Unraveling the effects of polyhydroxyalkanoates accumulation in Pseudomonas extremaustralis growth and survival under different pH conditions.

Polyhydroxyalkanoates (PHAs) are intracellular polymers that enhance bacterial fitness against various environmental stressors. Pseudomonas extremaustralis 14-3b is an Antarctic bacterium capable of accumulating, short-chain-length PHAs (sclPHAs), composed of C3-C5 monomers, as well as medium-chain-length PHAs (mclPHAs) containing ≥ C6 monomers. Since pH changes are pivotal in bacterial physiology, influencing microbial growth and metabolic processes, we propose that accumulated PHA increases P.

Spatial and Seasonal Variations in the Bacterial Community of an Anthropogenic Impacted Urban Stream.

Environmental changes and human activities can alter the structure and diversity of aquatic microbial communities. In this work, we analyzed the bacterial community dynamics of an urban stream to understand how these factors affect the composition of river microbial communities. Samples were taken from a stream situated in Buenos Aires, Argentina, which flows through residential, peri-urban horticultural, and industrial areas.

Microbiota Diversity Change as Quality Indicator of Soils Exposed to Intensive Periurban Agriculture.

In Argentina, periurban agriculture is performed by farmers with inadequate training in the use of pesticides and chemical fertilizers, developing horticulture with serious soil deterioration. The aim of this work was to monitor bacterial diversity of a horticultural soil (S) and a reference soil (R) as quality index for the design of future restoration strategies. As crops changed together with the agrochemical applications, sample collection was before harvest for strawberries, post-harvest for red peppers, pre-harvest broccoli crop and of a resting soil in treatment with poultry litter as a fertilizing amendment.

Effect of copper on diesel degradation in Pseudomonas extremaustralis.

Environments co-contaminated with heavy metals and hydrocarbons have become an important problem worldwide, especially due to the effect of metals on hydrocarbon degrading microorganisms. Pseudomonas extremaustralis, a bacterium isolated from a pristine pond in Antarctica, showed high capabilities to cope with environmental stress and a very versatile metabolism that includes alkane degradation under microaerobic conditions. In this work, we analyzed P.

MCAM knockdown impairs PPARγ expression and 3T3-L1 fibroblasts differentiation to adipocytes.

We investigated for the first time the expression of melanoma cell adhesion molecule (MCAM) and its involvement in the differentiation of 3T3-L1 fibroblasts to adipocytes. We found that MCAM mRNA increased subsequent to the activation of the master regulator of adipogenesis, PPARγ, and this increase was maintained in the mature adipocytes. On the other hand, MCAM knockdown impaired differentiation and induction of PPARγ as well as expression of genes activated by PPARγ.

Microaerophilic alkane degradation in Pseudomonas extremaustralis: a transcriptomic and physiological approach.

Diesel fuel is one of the most important sources of hydrocarbon contamination worldwide. Its composition consists of a complex mixture of n-alkanes, branched alkanes and aromatic compounds. Hydrocarbon degradation in Pseudomonas species has been mostly studied under aerobic conditions; however, a dynamic spectrum of oxygen availability can be found in the environment.

Novel Essential Role of Ethanol Oxidation Genes at Low Temperature Revealed by Transcriptome Analysis in the Antarctic Bacterium Pseudomonas extremaustralis.

Temperature is one of the most important factors for bacterial growth and development. Cold environments are widely distributed on earth, and psychrotolerant and psychrophilic microorganisms have developed different adaptation strategies to cope with the stress derived from low temperatures. Pseudomonas extremaustralis is an Antarctic bacterium able to grow under low temperatures and to produce high amounts of polyhydroxyalkanoates (PHAs).

Genome sequence analysis of Pseudomonas extremaustralis provides new insights into environmental adaptability and extreme conditions resistance.

The genome of the Antarctic bacterium Pseudomonas extremaustralis was analyzed searching for genes involved in environmental adaptability focusing on anaerobic metabolism, osmoregulation, cold adaptation, exopolysaccharide production and degradation of complex compounds. Experimental evidences demonstrated the functionality of several of these pathways, including arginine and pyruvate fermentation, alginate production and growth under cold conditions. Phylogenetic analysis along with genomic island prediction allowed the detection of genes with probable foreign origin such as those coding for acetate kinase, osmotic resistance and colanic acid biosynthesis.

Polyhydroxyalkanoate synthesis affects biosurfactant production and cell attachment to hydrocarbons in Pseudomonas sp. KA-08.

Stressful conditions prevailing in hydrocarbon-contaminated sites influence the diversity, distribution, and activities of microorganisms. Oil bioremediation agents should develop special characteristics to cope with these environments like surfactant production and cellular affinity to hydrocarbons. Additionally, polyhydroxyalkanoate (PHA) accumulation was proven to improve tolerance to stressful conditions.

Genome sequence of the polyhydroxybutyrate producer Pseudomonas extremaustralis, a highly stress-resistant Antarctic bacterium.

Pseudomonas extremaustralis 14-3b presents genes involved in the synthesis of different polyhydroxyalkanoates, in tolerance and degradation of pollutants, and in microaerobic metabolism. Several genomic islands were detected. Genetic machinery could contribute to the adaptability to stressful conditions.

Biofilm lifestyle enhances diesel bioremediation and biosurfactant production in the Antarctic polyhydroxyalkanoate producer Pseudomonas extremaustralis.

Diesel is a widely distributed pollutant. Bioremediation of this kind of compounds requires the use of microorganisms able to survive and adapt to contaminated environments. Pseudomonas extremaustralis is an Antarctic bacterium with a remarkable survival capability associated to polyhydroxyalkanoates (PHAs) production.

The alternative sigma factor, sigmaS, affects polyhydroxyalkanoate metabolism in Pseudomonas putida.

To determine whether the stationary sigma factor, sigma(S), influences polyhydroxyalkanoate metabolism in Pseudomonas putida KT2440, an rpoS-negative mutant was constructed to evaluate polyhydroxyalkanoate accumulation and expression of a translational fusion to the promoter region of the genes that code for polyhydroxyalkanoate synthase 1 (phaC1) and polyhydroxyalkanoate depolymerase (phaZ). By comparison with the wild-type, the rpoS mutant showed a higher polyhydroxyalkanoate degradation rate and increased expression of the translational fusion during the stationary growth phase. These results suggest that sigma(S) might control the genes involved in polyhydroxyalkanoate metabolism, possibly in an indirect manner.

Characterization of a mutant strain of Rhodovulum sulfidophilum lacking the pufA and pufB genes encoding the polypeptides for the light-harvesting complex 1 (B 870).

Contradictory results on the effectiveness of energy transfer from the light harvesting complex 2 (LH2) directly to the reaction center (RC) in mutant strains lacking the core light-harvesting complex 1 (LH1) have been obtained with cells of Rhodobacter capsulatus and Rhodobacter sphaeroides. A LH1(-) mutant of Rhodovulum sulfidophilum, named rsLRI, was constructed by deletion of the pufBA genes, resulting in a kanamycin resistant photosynthetically positive clone. To restore the wild type phenotype, a complemented strain C2 was constructed by inserting in trans a DNA segment containing the pufBA genes.