Microbiota and environmental stress: how pollution affects microbial communities in Manila clams.

Given the crucial role of microbiota in host development, health, and environmental interactions, genomic analyses focusing on host-microbiota interactions should certainly be considered in the investigation of the adaptive mechanisms to environmental stress. Recently, several studies suggested that microbiota associated to digestive tract is a key, although still not fully understood, player that must be considered to assess the toxicity of environmental contaminants. Bacteria-dependent metabolism of xenobiotics may indeed modulate the host toxicity. Conversely, environmental variables (including pollution) may alter the microbial community and/or its metabolic activity leading to host physiological alterations that may contribute to their toxicity. Here, 16s rRNA gene amplicon sequencing has been applied to characterize the hepatopancreas microbiota composition of the Manila clam, Ruditapes philippinarum. The animals were collected in the Venice lagoon area, which is subject to different anthropogenic pressures, mainly represented by the industrial activities of Porto Marghera (PM). Seasonal and geographic differences in clam microbiotas were explored and linked to host response to chemical stress identified in a previous study at the transcriptome level, establishing potential interactions among hosts, microbes, and environmental parameters. The obtained results showed the recurrent presence of putatively detoxifying bacterial taxa in PM clams during winter and over-representation of several metabolic pathways involved in xenobiotic degradation, which suggested the potential for host-microbial synergistic detoxifying actions. Strong interaction between seasonal and chemically-induced responses was also observed, which partially obscured such potentially synergistic actions. Seasonal variables and exposure to toxicants were therefore shown to interact and substantially affect clam microbiota, which appeared to mirror host response to environmental variation. It is clear that understanding how animals respond to chemical stress cannot ignore a key component of such response, the microbiota.

Microbial influence on Drosophila biology.

Commensal bacteria profoundly affect the biology of their animal partners. Drosophila melanogaster has been broadly used to study microbiota effects on invertebrates, whose findings are frequently applicable to translational studies. The beneficial role of commensal microbes on Drosophila biology is extensively described, ranging from growth to metabolism, immunity and even behaviour. However, the mechanisms underlying these effects are not well understood. Studies continue to discover new layers of complexity in the host-bacteria partnership that constantly changes depending on a plethora of different variables. This review discusses the latest advances in understanding the molecular bases of microbiota impact on Drosophila physiology and behaviour, emphasizing its broad influence and the intricate interdependence of the two partners in shaping their biology.

Reprint of 'Tracking the blue: a MLST approach to characterise the Pseudomonas fluorescens group'.

The Pseudomonas fluorescens group comprises several closely related species that are involved in food contamination and spoilage. Specifically, the interest in P. fluorescens as a spoiler of dairy products increased after the cases of "blue mozzarella" that occurred in Italy in 2010. A Multilocus Sequence Typing (MLST) scheme was developed and applied to characterise 136 isolates (reference strains and food borne isolates) at strain level, to reveal the genetic relationships among them and to disclose any possible genetic clustering of phenotypic markers involved in food spoilage (protease, lipase, lecithinase activities and pigmented or fluorescent molecule production). The production of dark blue diffusible pigment was evaluated on several bacterial culture media and directly on mozzarella cheese. The MLST scheme provided precise genotyping at the strain level, and the population analyses of the concatenated sequences allowed major taxa to be defined. This approach was revealed to be suitable for tracking the strains according to their origin, such as dairy plants or food matrices. The genetic analysis revealed the presence of a connection between the blue pigment production and a specific phylogenetic cluster. The development of the online database specific to the P. fluorescens group (http://pubmlst.org/pfluorescens) will facilitate the application of the scheme and the sharing of the data.

Tracking the blue: a MLST approach to characterise the Pseudomonas fluorescens group.

The Pseudomonas fluorescens group comprises several closely related species that are involved in food contamination and spoilage. Specifically, the interest in P. fluorescens as a spoiler of dairy products increased after the cases of "blue mozzarella" that occurred in Italy in 2010. A Multilocus Sequence Typing (MLST) scheme was developed and applied to characterise 136 isolates (reference strains and food borne isolates) at strain level, to reveal the genetic relationships among them and to disclose any possible genetic clustering of phenotypic markers involved in food spoilage (protease, lipase, lecithinase activities and pigmented or fluorescent molecule production). The production of dark blue diffusible pigment was evaluated on several bacterial culture media and directly on mozzarella cheese. The MLST scheme provided precise genotyping at the strain level, and the population analyses of the concatenated sequences allowed major taxa to be defined. This approach was revealed to be suitable for tracking the strains according to their origin, such as dairy plants or food matrices. The genetic analysis revealed the presence of a connection between the blue pigment production and a specific phylogenetic cluster. The development of the online database specific to the P. fluorescens group (http://pubmlst.org/pfluorescens) will facilitate the application of the scheme and the sharing of the data.

Sleep electroencephalogram alterations disclose initial stage of encephalopathy.

UNLABELLED: Minimal hepatic encephalopathy is often present in patients with chronic liver disease. The aim of this work was to determine changes in the dynamics of sleep electroencephalogram (EEG) in cirrhotic patients without overt encephalopathy. Twenty such cirrhotic subjects included in the protocol of hepatic transplantation of our hospital were studied and compared with 20 age-matched healthy volunteers. Spectral analysis of all-night EEG was estimated by computing the fast-Fourier transform in 2-second epochs, and averaging every 60 seconds. Artifacts were off-line suppressed, sleep stages (stage 2, stage 3-4 and REM) were determined, and the EEG mean dominant frequency (MDF) was calculated in each of these stages. Results show that in cirrhotic patients, nocturnal MDF evolution discloses a clear alteration of the ultradian EEG frequency oscillations present in controls. Also, the mean value of MDF in REM episodes was larger in cirrhotics than the corresponding value in controls. CONCLUSIONS: 1) sleep EEG evidences the existence of minimal hepatic encephalopathy; 2) the spectral analysis of EEG in minimal hepatic encephalopathy showed that the changes of MDF during sleep are an early marker of cerebral dysfunction in cirrhotic patients.