mVOC 4.0: a database of microbial volatiles.

Metabolomic microbiome research has become an important topic for understanding agricultural, ecological as well as health correlations. Only the determination of both the non-volatile and the volatile organic compound (mVOC) production by microorganisms allows a holistic view for understanding the complete potential of metabolomes and metabolic capabilities of bacteria. In the recent past, more and more bacterial headspaces and culture media were analyzed, leading to an accumulation of about 3500 mVOCs in the updated mVOC 4.

Evolution-guided engineering of -acyltransferase polyketide synthases.

Bacterial multimodular polyketide synthases (PKSs) are giant enzymes that generate a wide range of therapeutically important but synthetically challenging natural products. Diversification of polyketide structures can be achieved by engineering these enzymes. However, notwithstanding successes made with textbook -acyltransferase (-AT) PKSs, tailoring such large assembly lines remains challenging.

Volatilomes of human infection.

The human volatilome comprises a vast mixture of volatile emissions produced by the human body and its microbiomes. Following infection, the human volatilome undergoes significant shifts, and presents a unique medium for non-invasive biomarker discovery. In this review, we examine how the onset of infection impacts the production of volatile metabolites that reflects dysbiosis by pathogenic microbes.

Non-canonical Biosynthesis of the Brexane-Type Bishomosesquiterpene Chlororaphen through Two Consecutive Methylation Steps in Pseudomonas chlororaphis O6 and Variovorax boronicumulans PHE5-4.

A non-canonical biosynthetic pathway furnishing the first natural brexane-type bishomosesquiterpene (chlororaphen, C H ) was elucidated in the γ-proteobacterium Pseudomonas chlororaphis O6. A combination of genome mining, pathway cloning, in vitro enzyme assays, and NMR spectroscopy revealed a three-step pathway initiated by C10 methylation of farnesyl pyrophosphate (FPP, C ) along with cyclization and ring contraction to furnish monocyclic γ-presodorifen pyrophosphate (γ-PSPP, C ). Subsequent C-methylation of γ-PSPP by a second C-methyltransferase furnishes the monocyclic α-prechlororaphen pyrophosphate (α-PCPP, C ), serving as the substrate for the terpene synthase.

Modular Halogenation, α-Hydroxylation, and Acylation by a Remarkably Versatile Polyketide Synthase.

Bacterial multimodular polyketide synthases (PKSs) are large enzymatic assembly lines that synthesize many bioactive natural products of therapeutic relevance. While PKS catalysis is mostly based on fatty acid biosynthetic principles, polyketides can be further diversified by post-PKS enzymes. Here, we characterized a remarkably versatile trans-acyltransferase (trans-AT) PKS from Serratia that builds structurally complex macrolides via more than ten functionally distinct PKS modules.

Impact of bacterial volatiles on phytopathogenic fungi: an in vitro study on microbial competition and interaction.

Microorganisms in the rhizosphere are abundant and exist in very high taxonomic diversity. The major players are bacteria and fungi, and bacteria have evolved many strategies to prevail over fungi, among them harmful enzyme activities and noxious secondary metabolites. Interactions between plant growth promoting rhizobacteria and phytopathogenic fungi are potentially valuable since the plant would benefit from fungal growth repression.

The Endophytic Fungus Influences Growth of the Nonnatural Host Plant .

is a fungal endophyte from , a perennial plant from the northern part of Asia. Here, we demonstrated an interaction of with , Chinese cabbage, rapeseed, tomato, maize, or sunflower resulting in different phenotypes such as shorter main roots, massive lateral root growth, higher leaf and root biomass, and increased anthocyanin levels. In a variety of cocultivation assays, it was shown that these altered phenotypes are caused by fungal CO, volatile organic compounds, and soluble compounds, notably astins.

Metabolic Profiling of Rhizobacteria and Revealed Intra- and Interspecific Differences and Elicitation of Plipastatins and Short Peptides Due to Co-cultivation.

Rhizobacteria live in diverse and dynamic communities having a high impact on plant growth and development. Due to the complexity of the microbial communities and the difficult accessibility of the rhizosphere, investigations of interactive processes within this bacterial network are challenging. In order to better understand causal relationships between individual members of the microbial community of plants, we started to investigate the inter- and intraspecific interaction potential of three rhizobacteria, the isolates 4Rx13 and AS9 and B2g, using high resolution mass spectrometry based metabolic profiling of structured, low-diversity model communities.

Non-canonical substrates for terpene synthases in bacteria are synthesized by a new family of methyltransferases.

The 'biogenetic isoprene rule', formulated in the mid 20th century, predicted that terpenoids are biosynthesized via polymerization of C5 isoprene units. The polymerizing enzymes have been identified to be isoprenyl diphosphate synthases, products of which are catalyzed by terpene synthases (TPSs) to achieve vast structural diversity of terpene skeletons. Irregular terpenes (e.

Reaction mechanism of the farnesyl pyrophosphate C-methyltransferase towards the biosynthesis of pre-sodorifen pyrophosphate by Serratia plymuthica 4Rx13.

Classical terpenoid biosynthesis involves the cyclization of the linear prenyl pyrophosphate precursors geranyl-, farnesyl-, or geranylgeranyl pyrophosphate (GPP, FPP, GGPP) and their isomers, to produce a huge number of natural compounds. Recently, it was shown for the first time that the biosynthesis of the unique homo-sesquiterpene sodorifen by Serratia plymuthica 4Rx13 involves a methylated and cyclized intermediate as the substrate of the sodorifen synthase. To further support the proposed biosynthetic pathway, we now identified the cyclic prenyl pyrophosphate intermediate pre-sodorifen pyrophosphate (PSPP).

Sixty-One Volatiles Have Phylogenetic Signals Across Bacterial Domain and Fungal Kingdom.

Microorganisms are diverse in their genome sequences and subsequently in their encoded metabolic pathways, which enabled them to adapt to numerous environmental conditions. They produce thousands of small molecules, many of which are volatiles in nature and play important roles in signaling in intra- and inter-species to kingdom and domain interactions, survival, or virulence. Many of these compounds have been studied, characterized, and organized in the mVOC 2.

Volatilomes of Bacterial Infections in Humans.

Sense of smell in humans has the capacity to detect certain volatiles from bacterial infections. Our olfactory senses were used in ancient medicine to diagnose diseases in patients. As humans are considered holobionts, each person's unique odor consists of volatile organic compounds (VOCs, volatilome) produced not only by the humans themselves but also by their beneficial and pathogenic micro-habitants.

Publisher Correction: Interspecific formation of the antimicrobial volatile schleiferon.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has been fixed in the paper.

Interspecific formation of the antimicrobial volatile schleiferon.

Microorganisms release a plethora of volatile secondary metabolites. Up to now, it has been widely accepted that these volatile organic compounds are produced and emitted as a final product by a single organism e.g.

Interspecies interaction of Serratia plymuthica 4Rx13 and Bacillus subtilis B2g alters the emission of sodorifen.

Sodorifen is the major volatile of Serratia plymuthica 4Rx13. It is assumed to be a long-distance communication signal. However, so far the emission patterns of sodorifen had been studied using mono-cultures of S.

Sodorifen Biosynthesis in the Rhizobacterium Serratia plymuthica Involves Methylation and Cyclization of MEP-Derived Farnesyl Pyrophosphate by a SAM-Dependent C-Methyltransferase.

The rhizobacterium Serratia plymuthica 4Rx13 releases a unique polymethylated hydrocarbon (CH) with a bicyclo[3.2.1]octadiene skeleton called sodorifen.

A Polyketide Synthase Component for Oxygen Insertion into Polyketide Backbones.

Enzymatic core components from trans-acyltransferase polyketide synthases (trans-AT PKSs) catalyze exceptionally diverse biosynthetic transformations to generate structurally complex bioactive compounds. Here we focus on a group of oxygenases identified in various trans-AT PKS pathways, including those for pederin, oocydins, and toblerols. Using the oocydin pathway homologue (OocK) from Serratia plymuthica 4Rx13 and N-acetylcysteamine (SNAC) thioesters as test surrogates for acyl carrier protein (ACP)-tethered intermediates, we show that the enzyme inserts oxygen into β-ketoacyl moieties to yield malonyl ester SNAC products.

Carbon Catabolite Repression Regulates the Production of the Unique Volatile Sodorifen of 4Rx13.

Microorganisms are capable of synthesizing a plethora of secondary metabolites including the long-overlooked volatile organic compounds. Little knowledge has been accumulated regarding the regulation of the biosynthesis of such mVOCs. The emission of the unique compound sodorifen of isolates was significantly reduced in minimal medium with glucose, while succinate elevated sodorifen release.

mVOC 2.0: a database of microbial volatiles.

Metabolic capabilities of microorganisms include the production of secondary metabolites (e.g. antibiotics).

Effects of discrete bioactive microbial volatiles on plants and fungi.

Plants live in association with microorganisms, which are well known as a rich source of specialized metabolites, including volatile compounds. The increasing numbers of described plant microbiomes allowed manifold phylogenetic tree deductions, but less emphasis is presently put on the metabolic capacities of plant-associated microorganisms. With the focus on small volatile metabolites we summarize (i) the knowledge of prominent bacteria of plant microbiomes; (ii) present the state-of-the-art of individual (discrete) microbial organic and inorganic volatiles affecting plants and fungi; and (iii) emphasize the high potential of microbial volatiles in mediating microbe-plant interactions.

Effects of Phytoestrogen Extracts Isolated from Elder Flower on Hormone Production and Receptor Expression of Trophoblast Tumor Cells JEG-3 and BeWo, as well as MCF7 Breast Cancer Cells.

Hereinwe investigated the effect of elderflower extracts (EFE) and of enterolactone/enterodiol on hormone production and proliferation of trophoblast tumor cell lines JEG-3 and BeWo, as well as MCF7 breast cancer cells. The EFE was analyzed by mass spectrometry. Cells were incubated with various concentrations of EFE.

The α-Terpineol to 1,8-Cineole Cyclization Reaction of Tobacco Terpene Synthases.

Flowers of Nicotiana species emit a characteristic blend including the cineole cassette monoterpenes. This set of terpenes is synthesized by multiproduct enzymes, with either 1,8-cineole or α-terpineol contributing most to the volatile spectrum, thus referring to cineole or terpineol synthase, respectively. To understand the molecular and structural requirements of the enzymes that favor the biochemical formation of α-terpineol and 1,8-cineole, site-directed mutagenesis, in silico modeling, and semiempiric calculations were performed.

Novel volatiles of skin-borne bacteria inhibit the growth of Gram-positive bacteria and affect quorum-sensing controlled phenotypes of Gram-negative bacteria.

The skin microbiota is import for body protection. Here we present the first comprehensive analysis of the volatile organic compound (VOC) profiles of typical skin-resident corynebacterial and staphylococcal species. The VOC profile of Staphylococcus schleiferi DSMZ 4807 was of particular interest as it is dominated by two compounds, 3-(phenylamino)butan-2-one and 3-(phenylimino)butan-2-one (schleiferon A and B, respectively).

A Terpene Synthase Is Involved in the Synthesis of the Volatile Organic Compound Sodorifen of Serratia plymuthica 4Rx13.

Bacteria release a plethora of volatile organic compounds, including compounds with extraordinary structures. Sodorifen (IUPAC name: 1,2,4,5,6,7,8-heptamethyl-3-methylenebicyclo[3.2.