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The genus Thymus L., belonging to the Lamiaceae family, contains about 220 species with a distribution that mainly extends in Europe, northwest Africa, Ethiopia, Asia, and southern Greenland. Due to their excellent biological properties, fresh and/or dried leaves and aerial parts of several Thymus ssp. have been utilized in the traditional medicine of many countries. To evaluate not only the chemical aspects but also the biological properties, the essential oils (EOs), obtained from the pre-flowering and flowering aerial parts of Thymus richardii subsp. nitidus (Guss.) Jalas, endemic to Marettimo Island (Sicily, Italy), were investigated. The chemical composition of the EOs, obtained by classical hydrodistillation and GC-MS and GC-FID analyses, showed the occurrence of similar amounts of monoterpene hydrocarbons, oxygenated monoterpenes, and sesquiterpene hydrocarbons. The main constituents of the pre-flowering oil were β-bisabolene (28.54%), p-cymene (24.45%), and thymol methyl ether (15.90%). The EO obtained from the flowering aerial parts showed as principal metabolites β-bisabolene (17.91%), thymol (16.26%), and limonene (15.59%). The EO of the flowering aerial parts, and its main pure constituents, β-bisabolene, thymol, limonene, p-cymene, and thymol methyl ether were investigated for their antimicrobial activity against oral pathogens and for their antibiofilm and antioxidant properties.

Polyethylene (PE) is high molecular weight synthetic polymer, very hydrofobic and hardly biodegradable. To increase polyethylene bio-degradability it is very important to find microorganisms that improve the PE hydrophilic level and/or reduce the length of its polymeric chain by oxidation. In this study, we isolated Cladosporium halotolerans, a fungal species, from the gastric system of Galleria mellonella larvae. Here, we show that C. halotolerans grows in the presence of PE polymer, it is able to interact with plastic material through its hyphae and secretes enzymes involved in PE degradation.

In this work, the essential oil of the aerial parts of a not previously investigated accession of Prangos trifida (Mill.) Herrnst. & Heyn (Apiaceae), collected in Northern Italy, was analysed by GC/MS. Twenty-five compounds were identified, accounting for 91.30% of the total oil, which is characterised by a high content of monoterpene hydrocarbons (71.26%). The main constituents of the essential oil were cis-beta-ocimene (18.12%), alpha-phellandrene (12.14%), sylvestrene (11.32%), p-mentha-1,3,8-triene (9.56%) and alpha-pinene (8.85%). The essential oil of P. trifida showed a good antimicrobial activity directed above all against Gram-positive bacteria, and had an interesting antioxidant activity, thus making it an excellent candidate for future cosmetic and pharmaceutical applications.

The Stachys L. genus has been used in traditional medicine to treat skin inflammations, stomach disorders, and stress. The aim of this study was to investigate the chemical profile and biological activity of the methanolic extract of Stachys spreitzenhoferi Heldr. (Lamiaceae) aerial parts, collected on the island of Kythira, South Greece. The analysis by liquid chromatography coupled with electrospray ionization and high-resolution mass spectrometry [LC-(-)ESI/HRMSn] of the methanol extract revealed the occurrence of thirty-six compounds - flavonoids, phenylethanoid glycosides, iridoids, quinic acid derivatives, aliphatic alcohol glycosides, and oligosaccharides - highlighting the substantial presence, as main peaks, of the iridoid melittoside (2) along with flavonoid compounds such as 4'-O-methylisoscutellarein mono-acetyl-diglycoside/chrysoeriol mono-acetyl-diglycoside (24), trimethoxy- (35) and tetramethoxyflavones (36). This extract was tested for its antimicrobial properties against Gram-positive and negative pathogenic strains. The extract was not active against Gram-negative bacteria tested, but it possessed a good dose-dependent antimicrobial activity towards S. aureus (MIC: 1.0mg/mL) and L. monocytogenes (MIC: 1.0mg/mL) Gram-(+) strains. Furthermore, this extract has been tested for its possible antioxidant activity in vitro. In particular, it has been shown that these molecules cause a decrease in DPPH, ABTS, and H2O2 radicals. The extract of S. spreitzenhoferi exhibited anti-DPPH activity (IC50: 0.17mg/mL), anti-H2O2 activity (IC50: 0.125mg/mL), and promising antiradical effect with an IC50 value of 0.18mg/mL for anti-ABTS activity. S. spreitzenhoferi extract caused a decrease in ROS (at the concentration of 200μg/mL) and an increase in the activity of the antioxidant enzymes SOD, CAT, and GPX in OZ-stimulated PMNs. Furthermore, it exhibited antiproliferative activity against acute myeloid leukemia (U937cell), causing 50% of cell death at the 0.75mg/mL.

Anthemis secundiramea is a perennial herb native widespread throughout the Mediterranean basin. The oil obtained from the flowers of this plant has antimicrobial properties against gram-positive and -negative bacteria, and inhibits the biofilm formation. The extract of A. secundiramea also has antioxidant activity&mdash, increasing the activity of different enzymes (SOD, CAT, and GPx). Surprisingly, in the oil extracted from the flowers, there is a single molecule, called (+)-(E)-chrysanthenyl acetate: This makes the A. secundiramea flowers extract extremely interesting for future topical, cosmetic, and nutraceutical applications.

International audience; The evolution of antibacterial resistance has arisen as the main downside in fighting bacterial infections pushing researchers to develop novel, more potent and multimodal alternative drugs.Silver and its complexes have long been used as antimicrobial agents in medicine due to the lack of silver resistance and the effectiveness at low concentration as well as to their low toxicities compared to the most commonly used antibiotics. N-Heterocyclic Carbenes (NHCs) have been extensively employed to coordinate transition metals mainly for catalytic chemistry. However, more recently, NHC ligands have been applied as carrier molecules for metals in anticancer applications. In the present study we selected from literature two NHC-carbene based on acridinescaffoldand detailed nonclassicalpyrazole derived mono NHC-Ag neutral and bis NHC-Ag cationic complexes. Their inhibitor effect on bacterial strains Gram-negative and positivewas evaluated. Imidazolium NHC silver complex containing the acridine chromophore showed effectiveness at extremely low MIC values. Although pyrazole NHC silver complexes are less active than the acridine NHC-silver, they represent the first example of this class of compounds with antimicrobial properties. Moreover all complexesare not toxic and they show not significant activity againstmammalian cells (Hek lines) after 4 and 24 h. Based on our experimental evidence, we are confident that this promising class of complexes could represent a valuable starting point for developing candidates for the treatment of bacterial infections, delivering great effectiveness and avoiding the development of resistance mechanisms.

Acca sellowiana is an evergreen plant that produces edible fruit whit high nutritional properties, and also contains clinically relevant bioactive compounds, including polyphenols and essential oils. Numerous biological activities were demonstrated for A. sellowiana fruits: antifungal and antitumoral and anti-oxidant. It was also showed a strong antibacterial activity against Gram-positive and Gram-negative bacteria. Fruit are generally considered recalcitrant plant tissues for the difficulty to obtain high quality protein due to a low protein content and the presence of interfering substances. For this reason, the objective of the present work was obtain high quantity of protein extract, to determine the location in the fruit of the molecules responsible for the antibacterial activity, separate them according to molecular weight, test their thermo resistance, study the timing of action, isolate the protein fraction having activity and hypothesise a mechanism of action directed against bacterial membranes.

EFV12 is a small bioactive peptide produced by Lactobacillus gasseri SF1109, a human intestinal isolate with probiotic features. In this study, EFV12 antimicrobial and anti-inflammatory properties are characterised. In particular, we propose a possible mechanism of action for EFV12 involving bacterial membranes targeting. Moreover, we show that this small peptide is able to bind lipopolysaccharides (LPS) and to counteract its inflammatory insult preventing LPS action on Toll-like receptor 4, thus interfering with extracellular signal-regulated kinase, p38 and Jun N-terminal kinase, mitogen-activated protein kinases signalling pathways. Altogether these observations suggest that the bioactive peptide EFV12 is a good candidate to promote L. gasseri induced gut homeostasis and counteracting intestinal pathogens.

Nature has provided a valuable source of inspiration for developing high performance multifunctional materials. Particularly, catechol-containing amino acid l-3,4-dihydroxyphenylalanine (l-DOPA) has aroused the interest to design hybrid multifunctional materials with superior adhesive ability. DOPA oxidative polymerization mediated by either melanogenic enzymes or an alkaline environment involving catechol intermolecular cross-linking, ultimately leads to melanin oligomers. Recently, relevant studies disclosed the ability of Ti-based nanostructures to tune melanin&rsquo, s supramolecular structure during its formation, starting from melanogenic precursors, thus improving both antioxidant and antimicrobial properties. In this work, we propose a novel biomimetic approach to design hybrid DOPA melanin-like nanostructures through a hydrothermal synthesis opportunely modified by using citric acid to control hydrolysis and condensation reactions of titanium alkoxide precursors. UV-Vis and Electron paramagnetic resonance (EPR) spectroscopic evidences highlighted the key role of citrate&ndash, Ti(IV) and DOPA&ndash, Ti(IV) complexes in controlling DOPA polymerization, which specifically occurred during the hydrothermal step, mediating and tuning its conversion to melanin-like oligomers. Trasmission electron microscopy (TEM) images proved the efficacy of the proposed synthesis approach in tuning the formation of nanosized globular nanostructures, with high biocide performances. The obtained findings could provide strategic guidelines to set up biomimetic processes, exploiting the catechol-metal complex to obtain hybrid melanin-like nanosystems with optimized multifunctional behavior.

Conium maculatum is a nitrophilous weed belonging to the Apiaceae family and occurring in hedgerows, pastures, waste ground, along rivers and roadsides. Little is known on the chemistry and bioactivity of other secondary metabolites occurring in the plant. In the present work, we have analysed the chemical composition and antimicrobial activity of the essential oils hydrodistilled from leaves and inflorescenes of C. maculatum growing in Sicily, Italy. The composition of essential oils was achieved by gas chromatography-mass spectrometry (GC-MS) analysis, whereas the inhibitory effects on the growth of two Gram negative strains, namely Escherichia coli and Pseudomonas aeruginosa were assessed by two different analysis. The essential oils exhibited different chemical profiles (1-butylpiperidine and myrcene in the inflorescenes), (mostly (E)-caryophyllene in the leaves). The latter oil was particularly active in inhibiting the growth of P. aeruginosa. These results shed light on the possible application of hemlock essential oils as antimicrobial agents.

Heat stress affects the yield of medicinal plants and can reduce biomass and/or metabolite production. In order to evaluate the effect of heat-induced stress on the essential oil production in Mentha x piperita L. var. Mitcham (Mitcham mint) and Mentha arvensis var. piperascens Malinv. ex L. H. Bailey (Japanese mint), we studied the chemical composition of the oils of the two mint species under different heat shock stresses in growth chambers. The antibacterial activity of the essential oils was also evaluated, microscopic observation (fluorescence and electron transmission) was used to assess the effect of the tested samples on bacterial growth. The results obtained shed light on the mint essential oils composition and biological activity in relation to heat stress.

Bioactive peptides derived from the receptor-binding region of human apolipoprotein E have previously been reported. All these peptides, encompassing fragments of this region or designed on the basis of short repeated cationic sequences identified in the same region, show toxic activities against a broad spectrum of bacteria and interesting immunomodulatory effects. However, the ability of these molecules to exert antibiofilm properties has not been described so far. In the present work, we report the characterization of a novel peptide, corresponding to residues 133 to 167 of human apolipoprotein E, here named ApoE (133-167). This peptide, besides presenting interesting properties comparable with those reported for other ApoE-derived peptides, such as a direct killing activity against a broad spectrum of bacteria or the ability to downregulate lipopolysaccharide-induced cytokine release, is also endowed with significant antibiofilm properties. Indeed, the peptide is able to strongly affect the formation of the extracellular matrix and also the viability of encapsulated bacteria. Noteworthy, ApoE (133-167) is not toxic toward human and murine cell lines and is able to assume ordered conformations in the presence of membrane mimicking agents. Taken together, collected evidences about biological and structural properties of ApoE (133-167) open new perspectives in the design of therapeutic agents based on human-derived bioactive peptides. Copyright © 2018 European Peptide Society and John Wiley & Sons, Ltd.

Ten lactic acid bacteria (LAB) strains, previously isolated from human ileal biopsy of healthy volunteers, were screened for production and secretion of molecules having anti-bacterial and anti-biofilm activities. Because many recent reports indicate that LAB secreted molecules may exert immune-modulatory action, we also tested the effect on human intestinal HCT116 cells challenged with bacterial lipopolysaccharides. One of the Lactobacillus gasseri strains, SF1109, strongly inhibited: (1) Pseudomonas aeruginosa growth; (2) Escherichia coli biofilm production; (3) LPS induction of P-ERK1/2 in HCT116 cells, and was selected for further characterisation of the secreted active molecule. Cell-free supernatant of the L. gasseri SF1109 was analysed and one 1.3 kDa peptide has been characterised. Eight out twelve amino acids of this peptide were identified allowing the synthesis of an octa-peptide which still presented the mentioned activities.

Cationic antimicrobial peptides (AMPs) possess fast and broad-spectrum activity against both Gram-negative and Gram-positive bacteria, as well as fungi. It has become increasingly evident that many AMPs, including those that derive from fragments of host proteins, are multifunctional and able to mediate various immunomodulatory functions and angiogenesis. Among these, synthetic apolipoprotein-derived peptides are safe and well tolerated in humans and have emerged as promising candidates in the treatment of various inflammatory conditions. Here, we report the characterization of a new AMP corresponding to residues 133-150 of human apolipoprotein E. Our results show that this peptide, produced either by chemical synthesis or by recombinant techniques in Escherichia coli, possesses a broad-spectrum antibacterial activity. As shown for several other AMPs, ApoE (133-150) is structured in the presence of TFE and of membrane-mimicking agents, like SDS, or bacterial surface lipopolysaccharide (LPS), and an anionic polysaccharide, alginate, which mimics anionic capsular exo-polysaccharides of several pathogenic microorganisms. Noteworthy, ApoE (133-150) is not toxic toward several human cell lines and triggers a significant innate immune response, assessed either as decreased expression levels of proinflammatory cytokines in differentiated THP-1 monocytic cells or by the induction of chemokines released from PBMCs. This novel bioactive AMP also showed a significant anti-inflammatory effect on human keratinocytes, suggesting its potential use as a model for designing new immunomodulatory therapeutics.

Background The outermost layer of mycobacterial cell wall is rich in lipids and glycolipids, surface molecules which differ among species. Mycobacterium smegmatis, an attractive model for the study of both pathogenic and non-pathogenic mycobacteria, presents glycopeptidolipids (GPLs). All the genes necessary for the biosynthesis of such molecules are clustered in a single region of 65 kb and among them, the msmeg_0412 gene has not been characterized yet. Here we report the isolation and subsequent analysis of a MSMEG_0412 null mutant strain. Results The inactivation of the msmeg_0412 gene had a drastic impact on bacterial surface properties which resulted in the lack of sliding motility, altered biofilm formation and enhanced drug susceptibility. The GPLs analysis showed that the observed mutant phenotype was due to GPLs deficiencies on the mycobacterial cell wall. In addition, we report that the expression of the gene is enhanced in the presence of lipidic substrates and that the encoded protein has a membrane localization. Conclusion msmeg_0412 plays a crucial role for GPLs production and translocation on M. smegmatis surface. Its deletion alters the surface properties and the antibiotic permeability of the mycobacterial cell barrier. Electronic supplementary material The online version of this article (doi:10.1186/s12866-016-0888-z) contains supplementary material, which is available to authorized users.

We investigated the antimicrobial activity of PD-L4, a type 1 RIP from Phytolacca dioica. We found that this protein is active on different bacterial strains both in a native and denatured/alkylated form and that this biological activity is related to a cryptic peptide, named PDL440-65, identified by chemical fragmentation. This peptide showed the same antimicrobial activity of full-length protein and possessed, similarly to several antimicrobial peptides, an immunomodulatory effect on human cells. It assumes an alpha-helical conformation when interact with mimic membrane agents as TFE and likely bacterial membranes are a target of this peptide. To date PDL440-65 is the first antimicrobial peptide identified in a type 1 RIP. We investigated the antimicrobial activity of PD-L4, a type 1 RIP from Phytolacca dioica. We found that this protein is active on different bacterial strains both in a native and denatured/alkylated form and that this biological activity is related to a cryptic peptide, named PDL4(40-65), identified by chemical fragmentation. This peptide showed the same antimicrobial activity of full-length protein and possessed, similarly to several antimicrobial peptides, an immunomodulatory effect on human cells. It assumes an alpha-helical conformation when interact with mimic membrane agents as TFE and likely bacterial membranes are a target of this peptide. To date PDL4(40-65) is the first antimicrobial peptide identified in a type 1 RIP. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Organic materials are widely employed to tune surface chemistry and/or as structuring agents of inorganic materials. Here, we propose a novel synthesis approach whereby TiO2 not only promotes 5,6-dihydroxyindole-2-carboxylic acid (DHICA) polymerization but also acts as a templating agent for the formation itself. Hybrid TiO2–DHICA melanin nanostructures have been produced, showing biocide activity even under visible light conditions (activation). Hybrid nanostructures have been analyzed and characterized by multiple techniques, proving that both organic and inorganic phases strongly affect each other during in situ formation, as far as it concerns both morphology and microstructure, conferring unique biocide properties to the resulting nanomaterials. This strategy ensures much more far-reaching implementation in the synthesis of hybrid nanosystems, opening new perspectives in the design of multifunctional materials.

A new series of 5-substituted oxazolidinones derived from linezolid, having urea and thiourea moieties at the C-5 side chain of the oxazolidinone ring, were prepared and their in vitro antibacterial activity was evaluated. The compound 10f demonstrated high antimicrobial activity, comparable to that of linezolid against Staphylococcus aureus.

ATP synthase and protein kinase (PKs) are prime targets for drug discovery in a variety of diseases. It is well known that numerous stilbenes are capable to interact and inhibit ATP synthase and PKs. This work focuses on a series of azobenzene based molecules having high structural similarity with antimicrobial stilbenes. An investigation was carried out analyzing the potential toxicity of a large set of molecules by means of computational analysis. A small selection of potential low toxic molecules have been therefore synthesized, characterized and finally microbiologically tested. The synthesized compounds show potent bactericidal activity against Gram+ and a fungus, and are capable of inhibiting biofilm formation. Finally, the compounds demonstrated a thermal stability that makes them potential candidates for incorporation in polymer matrix for application as biomedical devices and food packaging.

Background Secondary metabolites ranging from furanone to exo-polysaccharides have been suggested to have anti-biofilm activity in various recent studies. Among these, Escherichia coli group II capsular polysaccharides were shown to inhibit biofilm formation of a wide range of organisms and more recently marine Vibrio sp. were found to secrete complex exopolysaccharides having the potential for broad-spectrum biofilm inhibition and disruption. Results In this study we report that a newly identified ca. 1800 kDa polysaccharide having simple monomeric units of α-D-galactopyranosyl-(1→2)-glycerol-phosphate exerts an anti-biofilm activity against a number of both pathogenic and non-pathogenic strains without bactericidal effects. This polysaccharide was extracted from a Bacillus licheniformis strain associated with the marine organism Spongia officinalis. The mechanism of action of this compound is most likely independent from quorum sensing, as its structure is unrelated to any of the so far known quorum sensing molecules. In our experiments we also found that treatment of abiotic surfaces with our polysaccharide reduced the initial adhesion and biofilm development of strains such as Escherichia coli PHL628 and Pseudomonas fluorescens. Conclusion The polysaccharide isolated from sponge-associated B. licheniformis has several features that provide a tool for better exploration of novel anti-biofilm compounds. Inhibiting biofilm formation of a wide range of bacteria without affecting their growth appears to represent a special feature of the polysaccharide described in this report. Further research on such surface-active compounds might help developing new classes of anti-biofilm molecules with broad spectrum activity and more in general will allow exploring of new functions for bacterial polysaccharides in the environment.

The terpene metabolite pattern of Mediterranean Spongia officinalis was chemically investigated. This study resulted in the isolation of a series of sesterterpenes and C21 furanoterpenes, according to the literature data on this sponge. Four new oxidized minor metabolites (compounds 1, 2, 3, and 4) were isolated along with six known compounds of the furospongin series (compounds 5-8, 9, and 10) and three scalarane sesterterpenes (compounds 11-13). Interestingly, tetrahydrofurospongin-2 (6) and dihydrofurospongin-2 (7), which were among the main metabolites, induced biofilm formation by Escherichia coli. All compounds isolated were also assayed for antibacterial and antifungal properties.

Background Chondroitin sulphate is a complex polysaccharide having important structural and protective functions in animal tissues. Extracted from animals, this compound is used as a human anti-inflammatory drug. Among bacteria, Escherichia coli K4 produces a capsule containing a non-sulphate chondroitin and its development may provide an efficient and cheap fermentative production of the polysaccharide. Results A random N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis was performed on E. coli K4 to isolate mutants showing an increased production of chondroitin. Several mutants were isolated, one of which, here named VZ15, produced about 80% more chondroitin than the wild type E. coli. We found that the mutant has a missense mutation in the codon 313 of kfoC, the gene encoding chondroitin polymerase (K4CP), with a change from arginine to glutamine. A docking analysis to explain the increased productivity of the K4CP enzyme is presented. Conclusion The enhanced chondroitin production by the E. coli K4 mutant reported here shows the validity of the strain improvement strategy for more cost-friendly fermentative processes in the production of this pharmaceutically important but so-far expensive polysaccharide.

Five new unsaturated 2-amino-3-alcohols, crucigasterins A–E (2–6), were isolated together with known related compound 7 from the Mediterranean ascidian Pseudodistoma crucigaster and characterised as diacetyl derivatives (2a–6a) by spectroscopic methods. The threo-relative configuration of the amino alcohol portion was inferred by NOE analysis of the oxazolidinone derivative of crucigasterin A (2) as well as by 13C NMR comparison with synthetic threo and erythro model compounds. The co-occurring metabolites were assumed to have the same relative configuration as 2 by comparison of the diagnostic carbon value of C-1. The absolute stereochemistry of compound 7 that had not been previously reported was determined by applying the modified Mosher’s method on the corresponding N-acetyl derivative. The same absolute configuration was suggested for the other co-occurring crucigasterins by biogenetic considerations. Antibacterial and antifungal activities of selected crucigasterins were also evaluated.

Streptococcus thermophilus is an important dairy starter used for the manufacture of fermented milks and cheeses. As for many other lactic acid bacteria, its survival during propagation and preservation of starter cultures and its performance in dairy fermentations are significantly affected by its ability to cope with many environmental stresses. This, in turn, is dependent on the expression of a several genes, which is often controlled by negative response regulators, and has complex relationships with the control of metabolism. In this paper we describe the effect of growth phase, adaptation and inactivation of genes for stress response regulators (hrcA, ctsR and rr01) on the growth, acid production and stress resistance and intracellular protein patterns in the yoghurt strain S. thermophilus Sfi39. Inactivation of stress response regulators significantly affected growth, acid production in milk and stress tolerance. Although mutants showed an increased resistance during the exponential phase compared to the wild type strain, the effect of the mutations was complex and in some cases mutants were unable to mount an acid- or heat-shock response after exposure to mild heat and acid stresses. Significant differences in intracellular protein patterns analyzed by SDS-PAGE and 2-DE/mass spectrometry were found as a function of growth phase, adaptation and mutation, but a detailed transcriptomic and proteomic study would be needed to provide a mechanistic interpretation of the effect of the mutations and to identify a strategy for the construction of food-grade mutants with improved growth and performances.

Background Heat and cold shock response are normally considered as independent phenomena. A small amount of evidence suggests instead that interactions may exist between them in two Lactococcus strains. Results We show the occurrence of molecular relationships between the mechanisms of cold and heat adaptations in Streptococcus thermophilus, a lactic acid bacterium widely used in dairy fermentation, where it undergoes both types of stress. We observed that cryotolerance is increased when cells are pre-incubated at high temperature. In addition, the production of a protein, identified as ClpL, a member of the heat-shock ATPase family Clp A/B, is induced at both high and low temperature. A knock-out clpL mutant is deficient in both heat and cold tolerance. However lack of production of this protein does not abolish the positive effect of heat pre-treatment towards cryotolerance. Conclusion Dual induction of ClpL by cold and heat exposure of cells and reduced tolerance to both temperature shocks in a clpL mutant indicates that the two stress responses are correlated in S. thermophilus. However this protein is not responsible by itself for cryotolerance of cells pre-treated at high temperature, indicating that ClpL is necessary for the two phenomena, but does not account by itself for the relationships between them.

A newly identified bglH gene coding for a phospho-β-glucosidase of Lactobacillus plantarum was isolated and expressed in Escherichia coli . The sequence analysis of the cloned DNA fragment showed an open reading frame encoding a 480-amino-acid protein with a calculated molecular mass of 53 kDa. The bglH gene was shown to be expressed on a monocistronic transcriptional unit. Its transcription was repressed 10-fold in L. plantarum cells grown on glucose compared to the β-glucoside salicin as a sole carbon source. A catabolite-responsive element (CRE) spanning from −3 to +11 with respect to the transcriptional start point was found, and its functionality was assessed by mutational analysis. In vitro and in vivo DNA binding experiments suggested the occurrence of a DNA-protein complex at the CRE site, which would mediate glucose repression of bglH expression.