Antonie van Leeuwenhoek最新文献

Abstract

Trichoderma harzianum is a filamentous fungus that can act as a mycoparasite, saprophyte, or a plant symbiotic. It is widely used as a biological control agent against phytopathogenic fungi and can also be used for plant growth promotion and biofortification. Interaction between T. harzianum and phytopathogenic fungi involves mycoparasitism, competition, and antibiosis. Extracellular vesicles (EVs) have been described as presenting a central role in mechanisms of communication and interaction among fungus and their hosts. In this study, we characterized extracellular vesicles of T. harzianum produced during growth in the presence of glucose or S. sclerotiorum mycelia. A set of vesicular proteins was identified using proteomic approach, mainly presenting predicted signal peptides.

The family Vibrionaceae is classified into many clades based on their phylogenetic relationships. The Ponticus clade is one of its clades and consists of four species, Vibrio panuliri, V. ponticus, V. rhodolitus, and V. taketomensis. Two strains, CAIM 703 and CAIM 1902, were isolated from the diseased spotted rose snapper external lesion (Lutjanus guttatus), they were analyzed to determine their taxonomic position, a phylogenetic analysis was performed based on the 16S rRNA sequences proved that the two strains are members of the genus Vibrio and they belong to the Ponticus clade. Then, a phylogenomic analysis was performed with four type strains and four reference strains isolated from marine organisms and aquatic environments. Multilocus Sequence Analysis (MLSA) of 139 single-copy genes showed that CAIM 703 and CAIM 1902 belong to V. panuliri. The 16S rRNA sequence similarity value between CAIM 703 and CAIM 1902 was 99.61%. The Ponticus clade species showed Average Nucleotide Identity (ANI) values between 78 to 80% against the two strains for ANIb, except V. panuliri LBS2^T (99% and 100% similarity). Finally, this analysis represents the first phylogenomic analysis of the Ponticus clade where V. panuliri strains are reported from Mexico.

Genes flbA-E are involved in sporulation and vegetative growth in Aspergillus nidulans. Inactivation of either of these genes results in a fluffy phenotype with delayed or even abolished sporulation. Previously, a non-sporulating phenotype was obtained by inactivating flbA in Aspergillus niger, which was accompanied by lysis, thinner cell walls, and an increased secretome complexity. Here, we further studied the role of the flb genes of A. niger. Strains ΔflbA, ΔflbB and ΔflbE showed increased biomass formation, while inactivation of flbA-D reduced, or even abolished, formation of conidia. Strain ΔflbA was more sensitive to H₂O₂, DTT, and the cell wall integrity stress compounds SDS and Congo Red (CR). Also, ΔflbC was more sensitive to SDS, while ΔflbB, ΔflbD, and ΔflbE were more sensitive to CR. On the other hand, inactivation of flbE increased resistance to H₂O₂. Enzyme secretion was impacted when the Δflb strains were grown on xylose. Strain ΔflbE showed reduced xylanase, cellulase and amylase secretion. On the other hand, amylase secretion at the periphery of the ΔflbA colony was reduced but not in its center, while secretion of this enzyme was increased in the center of the ΔflbB colony but not at its periphery. Inactivation of flbC and flbD also impacted zonal cellulase and amylase activity. Together, the Flb protein family of A. niger function in biomass formation, sporulation, stress response, and protein secretion.

A novel Gram-positive, anaerobic, nonspore-forming, rod-shaped bacterium, designated strain NGMCC 1.200840 ^T, was isolated from the alpacas fresh feces. The taxonomic position of the novel strain was determined using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed strain NGMCC 1.200840 ^T was a member of the genus Clostridium and closely related to Clostridium tertium DSM 2485 ^T (98.16% sequence similarity). Between strains NGMCC 1.200840 ^T and C. tertium DSM 2485 ^T, the average nucleotide identity (ANI) and digital DNA˗DNA hybridization (dDDH) were 79.91% and 23.50%, respectively. Genomic DNA G + C content is 28.44 mol%. The strain can utilise D-glucose, D-mannitol, D-lactose, D-saccharose, D-maltose, D-xylose, L-arabinose, D-cellobiose, D-mannose, D-melezitose, D-raffinose, D-sorbitol, L-rhamnose, D-trehalose, D-galactose and Arbutin to produce acid. The optimal growth pH was 7, the temperature was 37 °C, and the salt concentration was 0–0.5% (w/v). The major cellular fatty acids (> 10%) included iso-C_15:0, anteiso-C_15:0 and iso-C_17:0 3-OH. The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified phospholipids and two unidentified aminolipids. Based on phenotypic, phylogenetic and chemotaxonomic characteristics, NGMCC 1.200840 ^T represents a novel species within the genus Clostridium, for which the named Clostridium lamae sp. nov. is proposed. The type strain is NGMCC 1.200840 ^T (= CGMCC 1.18014 ^T = JCM 35704 ^T).

Vulvovaginal candidiasis is the second most common vaginal infection caused by drug-resistant Candida species that affects about 70–75% of reproductive age group women across the globe. As current-day antifungal drugs are ineffective against the biofilms formed by the drug-resistant Candida strains, several natural compounds and antagonistic microbes are being explored as alternative antifungal agents. In the present study, we investigated the anti-biofilm activity of Cell-Free Supernatant (CFS) extracted from the commercially available probiotics VSL-3 against the biofilms of Candida species and also evaluated their efficacy in curbing the yeast-to-hyphal transition. Various methodologies like crystal violet staining and scanning electron microscopy were used to study the effect of CFS against the biofilms formed by the species. The ability of CFS to interfere with yeast to hyphal transition in Candida was studied by colony morphology assay and visually confirmed with phase contrast microscopy. The potential of the CFS of the probiotics was also evaluated using goat buccal tissue, a novel ex-vivo model that mimics the vaginal environment. Moreover, the supernatant extracted from VSL-3 had the ability to down-regulate the expression of virulence genes of Candida from the biofilm formed over the ex-vivo model. These results emphasize the anti-fungal and anti-infective properties of the CFS of VSL-3 against drug-resistant Candida strains causing vulvovaginal candidiasis.

An obligately anaerobic, non-motile, Gram-stain-negative, and rod-shaped strain KGMB11183^T was isolated from the feces of healthy Koreans. The growth of strain KGMB11183^T occurred at 30–45 °C (optimum 37 °C), at pH 6–9 (optimum pH 7), and in the presence of 0–0.5% NaCl (optimum 0%). Strain KGMB11183^T showed 16S rRNA gene sequence similarities of 95.4% and 94.2% to the closest recognized species, Phocaeicola plebeius M12^T, and Phocaeicola faecicola AGMB03916^T. Phylogenetic analysis showed that strain KGMB11183^T is a member of the genus Phocaeiocla. The major end products of fermentation are acetic acid and isobutyric acid. The major cellular fatty acids (> 10%) of this isolate were C_18:1 cis 9, anteiso-C_15:0, and summed feature 11 (iso-C_17:0 3-OH and/or C_18:2 DMA). The assembled draft genome sequences of strain KGMB11183^T consisted of 3,215,271 bp with a DNA G + C content of 41.4%. According to genomic analysis, strain KGMB11183^T has a number of genes that produce acetic acid. The genome of strain KGMB11183^T encoded the starch utilization system (Sus) operon, SusCDEF suggesting that strain uses many complex polysaccharides that cannot be digested by humans. Based on the physiological, chemotaxonomic, phenotypic, and phylogenetic data, strain KGMB11183^T is regarded a novel species of the genus Phocaeicola. The type strain is KGMB11183^T (= KCTC 25284^T = JCM 35696^T).