Actinobacteria from Antarctica as a source for anticancer discovery.

Although many advances have been achieved to treat aggressive tumours, cancer remains a leading cause of death and a public health problem worldwide. Among the main approaches for the discovery of new bioactive agents, the prospect of microbial secondary metabolites represents an effective source for the development of drug leads. In this study, we investigated the actinobacterial diversity associated with an endemic Antarctic species, Deschampsia antarctica, by integrated culture-dependent and culture-independent methods and acknowledged this niche as a reservoir of bioactive strains for the production of antitumour compounds.

Higher phylogenetic diversity prevents loss of functional diversity caused by successive drying and rewetting cycles.

Microbial communities regulate nutrient cycling in soil, thus the impact of climate change on the structure and function of these communities can cause an imbalance of nutrients in the environment. Structural and functional changes of soil bacterial communities in two contrasting biomes in Brazil, the Atlantic Forest and the Tropical Dry Forest (Caatinga), were studied by simulating, in microcosms, rainfall and drought events. Soil samples were collected in three Brazilian states: Bahia, Pernambuco and São Paulo, in a total of four sampling sites.

Rhodococcus psychrotolerans sp. nov., isolated from rhizosphere of Deschampsia antarctica.

A novel actinobacterium, designated strain CMAA 1533, was isolated from the rhizosphere of Deschampsia antarctica collected at King George Island, Antarctic Peninsula. Strain CMAA 1533 was found to grow over a wide range of temperatures (4-28 °C) and pH (4-10). Macroscopically, the colonies were observed to be circular shaped, smooth, brittle and opaque-cream on most of the culture media tested.

Pseudomonas aestus sp. nov., a plant growth-promoting bacterium isolated from mangrove sediments.

Strain CMAA 1215, a Gram-reaction-negative, aerobic, catalase positive, polarly flagellated, motile, rod-shaped (0.5-0.8 × 1.

Saccharopolyspora spongiae sp. nov., a novel actinomycete isolated from the marine sponge Scopalina ruetzleri (Wiedenmayer, 1977).

A novel marine actinomycete, designated strain CMAA 1452T, was isolated from the sponge Scopalina ruetzleri collected from Saint Peter and Saint Paul Archipelago, in Brazil, and subjected to a polyphasic taxonomic investigation. The organism formed a distinct phyletic line in the Saccharopolyspora 16S rRNA gene tree and had chemotaxonomic and morphological properties consistent with its classification in this genus. It was found to be closely related to Saccharopolyspora dendranthemae KLBMP 1305T (99.

Streptomyces atlanticus sp. nov., a novel actinomycete isolated from marine sponge Aplysina fulva (Pallas, 1766).

The taxonomic position of a novel marine actinomycete isolated from a marine sponge, Aplysina fulva, which had been collected in the Archipelago of Saint Peter and Saint Paul (Equatorial Atlantic Ocean), was determined by using a polyphasic approach. The organism showed a combination of morphological and chemotaxonomic characteristics consistent with its classification in the genus Streptomyces and forms a distinct branch within the Streptomyces somaliensis 16S rRNA gene tree subclade. It is closely related to Streptomyces violascens ISP 5183 (97.