Search Results (3)

Aquaculture plays a vital role in meeting the global demand for high-quality protein. However, the fish industry is challenged by infectious diseases, including gill conditions such as epitheliocystis. Epitheliocystis is characterized by cyst-like epithelial lesions, which occur in the gills of fish, and is associated with intracellular bacteria including Chlamydia-related bacteria. Although epitheliocystis was initially regarded as of low significance, attention is increasing due to its impact on commercially important fish species in intense farming conditions. This review evaluates the roles of aquatic chlamydiae as pathogens contributing to fish morbidity and mortality, and as members of fish microbiota. Additionally, Chlamydia-related bacteria are thought to be involved in complex gill disease (CGD), characterized by lamellar fusion, epithelial hyperplasia, and inflammation. Recent discoveries have expanded the diversity of Chlamydiota isolated from fish, with novel species such as Candidatus (Ca.) Panilichlamydia rohitae, Ca. Piscichlamydia trichopodus, and Chlamydia vaughanii identified in different fish hosts. Most causative agents of epitheliocystis have not yet been cultured in vitro, although C. vaughanii, the first Chlamydiaceae member isolated from fish, was successfully cultured. As C. vaughanii was recently shown to be able to propagate in mammalian cells, it raises concerns about its zoonotic potential, although a pathogenic role has yet to be described. Full article

Mine-tailing dumps are one of the leading sources of environmental degradation, often with public health and ecological consequences. Due to the complex ecosystems generated, they are ideal sites for exploring the bacterial diversity of specially adapted microorganisms. We investigated the concentrations of trace metals in solid copper (Cu) mine tailings from the Ovejería Tailings Dam of the National Copper Corporation of Chile and used high-throughput sequencing techniques to determine the microbial community diversity of the tailings using 16S rRNA gene-based amplicon sequence analysis. The concentrations of the detected metals were highest in the following order: iron (Fe) > Cu > manganese (Mn) > molybdenum (Mo) > lead (Pb) > chromium (Cr) > cadmium (Cd). Furthermore, 16S rRNA gene-based sequence analysis identified 12 phyla, 18 classes, 43 orders, 82 families, and 154 genera at the three sampling points. The phylum Proteobacteria was the most dominant, followed by Chlamydiota, Bacteroidetes, Actinobacteria, and Firmicutes. Genera, such as Bradyrhizobium, Aquabacterium, Paracoccus, Caulobacter, Azospira, and Neochlamydia, showed high relative abundance. These genera are known to possess adaptation mechanisms in high concentrations of metals, such as Cd, Cu, and Pb, along with nitrogen-fixation capacity. In addition to their tolerance to various metals, some of these genera may represent pathogens of amoeba or humans, which contributes to the complexity and resilience of bacterial communities in the studied Cu mining tailings. This study highlights the unique microbial diversity in the Ovejería Tailings Dam, including the discovery of the genus Neochlamydia, reported for the first time for heavy metal resistance. This underscores the importance of characterizing mining sites, particularly in Chile, to uncover novel bacterial mechanisms for potential biotechnological applications. Full article

The glycoside hydrolase 107 (GH107) family includes fucanase enzymes from only two bacterial phyla, Bacteroidota and Pseudomonadota. The goal of this work was to explore the diversity of putative fucanase enzymes related to this family in organisms of the PVC superphylum (Planctomycetota, Verrucomicrobiota, Chlamydiota), in order to expand our knowledge of the fucoidan-degrading potential in this ecologically and biotechnologically relevant group. Using hidden Markov model- and peptide-based annotation tools, 26 GH107 homolog sequences were identified in metagenome and genome datasets. The sequences formed two distinct clusters in a phylogenetic analysis, only one including members of the GH107 family. The endo-acting fucoidan degrading activity was confirmed in an enzyme included in the most divergent cluster. The fucanase, which probably originated in an uncultured planctomycete from the sampled subantarctic sediments, was cloned and expressed in Escherichia coli. The enzyme catalyzed the rapid hydrolysis of internal glycosidic bonds of fucoidan from Macrocystis pyrifera, a macroalgae species abundant at the site. It was active in a wide range of temperatures (5–45 °C), salinities (9.5–861 mM NaCl), and pH values (4.5–9), mainly producing sulfated α-(1,3)-linked fuco-oligosaccharides of various lengths. The PVC superphylum represents a promising source of fucanase enzymes with various biotechnological applications. Full article