Prokaryotic diversity across a pH gradient in the “El Chichón” crater-lake: a naturally thermo-acidic environment

Tolerance to NSAIDs in Actinobacteria From a Mexican Volcano Crater: Genomics and Bioremediation Potential

Non-steroidal anti-inflammatory drugs (NSAIDs) are emerging contaminants that pose significant health and environmental risks due to their persistence, including their presence in drinking water. Bioremediation, particularly through microorganisms such as actinobacteria, offers a sustainable approach to mitigate these pollutants. Actinobacteria from poly-extreme environments exhibit unique genetic and metabolic adaptations, enabling resistance to and degradation of various contaminants. This study aimed to evaluate the tolerance of actinobacteria to NSAIDs and conduct a genomic analysis of a selected strain. Actinobacteria were isolated from the crater of the Chichonal volcano [Chiapas, Mexico), resulting in 16 isolates. Among these, Micrococcus luteus P8SUE1, Micrococcus yunnanensis P9AGU1, and Kocuria rhizophila P1AGU3 demonstrated tolerance to diclofenac, ibuprofen, and paracetamol at concentrations of 1 ppm, 10 ppm, and 100 ppm, respectively. Whole-genome sequencing of M. yunnanensis P9AGU1 identified genes linked to the degradation of aromatic compounds and adaptations to extreme environmental conditions, highlighting its potential for bioremediation applications.

Bacterial Community with Plant Growth-Promoting Potential Associated to Pioneer Plants from an Active Mexican Volcanic Complex

Microorganisms in extreme volcanic environments play an important role in the development of plants on newly exposed substrates. In this work, we studied the structure and diversity of a bacterial community associated to Andropogon glomeratus and Cheilanthes aemula at El Chichón volcano. The genetic diversity of the strains was revealed by genomic fingerprints and by 16S rDNA gene sequencing. Furthermore, a metagenomic analysis of the rhizosphere samples was carried out for pioneer plants growing inside and outside the volcano. Multifunctional biochemical tests and plant inoculation assays were evaluated to determine their potential as plant growth-promoting bacteria (PGPB). Through metagenomic analysis, a total of 33 bacterial phyla were identified from A. glomeratus and C. aemula rhizosphere samples collected inside the volcano, and outside the volcano 23 bacterial phyla were identified. For both rhizosphere samples, proteobacteria was the most abundant phylum. With a cultivable approach, 174 bacterial strains were isolated from the rhizosphere and tissue of plants growing outside the volcanic complex. Isolates were classified within the genera Acinetobacter, Arthrobacter, Bacillus, Burkholderia, Cupriavidus, Enterobacter, Klebsiella, Lysinibacillus, Pantoea, Pseudomonas, Serratia, Stenotrophomonas and Pandoraea. The evaluated strains were able to produce indole compounds, solubilize phosphate, synthesize siderophores, showed ACC deaminase and nitrogenase activity, and they had a positive effect on the growth and development of Capsicum chinense. The wide diversity of bacteria associated to pioneer plants at El Chichón volcano with PGPB qualities represent an alternative for the recovery of eroded environments, and they can be used efficiently as biofertilizers for agricultural crops growing under adverse conditions.

Did Homocysteine Take Part in the Start of the Synthesis of Peptides on the Early Earth?

Unlike its shorter analog, cysteine, and its methylated derivative, methionine, homocysteine is not today a proteinogenic amino acid. However, this thiol containing amino acid is capable of forming an activated species intramolecularly. Its thiolactone could have made it an interesting molecular building block at the origin of life on Earth. Here we study the cyclization of homocysteine in water and show theoretically and experimentally that in an acidic medium the proportion of thiolactone is significant. This thiolactone easily reacts with amino acids to form dipeptides. We envision that these reactions may help interpret why a methionine residue is introduced at the start of all protein synthesis.