Background Lactobacillus species produce biosurfactants that can contribute to the bacteria’s ability to prevent microbial infections associated with urogenital and gastrointestinal tracts and the skin. Here, we described the biological and physicochemical properties of biosurfactants produced by Lactobacillus jensenii P6A and Lactobacillus gasseri P65.ResultsThe biosurfactants produced by L. jensenii P6A and L. gasseri P65 reduced the water surface tension from 72 to 43.2 mN m−1 and 42.5 mN m−1 as their concentration increased up to the critical micelle concentration (CMC) values of 7.1 and 8.58 mg mL−1, respectively. Maximum emulsifying activity was obtained at concentrations of 1 and 5 mg mL−1 for the P6A and P65 strains, respectively. The Fourier transform infrared spectroscopy data revealed that the biomolecules consist of a mixture of carbohydrates, lipids and proteins. The gas chromatography-mass spectrum analysis of L. jensenii P6A biosurfactant showed a major peak for 14-methypentadecanoic acid, which was the main fatty acid present in the biomolecule; conversely, eicosanoic acid dominated the biosurfactant produced by L. gasseri P65. Although both biosurfactants contain different percentages of the sugars galactose, glucose and ribose; rhamnose was only detected in the biomolecule produced by L. jensenii P6A. Emulsifying activities were stable after a 60-min incubation at 100 °C, at pH 2–10, and after the addition of potassium chloride and sodium bicarbonate, but not in the presence of sodium chloride. The biomolecules showed antimicrobial activity against clinical isolates of Escherichia coli and Candida albicans, with MIC values of 16 µg mL−1, and against Staphylococcus saprophyticus, Enterobacter aerogenes and Klebsiella pneumoniae at 128 µg mL−1. The biosurfactants also disrupted preformed biofilms of microorganisms at varying concentrations, being more efficient against E. aerogenes (64%) (P6A biosurfactant), and E. coli (46.4%) and S. saprophyticus (39%) (P65 biosurfactant). Both strains of lactobacilli could also co-aggregate pathogens.ConclusionsThis report presents the first characterization of biosurfactants produced by L. jensenii P6A and L. gasseri P65. The antimicrobial properties and stability of these biomolecules indicate their potential use as alternative antimicrobial agents in the medical field for applications against pathogens that are responsible for infections in the gastrointestinal and urogenital tracts and the skin.

HighlightPhytopathogens can co-opt plant primary metabolism to enhance pathogenesis and pathogen nutrition. In witches’ broom disease of cacao, sensing and modulation of compartmentalized carbon availability can also temporally regulate disease development.

G-quadruplexes are secondary structures present in DNA and RNA molecules, which are formed by stacking of G-quartets (i.e., interaction of four guanines (G-tracts) bounded by Hoogsteen hydrogen bonding). Human PAX9 intron 1 has a putative G-quadruplex-forming region located near exon 1, which is present in all known sequenced placental mammals. Using circular dichroism (CD) analysis and CD melting, we showed that these sequences are able to form highly stable quadruplex structures. Due to the proximity of the quadruplex structure to exon-intron boundary, we used a validated double-reporter splicing assay and qPCR to analyze its role on splicing efficiency. The human quadruplex was shown to have a key role on splicing efficiency of PAX9 intron 1, as a mutation that abolished quadruplex formation decreased dramatically the splicing efficiency of human PAX9 intron 1. The less stable, rat quadruplex had a less efficient splicing when compared to human sequences. Additionally, the treatment with 360A, a strong ligand that stabilizes quadruplex structures, further increased splicing efficiency of human PAX9 intron 1. Altogether, these results provide evidences that G-quadruplex structures are involved in splicing efficiency of PAX9 intron 1.

The objectives of the present study were to evaluate in vitro the production of antagonistic compounds against Gardnerella vaginalis by Lactobacillus strains isolated from women with or without bacterial vaginosis (BV), and to select one of the better Lactobacillus producers of such a substance to be tested in vivo using a gnotobiotic animal model challenged with one of the more sensitive G. vaginalis isolates. A total of 24 isolates from women with and without BV were identified as G. vaginalis. A higher frequency (P,0.05) of this bacterium was observed in women with BV (56.7 %) when compared to healthy women (17.6 %). A total of 86 strains of Lactobacillus were obtained from healthy women and women with BV. Lactobacillus strains were more frequently present (P,0.05) in healthy women (97.5 %) than in women with BV (76.7 %). Lactobacillus crispatus was the predominating strain in both healthy women and women with BV. Lactobacillus jensenii, Lactobacillus johnsonii, Lactobacillus gasseri and Lactobacillus vaginalis were isolated with an intermediate frequency in the two groups. In vitro antagonism assays were performed using as indicators 17 reference strains and the G. vaginalis strains isolated from women with BV and from healthy women. Lactobacillus isolated from healthy women showed the higher antagonistic activity against all the indicator strains when compared with isolates from women with BV. Concerning the indicator strains, G. vaginalis found in women with BV was more resistant to the antagonism, particularly when Lactobacillus isolates from women with BV were used as producer strains. A high vaginal population level of G. vaginalis was obtained by intravaginal inoculation of germ-free mice, and this colonization was accompanied by vaginal histopathological lesions. A tenfold decrease in vaginal population level of G. vaginalis and a reduction of histological lesions were observed when the pathogenic challenge was performed in mice previously monoassociated with an L. johnsonii strain. Concluding, results of the present study suggest that progression of G. vaginalis-associated BV depends in part on a simultaneous presence of Lactobacillus populations with a low antagonistic capacity and of a G. vaginalis strain with a high resistance to this antagonism. The results could also explain why G. vaginalis is frequently found in the vaginal ecosystem of healthy women.

The hemibiotrophic basidiomycete fungus Moniliophthora perniciosa, the causal agent of Witches' broom disease (WBD) in cacao, is able to grow on methanol as the sole carbon source. In plants, one of the main sources of methanol is the pectin present in the structure of cell walls. Pectin is composed of highly methylesterified chains of galacturonic acid. The hydrolysis between the methyl radicals and galacturonic acid in esterified pectin, mediated by a pectin methylesterase (PME), releases methanol, which may be decomposed by a methanol oxidase (MOX). The analysis of the M. pernciosa genome revealed putative mox and pme genes. Real-time quantitative RT-PCR performed with RNA from mycelia grown in the presence of methanol or pectin as the sole carbon source and with RNA from infected cacao seedlings in different stages of the progression of WBD indicate that the two genes are coregulated, suggesting that the fungus may be metabolizing the methanol released from pectin. Moreover, immunolocalization of homogalacturonan, the main pectic domain that constitutes the primary cell wall matrix, shows a reduction in the level of pectin methyl esterification in infected cacao seedlings. Although MOX has been classically classified as a peroxisomal enzyme, M. perniciosa presents an extracellular methanol oxidase. Its activity was detected in the fungus culture supernatants, and mass spectrometry analysis indicated the presence of this enzyme in the fungus secretome. Because M. pernciosa possesses all genes classically related to methanol metabolism, we propose a peroxisome-independent model for the utilization of methanol by this fungus, which begins with the extracellular oxidation of methanol derived from the demethylation of pectin and finishes in the cytosol.

Antagonistic and synergistic substances are important for interactions between micro-organisms associated with human body surfaces, either in healthy or in diseased conditions. In the present study, such compounds produced by Gardnerella vaginalis strains isolated from women with bacterial vaginosis (BV) were detected in vitro and the antagonistic ones were partially characterized. Among 11 G. vaginalis strains tested, all showed antagonistic activity against at least one of the 22 indicator bacteria assayed. Interestingly, for some of these strains, antagonism reverted to synergism, favouring one of the indicator strains (Peptostreptococcus anaerobius) when the growth medium was changed. Partial characterization of antagonistic substances suggested a bacteriocin-like chemical nature. Depending on growth conditions, G. vaginalis isolated from women with BV produced antagonistic or synergistic compounds for other bacterial components of the vaginal ecosystem. This is the first report to our knowledge of the production of antagonistic and/or synergistic substances by G. vaginalis. This ability may be a pivotal factor in understanding BV and the ecological role of this bacterium in the vaginal environment.

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Here, we report the genome assembly of a Saccharomyces cerevisiae SA1-derived haploid (FMY097) indigenous strain isolated from a Brazilian ethanol distillery. FMY097 was recently reported to be a highly aldehyde-resistant strain capable of producing bioethanol in the presence of up to 40 mM furfural and 80 mM 5-hydroxymethylfurfural.