ALDO decreases COMT activity to increase NE levels in PAH. Accordingly, human PAEC were treated with ALDO (10 -7 mol/L), a level that is achieved clinically in PAH, for up to 72 h. Compared to vehicle-treated PAEC, ALDO decreased COMT activity by 59.2 ± 6.2% (p<0.01) to increase NE levels in the medium (122.4 ± 11.8 vs. 210.7 ± 15.5 pg/mL/mg protein, p<0.01). This occurred as a result of an ALDO-mediated decrease in COMT protein expression by 52.6 ± 9.3% (p<0.01) as well as an increase in intracellular calcium levels (102.9 ± 21.0 vs. 167.7 ± 17.8 nmol/L, p<0.05) to inhibit activity. These effects were abrogated by coincubation with spironolactone. To determine the in vivo relevance of these findings, COMT was examined in the rat monocrotaline model of PAH with confirmed hyperALDO. COMT was decreased (47.6 ± 10.2 %control, p<0.05) in remodeled pulmonary arterioles with a concomitant increase in lung NE levels (432.8 ± 44.5 vs. 899.7 ± 34.2 pg/mL, p<0.01) compared to control rats. In the porcine pulmonary vein banding model of pulmonary hypertension (PH-pigs) with elevated mean pulmonary artery pressure (15[13-15] vs. 35[27-43], p<0.01) and pulmonary vascular resistance (PVR) index (1.97[1.74-2.28] vs. 5.78[2.61-8.75], p <0.05), ALDO levels were also increased (27.1 ± 5.1 vs. 60.8 ± 10.6 pg/mL, p<0.03) in advance of right heart failure as compared to sham controls. PH-pigs demonstrated a 48.3 ± 9.9% (p<0.02) decrease in pulmonary vascular COMT expression and an increase in NE levels (114.6 ± 20.2 vs. 1,622.6 ± 489.2 pg/mL, p<0.02) that correlated positively with ALDO levels (R 2 =0.58, p<0.02). These findings were confirmed in patients with PAH. Together, these data indicate that there is crosstalk in the pulmonary vasculature between ALDO and the sympathetic nervous system to regulate NE levels in PAH, and thus, have implications for therapeutic interventions.

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Abstract 14532: Computational Drug Repurposing Identifies a Piperlongumine Analog That Controls a Gstp1-iscu Pathogenic Axis in Pulmonary Hypertension

Circulation ◽

10.1161/circ.142.suppl_3.14532 ◽

2020 ◽

Vol 142 (Suppl_3) ◽

Author(s):

Jimin Yang

Keyword(s):

Drug Repurposing ◽

Gene Clusters ◽

Loss Of Function ◽

Sequencing Data ◽

Glutathione S Transferase ◽

Computational Screening ◽

Therapeutic Development ◽

Pulmonary Arterial

Background and Hypothesis: Pulmonary arterial hypertension (PAH) is an incurable vascular disease for which chemotherapies are being considered for therapeutic development. There is no method reported to date for effective computational screening of these drugs for this disease. Big data analyses that leverage the molecular parallels between cancer and PH may define novel pathogenic mechanisms and facilitate repurposing of chemotherapies for PAH. More specifically, while functional deficiency of the iron-sulfur (Fe-S) biogenesis gene ISCU and oxidative metabolism in human pulmonary arterial endothelial cells (PAECs) is known to drive PAH, the pathogenic regulation of ISCU is not fully defined, and no tailored drugs have been identified to bolster ISCU activity. Methods and Results: We applied a computational algorithm EDDY (Evaluating Differential DependencY), which analyzes RNA sequencing data from 810 cancer cell lines exposed to 368 small molecules, in order to identify chemotherapeutics that depended upon rewired PH-related gene clusters. The top ranked drug was a piperlongumine (PL) analog (BRD2889) that was predicted to extensively rewire dependencies across PH gene clusters, mediated by ISCU. In vitro, coupling gain- and loss-of-function analyses of GSTP1 with BRD2889 exposure in PAECs, we found that BRD2889 inhibits glutathione S-transferase P1 (GSTP1), an enzyme which in turn catalyzes ISCU glutathionylation and increases its stability in hypoxia. Consequently, BRD2889 and GSTP1 knockdown phenocopy one another by increasing Fe-S-dependent Complex I activity and mitochondrial oxygen consumption while ameliorating pathogenic apoptosis. Consistent with these computational and in vitro results, in a mouse model of PAH (IL-6 transgenic mice in hypoxia), BRD2889 improved hemodynamic and molecular disease manifestations in vivo. Conclusions: Using a novel computational platform, we identified a coordinated connection between BRD342289 and GSTP1-ISCU axis, crucial to PAEC metabolism. This study offers insight to fundamental PH pathobiology and sets the stage for accelerated repurposing of chemotherapies such as BRD342289 in PH.

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A Novel Automethylation Reaction in the Aspergillus nidulans LaeA Protein Generates S-Methylmethionine

Journal of Biological Chemistry ◽

10.1074/jbc.m113.465765 ◽

2013 ◽

Vol 288 (20) ◽

pp. 14032-14045 ◽

Cited By ~ 37

Author(s):

Alexander N. Patananan ◽

Jonathan M. Palmer ◽

Graeme S. Garvey ◽

Nancy P. Keller ◽

Steven G. Clarke

Keyword(s):

Amino Acid ◽

Aspergillus Nidulans ◽

Point Mutations ◽

Pathogenic Fungi ◽

Gene Clusters ◽

Methionine Residue ◽

Cell Extracts ◽

Animal Pathogens

The filamentous fungi in the genus Aspergillus are opportunistic plant and animal pathogens that can adapt to their environment by producing various secondary metabolites, including lovastatin, penicillin, and aflatoxin. The synthesis of these small molecules is dependent on gene clusters that are globally regulated by the LaeA protein. Null mutants of LaeA in all pathogenic fungi examined to date show decreased virulence coupled with reduced secondary metabolism. Although the amino acid sequence of LaeA contains the motifs characteristic of seven-β-strand methyltransferases, a methyl-accepting substrate of LaeA has not been identified. In this work we did not find a methyl-accepting substrate in Aspergillus nidulans with various assays, including in vivo S-adenosyl-[methyl-3H]methionine labeling, targeted in vitro methylation experiments using putative protein substrates, or in vitro methylation assays using whole cell extracts grown under different conditions. However, in each experiment LaeA was shown to self-methylate. Amino acid hydrolysis of radioactively labeled LaeA followed by cation exchange and reverse phase chromatography identified methionine as the modified residue. Point mutations show that the major site of modification of LaeA is on methionine 207. However, in vivo complementation showed that methionine 207 is not required for the biological function of LaeA. LaeA is the first protein to exhibit automethylation at a methionine residue. These findings not only indicate LaeA may perform novel chemistry with S-adenosylmethionine but also provide new insights into the physiological function of LaeA.

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Victorin, the host-selective cyclic peptide toxin from the oat pathogen Cochliobolus victoriae, is ribosomally encoded

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2010573117 ◽

2020 ◽

Vol 117 (39) ◽

pp. 24243-24250

Author(s):

Simon C. Kessler ◽

Xianghui Zhang ◽

Megan C. McDonald ◽

Cameron L. M. Gilchrist ◽

Zeran Lin ◽

...

Keyword(s):

Cyclic Peptide ◽

Amine Oxidase ◽

Gene Clusters ◽

Oxidative Cyclization ◽

Gene Encoding ◽

Peptide Backbone ◽

Cochliobolus Victoriae ◽

Cyclic Hexapeptides ◽

Core Peptide

The necrotrophic fungal pathogen Cochliobolus victoriae produces victorin, a host-selective toxin (HST) essential for pathogenicity to certain oat cultivars with resistance against crown rust. Victorin is a mixture of highly modified heterodetic cyclic hexapeptides, previously assumed to be synthesized by a nonribosomal peptide synthetase. Herein, we demonstrate that victorin is a member of the ribosomally synthesized and posttranslationally modified peptide (RiPP) family of natural products. Analysis of a newly generated long-read assembly of the C. victoriae genome revealed three copies of precursor peptide genes (vicA1–3) with variable numbers of “GLKLAF” core peptide repeats corresponding to the victorin peptide backbone. vicA1–3 are located in repeat-rich gene-sparse regions of the genome and are loosely clustered with putative victorin biosynthetic genes, which are supported by the discovery of compact gene clusters harboring corresponding homologs in two distantly related plant-associated Sordariomycete fungi. Deletion of at least one copy of vicA resulted in strongly diminished victorin production. Deletion of a gene encoding a DUF3328 protein (VicYb) abolished the production altogether, supporting its predicted role in oxidative cyclization of the core peptide. In addition, we uncovered a copper amine oxidase (CAO) encoded by vicK, in which its deletion led to the accumulation of new glycine-containing victorin derivatives. The role of VicK in oxidative deamination of the N-terminal glycyl moiety of the hexapeptides to the active glyoxylate forms was confirmed in vitro. This study finally unraveled the genetic and molecular bases for biosynthesis of one of the first discovered HSTs and expanded our understanding of underexplored fungal RiPPs.

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Bacillus velezensis 83 a bacterial strain from mango phyllosphere, useful for biological control and plant growth promotion

AMB Express ◽

10.1186/s13568-020-01101-8 ◽

2020 ◽

Vol 10 (1) ◽

Cited By ~ 1

Author(s):

Karina A. Balderas-Ruíz ◽

Patricia Bustos ◽

Rosa I. Santamaria ◽

Víctor González ◽

Sergio Andrés Cristiano-Fajardo ◽

...

Keyword(s):

Biological Control ◽

Plant Growth ◽

Biological Control Agent ◽

Gene Clusters ◽

In Vitro Assays ◽

Shoot Biomass ◽

Plant Growth Promoting Bacteria ◽

Bacillus Velezensis

Abstract Bacillus velezensis 83 was isolated from mango tree phyllosphere of orchards located in El Rosario, Sinaloa, México. The assessment of this strain as BCA (biological control agent), as well as PGPB (plant growth-promoting bacteria), were demonstrated through in vivo and in vitro assays. In vivo assays showed that B. velezensis 83 was able to control anthracnose (Kent mangoes) as efficiently as chemical treatment with Captan 50 PH™ or Cupravit hidro™. The inoculation of B. velezensis 83 to the roots of maize seedlings yielded an increase of 12% in height and 45% of root biomass, as compared with uninoculated seedlings. In vitro co-culture assays showed that B. velezensis 83 promoted Arabidopsis thaliana growth (root and shoot biomass) while, under the same experimental conditions, B. velezensis FZB42 (reference strain) had a suppressive effect on plant growth. In order to characterize the isolated strain, the complete genome sequence of B. velezensis 83 is reported. Its circular genome consists of 3,997,902 bp coding to 3949 predicted genes. The assembly and annotation of this genome revealed gene clusters related with plant-bacteria interaction and sporulation, as well as ten secondary metabolites biosynthetic gene clusters implicated in the biological control of phytopathogens. Despite the high genomic identity (> 98%) between B. velezensis 83 and B. velezensis FZB42, they are phenotypically different. Indeed, in vitro production of compounds such as surfactin and bacillomycin D (biocontrol activity) and γ-PGA (biofilm component) is significantly different between both strains.

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