Zheng Fu

Glycosaminoglycans (GAGs) and their degrading enzymes have extensive applications and biotechnology and medicine, and play a crucial role in the recycling of organic matter in oceans. In this study, a potential GAG utilization gene cluster was identified in the genome of a novel marine Bacteroidetes, Roseihalotalea indica gen. nov. sp. nov. TK19036^T, through sole carbon source cultivation and differential proteomic analysis. Multiple GAG-lyases within this locus were purified and characterized. RiPL8 comprises a functionally unknown N-terminal domain and a catalytic C-terminal domain, exhibiting specificity for degrading hyaluronic acid (HA). The activity of RiPL35 is sensitive to Ca²⁺ ion concentration with an optimum at 10 mM. RiPL38 is the first reported member of the PL38 family capable of degrading HA and chondroitin sulfate (CS). In summary, our study reveals Roseihalotalea indica gen. nov. sp. nov. TK19036^T harbors an unpredicted GAG degradation gene cluster, and the encoded GAG-lyases exhibit distinct substrate specificities compared to the host organism.

Dendrobium polysaccharides (DOPs) have been demonstrated to possess protective activities against UVB-induced skin damage and oxidative stress, but their role in wound healing remains unexplored. This study employed multiple enzymatic hydrolysis methods to prepare Dendrobium polysaccharide hydrolysates and systematically evaluated their wound-healing activity and molecular mechanisms in an in vitro HaCaT keratinocyte model and an in vivo mouse wound model. In vitro results demonstrated that enzymatically extracted DOPs promoted the proliferation and migration of HaCaT keratinocytes, with the composite enzymatic product (D-ceh) exhibiting optimal efficacy. Mechanistic analyses revealed that D-ceh activated the NF-κB signaling pathway and upregulated pro-inflammatory cytokines, thereby enhancing keratinocyte proliferation and migration. In vivo experiments demonstrated that D-ceh considerably enhanced collagen deposition and extracellular matrix remodeling, accelerating wound closure. These findings reveal that enzymatically processed DOPs have potential therapeutic value in accelerated skin wound healing, and the NF-κB signaling pathway plays a pivotal role in its biphasic regulation, promoting inflammation in the early phase and remodeling in the mid-to-late phase, thereby supporting the clinical development prospects of DOPs as natural wound healing promoters.

Alginate, a major polysaccharide in brown algae, is vital for the carbon cycling of the ocean ecosystem and holds promise for biotechnological applications. Marine Bacteroidetes, known for the ability to degrade complex polysaccharides, play an important role in the ocean carbon cycle; however, the detailed alginate degradation pattern remains to be further explored. In this study, an alginate utilization locus was identified in the genome of a new marine Bacteroidetes, Roseihalotalea indica gen. nov. sp. nov. TK19036^T, and encodes two new alginate lyases, RiAlyPL6 and RiAlyPL17, which play potential roles in the degradation and utilization of alginate. RiAlyPL6 and RiAlyPL17 have distinct degradation products and substrate preferences, revealing the adaptation of the strain to utilize alginate with different M/G ratios. Based on the results in this paper, we have proposed a model for the degradation and utilization mechanism of alginate in Roseihalotalea indica gen. nov. sp. nov. TK19036^T. All in all, our research provides a new insight into the alginate mechanisms within marine Roseihalotalea, and the two novel alginate lyases are excellent candidates for preparation and application.