The symbiosis between bacteria and sponges has arguably the longest evolutionary history for any extant metazoan lineage, yet little is known about bacterial evolution or adaptation in this process. An example of often dominant and widespread bacterial symbionts of sponges is a clade of uncultured and uncharacterised Proteobacteria. Here we set out to characterise this group using metagenomics, in-depth phylogenetic analyses, metatranscriptomics, and fluorescence in situ hybridisation microscopy. We obtained five metagenome-assembled-genomes (MAGs) from different sponge species that, together with a previously published MAG (AqS2), comprise two families within a new gammaproteobacterial order that we named ^UTethybacterales. Members of this order share a heterotrophic lifestyle but vary in their predicted ability to use various carbon, nitrogen and sulfur sources, including taurine, spermidine and dimethylsulfoniopropionate. The deep branching of the ^UTethybacterales within the Gammaproteobacteria and their almost exclusive presence in sponges suggests they have entered a symbiosis with their host relatively early in evolutionary time and have subsequently functionally radiated. This is reflected in quite distinct lifestyles of various species of ^UTethybacterales, most notably their diverse morphologies, predicted substrate preferences, and localisation within the sponge tissue. This study provides new insight into the evolution of metazoan–bacteria symbiosis.

Aquaculture plays a major role in the coastal economy of the Mediterranean Sea. This raises the issue of the impact of fish cages on the surrounding environment. Here, we explore the impact of aquaculture on the composition of the digestive gland microbiome of a representative locally dwelling wild holobiont, the grazer gastropod Patella caerulea, at an aquaculture facility located in Southern Sicily, Italy. The microbiome was assessed in individuals collected on sea bream aquaculture cages and on a rocky coastal tract located about 1.2 km from the cages, as the control site. Patella caerulea microbiome variations were explained in the broad marine metacommunity context, assessing the water and sediment microbiome composition at both sites, and characterizing the microbiome associated with the farmed sea bream. The P. caerulea digestive gland microbiome at the aquaculture site was characterized by a lower diversity, the loss of microorganisms sensitive to heavy metal contamination, and by the acquisition of fish pathogens and parasites. However, we also observed possible adaptive responses of the P. caerulea digestive gland microbiome at the aquaculture site, including the acquisition of putative bacteria able to deal with metal and sulfide accumulation, highlighting the inherent microbiome potential to drive the host acclimation to stressful conditions.

Poultry farms are hotspots for the development and spread of antibiotic resistance genes (ARGs), due to high stocking densities and extensive use of antibiotics, posing a threat of spread and contagion to workers and the external environment. Here, we applied shotgun metagenome sequencing to characterize the gut microbiome and resistome of poultry, workers and their households - also including microbiomes from the internal and external farm environment - in three different farms in Italy during a complete rearing cycle. Our results highlighted a relevant overlap among the microbiomes of poultry, workers, and their families (gut and skin), with clinically relevant ARGs and associated mobile elements shared in both poultry and human samples. On a finer scale, the reconstruction of species-level genome bins (SGBs) allowed us to delineate the dynamics of microorganism and ARGs dispersion from farm systems. We found the associations with worker microbiomes representing the main route of ARGs dispersion from poultry to human populations. Collectively, our findings clearly demonstrate the urgent need to implement more effective procedures to counteract ARGs dispersion from poultry food systems and the relevance of metagenomics-based metacommunity approaches to monitor the ARGs dispersion process for the safety of the working environment on farms.

Aplysina aerophoba is an emerging model marine sponge, with a well-characterized microbial community in terms of diversity and structure. However, little is known about the expressed functional capabilities of its associated microbes. Here, we present the first metaproteomics-based study of the microbiome of A. aerophoba. We found that transport and degradation of halogenated and chloroaromatic compounds are common active processes in the sponge microbiomes. Our data further reveal that the highest number of proteins were affiliated to a sponge-associated Tectomicrobium, presumably from the family Entotheonellaceae, as well as to the well-known symbiont “Candidatus Synechococcus spongiarium”, suggesting a high metabolic activity of these two microorganisms in situ. Evidence for nitric oxide (NO) conversion to nitrous oxide was consistently observed for Tectomicrobia across replicates, by production of the NorQ protein. Moreover, we found a potential energy-yielding pathway through CO oxidation by putative Chloroflexi bacteria. Finally, we observed expression of enzymes that may be involved in the transformation of chitin, glycoproteins, glycolipids and glucans into smaller molecules, consistent with glycosyl hydrolases predicted from analyses of the genomes of Poribacteria sponge symbionts. Thus, this study provides crucial links between expressed proteins and specific members of the A. aerophoba microbiome.

Body lesions in pigs are a common welfare concern, particularly during the weaning period. These lesions can lead to pain, infection, and impaired mobility, resulting in reduced growth performance and increased mortality. Moreover, weaning stress can affect gut microbiota, immune response and increase the oxidative stress of piglets during this transition period. It has been hypothesised that social stress and body lesions could contribute to affect the gut microbiota, physiological and immune response of piglets. The study aims to evaluate the impact of the body lesions due to social stress on microbial profile, immune response, and oxidative status of weaned piglets. Lesion score (LS) on skin, tail, ear, neck, middle trunk, and hind quarters was measured 1 week (28 days of age, T1) and 7 weeks postweaning (T2) on 45 tail-docked pigs according to the method suggested from the Walfer Quality® (2009) on a scale from 0 to 2. Based on the LS, at T1, piglets were classified as High LS (n = 16), when LS was >1 in at least two of the areas considered, or Low LS (n = 29). At T2, based on the same scoring system and to the LS observed at T1, piglets were divided into four groups: High to Low LS (H-L, n = 11), High to High LS (H-H, n = 5), Low to Low LS (L-L, n = 21) and Low to High LS (L-H, n = 8). Blood and faecal samples were collected at T1 and T2. At T1, pigs with a high LS had a lower biological antioxidant potential compared with the L group (P < 0.02). At T2, the L-H group had a lower Reactive Oxygen Metabolites concentration compared with the H-H group (P = 0.03) while the L-L group had a lower concentration of Immunoglobulin A compared with H-H and L-H groups (P = 0.02 and P = 0.04, respectively). At T1, piglets with high LS had a different microbiota compared to piglets with low LS (R² = 0.04, P < 0.01). Low LS pigs were characterised by a higher abundance of Firmicutes, Blautia, Eubacterium coprostanoligenes, Faecalibacterium, Megasphaera, Subdoligranulum (P.adj < 0.05), while pigs with high LS were characterised by higher abundance of Bacteroidota, Rikenellaceae RC9, Prevotellaceae UCG-003, uncultured-Lachnospiraceae and uncultured-Oscillospiraceae (P.adj < 0.05). At T2, the H-H group were characterised by Oscillospirales-UCG-010, H-L by Agatobachter and L-L by Alloprevotella (P.adj < 0.05). Overall, this study provides valuable insights into the relationship between body lesions, oxidative stress, and gut microbiota in weaned pigs.