Microbial Secondary Metabolites Research Articles

Chemical Ecology of Streptomyces albidoflavus Strain A10 Associated with Carpenter Ant Camponotus vagus.

Antibiotics produced by symbiotic microorganisms were previously shown to be of crucial importance for ecological communities, including ants. Previous works on ant–actinobacteria symbiosis are mainly focused on farming ants, which use antifungal microbial secondary metabolites to control pathogens in their fungal gardens. In this work, we studied microorganisms associated with carpenter ant Camponotus vagus. Pronounced antifungal activity of isolated actinobacteria strain A10 was found to be facilitated by biosynthesis of the antimycin A complex, consisting of small hydrophobic depsipeptides with high antimicrobial and cytotoxic activity. The actinomycete strain A10 was identified as Streptomyces albidoflavus. We studied the antagonistic activity of strain A10 against several entomopathogenic microorganisms. The antifungal activity of this strain potentially indicates a defensive symbiosis with the host ant, producing antimycins to protect carpenter ants against infections. The nature of this ant-microbe association however remains to be established.

Discovery of γ-Lactam Alkaloid Derivatives as Potential Fungicidal Agents Targeting Steroid Biosynthesis.

Biological control of plant pathogens is considered as one of the green and effective technologies using beneficial microorganisms or microbial secondary metabolites against plant diseases, and so microbial natural products have played important roles in the research and development of new and green agrochemicals. To explore the potential applications for natural γ-lactam alkaloids and their derivatives, 26 γ-lactams that have flexible substituent patterns were synthesized and characterized, and their in vitro antifungal activities against eight kinds of plant pathogens belonging to oomycetes, basidiomycetes, and deuteromycetes were fully evaluated. In addition, the high potential compounds were further tested using an in vivo assay against Phytophthora blight of pepper to verify a practical application for controlling oomycete diseases. The potential modes of action for compound D1 against Phytophthora capsici were also investigated using microscopic technology (optical microscopy, scanning electron microscopy, and transmission electron microscopy) and label-free quantitative proteomics analysis. The results demonstrated that compound D1 may be a potential novel fungicidal agent against oomycete diseases (EC50 = 4.9748 μg·mL-1 for P. capsici and EC50 = 5.1602 μg·mL-1 for Pythium aphanidermatum) that can act on steroid biosynthesis, which can provide a certain theoretical basis for the development of natural lactam derivatives as potential antifungal agents.

Global Regulators to Activate Silent Biosynthetic Gene Clusters

Genome mining has recently emerged as a powerful strategy to discover novel microbial secondary metabolites. However, more than 50% of biosynthetic gene clusters are not transcribed under standardized laboratory culture condition. Several methods have been applied to activate silent biosynthetic gene clusters in the microbes so far. Among the regulatory systems for production of secondary metabolites, global regulators, which affect transcription of genes through regulatory cascades, typically govern the production of small molecules. In this review, global regulators to affect production of microbial secondary metabolites were discussed.

Beyond Toxin Transport: Novel Role of ABC Transporter for Enzymatic Machinery of Cereulide NRPS Assembly Line.

Nonribosomal peptide synthetases (NRPSs) and polyketide synthetases (PKSs) play a pivotal role in the production of bioactive natural products, such as antibiotics and cytotoxins. Despite biomedical and pharmaceutical importance, the molecular mechanisms and architectures of these multimodular enzyme complexes are not fully understood. Here, we report on an ABC transporter that forms a vital part of the nonribosomal peptide biosynthetic machinery. Emetic Bacillus cereus produces the highly potent, mitochondrial active nonribosomal depsipeptide cereulide, synthesized by the NRPS Ces. The ces gene locus includes, next to the structural cesAB genes, a putative ABC transporter, designated cesCD Our study demonstrates that tethering of CesAB synthetase to the cell membrane by CesCD is critical for peptide assembly. In vivo studies revealed that CesAB colocalizes with CesCD on the cell membrane, suggesting direct involvement of this ABC transporter in the biosynthesis of a nonribosomal peptide. Mutation of cesCD, disrupting the assembly of the CesCD complex, resulted in decreased interaction with CesAB and, as a consequence, negatively affected cereulide biosynthesis. Specific domains within CesAB synthetase interacting with CesC were identified. Furthermore, we demonstrated that the structurally similar BerAB transporter from Bacillus thuringiensis complements CesCD function in cereulide biosynthesis, suggesting that the direct involvement of ABC transporter in secondary metabolite biosynthesis could be a widespread mechanism. In summary, our study revealed a novel, noncanonical function for ABC transporter, which is essential for megaenzyme functionality of NRPS. The new insights into natural product biosynthesis gained may facilitate the discovery of new metabolites with bioactive potential.IMPORTANCE This study revealed a novel, potentially conserved mechanism involved in the biosynthesis of microbial natural products, exemplified by the mitochondrial active depsipeptide cereulide. Similar to other bioactive substances, such as the last-resort antibiotics vancomycin and daptomycin, the antitumor drug cryptophycin or the cholesterol-lowering agent lovastatin, cereulide is synthesized nonribosomally by multienzyme machinery, requiring the concerted actions of multiple proteins to ensure correct product assembly. Given the importance of microbial secondary metabolites in human and veterinary medicine, it is critical to understand how these processes are orchestrated within the host cells. By revealing that tethering of a biosynthetic enzyme to the cell membrane by an ABC transporter is essential for nonribosomal peptide production, our study provides novel insights into synthesis of microbial secondary metabolites, which could contribute to isolation of novel compounds from cryptic secondary metabolite clusters or improve the yield of produced pharmaceuticals.

Urgency and Mechanism of Biosynthesis of Marine Microbial Secondary Metabolites

Marine microorganism is one of biologically active potential resources of secondary metabolites. Its potency are so promising that the knowledge of how its secondary metabolite occured need to be studied and collected. Those knowledges will enable further study is improving secondary metabolite production in the laboratory. In nature, secondary metabolites synthesis occur when there are effect of both biotic and abiotic factors such as sea water and microbe symbiosis with other living materials. When this is explained in metabolic pathways, secondary metabolite synthesis affected by available nutrient and regulated by autoinducer molecules through quorum sensing mechanism.

Antiviral potential of natural products from marine microbes.

Humans have been suffered from viral infections over the centuries, such as influenza, HSV, and HIV, which have killed millions of people worldwide. However, the availability of effective treatments for infectious diseases remains limited until now, as most of the viral pathogens resisted to many medical treatments. Marine microbes are currently one of the most copious sources of pharmacologically active natural products, which have constantly provided promising antivirus agents. To date, a large number of marine microbial secondary metabolites with antiviral activities have been widely reported. In this review, we have summarized the potential antivirus compounds from marine microorganisms over the last decade. In addition, the structures, bioactivities, and origins of these compounds were discussed as well.

The Structural Diversity of Marine Microbial Secondary Metabolites Based on Co-Culture Strategy: 2009-2019.

Marine microorganisms have drawn great attention as novel bioactive natural product sources, particularly in the drug discovery area. Using different strategies, marine microbes have the ability to produce a wide variety of molecules. One of these strategies is the co-culturing of marine microbes; if two or more microorganisms are aseptically cultured together in a solid or liquid medium in a certain environment, their competition or synergetic relationship can activate the silent biosynthetic genes to produce cryptic natural products which do not exist in monocultures of the partner microbes. In recent years, the co-cultivation strategy of marine microbes has made more novel natural products with various biological activities. This review focuses on the significant and excellent examples covering sources, types, structures and bioactivities of secondary metabolites based on co-cultures of marine-derived microorganisms from 2009 to 2019. A detailed discussion on future prospects and current challenges in the field of co-culture is also provided on behalf of the authors’ own views of development tendencies.

Integration of Genetic and Process Engineering for Optimized Rhamnolipid Production Using Pseudomonas putida.

Rhamnolipids are biosurfactants produced by microorganisms with the potential to replace synthetic compounds with petrochemical origin. To promote industrial use of rhamnolipids, recombinant rhamnolipid production from sugars needs to be intensified. Since this remains challenging, the aim of the presented research is to utilize a multidisciplinary approach to take a step toward developing a sustainable rhamnolipid production process. Here, we developed expression cassettes for stable integration of the rhamnolipid biosynthesis genes into the genome outperformed plasmid-based expression systems. Furthermore, the genetic stability of the production strain was improved by using an inducible promoter. To enhance rhamnolipid synthesis, energy- and/or carbon-consuming traits were removed: mutants negative for the synthesis of the flagellar machinery or the storage polymer PHA showed increased production by 50%. Variation of time of induction resulted in an 18% increase in titers. A scale-up from shake flasks was carried out using a 1-L bioreactor. By recycling of the foam, biomass loss could be minimized and a rhamnolipid titer of up to 1.5 g/L was achieved without using mechanical foam destroyers or antifoaming agents. Subsequent liquid–liquid extraction was optimized by using a suitable minimal medium during fermentation to reduce undesired interphase formation. A technical-scale production process was designed and evaluated by a life-cycle assessment (LCA). Different process chains and their specific environmental impact were examined. It was found that next to biomass supply, the fermentation had the biggest environmental impact. The present work underlines the need for multidisciplinary approaches to address the challenges associated with achieving sustainable production of microbial secondary metabolites. The results are discussed in the context of the challenges of microbial biosurfactant production using hydrophilic substrates on an industrial scale.

Actinobacteria from Antarctica as a source for anticancer discovery

Although many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. Among the main approaches for the discovery of new bioactive agents, the prospect of microbial secondary metabolites represents an effective source for the development of drug leads. In this study, we investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds. The 16S rRNA-based analysis showed the predominance of the Actinomycetales order, a well-known group of bioactive metabolite producers belonging to the Actinobacteria phylum. Cultivation techniques were applied, and 72 psychrotolerant Actinobacteria strains belonging to the genera Actinoplanes, Arthrobacter, Kribbella, Mycobacterium, Nocardia, Pilimelia, Pseudarthrobacter, Rhodococcus, Streptacidiphilus, Streptomyces and Tsukamurella were identified. The secondary metabolites were screened, and 17 isolates were identified as promising antitumour compound producers. However, the bio-guided assay showed a pronounced antiproliferative activity for the crude extracts of Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653. The TGI and LC50 values revealed the potential of these natural products to control the proliferation of breast (MCF-7), glioblastoma (U251), lung/non-small (NCI-H460) and kidney (786-0) human cancer cell lines. Cinerubin B and actinomycin V were the predominant compounds identified in Streptomyces sp. CMAA 1527 and Streptomyces sp. CMAA 1653, respectively. Our results suggest that the rhizosphere of D. antarctica represents a prominent reservoir of bioactive actinobacteria strains and reveals it as an important environment for potential antitumour agents.

Unique features of the ketosynthase domain in a nonribosomal peptide synthetase–polyketide synthase hybrid enzyme, tenuazonic acid synthetase 1

Many microbial secondary metabolites are produced by multienzyme complexes comprising nonribosomal peptide synthetases (NRPSs) and polyketide synthases (PKSs). The ketosynthase (KS) domains of polyketide synthase normally catalyze the decarboxylative Claisen condensation of acyl and malonyl blocks to extend the polyketide chain. However, the terminal KS domain in tenuazonic acid synthetase 1 (TAS1) from the fungus Pyricularia oryzae conducts substrate cyclization. Here, we report on the unique features of the KS domain in TAS1. We observed that this domain is monomeric, not dimeric as is typical for KSs. Analysis of a 1.68-Å resolution crystal structure suggests that the substrate cyclization is triggered via proton abstraction from the active methylene moiety in the substrate by a catalytic His-322 residue. Additionally, we show that TAS1 KS promiscuously accepts aminoacyl substrates and that this promiscuity can be increased by a single amino acid substitution in the substrate-binding pocket of the enzyme. These findings provide insight into a KS domain that accepts the amino acid-containing substrate in an NRPS-PKS hybrid enzyme and provide hints to the substrate cyclization mechanism performed by the KS domain in the biosynthesis of the mycotoxin tenuazonic acid.

Biochemical basis for the regulation of biosynthesis of antiparasitics by bacterial hormones.

Diffusible small molecule microbial hormones drastically alter the expression profiles of antibiotics and other drugs in actinobacteria. For example, avenolide (a butenolide) regulates the production of avermectin, derivatives of which are used in the treatment of river blindness and other parasitic diseases. Butenolides and γ-butyrolactones control the production of pharmaceutically important secondary metabolites by binding to TetR family transcriptional repressors. Here, we describe a concise, 22-step synthetic strategy for the production of avenolide. We present crystal structures of the butenolide receptor AvaR1 in isolation and in complex with avenolide, as well as those of AvaR1 bound to an oligonucleotide derived from its operator. Biochemical studies guided by the co-crystal structures enable the identification of 90 new actinobacteria that may be regulated by butenolides, two of which are experimentally verified. These studies provide a foundation for understanding the regulation of microbial secondary metabolite production, which may be exploited for the discovery and production of novel medicines.

Bacterial Consortium and Microbial Metabolites Increase Grain Quality and Soybean Yield

The effects of Bradyrhizobium inoculation on soybean growth and productivity are well known, but plant responses to consortia of other beneficial microbes and microbial molecules have not yet been well explored. Therefore, the main aim of this study was to evaluate the effect of different combinations of beneficial bacteria with and without microbial secondary metabolites (MSM) on two soybean cultivars in three cropping seasons under tropical field conditions. The bacterial consortia consisted of Bradyrhizobium japonicum (strain SEMIA 5079) plus Bradyrhizobium diazoefficiens (strain SEMIA 5080) inoculated with different combinations of Bacillus subtilis (strain QST 713), Azospirillum brasilense (strains Ab-V5 and Ab-V6), and MSM (metabolites enriched in lipo-chitooligosaccharides (LCOs) extracted from B. diazoefficiens (strain USDA 110) and from Rhizobium tropici (strain CIAT 889)). Standard inoculation of Bradyrhizobium combined with Azospirillum brasilense and microbial secondary metabolites increased leaf total N (7.1%), total P (11.1%), and N-ureide (16.5%); nodule number (NN, 26%) and dry weight (NDW, 22%); root (RDW, 15.4%) and shoot dry weight (SDW, 6%); 100-seed weight (3.7%); grain yield (up to 516 kg ha−1); grain crude protein concentration (2.4%); and the agronomic efficiency index (AEI) (11%). Inoculation with bacterial consortia and metabolites increased grain yield and quality, representing a promising technology for sustainable soybean cropping in tropical regions.

Bioactivities and Structure–Activity Relationships of Natural Tetrahydroanthraquinone Compounds: A Review

Tetrahydroanthraquinones are a kind of important microbial secondary metabolites with promising biological activities. Most of them were found in microorganisms, a few were derived from Chinese herbal medicine. In this review, aiming to provide basis for the further research and development of tetrahydroanthraquinone compounds, we summarized the physiological activities of natural tetrahydroanthraquinone compounds, including anti-cancer, anti-microbial, and antidiabetic activities. The source, structure, and action mechanisms of active tetrahydroanthraquinones are described in detail. Furthermore, this review firstly analyzed the structure–activity relationship of tetrahydroanthraquinones. Our study will serve as a valuable guideline for further research on the structural optimization, mechanism study, and development of tetrahydroanthraquinone as novel drugs. Aiming to provide references for further studies and development of tetrahydroanthraquinone compounds.

The Antifungal Test: An Efficient Screening Tool for the Discovery of Microbial Metabolites with Respiratory Inhibitory Activity

Valuable natural compounds produced by a variety of microorganisms can be used as lead molecules for development of new agrochemicals. Furthermore, high-throughput in vitro screening systems with specific modes of action can increase the probability of discovery of new fungicides. In the current study, a rapid assay tested with various microbes was developed to determine the degree of respiratory inhibition of Saccharomyces cerevisiae in two different liquid media, YG (containing a fermentable carbon source) and NFYG (containing a non-fermentable carbon source). Based on this system, we screened 100 fungal isolates that were classified into basidiomycetes, to find microbial secondary metabolites that act as respiratory inhibitors. Consequently, of the 100 fungal species tested, the culture broth of an IUM04881 isolate inhibited growth of S. cerevisiae in NFYG medium, but not in YG medium. The result is comparable to that from treatment with kresoxim-methyl used as a control, suggesting that the culture broth of IUM04881 isolate might contain active compounds showing the inhibition activity for respiratory chain. Based on the assay developed in this study and spectroscopic analysis, we isolated and identified an antifungal compound (-)-oudemansin A from culture broth of IUM04881 that is identified as Oudemansiella venosolamellata. This is the first report that (-)-oudemansin A is identified from O. venosolamellata in Korea. Taken together, the development of this assay will accelerate efforts to find and identify natural respiratory inhibitors from various microbes.

Growth intensity and antibacterial properties of Enterococcus faecium and Enterococcus durans strains isolated from traditional Carpathian brynza

The article presents the results of the study the ability of four not studied strains of enterococci (E. durans, SB6, E. faecium SB12, E. durans SB18, E. durans SB20), which were isolated from the Carpathian brynza, to reduce the acidity of medium of cultivation, the rate of biomass accumulation and the ability to exhibit antagonistic properties to the opportunistic microflora. Lactic acid and minor compounds are producing in a result of lactose fermentation, which form the specific taste and aroma properties of the product. The activity of acid formation has crucial because it directly connected with the coagulation of proteins and the prevention of the growing of extraneous microflora. Therefore, the rate of acidity increasing of the medium is one of the most important characteristics in selection of strains of lactic acid bacteria for the manufacture of dairy products. High growth rate, resistance to the contamination of extraneous microflora and preservation of their properties in the finished product are the technological properties of the strains. The inhibition of the growth of pathogenic cultures of microorganisms is the main probiotic functions of beneficial bacteria namely antagonistic activity. It was found, that the strain E. durans SB20 manifested the highest ability to increase the acidity of the medium under the cultivation for 24 hours at 37 °C as it reduced the pH on 30.3 %, and the strain E. durans SB18 increased the acidity on 29.9 %. Under 48 hours strains E. durans SB20 and SB18 increased the acidity on 31.1 and 30.5 % (P< 0.001) respectively compared with the control. The growth rate of stains E. durans SB20 and E. durans SB18 were in 18,0 and 17,6 times higher than in control under the cultivation for 24 hours at 37 °C, the optical density were in 18.3 and 18.2 times higher respectively than in the control sample under the cultivation for 48 hours at the same temperature. Furthermore, strains of enterococci showed antagonistic properties against conditionally pathogenic cultures of microorganisms on 24 and 48 hour of cultivation. In addition, it was found that with an increasing temperature of the antagonistic activity of the strains cultivation increased. Obviously, it was connected that more biologically active substances and microbial secondary metabolites are formed under the longer cultivation and higher temperatures. In particular on 48 hours at 37 °C almost of all the tested strains showed moderate antagonistic activity against E. coli, S. enteritidis, E. aerogenes, P. mirabilis and P. aeruginosa. However, all four strains didn`t have antagonistic activity against the test-strain S. aureus.

Isolation and Single Cell Chemical Biological Analysis of Natural Product Producing Cave Microorganisms

Microbial secondary metabolites (natural products) constitute a large fraction of pharmaceuticals, with applications as antibiotics and anti‐cancer therapeutics. However, the discovery of new natural product drug leads is increasingly difficult as isolation studies using traditional methods, and from traditional sources, have resulted in progressively fewer novel compounds discovered. Historically, searching for new sources of biodiversity from unique ecosystems has resulted in increased discovery rates. The cave environment, a previously uninvestigated ecosystem, is a promising terrain to discover bacteria with novel natural products because of its unique conditions, which include low light, relatively constant temperature year‐round, abundant oxygen content, and low nutrient content (oligotrophy). We hypothesize that the oligotrophic environment present in caves forces microorganisms to compete or cooperate with each other, which require the development of natural products as communication, offensive, or defensive chemicals. Non‐Streptomyces actinomycetes are a group of bacteria found in caves that represent good candidates for the isolation of new natural products. We acquire bacterial samples by swabbing rock formations and collecting sediment inside a cave. These samples are diluted and incubated on a number of different agar plating conditions. Individual colonies are then isolated and identified by their 16S rRNA sequences. Isolated actinomycetes are stimulated using a battery of chemical and biological conditions known to elicit secondary metabolism (coculture strains, heavy metals, and antibiotics), and then culture extracts are analyzed for possible cellular activity using multiplexed biological assays against mammalian cells. Specifically, extracts are tested using single cell analysis via a flow cytometry platform termed Multiplexed Activity Metabolomics (MAM), which identifies compounds for isolation by analyzing extracts and metabolomic arrays against multiple cell status markers.Support or Funding InformationNational Cancer Institutes R01 CA226833

Cryptic Chemical Communication: Secondary Metabolic Responses Revealed by Microbial Co-culture.

Microbial secondary metabolites (SMs) have long been viewed as a significant source of novel pharmaceutical and agrochemical molecules. With the increasing availability of genomic data, numerous biosynthetic gene clusters (BGCs) have been discovered. Despite the presence of tens of thousands of BGCs that can theoretically produce extremely diverse SMs, many gene clusters remain in a silent state under axenic culture conditions. Co-culture is a promising research approach as it stimulates the expression of cryptic BGCs to produce novel metabolites and also mimics natural interspecies interactions in a laboratory environment. In recent years, the roles of SMs in microbial communication have caught the attention of researchers and our understanding of microbes and their production of remarkable SMs has improved. SMs may be extensively involved in a variety of communication events among microorganisms. We herein summarize certain representative findings in the field of chemical communication involving SMs in co-culture systems.

Sungeidines from a Non-canonical Enediyne Biosynthetic Pathway.

We report the genome-guided discovery of sungeidines, a class of microbial secondary metabolites with unique structural features. Despite evolutionary relationships with dynemicin-type enediynes, the sungeidines are produced by a biosynthetic gene cluster (BGC) that exhibits distinct differences from known enediyne BGCs. Our studies suggest that the sungeidines are assembled from two octaketide chains that are processed differently than those of the dynemicin-type enediynes. The biosynthesis also involves a unique activating sulfotransferase that promotes a dehydration reaction. The loss of genes, including a putative epoxidase gene, is likely to be the main cause of the divergence of the sungeidine pathway from other canonical enediyne pathways. The findings disclose the surprising evolvability of enediyne pathways and set the stage for characterizing the intriguing enzymatic steps in sungeidine biosynthesis.

Microbial diversity and related secondary metabolite gene assortment at an estuarine mangrove ecosystem

Mangrove ecosystems are a major biodiversity hotspot of the world. The world heritage site Sundarbans is an archipelago with an estuarine mangrove ecosystem. It is assumed that each individual Island of the Sundarbans possess a unique biodiversity due to the seasonal variation of physicochemical parameters, along with tidal dynamics of Bay of Bengal. This study unfolds a time series analysis of microbial diversity using high-resolution 16S rRNA tag pyrosequencing. Eight soil samples were collected over three years at a pristine temperate estuarine site located at the sea mangrove interface at the island of Kalash. Apart from the predominant phyla such as Proteobacteria [31.6%], Chloroflexi [10.7%], Firmicutes [7%] Bacteroidetes [7%] and Actinobacteria [1.2%], soil from Kalash also contained a significant amount of rare phyla NC10 and WS3 categorized as microbial dark matter (MDM). Variation in bacterial community composition occurs mainly as a result of the seasonal changes and consequent alterations of physicochemical parameters leading to microbial adaptations. Further we performed functional metagenomics to estimate the possibility of the synthesis of new natural compounds by diverse Polyketide Synthase (PKS). The data indicated diverse microbial origins of keto synthase sequences from polyketide synthase genes. Presence of this unique keto synthases confirmed the existence of a potential microbiome which may be capable of producing novel small molecules. This is the pioneering report to correlate the microbial community structure of Sundarbans with their potential to produce essential bioactive compounds.

Postharvest disease control efficacy of the polyene macrolide lucensomycin produced by Streptomyces plumbeus strain CA5 against gray mold on grapes

Abstract Microbial secondary metabolites have been a valuable source of antifungal compounds for the fungicide industry to develop plant disease control agents. In order to find natural antifungal compounds useful for the control of Botrytis cinerea causing postharvest gray mold, we screened microbial culture extracts and found the extract of Streptomyces plumbeus strain CA5 which was isolated from the soil sample of Chuncheon Province. The cell extract of CA5 strain markedly reduced the disease incidence of gray mold on grapes to a value of 22.2 % while the non-treated control showed 100 % disease incidence. The active ingredient (CA5A) was identified from the cell extract of CA5 strain using a variety of chromatographic methods and spectroscopic analyses. The structure of CA5A was determined to be the polyene macrolide lucensomycin. Lucensomycin showed inhibitory effects against the spores of B. cinerea at a concentration as low as 1 mg L−1 and completely inhibited gray mold development on grapes at a concentration of 100 mg L−1.