Halomonas maris sp. nov., a moderately halophilic bacterium isolated from sediment in the southwest Indian Ocean

Engineered Lactobacillus rhamnosus Producing 3-Hydroxybutyrate: A Dual-Action Therapeutic Strategy for Colon Cancer Cachexia

3-hydroxybutyrate (3-HB), an essential endogenous metabolite, shows significant therapeutic potential in several disease contexts. However, its clinical application has been hampered by limitations, such as adverse effects on the gut microbiota. This study introduces a genetically engineered strain of Lactobacillus rhamnosus GG (LGGK) that integrates the benefits of 3-HB production with the probiotic properties of LGG. Using a murine colon cancer cachexia (CAC) model, LGGK supplementation significantly improved survival, reduced tumor progression, and alleviated muscle wasting. LGGK restored gut microbial diversity, increased the abundance of beneficial bacteria, and increased the production of short-chain fatty acids while reducing harmful microbial populations. In addition, LGGK supplementation demonstrated anti-inflammatory effects, effectively reducing elevated pro-inflammatory cytokines in serum and skeletal muscle. These findings highlight LGGK as a dual-action therapeutic approach that utilizes the metabolic benefits of 3-HB and the gut-modulating properties of LGG. This innovation offers a promising strategy for the treatment of CAC and potentially other metabolic and inflammatory disorders, and highlights the potential of engineered probiotics in advanced therapeutic applications.

Genomic analysis of Vreelandella sp. F11 reveals its role in alginate utilization

Alginate, mainly produced by brown algae, is an important polysaccharide that supports the growth of marine bacteria. Vreelandella sp. F11 is a Gram-negative and aerobic marine bacterium, which was isolated from the brown algae sample collected from the Weihai coast, the Yellow Sea, China. Here, we present the complete genome of strain F11 and its genomic characteristics to utilize alginate. The genome of strain F11 comprises one circular chromosome with 4,840,724 bp and a GC content of 55.04 %. Strain F11 could grow with alginate as the sole carbon source. Genomic analysis revealed that strain F11 contains a gene cluster, encoding the enzymes, transporters and a regulator protein involved in utilizing alginate. Gene annotations suggested that the alginate utilization system of strain F11 is similar to those in Vibrio strains. However, strain F11 does not contain homologs of known KdgF (a key enzyme involved in the metabolism of alginate monomer) and inner membrane transporters of alginate oligomer uptake. The result indicated that strain F11 contains novel KdgF and inner membrane transporter system, which warrants further investigation. These data suggested that Vreelandella strains play a role in alginate utilization in the ocean and lay a foundation for the application of Vreelandella in the conversion of brown algae.

A long-awaited taxogenomic investigation of the family Halomonadaceae

The family Halomonadaceae is the largest family composed of halophilic bacteria, with more than 160 species with validly published names as of July 2023. Several classifications to circumscribe this family are available in major resources, such as those provided by the List of Prokaryotic names with Standing in Nomenclature (LPSN), NCBI Taxonomy, Genome Taxonomy Database (GTDB), and Bergey's Manual of Systematics of Archaea and Bacteria (BMSAB), with some degree of disagreement between them. Moreover, regardless of the classification adopted, the genus Halomonas is not phylogenetically consistent, likely because it has been used as a catch-all for newly described species within the family Halomonadaceae that could not be clearly accommodated in other Halomonadaceae genera. In the past decade, some taxonomic rearrangements have been conducted on the Halomonadaceae based on ribosomal and alternative single-copy housekeeping gene sequence analysis. High-throughput technologies have enabled access to the genome sequences of many type strains belonging to the family Halomonadaceae; however, genome-based studies specifically addressing its taxonomic status have not been performed to date. In this study, we accomplished the genome sequencing of 17 missing type strains of Halomonadaceae species that, together with other publicly available genome sequences, allowed us to re-evaluate the genetic relationship, phylogeny, and taxonomy of the species and genera within this family. The approach followed included the estimate of the Overall Genome Relatedness Indexes (OGRIs) such as the average amino acid identity (AAI), phylogenomic reconstructions using amino acid substitution matrices customized for the family Halomonadaceae, and the analysis of clade-specific signature genes. Based on our results, we conclude that the genus Halovibrio is obviously out of place within the family Halomonadaceae, and, on the other hand, we propose a division of the genus Halomonas into seven separate genera and the transfer of seven species from Halomonas to the genus Modicisalibacter, together with the emendation of the latter. Additionally, data from this study demonstrate the existence of various synonym species names in this family.