Microbiological interactions with cold plasma

There is a diverse range of microbiological challenges facing the food, healthcare and clinical sectors. The increasing and pervasive resistance to broad‐spectrum antibiotics and health‐related concerns with many biocidal agents drives research for novel and complementary antimicrobial approaches. Biofilms display increased mechanical and antimicrobial stability and are the subject of extensive research. Cold plasmas (CP) have rapidly evolved as a technology for microbial decontamination, wound healing and cancer treatment, owing to the chemical and bio‐active radicals generated known collectively as reactive oxygen and nitrogen species. This review outlines the basics of CP technology and discusses the interactions with a range of microbiological targets. Advances in mechanistic insights are presented and applications to food and clinical issues are discussed. The possibility of tailoring CP to control specific microbiological challenges is apparent. This review focuses on microbiological issues in relation to food‐ and healthcare‐associated human infections, the role of CP in their elimination and the current status of plasma mechanisms of action.     

Investigating a flower-insect forager network in a mountain grassland community using pollen DNA barcoding

Faced with the decline of pollinators, it is relevant to strengthen our understanding of the whole plant-pollinator web in semi-natural grasslands that serve as refuges for pollinator populations. The aim of this study was to explore the diversity of flower-foraging insects involved in pollen transfer in mountain semi-natural grasslands. Insects actively collecting pollen and/or nectar were caught in spring in six mountain semi-natural grasslands displaying a floristic richness gradient. Individual determinations of insects were made at the finest possible taxonomic scale and pollen loads were removed from the insect body. Using next-generation DNA sequencing, pollens were identified through the ribosomal DNA cistron using the ITS2 database and the ITS plant rDNA cistron sequences from Genbank. A total of 236 flower-foraging insects were collected. Diptera represented 82% of the total catches distantly followed by Hymenoptera (15%) and Apoidea (bees) (11%). Visual observations revealed that Diptera foraged on 16 of the 21 flower species visited by insects. DNA metabarcoding showed that 82% (191) of all of the collected insects were carrying pollen and 44% (104) were carrying two genera of plants or more. Our results demonstrate that Diptera are potential key-pollinators in mountain semi-natural grasslands that cannot be overlooked by the scientific community. However difficulties of taxonomic determination due to severe shortage of experts for Diptera have to be urgently overcome. Further studies on the link between pollen transfer and actual pollination in a global change context are also required. Moreover, our results support the idea that DNA metabarcoding provides accurate information about the plants-insects networks but it also pointed out sensitive issues, especially the necessity to build reliable national barcode databases.     

Pectinase production by <Emphasis Type="Italic">Aspergillus giganteus</Emphasis> in solid-state fermentation: optimization,scale-up,biochemical characterization and its application in olive-oil extraction

The application of pectinases in industrial olive-oil processes is restricted by its production cost. Consequently, new fungal strains able to produce higher pectinase titers are required. The aim of this work was to study the capability of Aspergillus giganteus NRRL10 to produce pectinolytic enzymes by SSF and evaluate the application of these in olive-oil extraction. A. giganteus was selected among 12 strains on the basis of high pectinolytic activity and stability. A mixture composed by wheat bran, orange, and lemon peels was selected as the best substrate for enzyme production. Statistical analyses of the experimental design indicated that pH, temperature, and CaCl₂ are the main factors that affect the production. Subsequently, different aeration flows were tested in a tray reactor; the highest activity was achieved at 20 L min^?1 per kilogram of dry substrate (kgds). Finally, the pectinolytic enzymes from A. giganteus improved the oil yield and rheological characteristics without affecting oil chemical properties.     

Comparative metabolomics reveals the mechanism of avermectin production enhancement by <Emphasis Type="Italic">S</Emphasis>-adenosylmethionine

It was found that S-adenosylmethionine (SAM) could effectively improve avermectin titer with 30–60 μg/mL addition to FH medium. To clearly elucidate the mechanism of SAM on intracellular metabolites of Streptomyces avermitilis, a GC–MS-based comparative metabolomics approach was carried out. First, 230 intracellular metabolites were identified and 14 of them remarkably influenced avermectin biosynthesis were discriminative biomarkers between non-SAM groups and SAM-treated groups by principal components analysis (PCA) and partial least squares (PLS). Based on further key metabolic pathway analyses, these biomarkers, such as glucose, oxaloacetic acid, fatty acids (in soybean oil), threonine, valine, and leucine, were identified as potentially beneficial precursors and added in medium. Compared with single-precursor feeding, the combined feeding of the precursors and SAM markedly increased the avermectin titer. The co-feeding approach not only directly verified our hypothesis on the mechanism of SAM by comparative metabolomics, but also provided a novel strategy to increase avermectin production.     

Intrinsic and extrinsic drivers of recruitment across the distribution range of a seed-dimorphic herb

Recruitment of new individuals, through germination and seedling survival, is a key process for short-lived plants. Here, we analyzed intraspecific variation in recruitment across the latitudinal range of Plantago coronopus, a widespread herb that produces both large basal seeds with a mucilaginous coat and small apical seeds without coat. We experimentally tested the effects of seed traits and water availability on recruitment, by using seeds from a wide environmental stress gradient from N Africa to N Europe. Our experiments were carried out in controlled environmental conditions and in dunes where the species naturally occurs. Water shortage decreased seed germination and seedling survival for all populations, showing the importance of water supply for P. coronopus. Basal seeds showed higher and faster germination rates than apical seeds. Since among-population variation in seed mass was not related to potential germination rate, it is the mucilaginous coat rather than size difference that likely drives the differential success between seed morphs. Seed mass positively affected seedling survival instead, but only in controlled conditions with regular water supply. An experiment in a dune showed indeed that the highest survival corresponded to the local population and not the one with the largest seeds. Our results demonstrate that both intrinsic and extrinsic factors drive inter-population variation in the early life stages of this short-lived plant, allowing it to adapt across the environmentally heterogeneous distribution range. Gathering information on intraspecific variation in recruitment-related traits will help us to understand and predict plant responses in a context of climatic change.     

Secondary biochemical and morphological consequences in lysosomal storage diseases

More than 50 hereditary lysosomal storage disorders (LSDs) are currently described. Most of these disorders are due to a deficiency of certain hydrolases/glycosidases and subsequent accumulation of nonhydrolyzable carbohydrate-containing compounds in lysosomes. Such accumulation causing hypertrophy of the lysosomal compartment is a characteristic feature of affected cells in LSDs. The investigation of biochemical and cellular parameters is of particular interest for understanding “life” of lysosomes in the normal state and in LSDs. This review highlights the wide spectrum of biochemical and morphological changes during developing LSDs that are extremely critical for many metabolic processes inside the various cells and tissues of affected persons. The data presented will help establish new complex strategies for metabolic correction of LSDs.