Exploring Rhodospirillum rubrum response to high doses of carbon monoxide under light and dark conditions.

Environmental concerns about residues and the traditional disposal methods are driving the search for more environmentally conscious processes, such as pyrolysis and gasification. Their main final product is synthesis gas (syngas) composed of CO, CO2, H2, and methane. Syngas can be converted into various products using CO-tolerant microorganisms. Among them, Rhodospirillum rubrum is highlighted for its biotechnological potential. However, the extent to which high doses of CO affect its physiology is still opaque. For this reason, we have studied R. rubrum behavior under high levels of this gas (up to 2.5 bar), revealing a profound dependence on the presence or absence of light. In darkness, the key variable affected was the lag phase, where the highest levels of CO retarded growth to more than 20 days. Under light, R. rubrum ability to convert CO into CO2 and H2 depended on the presence of an additional carbon source, such as acetate. In those conditions where CO was completely exhausted, CO2 fixation was unblocked, leading to a diauxic growth. To enhance R. rubrum tolerance to CO in darkness, a UV-accelerated adaptive laboratory evolution (UVa-ALE) trial was conducted to isolate clones with shorter lag phases, resulting in the isolation of clones 1.4-2B and 1.7-2A. The adaptation of 1.4-2B was mainly based on mutated enzymes with a metabolic function, while 1.7-3A was mostly affected at regulatory genes, including the anti-repressor PpaA/AerR. Despite these mutations having slight effects on biomass and pigment levels, they successfully provoked a significant reduction in the lag phase (-50%). KEYPOINTS: • CO affects principally R. rubrum lag phase (darkness) and growth rate (light) • CO is converted to CO2/H2 during acetate uptake and inhibits CO2 fixation (light) • UVa-ALE clones showed a 50% reduction in the lag phase (darkness).

Hints from nature for a PHA circular economy: Carbon synthesis and sharing by Pseudomonas solani GK13.

Polyhydroxyalkanoates (PHAs) are a well-known group of biodegradable and biocompatible bioplastics that are synthesised and stored by microorganisms as carbon and energy reservoirs. Extracellular PHA depolymerases (ePhaZs), secreted by a limited range of microorganisms, are the main hydrolytic enzymes responsible for their environmental degradation. Pseudomonas sp. GK13, initially identified as P. fluorescens GK13, produces PHA and a prototypic ePhaZ that specifically degrades mcl-PHA. In this study, a comprehensive characterization of strain GK13 was performed. The whole genomic sequence of GK13 was consolidated into one complete chromosome, leading to its reclassification as P. solani GK13. We conducted a detailed in silico examination of the bacteria genomic sequence, specifically targeting PHA metabolic functions. From the different growth conditions explored, PHA accumulation occurred only under carbon/nitrogen (C/N) imbalance, whereas ePhaZ production was induced even at balanced C/N ratios in mineral media. We extend our study to other bacteria belonging to the Pseudomonas genus revealing that the ePhaZ production capacity is closely associated with mcl-PHA synthesis capacity, as also suggested by metagenomic samples. This finding suggests that these types of microorganisms could contribute to the carbon economy of the microbial community, by storing PHA in carbon-rich times, and sharing it with the rest of the population during times of carbon scarcity through PHA hydrolysis. The conclusion pointed that carbon cycle metabolism performed by P. solani GK13 may contribute to the environmental circular economy at a microscopic scale.

[Etanercept as a possible trigger of fatal pulmonary fibrosis]. / Fibrosis pulmonar mortal, con etanercept como posible desencadenante.

Pulmonary fibrosis can be caused by external agents, including certain drugs. For some time now, tumor necrosis factor antagonists such as etanercept have been used to treat certain autoimmune diseases. Fibrosis caused by medication responds to withdrawal of the drug and treatment with corticosteroids. Very rarely, fibrosis is irreversible. We present the case of a patient who developed pulmonary fibrosis after initiating treatment with etanercept. The clinical course was fulminant despite withdrawal of the drug and high doses of corticosteroids.

Síndrome de Contarini: ¿una entidad olvidada? / Contarini’s syndrome: a forgotten entity?

El síndrome de Contarini es una presentación infrecuente de derrame pleural bilateral en la cual el líquido pleural en cada hemitórax presenta diferentes características, y puede explicarse por diferentes causas. Hay escasa literatura al respecto, por lo que presentamos un caso de derrame pleural bilateral que sería compatible con dicho síndrome (AU)

Contarini’s syndrome is an infrequent presentation of bilateral pleural effusion, in which the pleural fluid in each hemithorax has different characteristics and can be explained by different causes. There is limited literature on this syndrome, so we present a case of bilateral pleural effusion that would be compatible with this syndrome (AU)

Fibrosis pulmonar mortal, con etanercept como posible desencadenante / Etanercept as a possible trigger of fatal pulmonary fibrosis

La fibrosis pulmonar es una enfermedad que puede estar causada por agentes externos como determinados fármacos. Desde hace un tiempo se utilizan fármacos antagonistas del factor de necrosis tumoral (TNF) para ciertas enfermedades autoinmunitarias, siendo un ejemplo de estos fármacos el etanercept. Las fibrosis secundarias a medicamentos se caracterizan por la respuesta a la retirada del fármaco y a esteroides. En muy raras ocasiones se produce una fibrosis irreversible. Presentamos el caso de un paciente que desarrolló una fibrosis pulmonar tras iniciar tratamiento con etanercept y que tuvo un curso clínico nefasto a pesar de la retirada del anti-TNF y dosis altas de esteroides

Pulmonary fibrosis can be caused by external agents, including certain drugs. For some time now, tumor necrosis factor antagonists such as etanercept have been used to treat certain autoimmune diseases. Fibrosis caused by medication responds to withdrawal of the drug and treatment with corticosteroids. Very rarely, fibrosis is irreversible. We present the case of a patient who developed pulmonary fibrosis after initiating treatment with etanercept. The clinical course was fulminant despite withdrawal of the drug and high doses of corticosteroids (AU)