Responses of environmental Amycolatopsis strains to copper stress.

Copper is a redox-active metal, which acts as a catalyst in the formation of Reactive Oxygen Species (ROS) encouraging oxidative stress. Protection against oxidants is intrinsic to every living cell; however, in stress conditions, cells are forced to increase and expand their antioxidative network. In this work, the novel copper-resistant strain Amycolatopsis tucumanensis and the copper-sensitive Amycolatopsis eurytherma were grown under copper increasing concentrations in order to elucidate the dissimilar effects of the metal on the strains viability, mainly on morphology and antioxidant capacity. Although biosorbed copper encouraged ROS production in a dose-dependent manner in both strains, the increase in ROS production from the basal level to the stress conditions in A. tucumanensis is lesser than in the copper-sensitive strain; likewise, in presence of copper A. eurytherma suffered inexorable morphological alteration while A. tucumanensis was not affected. The levels of antioxidant enzymes and metallothioneins (MT) were all greater in A. tucumanensis than in A. eurytherma; in addition MT levels as well as superoxide dismutase and thioredoxin reductase activities in A. tucumanensis, were higher as higher the concentration of copper in the culture medium. This work has given evidence that an efficient antioxidant defense system might aid microorganisms to survive in copper-stress conditions; besides it constitutes the first report of oxidative stress study in the genus Amycolatopsis and contributes to enlarge the knowledge on the copper-resistance mechanisms of A. tucumanensis.

Copper bioaccumulation by the actinobacterium Amycolatopsis sp. AB0.

Amycolatopsis sp. AB0, a copper resistant actinobacterium isolated from polluted sediments, has shown high copper specific biopsortion ability (25 mg g(-1)). Two approaches were used to confirm metal accumulation in growing cells of Amycolatopsis sp. AB0; we performed subcellular fractioning assays which showed that the retained copper was associated with the extra-cellular fraction (exopolymer, 40%), but mainly within the cells. Intracellular distribution of copper was: 86% in the cytosolic fraction, 11% at the cell wall and 3% associated with the ribosome/membrane fraction. Its copper bioaccumulation ability was corroborated by using silver enhanced staining of copper with the Timm's reagent technique, which has not been used to detect metal deposits in bacteria before. In addition, we constructed specific oligonucleotides for targeting genes coding for copper P-Type ATPases that could be involved in the copper uptake ability of this strain. A 607 bp DNA fragment was amplified and sequenced from Amycolatopsis sp AB0. BLAST search analysis showed 71% protein homology of the deduced sequence with a putative cation-transporting ATPase of Nocardia farcinica and 65% with a copper translocating ATPase of Mycobacterium flavescens. To our knowledge this is the first report of the presence of copper P-type ATPase genes in the Amycolotopsis genus.

Los actinomicetos termofilos de JuJuy: I. Monosporados / The Actinomycetes thermophiles of Jujuy, Argentina: I. Monosporium

Se aislaron cepas de Thermoactinomyces thalpophilus, T. dichotomica y Saccharomonospora viridis, a partir de restos vegetales y residuos de la industria azucarera obtenidos en la zona subtropical jujeña. Estas especies están consideradas como agentes causales de neumonitis alérgica

Los actinomicetos termofilos de JuJuy: I. Monosporados / The Actinomycetes thermophiles of Jujuy, Argentina: I. Monosporium

Se aislaron cepas de Thermoactinomyces thalpophilus, T. dichotomica y Saccharomonospora viridis, a partir de restos vegetales y residuos de la industria azucarera obtenidos en la zona subtropical jujeña. Estas especies están consideradas como agentes causales de neumonitis alérgica (AU)