Neoagaro-oligosaccharides (NAOs) belong to the algae oligosaccharides. NAOs have been found to have diverse biological activities. However, the effects of NAOs on depression and their underlying mechanism have not been thoroughly studied. A chronic restraint stress (CRS)-induced C57BL/6J mouse model was used to assess the antidepressant effects of NAOs. Anxiety and depression behaviors were assessed by open field tests (OFT) and forced swimming tests (FST), while interleukin 18 (IL-18), 5-hydroxytryptamine (5-HT) and brain-derived neurotrophic factor (BDNF) were the molecular biomarkers of depression. Fecal microbiota transplantation (FMT) was performed. The results showed that NAO treatment significantly improved the body weight of depressed mice and reduced the central area time in the OFT and immobility time in the FST. NAO treatment decreased the levels of IL-18 in the serum and increased the levels of 5-HT in the serum and whole brain and of BDNF in the whole brain. NAO treatment mitigated the gut microbiota dysbiosis in the depressed mice and reversed the decreased levels of short-chain fatty acids (SCFAs) in the cecum of the depressed mice. FMT indicated that the gut microbiota is, indeed, linked to depression, which was reflected in the changes in weight gain and behaviors. In a word, NAOs effectively reversed the CRS-induced mice model of depression, which depended on the changes in the gut microbiota and SCFAs, as well as its modulation of 5-HT and BDNF.

The elevated NH₃-N and NO₂-N pollution problems in mariculture have raised concerns because they pose threats to animal health and coastal and offshore environments. Supplement of Marichromatium gracile YL28 (YL28) into polluted shrimp rearing water and sediment significantly decreased ammonia and nitrite concentrations, showing that YL28 functioned as a novel safe marine probiotic in the shrimp culture industry. The diversity of aquatic bacteria in the shrimp mariculture ecosystems was studied by sequencing the V4 region of 16S rRNA genes, with respect to additions of YL28 at the low and high concentrations. It was revealed by 16S rRNA sequencing analysis that Proteobacteria, Planctomycete and Bacteroidetes dominated the community (>80% of operational taxonomic units (OTUs)). Up to 41.6% of the predominant bacterial members were placed in the classes Gammaproteobacteria (14%), Deltaproteobacteria (14%), Planctomycetacia (8%) and Alphaproteobacteria (5.6%) while 40% of OTUs belonged to unclassified ones or others, indicating that the considerable bacterial populations were novel in our shrimp mariculture. Bacterial communities were similar between YL28 supplements and control groups (without addition of YL28) revealed by the β-diversity using PCoA, demonstrating that the additions of YL28 did not disturb the microbiota in shrimp mariculture ecosystems. Instead, the addition of YL28 increased the relative abundance of ammonia-oxidizing and denitrifying bacteria. The quantitative PCR analysis further showed that key genes including nifH and amoA involved in nitrification and nitrate or nitrite reduction significantly increased with YL28 supplementation (p < 0.05). The supplement of YL28 decreased the relative abundance of potential pathogen Vibrio. Together, our studies showed that supplement of YL28 improved the water quality by increasing the relative abundance of ammonia-oxidizing and denitrifying bacteria while the microbial community structure persisted in shrimp mariculture ecosystems.

Roughly 25% of abalone viscera generated during processing is currently discarded, resulting in substantial protein wastage and environmental contamination. In the present study, abalone viscera served as the raw material; four commercial proteases—papain, bromelain, neutral protease and trypsin—were comparatively evaluated. Among them, the neutral-protease hydrolysate of abalone viscera (AVZH) exhibited the strongest suppression of nitric oxide (NO) release from lipopolysaccharide (LPS)-stimulated RAW264.7 macrophages. Liquid chromatography with tandem mass spectrometry (LC-MS/MS) analysis ultimately led to the identification of 18 novel peptides. Integrating bioinformatic prediction with solid-phase synthesis, two sequences—GYSFTTTAER and IKKPPQDEWGTGL—were further screened and confirmed to possess excellent cytocompatibility and pronounced anti-inflammatory potency. Mechanistic investigations revealed that both peptides dose-dependently attenuated the secretion and mRNA expression of IL-1β, IL-6 and TNF-α and concurrently blocked mitogen-activated protein kinase (MAPK) signaling by down-regulating the phosphorylation of ERK, JNK and p38. These findings demonstrate that abalone viscera represent an abundant reservoir of anti-inflammatory peptides, offering both a theoretical framework and a technological roadmap for the valorisation of marine waste proteins and the development of next-generation natural anti-inflammatory agents.

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.

Osteoarthritis (OA) is a prevalent chronic joint disease lacking disease-modifying drugs. Animal models with distinct pathogenic mechanisms—monosodium iodoacetate (MIA) for metabolic toxicity and collagenase-induced osteoarthritis (CIOA) for matrix degradation—are essential for therapeutic evaluation. In this study, topical application of neoagarohexaose (NA6) at 5 and 10 mg/kg twice daily was assessed in MIA- and CIOA-induced mouse OA models. NA6 at both doses reduced paw swelling, improved serum oxidative stress markers (catalase (CAT), malondialdehyde (MDA), myeloperoxidase (MPO)), ameliorated cartilage damage and Osteoarthritis Research Society International (OARSI) scores, and decreased inflammatory cell infiltration. Immunohistochemistry showed that NA6 downregulated interleukin-1β (IL-1β) and interleukin-6 (IL-6), upregulated NAD(P)H:quinone oxidoreductase 1 (NQO1), and restored the compensatorily elevated heme oxygenase-1 (HO-1) toward baseline levels. The high-dose NA6 (10 mg/kg) showed comparable or favorable efficacy at the tested doses relative to the positive control diclofenac. These results demonstrate that NA6 exerts anti-inflammatory, antioxidant, and chondroprotective effects in both OA models, supporting its potential as a topical therapeutic candidate for OA symptom management and structural protection.