Potential of Indigenous Strains Isolated from the Wastewater Treatment Plant of a Crude Oil Refinery.

Contamination of the environment with crude oil or other fuels is an enormous disaster for all organisms. The microbial communities for bioremediation have been an effective tool for eliminating pollution. This study aimed to determine individual cultures' and a strain mixture's ability to utilize alkanes (single alkanes and crude oil).

Biofilm Depends on the vWFa-Domain of LapA in Peptides-Containing Growth Medium.

The biofilm of is complexly regulated by several intercellular and extracellular factors. The cell surface adhesin LapA of this bacterium is a central factor for the biofilm and, consequently, the regulation of expression, for example, by Fis. It has been recently shown that peptides in growth media enhance the formation of biofilm, but not as a source of carbon and nitrogen.

Tryptone in Growth Media Enhances Biofilm.

Extracellular factors and growth conditions can affect the formation and development of bacterial biofilms. The biofilm of has been studied for decades, but so far, little attention has been paid to the components of the medium that may affect the biofilm development in a closed system. It is known that Fis strongly enhances biofilm in complete LB medium.

Colonization efficiency of Pseudomonas putida is influenced by Fis-controlled transcription of nuoA-N operon.

Root colonization of plant growth-promoting bacteria is a complex multistep process that is influenced by several factors. For example, during adherence to plant roots, bacteria have to endure reactive oxygen species (ROS) produced by plants. In this study, we report that the global transcriptional regulator Fis is involved in the regulation of ROS-tolerance of Pseudomonas putida and thereby affects barley root colonization.

Correction: The promoter region of lapA and its transcriptional regulation by Fis in Pseudomonas putida.

[This corrects the article DOI: 10.1371/journal.pone.

The promoter region of lapA and its transcriptional regulation by Fis in Pseudomonas putida.

LapA is the biggest protein in Pseudomonas putida and a key factor for biofilm formation. Its importance and posttranslational regulation is rather thoroughly studied but less is known about the transcriptional regulation. Here we give evidence that transcription of lapA in LB-grown bacteria is initiated from six promoters, three of which display moderate RpoS-dependence.

LapF and Its Regulation by Fis Affect the Cell Surface Hydrophobicity of Pseudomonas putida.

The ability of bacteria to regulate cell surface hydrophobicity is important for the adaptation to different environmental conditions. The hydrophobicity of cell surface can be determined by several factors, including outer membrane and surface proteins. In this study, we report that an adhesin LapF influences cell surface hydrophobicity of Pseudomonas putida.

NHEJ enzymes LigD and Ku participate in stationary-phase mutagenesis in Pseudomonas putida.

Under growth-restricting conditions bacterial populations can rapidly evolve by a process known as stationary-phase mutagenesis. Bacterial nonhomologous end-joining (NHEJ) system which consists of the DNA-end-binding enzyme Ku and the multifunctional DNA ligase LigD has been shown to be important for survival of bacteria especially during quiescent states, such as late stationary-phase populations or sporulation. In this study we provide genetic evidence that NHEJ enzymes participate in stationary-phase mutagenesis in a population of carbon-starved Pseudomonas putida.

Pseudomonas putida Fis binds to the lapF promoter in vitro and represses the expression of LapF.

The biofilm matrix of the rhizospheric bacterium Pseudomonas putida consists mainly of a proteinaceous component. The two largest P. putida proteins, adhesins LapA and LapF, are involved in biofilm development but prevail in different developmental stages of the biofilm matrix.

Fis overexpression enhances Pseudomonas putida biofilm formation by regulating the ratio of LapA and LapF.

Bacteria form biofilm as a response to a number of environmental signals that are mediated by global transcription regulators and alarmones. Here we report the involvement of the global transcription regulator Fis in Pseudomonas putida biofilm formation through regulation of lapA and lapF genes. The major component of P.

Mutation frequency and spectrum of mutations vary at different chromosomal positions of Pseudomonas putida.

It is still an open question whether mutation rate can vary across the bacterial chromosome. In this study, the occurrence of mutations within the same mutational target sequences at different chromosomal locations of Pseudomonas putida was monitored. For that purpose we constructed two mutation detection systems, one for monitoring the occurrence of a broad spectrum of mutations and transposition of IS element IS1411 inactivating LacI repressor, and another for detecting 1-bp deletions.

Homologous recombination is facilitated in starving populations of Pseudomonas putida by phenol stress and affected by chromosomal location of the recombination target.

Homologous recombination (HR) has a major impact in bacterial evolution. Most of the knowledge about the mechanisms and control of HR in bacteria has been obtained in fast growing bacteria. However, in their natural environment bacteria frequently meet adverse conditions which restrict the growth of cells.

Fis regulates the competitiveness of Pseudomonas putida on barley roots by inducing biofilm formation.

An important link between the environment and the physiological state of bacteria is the regulation of the transcription of a large number of genes by global transcription factors. One of the global regulators, Fis (factor for inversion stimulation), is well studied in Escherichia coli, but the role of this protein in pseudomonads has only been examined briefly. According to studies in Enterobacteriaceae, Fis regulates positively the flagellar movement of bacteria.

Involvement of specialized DNA polymerases Pol II, Pol IV and DnaE2 in DNA replication in the absence of Pol I in Pseudomonas putida.

The majority of bacteria possess a different set of specialized DNA polymerases than those identified in the most common model organism Escherichia coli. Here, we have studied the ability of specialized DNA polymerases to substitute Pol I in DNA replication in Pseudomonas putida. Our results revealed that P.

Elevated mutation frequency in surviving populations of carbon-starved rpoS-deficient Pseudomonas putida is caused by reduced expression of superoxide dismutase and catalase.

RpoS is a bacterial sigma factor of RNA polymerase which is involved in the expression of a large number of genes to facilitate survival under starvation conditions and other stresses. The results of our study demonstrate that the frequency of emergence of base substitution mutants is significantly increased in long-term-starved populations of rpoS-deficient Pseudomonas putida cells. The increasing effect of the lack of RpoS on the mutation frequency became apparent in both a plasmid-based test system measuring Phe(+) reversion and a chromosomal rpoB system detecting rifampin-resistant mutants.

Fis negatively affects binding of Tn4652 transposase by out-competing IHF from the left end of Tn4652.

Transposition activity in bacteria is generally maintained at a low level. The activity of mobile DNA elements can be controlled by bacterially encoded global regulators. Regulation of transposition of Tn4652 in Pseudomonas putida is one such example.

Simultaneous degradation of atrazine and phenol by Pseudomonas sp. strain ADP: effects of toxicity and adaptation.

The strain Pseudomonas sp. strain ADP is able to degrade atrazine as a sole nitrogen source and therefore needs a single source for both carbon and energy for growth. In addition to the typical C source for Pseudomonas, Na(2)-succinate, the strain can also grow with phenol as a carbon source.

IHF is the limiting host factor in transposition of Pseudomonas putida transposon Tn4652 in stationary phase.

Transpositional activity of mobile elements is not constant. Conditional regulation of host factors involved in transposition may severely change the activity of mobile elements. We have demonstrated previously that transposition of Tn4652 in Pseudomonas putida is a stationary phase-specific event, which requires functional sigma S (Ilves et al.