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In recent years, research in the field of Microbial Ecology has revealed the tremendous diversity and complexity of microbial communities across different ecosystems. Microbes play a major role in ecosystem functioning and contribute to the health and fitness of higher organisms. Scientists are now facing many technological and methodological challenges in analyzing these complex natural microbial communities. The advances in analytical and omics techniques have shown that microbial communities are largely shaped by chemical interaction networks mediated by specialized (water-soluble and volatile) metabolites. However, studies concerning microbial chemical interactions need to consider biotic and abiotic factors on multidimensional levels, which require the development of new tools and approaches mimicking natural microbial habitats. In this review, we describe environmental factors affecting the production and transport of specialized metabolites. We evaluate their ecological functions and discuss approaches to address future challenges in microbial chemical ecology (MCE). We aim to emphasize that future developments in the field of MCE will need to include holistic studies involving organisms at all levels and to consider mechanisms underlying the interactions between viruses, micro-, and macro-organisms in their natural environments.

Fusarium culmorum is one of the most important fungal plant pathogens that causes diseases on a wide diversity of cereal and non-cereal crops. We report herein for the first time the genome sequence of F. culmorum strain PV and its associated secondary metabolome that plays a role in the interaction with other microorganisms and contributes to its pathogenicity on plants. The genome revealed the presence of two terpene synthases, trichodiene and longiborneol synthase, which generate an array of volatile terpenes. Furthermore, we identified two gene clusters, deoxynivalenol and zearalenone, which encode for the production of mycotoxins. Linking the production of mycotoxins with in vitro bioassays, we found high virulence of F. culmorum PV on maize, barley and wheat. By using ultra-performance liquid chromatography–mass spectrometry, we confirmed several compounds important for the behaviour and lifestyle of F. culmorum. This research sets the basis for future studies in microbe–plant interactions.

The ability of bacteria and fungi to communicate with each other is a remarkable aspect of the microbial world. It is recognized that volatile organic compounds (VOCs) act as communication signals, however the molecular responses by bacteria to fungal VOCs remain unknown. Here we perform transcriptomics and proteomics analyses of Serratia plymuthica PRI-2C exposed to VOCs emitted by the fungal pathogen Fusarium culmorum. We find that the bacterium responds to fungal VOCs with changes in gene and protein expression related to motility, signal transduction, energy metabolism, cell envelope biogenesis, and secondary metabolite production. Metabolomic analysis of the bacterium exposed to the fungal VOCs, gene cluster comparison, and heterologous co-expression of a terpene synthase and a methyltransferase revealed the production of the unusual terpene sodorifen in response to fungal VOCs. These results strongly suggest that VOCs are not only a metabolic waste but important compounds in the long-distance communication between fungi and bacteria

Background Collimonas is a genus belonging to the class of Betaproteobacteria and consists mostly of soil bacteria with the ability to exploit living fungi as food source (mycophagy). Collimonas strains differ in a range of activities, including swimming motility, quorum sensing, extracellular protease activity, siderophore production, and antimicrobial activities. Results In order to reveal ecological traits possibly related to Collimonas lifestyle and secondary metabolites production, we performed a comparative genomics analysis based on whole-genome sequencing of six strains representing 3 recognized species. The analysis revealed that the core genome represents 43.1 to 52.7 % of the genomes of the six individual strains. These include genes coding for extracellular enzymes (chitinase, peptidase, phospholipase), iron acquisition and type II secretion systems. In the variable genome, differences were found in genes coding for secondary metabolites (e.g. tripropeptin A and volatile terpenes), several unknown orphan polyketide synthase-nonribosomal peptide synthetase (PKS-NRPS), nonribosomal peptide synthetase (NRPS) gene clusters, a new lipopeptide and type III and type VI secretion systems. Potential roles of the latter genes in the interaction with other organisms were investigated. Mutation of a gene involved in tripropeptin A biosynthesis strongly reduced the antibacterial activity against Staphylococcus aureus, while disruption of a gene involved in the biosynthesis of the new lipopeptide had a large effect on the antifungal/oomycetal activities. Conclusions Overall our results indicated that Collimonas genomes harbour many genes encoding for novel enzymes and secondary metabolites (including terpenes) important for interactions with other organisms and revealed genomic plasticity, which reflect the behaviour, antimicrobial activity and lifestylesof Collimonas spp.

A prototype tilted jaw crusher has been successfully tested on the surface at a limestone quarry. Underground production testing is planned for 1982, during which detailed maintenance and cost data will be obtained. The mobility of the crusher is of particular interest as it will have to be kept close to the mine face., A prototype tilted jaw crusher has been successfully tested on the surface at a limestone quarry. Underground production testing is planned for 1982, during which detailed maintenance and cost data will be obtained. The mobility of the crusher is of particular interest as it will have to be kept close to the mine face.

The US Bureau of Mines has a long-term programme on non-explosive fragmentation of hard rock. The thrust of this research has been water-jet and mechanical fragmentation. The ultimate objective is to develop equipment and procedures for continuous hard rock extraction as an alternative to the cyclic drill-blast-muck system used in most underground hard rock mines. Two mechanical mining systems, the radial-axial splitter and the ripper-miner, have been shown to be capable of continuous hard rock fragmentation., The US Bureau of Mines has a long-term programme on non-explosive fragmentation of hard rock. The thrust of this research has been water-jet and mechanical fragmentation. The ultimate objective is to develop equipment and procedures for continuous hard rock extraction as an alternative to the cyclic drill-blast-muck system used in most underground hard rock mines. Two mechanical mining systems, the radial-axial splitter and the ripper-miner, have been shown to be capable of continuous hard rock fragmentation.

The USBM has developed a hardrock cutting concept and incorporated it into an extraction system called the ripper miner. The history of the development of the ripper miner from the initial laboratory tests through the construction and testing of the full-scale, laboratory prototype is presented. It includes a comparison of the ripper miner to systems currently used from the standpoint of energy efficiencies and operating costs., The USBM has developed a hardrock cutting concept and incorporated it into an extraction system called the ripper miner. The history of the development of the ripper miner from the initial laboratory tests through the construction and testing of the full-scale, laboratory prototype is presented. It includes a comparison of the ripper miner to systems currently used from the standpoint of energy efficiencies and operating costs.