Protease treatment affects both invasion ability and biofilm formation in Listeria monocytogenes

Listeria monocytogenes is a notably invasive bacterium associated with life-threatening food-borne disease in humans. Several surface proteins have been shown to be essential in the adhesion of L. monocytogenes, and in the subsequent invasion of phagocytes. Because the control of the invasion of host cells by Listeria could potentially hinder its spread in the infected host, we have examined the effects of a protease treatment on the ability of L. monocytogenes to form biofilms and to invade tissues. We have chosen serratiopeptidase (SPEP), an extracellular metalloprotease produced by Serratia marcescens that is already widely used as an anti-inflammatory agent, and has been shown to modulate adhesin expression and to induce antibiotic sensitivity in other bacteria. Treatment of L. monocytogenes with sublethal concentrations of SPEP reduced their ability to form biofilms and to invade host cells. Zymograms of the treated cells revealed that Ami4b autolysin, internalinB, and ActA were sharply reduced. These cell-surface proteins are known to function as ligands in the interaction between these bacteria and their host cells, and our data suggest that treatment with this natural enzyme may provide a useful tool in the prevention of the initial adhesion of L. monocytogenes to the human gu

LABs Fermentation Side-Product Positively Influences Rhizosphere and Plant Growth in Greenhouse Lettuce and Tomatoes

New agronomical policies aim to achieve greener agricultural systems, sustainable fertilizers and fungicides, a reduction in Greenhouse gases (GHG), and an increase in circular economic models. In this context, new solutions are needed for the market, but it is necessary to carefully assess both their efficacy and their ecological impact. Previously, we reported the biostimulatory activity on soil microbiome for a side-product from Lactic Acid Bacteria (LABs) fermentation: a concentrated post-centrifugation eluate. In the present study, we investigated whether this solution could partially substitute mineral N (N70% + N30% from eluate) in a fertigation (N100% vs. N70%) regime for tomato and lettuce under greenhouse conditions. The impact of the application was investigated through plant physiological parameters (number and weight of ripened fruits, shoots, and roots biomass) and biodiversity of the rhizosphere microbial composition of bacteria and fungi (High-Throughput Sequencing-HTS). The eluate (i) enhanced the plant canopy in lettuce; (ii) increased the shoot/root biomass ratio in both tomato and lettuce; and (iii) increased the harvest and delayed fruit ripening in tomato. Moreover, we found a strong correlation between the eluate and the enrichment for OTUs of plant-growth-promoting microbes (PGPMs) such as Sphingomonas sediminicola, Knoellia subterranean, and Funneliformis mosseae. These findings suggest that integrating the eluate was beneficial for the plant growth, performance, and yield in both tomato and lettuce, and additionally, it enriched specialized functional microbial communities in the rhizosphere. Further studies will investigate the underlying mechanisms regulating the selective activity of the eluate toward PGPMs and its biostimulatory activity towards target crops

Is the interplay between epigenetic markers related to the acclimation of Cork oak plants to high temperatures?

Trees necessarily experience changes in temperature, requiring efficient short-term strategies that become crucial in environmental change adaptability. DNA methylation and histone posttranslational modifications have been shown to play a key role in both epigenetic control and plant functional status under stress by controlling the functional state of chromatin and gene expression. Cork oak (Quercus suber L.) is a key stone of the Mediterranean region, growing at temperatures of 45°C. This species was subjected to a cumulative temperature increase from 25°C to 55°C under laboratory conditions in order to test the hypothesis that epigenetic code is related to heat stress tolerance. Electrolyte leakage increased after 35°C, but all plants survived to 55°C. DNA methylation and acetylated histone H3 (AcH3) levels were monitored by HPCE (high performance capillary electrophoresis), MS-RAPD (methylation-sensitive random-amplified polymorphic DNA) and Protein Gel Blot analysis and the spatial distribution of the modifications was assessed using a confocal microscope. DNA methylation analysed by HPCE revealed an increase at 55°C, while MS-RAPD results pointed to dynamic methylation-demethylation patterns over stress. Protein Gel Blot showed the abundance index of AcH3 decreasing from 25°C to 45°C. The immunohistochemical detection of 5-mC (5-methyl-2'-deoxycytidine) and AcH3 came upon the previous results. These results indicate that epigenetic mechanisms such as DNA methylation and histone H3 acetylation have opposite and particular dynamics that can be crucial for the stepwise establishment of this species into such high stress (55°C), allowing its acclimation and survival. This is the first report that assesses epigenetic regulation in order to investigate heat tolerance in forest trees.This work is supported by FEDER through COMPETE (Programa Operacional Factores de Competitividade) and by the FCT project PTDC/AGR-CFL/ 112996/2009. G. Pinto is hired under the programme Cie ˆncia 2008 (FCT, Portugal), co-funded by the Human Potential Operational Programme (National Strategic Reference Framework 2007–2013) and European Social Fund (EU). FCT supported the fellowship of M.C. Dias (SFRH/BPD/41700/2007). L. Valledor fellow was supported by a Marie Curie Action of the European Union (FP7-PEOPLE-IEF). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.publishe

Effect of a Saccharomyces cerevisiae culture on growth and lactate utilization by the ruminal bacterium Megasphaera elsdenii

International audienc

Lactobacillus protoplast transformation. Plasmid 17, 73-75.

A method for the transformation of Lactobacillus protoplasts by plasmid DNA is reported. The procedure involves polyethylene glycol treatment of protoplasts to induce DNA uptake. A transformation efficiency ranging from 5 to 1000 transformants per microgram of DNA is achieved; the efficiency of protoplast regeneration ranged from 10 to 20%

Draft genome sequence of Clostridium sporogenes strain UC9000 isolated from raw milk

Clostridium sporogenes is a causative agent of food spoilage and is often used as the nontoxigenic surrogate for Clostridium botulinum. Here, we described the draft genome sequence and annotation of C. sporogenes strain UC9000 isolated from raw milk

Disruption of the gene encoding glutamate dehydrogenase affects growth, amino acids catabolism and survival of Lactobacillus plantarum UCC1001

The role played by glutamatedehydrogenase (GDH) in Lactobacillusplantarum was investigated by preparing a GDH-deficient mutant UC1001G. The growth rate and acidification displayed by this mutant were lower than those of the wild-type UC1001. Compared with UC1001G, UC1001 increased the synthesis of proteins that confer a competitive advantage of cell resistance. When both strains were used as adjunct starter for cheese-making, the highest cell survival was found for UC1001. Cheeses made with the adjunct of UC1001 showed the lowest level of free aminoacids and the highest content of volatile organic compounds. Both strains produced high level of γ-aminobutyric acid in cheese and under simulated gastrointestinal conditions. The findings of this study provide an evidence of the important role of GDH on growth and survival of Lb. plantarum under different environmental conditions that influences some important functional features of the strain