We obtained two novel draft genomes of type Zobellia strains with estimated genome sizes of 5.14 Mb for Z. amurskyensis KMM 3526^Т and 5.16 Mb for Z. laminariae KMM 3676^Т. Comparative genomic analysis has been carried out between obtained and known genomes of Zobellia representatives. The pan-genome of Zobellia genus is composed of 4853 orthologous clusters and the core genome was estimated at 2963 clusters. The genus CAZome was represented by 775 GHs classified into 62 families, 297 GTs of 16 families, 100 PLs of 13 families, 112 CEs of 13 families, 186 CBMs of 18 families and 42 AAs of six families. A closer inspection of the carbohydrate-active enzyme (CAZyme) genomic repertoires revealed members of new putative subfamilies of GH16 and GH117, which can be biotechnologically promising for production of oligosaccharides and rare monomers with different bioactivities. We analyzed AA3s, among them putative FAD-dependent glycoside oxidoreductases (FAD-GOs) being of particular interest as promising biocatalysts for glycoside deglycosylation in food and pharmaceutical industries.

Six Gram-stain-negative, aerobic, rod-shaped, and motile by gliding bacterial strains were isolated from Pacific green and red algae. Phylogenetic analysis based on 16S rRNA gene sequences placed the novel strains into the genus Zobellia as a distinct evolutionary lineage close to Zobellia nedashkovskayae Asnod2-B07-B^T and Zobellia laminariae KMM 3676^T sharing the highest similarity of 99.7% and 99.5%, respectively. The average nucleotide identity and the average amino acid identity values between strains 36-CHABK-3-33^T and Z. nedashkovskayae Asnod2-B07-B^T and Z. laminariae KMM 3676^T were 89.7%/92.9% and 94.2%/95.8%, respectively. The digital DNA–DNA hybridization values based on the draft genomes between strains 36-CHABK-3-33^T and Z. nedashovskayae Asnod2-B07-B^T and Z. laminariae KMM 3676^T were 39.5 ± 2.5% and 59.6 ± 2.7%, respectively. Multilocus sequence analysis based on house-keeping genes (dnaK, gyrB, pyrH, recA and topA) assigned the alga-associated isolates to the same species, which clustered separately from the recognized species of the genus Zobellia. The strains under study grew at 4–32 °C and with 0.5–8% NaCl and decomposed aesculin, gelatin, DNA, and Tweens 20 and 80, and weakly agar. The DNA G+C content was 36.7% calculated from genome sequence analysis for the strain 36-CHABK-3-33^T. The predominant fatty acids of strain 36-CHABK-3-33^T (>5% of the total fatty acids) were iso-C_17:0 3-OH, summed feature 3 (comprising C_16:1ω7c and/or iso-C_15:0 2-OH fatty acids), iso-C_15:0, iso-C_15:1 G, and C_15:0. The major polar lipids were phosphatidylethanolamine, three unidentified lipids, and two unidentified aminolipids. The only detected respiratory quinone was MK-6. The significant molecular distinctiveness between the novel isolates and their nearest neighbor was strongly supported by differences in physiological and biochemical tests. Therefore, the six novel strains represent a novel species of the genus Zobellia, for which the name Zobellia barbeyronii sp. nov. is proposed. The type strain is 36-CHABK-3-33^T (= KACC 21790^T = KMM 6746^T).

We carried out a detailed investigation of PL7 alginate lyases across the Zobellia genus. The main findings were obtained using the methods of comparative genomics and spatial structure modeling, as well as a phylogenomic approach. Initially, in order to elucidate the alginolytic potential of Zobellia, we calculated the content of polysaccharide lyase (PL) genes in each genome. The genus-specific PLs were PL1, PL6, PL7 (the most abundant), PL14, PL17, and PL40. We revealed that PL7 belongs to subfamilies 3, 5, and 6. They may be involved in local and horizontal gene transfer and gene duplication processes. Most likely, an individual evolution of PL7 genes promotes the genetic variability of the Alginate Utilization System across Zobellia. Apparently, the PL7 alginate lyases may acquire a sub-functionalization due to diversification between in-paralogs.

A strictly aerobic, Gram-stain-negative, rod-shaped, and motile bacterium, designated strain KMM 296, isolated from the coelomic fluid of the mussel Crenomytilus grayanus, was investigated in detail due to its ability to produce a highly active alkaline phosphatase CmAP of the structural family PhoA. A previous taxonomic study allocated the strain to the species Cobetia marina, a member of the family Halomonadaceae of the class Gammaproteobacteria. However, 16S rRNA gene sequencing showed KMM 296’s relatedness to Cobetia amphilecti NRIC 0815^T. The isolate grew with 0.5–19% NaCl at 4–42 °C and hydrolyzed Tweens 20 and 40 and L-tyrosine. The DNA G+C content was 62.5 mol%. The prevalent fatty acids were C_18:1 ω7c, C_12:0 3-OH, C_18:1 ω7c, C_12:0, and C_17:0 cyclo. The polar lipid profile was characterized by the presence of phosphatidylethanolamine, phosphatidylglycerol, phosphatidic acid, and also an unidentified aminolipid, phospholipid, and a few unidentified lipids. The major respiratory quinone was Q-8. According to phylogenomic and chemotaxonomic evidence, and the nearest neighbors, the strain KMM 296 represents a member of the species C. amphilecti. The genome-based analysis of C. amphilecti NRIC 0815^T and C. litoralis NRIC 0814^T showed their belonging to a single species. In addition, the high similarity between the C. pacifica NRIC 0813^T and C. marina LMG 2217^T genomes suggests their affiliation to one species. Based on the rules of priority, C. litoralis should be reclassified as a later heterotypic synonym of C. amphilecti, and C. pacifica is a later heterotypic synonym of C. marina. The emended descriptions of the species C. amphilecti and C. marina are also proposed.

Twenty-three bacterial strains were isolated from the secreted mucus trapping net of the marine polychaete Chaetopterus variopedatus (phylum Annelida) and twenty strains were identified using 16S rRNA gene analysis. Strain CB1-14 was recognized as a new species of the genus Vibrio using the eight-gene multilocus sequence analysis (MLSA) and genome sequences of nineteen type Vibrio strains. This Vibrio sp. was cultured, and 6-epi-monanchorin (2), previously isolated from the polychaete and two sponge species, was found in the cells and culture broth. The presence of the 6-epi-monanchorin was confirmed by its isolation followed by ¹H NMR and HRESIMS analysis. These results showed the microbial origin of the bicyclic guanidine alkaloid 2 in C. variopedatus.

Diabetes mellitus is one of the most serious diseases of our century. The drugs used are limited or have serious side effects. The search for new sources of compounds for effective treatment is relevant. Magnificamide, a peptide inhibitor of mammalian α-amylases, isolated from the venom of sea anemone Heteractis magnifica, can be used for the control of postprandial hyperglycemia in diabetes mellitus. Using the RACE approach, seven isoforms of magnificamide were detected in H. magnifica tentacles. The exon–intron structure of magnificamide genes was first established, and intron retention in the mature peptide-encoding region was revealed. Additionally, an α-amylase inhibitory domain was discovered in the mucins of some sea anemones. According to phylogenetics, sea anemones diverge into two groups depending on the presence of β-defensin-like α-amylase inhibitors and/or mucin-inhibitory domains. It is assumed that the intron retention phenomenon leads to additional diversity in the isoforms of inhibitors and allows for its neofunctionalization in sea anemone tentacles. Bioprospecting of sea anemones of the order Actiniaria for β-defensin-like α-amylase inhibitors revealed a diversity of inhibitory sequences that represents a starting point for the design of effective glucose-lowering drugs.