A new theta-type thermosensitive replicon from Lactoccocus lactis as an integration vector for Enterococcus faecalis

We isolated a replication thermosensitive mutant of the theta-type lactococcal pUCL22 replicon. An improved version of this thermosensitive replicon was obtained by fusioning the replication repA gene with the downstream repB gene. The resulting plasmid was named pUCB3522Ts. It is highly instable at 42°C in Enterococcus faecalis. Integration into the chromosome via homologous recombination was monitored using the npr gene of E. faecalis JH2-2 as a target. A 513 bp PCR amplification product from an internal region of this npr gene was cloned into pUCB3522Ts. Integration of this construction into the JH2-2 npr gene was selected by shift temperature, from 30°C to 42°C. 85% of the analysed clones showed integration into the npr gene, demonstrating the practicality of this thermosensitive replicon as a genetic integrative tool for E. faecali

Antifungal lipopeptides from Bacillus strains isolated from rhizosphere of Citrus trees

peer reviewedThe microbial ecology within the rhizosphere of Tylenchulus semipenetrans-infected Citrus L. trees was examined. Sixty bacterial strains were obtained from the roots of infected trees and from the eggs of T. semipenetrans. Among these strains some were obtained from the agar plates of two nematophagous fungi, Dactylellina gephyropaga (Drechsler) Ying Yang & Xing Z. Liu and Arthrobotrys conoides Drechsler. Bacterial strains were identified using 16S rDNA, gyrA and rpoB genes sequence analysis. Bacterial strains identified as Bacillus spp. were examined for their ability to synthesize surfactin, iturin, fengycin, kurstakin and bacillomycin using PCR amplification and sequencing of the encoding genes. Additionally, Bacillus strains were screened for their antifungal activity against F. solani, D. gephyropaga and A. conoides using the dual culture technique. Lipopeptide from whole cells and from supernatants of Bacillus spp. were screened using MALDI-TOF-MS analysis. The majority of the identified bacterial strains belong to the genus Bacillus with the predominance of B. cereus, B. thuringiensis, B. pumilus and B. subtilis. A total of fifteen Bacillus strains demonstrated an antifungal activity against F. solani, D. gephyropaga and A. conoides with the strongest effect found in B. amyloliquefaciens. The analysis of lipopeptides showed a high diversity of molecules, including majorly iturin C, bacillomycin D, fengycin A/B and Kurstakin found especially in B. subtilis strains. Moreover, MALDI-TOF-MS analysis showed that the responsible antibiotics for the antifungal Bacillus strains were associated with the presence of Surfactins/Pumilacidin and Fengycin A/B. Our results demonstrated the wide diversity of lipopeptides among Bacillus strains associated with citrus rhizosphere and demonstrated their antifungal ability. Our results extend the importance of Bacillus strains as potential candidates for antimicrobial activities due to their ability to synthesize and secrete cyclic lipopeptides

Etude de la microbiologie de l’eau: survie et adaptation des entérocoques fécaux

info:eu-repo/semantics/publishe

Physiological study of acquired resistance induced by physical and chemical stress in Enterococcus faecalis

info:eu-repo/semantics/nonPublishe

Etude de la microbiologie de l’eau: survie et adaptation des entérocoques fécaux

info:eu-repo/semantics/publishe

Réponse à l'action d'agents chaotropiques chez Enterococcus faecalis ATCC19433

info:eu-repo/semantics/nonPublishe

La tolérance aux stress peut-elle être conférée par la synthèse de protéines spécifiques ?

1er prix 'Pharmacia' de la communication oraleinfo:eu-repo/semantics/nonPublishe

Physiological and biochemical studies on heat stress response in Pectinatus

info:eu-repo/semantics/nonPublishe

Opposite requirements of agr in regulation of hla and spa expressions during biofilm accumulation compared to planktonic in vitro cultures, in clinical isolate of S. aureus

info:eu-repo/semantics/nonPublishe

On the importance of mechanisms analysis in the degradation of micropollutants by laccases: The case of Remazol Brilliant Blue R

The efficiency of methods to reduce the pollution induced by dyes is often evaluated using a color change measurement. This approach might hide complex mechanisms, that, if neglected, can lead to inadequate design of treatment units. This paper highlights this complexity on the case of Remazol Brilliant Blue R (RBBR), an industrial anthraquinone dye, degraded using Trametes versicolor laccases. A kinetic model describing the degradation of RBBR and the formation of degradation byproducts, one of which was found to have an orange color, is proposed. The complex links between RBBR degradation and the decolorization of the medium are highlighted, allowing to identify limits to the degradation achievable by the laccases in this case.SCOPUS: ar.jinfo:eu-repo/semantics/publishe