Saccharopolyspora sp. NFXS83 in Marine Biotechnological Applications: From Microalgae Growth Promotion to the Production of Secondary Metabolites.

Marine bacteria are a significant source of bioactive compounds for various biotechnological applications. Among these, actinomycetes have been found to produce a wide range of secondary metabolites of interest. Saccharopolyspora is one of the genera of actinomycetes that has been recognized as a potential source of these compounds. This study reports the characterization and genomic analysis of Saccharopolyspora sp. NFXS83, a marine bacterium isolated from seawater from the Sado estuary in Portugal. The NFXS83 strain produced multiple functional and stable extracellular enzymes under high-salt conditions, showed the ability to synthesize auxins such as indole-3-acetic acid, and produced diffusible secondary metabolites capable of inhibiting the growth of Staphylococcus aureus. Furthermore, when Phaeodactylum tricornutum was co-cultivated with strain NFXS83 a significant increase in microalgae cell count, cell size, auto-fluorescence, and fucoxanthin content was observed. Detailed analysis revealed the presence of clusters involved in the production of various secondary metabolites, including extracellular enzymes, antimicrobial compounds, terpenes, and carotenoids in the genome of strain NFXS83. Ultimately, these findings indicate that Saccharopolyspora sp. NFXS83 has a significant potential for a wide range of marine biotechnological applications.

Phylogenomic and comparative analyses support the reclassification of several Komagataeibacter species as novel members of the Novacetimonas gen. nov. and bring new insights into the evolution of cellulose synthase genes.

The genus Komagataeibacter harbours bacteria presenting the ability to produce increased levels of crystalline nanocellulose, as well as strains used in the industrial production of fermented products and beverages. Still, most of the studies of this biotechnologically relevant genus were conducted based on limited phenotypic methodologies and taxonomical classifications. In this work, a detailed analysis of the currently described genus Komagataeibacter was conducted based on phylogenomic analysis, unveiling the phylogenomic relationships within the genus and allowing a detailed phylogenetic analysis of biotechnologically important genes such as those involved in cellulose biosynthesis (bcs genes). Phylogenomic and comparative genomic analysis revealed that several type strains formed an independent genomic group from those of other Komagataeibacter, prompting their reclassification as members of a novel genus, hereby termed Novacetimonas gen. nov. The results support the reclassification of Komagataeibacter hansenii, Komagataeibacter cocois, Komagataeibacter maltaceti and Komagataeibacter pomaceti as novel members of the genus Novacetimonas. The Novacetimonas hansenii species is the proposed representative of the novel genus. Importantly, phylogenetic analysis based on cellulose biosynthesis genes (bcsABCD, bcsAB2XYC2, bcsAB3C3, bcsAB4), showed that the evolutionary history of these genes is closely related to the strain's phylogenomic/taxonomic classification. Hence, the robust taxonomic classification of these bacteria will allow the better characterization and selection of strains for biotechnological applications.

Functional and genomic characterization of Komagataeibacter uvaceti FXV3, a multiple stress resistant bacterium producing increased levels of cellulose.

Bacterial cellulose is one of the most promising biomaterials for the development of a wide array of novel biotechnological solutions. Nevertheless, the commercial production of bacterial cellulose is still a challenge and obtaining novel strains presenting increased cellulose biosynthesis and stress resistance properties is of extreme importance. This work demonstrates the increased stress resistance, cellulose production abilities, and overall genomic properties of Komagataeibacter uvaceti FXV3, a novel cellulose-producing and stress resistant strain isolated from a fermented grape must. K. uvaceti FXV3 was able to grow under several stress conditions, including the presence of high concentrations of ethanol (up to 7.5 % v/v), a trait that is not observed in the model strain K. xylinus CECT 7351T. Moreover, K. uvaceti FXV3 produced increased concentrations of cellulose (4.31 mg/mL, 7 days after inoculation-DAI) when compared to K. xylinus CECT 7351T (1.42 mg/mL, 7 DAI). Moreover, the detailed analysis of strain FXV3 genome revealed the presence of several genes involved in cellulose and acetan biosynthesis, quorum-sensing and quenching mechanisms, carbohydrate, amino acid, alcohol and aldehyde metabolism, as well as several other genes involved in stress resistance. Additionally, comparative genomic analysis revealed the increased prevalence of stress resistance genes in K. uvaceti FXV3 when compared to K. xylinus CECT 7351T. Ultimately, this study reveals the increased biotechnological potential of K. uvaceti FXV3 and brings new insights into the genetics behind Komagataeibacter stress resistance and cellulose production abilities.