Pathogenic and molecular detection of Fusarium oxysporum f. sp. albedinis isolates from different areas in southwest Algeria

Purpose: To investigate the intra-specific variations in eleven Fusarium oxysporum isolates from infected date palm using pathogenicity and molecular methods.Methods: Eleven isolates of Fusarium oxysporum obtained from infected date palms in the south-west region of Algeria were subjected to confirmatory test using a specific polymerase chain reaction (PCR) technique with the primer pairs, TL3-FOA28 and BIO3-FOA1. Polymorphism in the 5’ domain of the large subunit rRNA was investigated. Small libraries of the domain, amplified by the primer pair, LR3/LROR, were constructed and the inserts sequenced.Results: The 11 isolates of Fusarium oxysporum collected from the infected date palm were confirmed as Fusarium oxysporun f. sp albedinis. Results from the investigation of polymorphism in the 5’ domain of the large subunit rRNA revealed that the sequences were 100 % homologous or extremely close (> 99.4 %, differing by no more than one to three nucleotides) to several Fusarium oxysporum sequences. In addition, F. inflexum (U34548.1) was highly homologous to one of the F. oxysporum f. sp. albedinis.Conclusion: The sequences of the 11 isolates are almost 100 % homologous to several F. oxysporum species. It is noteworthy that a sequence highly homologous to one of the F. oxysporum f. sp. albedinis is obtainable from a different species, F. inflexum (U34548.1).Keywords:  Fusarium oxysporum f. sp. albedinis, Date palm, rRNA gene polymorphis

Antimicrobial properties of Pseudomonas strains producing the antibiotic mupirocin

peer reviewe

La dégradation de l'arginine, en aérobiose et en anaérobiose, chez les pseudomonas

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

La dégradation de l'arginine, en aérobiose et en anaérobiose, chez les pseudomonas

Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Purification of ArcR, an oxidation-sensitive regulatory protein from Bacillus licheniformis

In Bacillus licheniformis, ArcR, a transcriptional activator of the Crp/Fnr family, is required for expression of the anaerobic pathway of arginine catabolism, the arginine deiminase pathway. The method described here allows the purification of milligram quantities of functional ArcR from a recombinant Escherichia coli strain. The solubility properties of ArcR were much exploited during the purification process. The protein appeared highly sensitive to oxidation. Oxidation-induced precipitation of the protein was attributed to the formation of intermolecular disulfide bridges. Alkylation of mutant proteins with single substitutions showed that both cysteine residues of the protein, C178 and C205, are involved in formation of the disulfide bridges. Substitution of both cysteines yielded a functional protein insensitive to oxidation and able to form a complex with its cognate target on the DNA. © 2004 Elsevier Inc. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Biodegradation of polycaprolactone by micro-organisms from an industrial compost of household refuse

SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Biodegradation of polycaprolactone and its blends with poly(vinylalcohol) by micro-organisms from a compost of house-hold refuse

Polycaprolactone (PCL), poly(vinylalcohol) (PVA1) and their blends have been incubated in the presence of a pure strain of micro-organisms isolated from an industrial compost for house-hold refuse. In the conditions used in this work, pure polycaprolactone (PCL) films are completely assimilated over periods of 600-800 h. Pure PVA1 is not degraded even for much longer exposure times. Unexpectedly, the blends, even PCL rich, are not altered (neither weight loss, oxygen uptake nor micro-organism growth) in the presence of these micro-organisms. It has been shown that inactivation of the strain by PVA1 does not occur and is not responsible for this. PVA1, even when present in small amounts in the incubation medium, adsorbs on the surface of PCL or blend films; PCL is then inaccessible to micro-organisms. © 1996 Elsevier Science Limited.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Control of enzyme synthesis in the oxalurate catabolic pathway of Streptococcus faecalis ATCC 11700: Evidence for the existence of a third carbamate kinase

Streptococcus faecalis ATCC 11700 uses oxalurate as a sole energy source for growth. An oxamate carbamoyltransferase and a carbamate kinase, both induced by oxalurate, are involved in this process. The oxalurate-induced kinase is specific for the pathway. Its properties are different from those of the previously characterized agmatine and arginine-induced kinases. Glucose, but not arginine, nor agmatine, two other energy sources, represses the oxalurate pathway. In contrast, oxalurate was found to be at least as effective as glucose in repressing the arginine deiminase pathway in arginine grown cells or the agmatine deiminase pathway during growth on agmatine. © 1986 Springer-Verlag.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Catabolism of arginine, citrulline and ornithine by Pseudomonas and related bacteria.

The distribution of the arginine succinyltransferase pathway was examined in representative strains of Pseudomonas and related bacteria able to use arginine as the sole carbon and nitrogen source for growth. The arginine succinyltransferase pathway was induced in arginine-grown cells. The accumulation of succinylornithine following in vivo inhibition of succinylornithine transaminase activity by aminooxyacetic acid showed that this pathway is responsible for the dissimilation of the carbon skeleton of arginine. Catabolism of citrulline as a carbon source was restricted to relatively few of the organisms tested. In P. putida, P. cepacia and P. indigofera, ornithine was the main product of citrulline degradation. In most strains which possessed the arginine succinyltransferase pathway, the first step of ornithine utilization as a carbon source was the conversion of ornithine into succinylornithine through an ornithine succinyltransferase. However P. cepacia and P. putida used ornithine by a pathway which proceeded via proline as an intermediate and involved an ornithine cyclase activity.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Highlighting the factors governing transglycosylation in the GH5_5 endo-1,4-β-glucanase RBcel1

Transglycosylating glycoside hydrolases (GHs) offer great potential for the enzymatic synthesis of oligosaccharides. Although knowledge is progressing, there is no unique strategy to improve the transglycosylation yield. Obtaining efficient enzymatic tools for glycan synthesis with GHs remains dependent on an improved understanding of the molecular factors governing the balance between hydrolysis and transglycosylation. This enzymatic and structural study of RBcel1, a transglycosylase from the GH5_5 subfamily isolated from an uncultured bacterium, aims to unravel such factors. The size of the acceptor and donor sugars was found to be critical since transglycosylation is efficient with oligosaccharides at least the size of cellotetraose as the donor and cellotriose as the acceptor. The reaction pH is important in driving the balance between hydrolysis and transglycosylation: hydrolysis is favored at pH values below 8, while transglycosylation becomes the major reaction at basic pH. Solving the structures of two RBcel1 variants, RBcel1_E135Q and RBcel1_Y201F, in complex with ligands has brought to light some of the molecular factors behind transglycosylation. The structure of RBcel1_E135Q in complex with cellotriose allowed a +3 subsite to be defined, in accordance with the requirement for cellotriose as a transglycosylation acceptor. The structure of RBcel1_Y201F has been obtained with several transglycosylation intermediates, providing crystallographic evidence of transglycosylation. The catalytic cleft is filled with (i) donors ranging from cellotriose to cellohexaose in the negative subsites and (ii) cellobiose and cellotriose in the positive subsites. Such a structure is particularly relevant since it is the first structure of a GH5 enzyme in complex with transglycosylation products that has been obtained with neither of the catalytic glutamate residues modified.info:eu-repo/semantics/publishe