A Rich Morphological Diversity of Biosaline Drying Patterns Is Generated by Different Bacterial Species, Different Salts and Concentrations: Astrobiological Implications.

Unlabelled: Biosaline formations (BSFs) are complex self-organized biomineral patterns formed by "hibernating" bacteria as the biofilm that contains them dries out. They were initially described in drying biofilms of Escherichia coli cells + NaCl. Due to their intricate 3-D morphology and anhydrobiosis, these biomineralogical structures are of great interest in astrobiology.

Drying bacterial biosaline patterns capable of vital reanimation upon rehydration: novel hibernating biomineralogical life formations.

Water is the fundamental molecule for life on Earth. Thus, the search for hibernating life-forms in waterless environments is an important research topic for astrobiology. To date, however, the organizational patterns containing microbial life in extremely dry places, such as the deserts of Earth, the Dry Valleys of Antarctica, or Mars analog regolith, have been poorly characterized.

Crowning: a novel Escherichia coli colonizing behaviour generating a self-organized corona.

Background: Encased in a matrix of extracellular polymeric substances (EPS) composed of flagella, adhesins, amyloid fibers (curli), and exopolysaccharides (cellulose, β-1,6-N-acetyl-D-glucosamine polymer-PGA-, colanic acid), the bacteria Escherichia coli is able to attach to and colonize different types of biotic and abiotic surfaces forming biofilms and colonies of intricate morphological architectures. Many of the biological aspects that underlie the generation and development of these E. coli's formations are largely poorly understood.

A novel role for RecA under non-stress: promotion of swarming motility in Escherichia coli K-12.

Background: Bacterial motility is a crucial factor in the colonization of natural environments. Escherichia coli has two flagella-driven motility types: swimming and swarming. Swimming motility consists of individual cell movement in liquid medium or soft semisolid agar, whereas swarming is a coordinated cellular behaviour leading to a collective movement on semisolid surfaces.

PBP3 inhibition elicits adaptive responses in Pseudomonas aeruginosa.

Adaptive evolution depends on both the genetic variability in a population of organisms and the selection of the better adapted genotypes. However, for the fittest variants to be selected they must survive over a sufficient period under the new conditions. Bacteria are often exposed to different types of stress in nature, including antibiotics.

Iron meteorites can support the growth of acidophilic chemolithoautotrophic microorganisms.

Chemolithoautotrophy based on reduced inorganic minerals is considered a primitive energy transduction system. Evidence that a high number of meteorites crashed into the planet during the early period of Earth history led us to test the ability of iron-oxidizing bacteria to grow using iron meteorites as their source of energy. Here we report the growth of two acidophilic iron-oxidizing bacteria, Leptospirillum ferrooxidans and Acidithiobacillus ferrooxidans, on a piece of the Toluca meteorite as the only source of energy.

SOS-independent induction of dinB transcription by beta-lactam-mediated inhibition of cell wall synthesis in Escherichia coli.

Transcription of the dinB gene, encoding DNA polymerase IV, is induced by the inhibition of cell wall synthesis at different levels. Using the beta-lactam antibiotic ceftazidime, a PBP3 inhibitor, as a model, we have shown that this induction is independent of the LexA/RecA regulatory system. Induction of dinB transcription mediated by ceftazidime produces an increase in the reversion of a +1 Lac frameshift mutation.

Mutation and evolution of antibiotic resistance: antibiotics as promoters of antibiotic resistance?

Antibiotic resistance appearance and spread have been classically considered the result of a process of natural selection, directed by the use of antibiotics. Bacteria, that have to face the antibiotic challenge, evolve to acquire resistance and, under this strong selective pressure, only the fittest survive, leading to the spread of resistance mechanisms and resistant clones. Horizontal transference of resistance mechanisms seems to be the main way of antibiotic resistance acquisition.