Acinetobacter baumannii is a Gram-negative bacterium appearing as an opportunistic pathogen in hospital settings. Superoxide dismutase (SOD) contributes to virulence in several pathogenic bacteria by detoxifying reactive oxygen species released in the course of host defense reactions. However, the biological role of SODs in A. baumannii has not yet been elucidated. Here, we inactivated in A. ba...

Dickeya dadantii 3937 (ex Erwinia chrysanthemi), a member of the Enterobacteriaceae, causes soft rot in many economically important crops. A successful pathogen has to reach the interior of the plant in order to cause disease. To study the role of motility and chemotaxis in the pathogenicity of D. dadantii 3937, genes involved in the chemotactic signal transduction system (cheW, cheB, cheY and ...

BACKGROUND AND OBJECTIVES Astaxanthin, an orange-red carotenoid pigment, acts as a protective agent against oxidative damage to cells in vivo. The astaxanthin synthetase gene (crtS) size consists of 3995 bp. This gene has been suggested to catalyse β-carotene to astaxanthin in Phaffia rhodozyma. The aim of this research was to find any possible changes in this gene in two mutant strains, Gam1 a...

Chemical mutagenesis of Staphylococcus aureus RN450 generated two strains that displayed a stable reduction (30- to 60-fold) in susceptibility to evernimicin. Cell-free translation reactions demonstrated that the resistance determinant was located in the ribosomal fraction. Compared to ribosomes isolated from a wild-type strain, ribosomes from the mutant strains displayed an 8- to 10-fold reduc...

Helicobacter pylori infection is among the most prevalent infections in the world involving more than half the adult population. H. pylori infection results in active chronic gastritis, peptic ulcers and enhances the risk of gastric malignancies. It is of utmost importance to prevent H. pylori infection particularly in highly prevalent countries including Iran. The urease holoenzyme produced by...

materials and methods statistical and regressive modeling methods were used to investigate the effects of the carbon source and to optimize the production media. results the spinosad production of s. spinosa co121 increased 77.13%, from 310.44 ± 21.84 μg/ml in the initial fermentation medium (with glucose as the main carbon source) to 549.89 ± 38.59 μg/ml in a new optimized fermentation medium ...

The Lesch-Nyhan syndrome has been characterized by an apparently complete deficiency in erythrocytes of an enzyme of purine metabolism, hypoxanthine-guanine phosphoribosyltransferase. Recent studies have suggested that low levels of this enzyme may be present in skin fibroblasts cultured from these patients. In the present study, we have confirmed the presence of hypoxanthine-guanine phosphorib...

The physiological role of the non-homologous end-joining (NHEJ) pathway in the repair of DNA double-strand breaks (DSBs) was examined in Mycobacterium smegmatis using DNA repair mutants (DeltarecA, Deltaku, DeltaligD, Deltaku/ligD, DeltarecA/ku/ligD). Wild-type and mutant strains were exposed to a range of doses of ionizing radiation at specific points in their life-cycle. NHEJ-mutant strains (...

The Lesch-Nyhan syndrome has been characterized by an apparently complete deficiency in erythrocytes of an enzyme of purine metabolism, hypoxanthine-guanine phosphoribosyltransferase. Recent studies have suggested that low levels of this enzyme may be present in skin fibroblasts cultured from these patients. In the present study, we have confirmed the presence of hypoxanthine-guanine phosphorib...

A soy sauce koji mold, Aspergillus flavus var. columnaris Raper and Fennel (ATCC 44310), was treated with UV irradiation to obtain mutant strains possessing high protease activities, high amylase activities, and light-colored conidia. Selected mutant strains were tested for toxicity, and some were found acutely toxic to weanling rats, although all were negative for aflatoxin production.