Talaromyces, a filamentous fungus widely distributed across terrestrial and marine environments, can produce a diverse array of natural products, including alkaloids, polyketones, and polyketide-terpenoids. Among these, chrodrimanins represented a typical class of natural products. In this study, we isolated three previously undescribed pentaketide-sesquiterpenes, 8,9-epi-chrodrimanins (1–3), along with eight known compounds (4–11). The structures of compounds 1–3 were elucidated using nuclear magnetic resonance (NMR) and mass spectrometry (MS), while their absolute configurations were determined through X-ray crystallography and electronic circular dichroism (ECD) computations. The biosynthetic pathways of compounds 1–3 initiate with 6-hydroxymellein and involve multiple stages of isoprenylation, cyclization, oxidation, and acetylation. We selected four strains of gastrointestinal cancer cells for activity evaluation. We found that compound 3 selectively inhibited MKN-45, whereas compounds 1 and 2 exhibited no significant inhibitory activity against the four cell lines. These findings suggested that 8,9-epi-chrodrimanins could serve as scaffold compounds for further structural modifications, potentially leading to the development of targeted therapies for gastric cancer.

Two novel marine hydrogen- and sulfur-oxidizing bacteria, designated HSL1-7^T and HSL3-1^T, were isolated from mangrove sediments from Fujian Province, China. Strain HSL1-7^T exhibited Gram-negative, rod-shaped to slightly curved morphology with polar flagellum-driven motility, whereas strain HSL3-1^T was Gram-negative, rod-shaped and non-motile. Strain HSL1-7^T and HSL3-1^T were obligate chemolithoautotrophs, capable of using molecular hydrogen and thiosulfate as an energy source, and molecular oxygen and elemental sulfur as the electron acceptors for growth. Cellular fatty acid profiles revealed similar predominant components (C_16:1ω7c, C_16:0, C_18:1ω7c, and C_14:0) in both strains. Strains HSL1-7^T and HSL3-1^T were strongly diazotrophic, as demonstrated by ¹⁵N₂ fixation when a fixed nitrogen source was absent from the growth medium. The DNA G+C contents of strains HSL1-7^T and HSL3-1^T were determined to be 36.1% and 57.3%, respectively. Based on the 16S rRNA gene sequences, strains HSL1-7^T and HSL3-1^T exhibited the highest sequence similarities with Sulfurimonas marina B2^T (98.5% and 94.45%, respectively). Notably, the 16S rRNA gene sequence similarity between strains HSL1-7^T and HSL3-1^T was 93.19%, indicating that they represent distinct species within the genus Sulfurimonas. Comparative genomic analyses revealed the presence of diverse metabolic profiles in strains HSL1-7^T and HSL3-1^T, including carbon fixation, hydrogen oxidation, sulfur oxidation, and nitrogen fixation. The combined phenotypic, chemotaxonomic, and phylogenetic evidence, including average nucleotide identity and in silico DNA-DNA hybridization values, shows that strains HSL1-7^T and HSL3-1^T represent two novel species of the genus Sulfurimonas for which the names Sulfurimonas microaerophilic sp. nov. and Sulfurimonas diazotrophicus sp. nov. are proposed, with the type strains HSL1-7^T (=MCCC 1A18899^T = KCTC 25640^T) and HSL3-1^T (=MCCC 1A18844^T), respectively.

As the most abundant biological entities, viruses are the major players in marine ecosystems. However, our knowledge on virus diversity and virus–host interactions in the deep sea remains very limited. In this study, vB_BteM-A9Y, a novel bacteriophage infecting Bacillus tequilensis, was isolated from deep-sea sediments in the South China Sea. vB_BteM-A9Y has a hexametric head and a long, complex contractile tail, which are typical features of myophages. vB_BteM-A9Y initiated host lysis at 60 min post infection with a burst size of 75 PFU/cell. The phage genome comprises 38,634 base pairs and encodes 54 predicted open reading frames (ORFs), of which 27 ORFs can be functionally annotated by homology analysis. Interestingly, abundant ORFs involved in DNA damage repair were identified in the phage genome, suggesting that vB_BteM-A9Y encodes multiple pathways for DNA damage repair, which may help to maintain the stability of the host/phage genome. A BLASTn search of the whole genome sequence of vB_BteM-A9Y against the GenBank revealed no existing homolog. Consistently, a phylogenomic tree and proteome-based phylogenetic tree analysis showed that vB_BteM-A9Y formed a unique branch. Further comparative analysis of genomic nucleotide similarity and ORF homology of vB_BteM-A9Y with its mostly related phages showed that the intergenomic similarity between vB_BteM-A9Y and these phages was 0–33.2%. Collectively, based on the comprehensive morphological, phylogenetic, and comparative genomic analysis, we propose that vB_BteM-A9Y belongs to a novel genus under Caudoviricetes. Therefore, our study will increase our knowledge on deep-sea virus diversity and virus–host interactions, as well as expanding our knowledge on phage taxonomy.