Alterations in intestinal microbiota composition are associated with several chronic conditions, including obesity and inflammatory diseases. The microbiota of older people displays greater inter-individual variation than that of younger adults. Here we show that the faecal microbiota composition from 178 elderly subjects formed groups, correlating with residence location in the community, day-hospital, rehabilitation or in long-term residential care. However, clustering of subjects by diet separated them by the same residence location and microbiota groupings. The separation of microbiota composition significantly correlated with measures of frailty, co-morbidity, nutritional status, markers of inflammation and with metabolites in faecal water. The individual microbiota of people in long-stay care was significantly less diverse than that of community dwellers. Loss of community-associated microbiota correlated with increased frailty. Collectively, the data support a relationship between diet, microbiota and health status, and indicate a role for diet-driven microbiota alterations in varying rates of health decline upon ageing.

SummarySafracin is an antibiotic with anti-tumour activity produced by Pseudomonas fluorescens A2-2. The entire safracin synthetic gene cluster spanning 17.5 kb has been identified, cloned and sequenced. The safracin cluster comprises 10 open reading frames (ORFs) encoding proteins for three non-ribosomal peptide synthetases (NRPS), three safracin precursor biosynthetic enzymes, two safracin tailoring enzymes, a safracin resistance protein and a small hypothetical protein of unknown function. These genes are organized in two divergent operons of eight and two genes respectively. This pathway exhibits unusual features when compared with other NRPS systems. We have demonstrated by heterologous expression of the cluster that it is able to direct the synthesis of safracin in other strains. Cross-feeding experiments have confirmed that 3-hydroxy-5-methyl-O -methyltyrosine is the precursor of two amino acids of the molecule. Genetic analyses have allowed us to demonstrate that the bicistronic operon encodes the hydroxylation and N-methylation activities of the pathway. The cloning and expression of the safracin cluster has settled the basis for the in vivo and in vitro production of a wide variety of compounds, such as the promising ecteinascidins anti-cancer compounds.

Pseudomonas putida KT2440 is a chloramphenicol-resistant bacterium that is able to grow in the presence of this antibiotic at a concentration of up to 25 g/ml. Transcriptomic analyses revealed that the expression profile of 102 genes changed in response to this concentration of chloramphenicol in the culture medium. The genes that showed altered expression include those involved in general metabolism, cellular stress response, gene regulation, efflux pump transporters, and protein biosynthesis. Analysis of a genome-wide collection of mutants showed that survival of a knockout mutant in the TtgABC resistance-nodulation-division (RND) efflux pump and mutants in the biosynthesis of pyrroloquinoline (PQQ) were compromised in the presence of chloramphenicol. The analysis also revealed that an ABC extrusion system (PP2669/PP2668/PP2667) and the AgmR regulator (PP2665) were needed for full resistance toward chloramphenicol. Transcriptional arrays revealed that AgmR controls the expression of the pqq genes and the operon encoding the ABC extrusion pump from the promoter upstream of open reading frame (ORF) PP2669.

The impact of antibiotic therapy on the intestinal microbiota in the elderly should be considered for long-term health effects, and differential susceptibility may require the development of products (e.g. prebiotics and probiotics) for at-risk subjects.

ABSTRACTIn this work, we explore the potential use of thePseudomonas putidaKT2440 strain for bioremediation of naphthalene-polluted soils.Pseudomonas putidastrain KT2440 thrives in naphthalene-saturated medium, establishing a complex response that activates genes coding for extrusion pumps and cellular damage repair enzymes, as well as genes involved in the oxidative stress response. The transfer of the NAH7 plasmid enables naphthalene degradation byP. putidaKT2440 while alleviating the cellular stress brought about by this toxic compound, without affecting key functions necessary for survival and colonization of the rhizosphere.Pseudomonas putidaKT2440(NAH7) efficiently expresses the Nah catabolic pathwayin vitroandin situ, leading to the complete mineralization of [14C]naphthalene, measured as the evolution of14CO2, while the rate of mineralization was at least 2-fold higher in the rhizosphere than in bulk soil.