Identification and partial characterization of antifungal and antibacterial activities of two Bacillus sp. strains isolated from salt soil in Tunisia

Two Bacillus sp. strains (B29 and B27) isolated from soil in the South of Tunisia were tested for their abilities to produce antimicrobial compounds. Both strains showed antimicrobial activity against Gram-positive and Gram-negative bacteria, yeasts and fungi. The produced compounds were extracted by using four different solvents. The hexane solvent allowed to obtain maximum of activity of the strain B29. The activity of the strain B27 was not elucidated by the four solvents used. Bio-autography results of B29 hexane extract revealed presence of different antibiotics and antifungal compounds with different Rf values of 0.3 and 0.76 for antifungal compounds and of 0.12, 0.14, 0.19 and 0.3 for antibacterial ones. Two active fractions were isolated from the culture broth of the strain B29 by semi-preparative high performance liquid chromatography (HPLC). The partial sequencing of the 16S rDNA gene was used to identify the two Bacillus strains. They may be assigned to new Bacillus specie

A novel hydroxamic acid-containing antibiotic produced by a Saharan soil-living Streptomyces strain

During screening for potentially antimicrobial actinobacteria, a highly antagonistic strain, designated WAB9, was isolated from a Saharan soil of Algeria. A polyphasic approach characterized the strain taxonomically as a member of the genus Streptomyces. The strain WAB9 exhibited a broad spectrum of antimicrobial activity toward various multidrug‐resistant micro‐organisms. A PCR‐based assay of genomic potential for producing bioactive metabolites revealed the presence of PKS‐II gene. After 6 days of strain fermentation, one bioactive compound was extracted from the remaining aqueous phase and then purified by HPLC. The chemical structure of the compound was determined by spectroscopic (UV–visible, and 1H and 13C NMR) and spectrometric analysis. The compound was identified to be 2‐amino‐N‐(2‐amino‐3‐phenylpropanoyl)‐N‐hydroxy‐3‐phenylpropanamide, a novel hydroxamic acid‐containing molecule. The pure molecule showed appreciable minimum inhibitory concentration values against a selection of drug‐resistant bacteria, filamentous fungi and yeasts

Characterization and antagonistic properties of Streptomyces strains isolated from Saharan soils, and evaluation of their ability to control seedling blight of barley caused by Fusarium culmorum

Significance and Impact of the Study: The genus Fusarium is considered to be one of the most problematic phytopathogenic fungi for crop culture worldwide. Inside this genus, F. culmorum is the aetiological agent of seedling blight in various monocotyledonous plants such as barley and cause extensive yield and quality losses in humid and semi-humid regions. Biological control may be a successful alternative to chemical control, particularly with the controversy surrounding the use of the fungicides and the limited obtained results to control F. culmorum. This study highlights the effectiveness of some antagonistic Streptomyces isolated from Algerian Saharan soils to control F. culmorum by the reduction in disease occurrence and disease severity suggesting their use on microbial biocontrol formulation against soilborne diseases

Early events induced by the toxin deoxynivalenol lead to programmed cell death in Nicotiana tabacum cells

Deoxynivalenol (DON) is a mycotoxin affecting animals and plants. This toxin synthesized by Fusarium culmorum and Fusarium graminearum is currently believed to play a decisive role in the fungal phytopathogenesis as a virulence factor. Using cultured cells of Nicotiana tabacum BY2, we showed that DON-induced programmed cell death (PCD) could require transcription and translation processes, in contrast to what was observed in animal cells. DON could induce different cross-linked pathways involving (i) reactive oxygen species (ROS) generation linked, at least partly, to a mitochondrial dysfunction and a transcriptional down-regulation of the alternative oxidase (Aox1) gene and (ii) regulation of ion channel activities participating in cell shrinkage, to achieve PCD

Biocontrol of Rhizoctonia solani damping-off and promotion of tomato plant growth by endophytic actinomycetes isolated from native plants of Algerian Sahara

Thirty-four endophytic actinomycetes were isolated from the roots of native plants of the Algerian Sahara. Morphological and chemical studies showed that twenty-nine isolates belonged to the Streptomycesgenus and five were non-Streptomyces. All isolates were screened for their in vitro antifungal activityagainst Rhizoctonia solani. The six that had the greatest pathogen inhibitory capacities were subsequentlytested for their in vivo biocontrol potential on R. solani damping-off in sterilized and non-sterilized soils,and for their plant-growth promoting activities on tomato seedlings. In both soils, coating tomato seedswith antagonistic isolates significantly reduced (P < 0.05) the severity of damping-off of tomato seedlings.Among the isolates tested, the strains CA-2 and AA-2 exhibited the same disease incidence reduction asthioperoxydicarbonic diamide, tetramethylthiram (TMTD) and no significant differences (P < 0.05) wereobserved. Furthermore, they resulted in a significant increase in the seedling fresh weight, the seedling length and the root length of the seed-treated seedlings compared to the control. The taxonomic positionbased on 16S rDNA sequence analysis and phylogenetic studies indicated that the strains CA-2 AA-2were related to Streptomyces mutabilis NBRC 12800ᵀ(100% of similarity) and Streptomyces cyaneofuscatus JCM 4364ᵀ(100% of similarity), respectively

Increased Anion Channel Activity Is an Unavoidable Event in Ozone-Induced Programmed Cell Death

Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death.-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s) for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation

Rôle de l’acide oxalique, facteur de pathogénie de différents champignons nécrotrophes dans l’induction de réponses de défense chez Arabidopsis thaliana

International audienc

Rôle de l’acide oxalique, facteur de pathogénie de différents champignons nécrotrophes dans l’induction de réponses de défense chez Arabidopsis thaliana

International audienc

Rôle de l’acide oxalique, facteur de pathogénie de différents champignons nécrotrophes dans l’induction de réponses de défense chez Arabidopsis thaliana

International audienc

Hypopituitarism consecutive to the brain damage: a widely unexpected prevalence

Alors que la prévalence de l’hypopituitarisme est largement sous-estimée, son étiologie est souvent méconnue. Des données récentes indiquent que le traumatisme crânien constitue actuellement une cause importante d’hypopituitarisme acquis chez l’adulte. Les traumatismes crâniens représentent un problème majeur de santé publique, avec une incidence annuelle en Belgique de 30.000 patients par an. Plusieurs séries rétrospectives et prospectives ont identifié plus de 5.000 patients avec un traumatisme crânien et souffrant d’un déficit isolé ou combiné en hormone de croissance, gonadotrophines, adrénocorticotrophine, thyrotrophine et, occasionnellement, de prolactine et d’hormone antidiurétique. Nous faisons le point sur ces données récentes et discutons du diagnostic et de la prise en charge de l’hypopituitarisme secondaire au traumatisme crânien.While the prevalence of Hypopituitarism is widely underestimated, its etiology is often misunderstood. Recent data indicate that head trauma is currently a major cause of acquired Hypopituitarism in adulthood. Injuries are a major public health problem, with an annual incidence in Belgium of 30,000 patients per year. Several retrospective and prospective series have identified more than 5,000 patients with trauma injury and suffering from an isolated or in combination hormone growth deficiency, gonadotrophins, adrenocorticotrophin, thyrotrophin and, less frequently prolactin and antidiuretic hormone deficiency. In this presentation , we make the point on these recent data and discuss the diagnosis and management of the secondary Hypopituitarism injury, according to our experience and the review of the litterature