Corynebacterium alimapuense sp. nov., an obligate marine actinomycete isolated from sediment of Valparaíso bay, Chile

Unveiling metabolo-genomic insights of potent antitumoral and antibiotic activity in Streptomyces sp. VB1 from Valparaíso Bay

Streptomyces sp. VB1, an actinomycete isolated from marine sediments in Valparaíso Bay, Chile, synthesizes antimicrobial and antiproliferative compounds. This study presents comprehensive metabolomics and comparative genomics analyses of strain VB1. LC-HRMS dereplication and Molecular Networking analysis of crude extracts identified antibiotics such as globomycin and daunorubicin, along with known and potentially novel members of the arylomycin family. These compounds exhibit activity against a range of clinically relevant bacterial and cancer cell lines. Phylogenomic analysis underscores the uniqueness of strain VB1, suggesting it represents a novel taxon. Such uniqueness is further supported by its Biosynthetic Novelty Index (BiNI) and BiG-SCAPE analysis of Gene Cluster Families (GCFs). Notably, two Biosynthetic Gene Clusters (BGCs) were found to be unique to VB1 compared to closely related strains: BGC #15, which encodes potentially novel anthracycline compounds with cancer cell growth inhibition properties, and BGC #28, which features a non-canonical configuration combining arylomycin, globomycin, and siamycin BGCs. This supercluster, the first described to consist of more than two adjacent and functional BGCs, co-produces at least three antimicrobial compounds from different antibiotic families. These findings highlight Streptomyces sp. VB1's potential for discovering new bioactive molecules, positioning it as a promising candidate for further research.

Corynebacterium anserum sp. nov., isolated from the faeces of greater white-fronted geese (Anser albifrons) at Poyang Lake, PR China

Two Gram-stain-positive, facultatively aerobic, non-motile and rod- to coccoid-shaped bacterial strains, 23H37-10^T and 4HC-13, were isolated from the faeces of greater white-fronted geese (Anser albifrons) at Poyang Lake, Jiangxi Province, PR China. Optimal growth was observed at 35-37 °C, pH 7.0-8.0 and with 0.5-1.5 % (w/v) NaCl. The 16S rRNA gene sequences of strains 23H37-10^T and 4HC-13 were identical. Phylogenetic and phylogenomic analyses indicated that strains 23H37-10^T and 4HC-13 formed an independent cluster within the genus Corynebacterium and showed 98.8, 97.4, 97.4 and 97.2 % 16S rRNA gene sequence similarity to Corynebacterium urogenitale LMM 1652^T, Corynebacterium urealyticum DSM 7109^T, Corynebacterium falsenii DSM 44353^T and Corynebacterium jeikeium NCTC 11913^T, respectively. Cells contained C_18 :1 ω9c, C_18 : 0 and C_16 : 0 as the major cellular fatty acids and MK-9 (H₂) as the predominant respiratory quinone. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol, phosphatidyl inositol mannosides, two unidentified phospholipids, four unidentified glycolipids and one unidentified lipid. Strain 23H37-10^T contained mycolic acids, with meso-diaminopimelic acid and arabinose as the major whole-cell hydrolysates. The genome G+C content of strains 23H37-10^T and 4HC-13 was 55.2 mol%. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) values between strains 23H37-10^T and 4HC-13 were 94.4 and 99.6 %, respectively. Strains 23H37-10^T and 4HC-13 had dDDH and ANI values of less than 70 and 96 % with all available genomes of the genus Corynebacterium, respectively. The differential genotypic inferences, together with phenotypic and biochemical characteristics, suggested that strains 23H37-10^T and 4HC-13 represent a novel species within the genus Corynebacterium, for which the name Corynebacterium anserum sp. nov. is proposed. The type strain is 23H37-10^T (=GDMCC 1.1737^T=KACC 21672^T).