JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2023
·
IF 6.1
Zhibo Hu,Yujiao Zhu,Junjie Chen,Jun Chen,Chunyuan Li,Zhizeng Gao,Jing Li,Lan Liu
The emerging outbreak of bacterial diseases is a major challenge for the aquaculture industry. The development of new antibacterial agents from natural resources to curb fish bacterial diseases in aquaculture is becoming increasingly popular. In this study, eight new benzoic acid-containing alkaloids, asperalin A–F (1–6), asperalumazine A (7), and N-(3-acetamidopropyl)-3,4-dihydroxybenzamide (8), along with four known compounds (9–12) were isolated and identified from a seagrass-derived Aspergillus alabamensis. Their chemical structures were established on the basis of extensive spectroscopic analyses (including HRESIMS, 1D and 2D NMR spectroscopy), NMR computational methods, and electronic circular dichroism (ECD) calculations. Compounds 1–6 exhibited moderate or potent inhibitory activities against at least one fish pathogenic bacterium, among Edwardsiella ictalurid, Streptococcus iniae, and Streptococcus parauberis, and these compounds represent the first report of the coupling of dihydroquinolone alkaloids with benzoic acid derivatives. Compounds 3 and 4 showed strong activities against Staphylococcus aureus, S. iniae, and S. parauberis, with an MIC value of 10.1, 5.0, and 10.1 μM, respectively. Compound 5, an N-alkylated product of 4, exhibited the strongest inhibitory effects against S. iniae, with an MIC value of 2.2 μM. Notably, compound 6, as a new natural bactericide, showed moderate to potent inhibitory activity toward all strains tested, including one Gram-negative bacterium E. ictalurid (10.9 μM, MIC) and four Gram-positive bacteria S. iniae (43.6 μM, MIC), S. aureus (21.8 μM, MIC), S. parauberis (87.3 μM, MIC), and Bacillus subtilis (21.8 μM, MIC). Compound 7 represents the first example of a lumazine derivative directly coupled to a benzoic acid moiety by a hydroxymethyl group.
研究领域:
水产养殖
·
微生物学
·
药物化学
·
天然产物
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY
·
2026
·
IF 6.2
Yiwen Jing,Xiangfan Yu,Lei Liu,Zhenyu Ma,Xukai Jiang,Li Xu,Min Xiao
Hyaluronate lyases are widely used for the degradation of hyaluronic acid (HA) and preparation of HA oligosaccharides. Herein, a putative PL8 hyaluronate lyase SinHL (128.3 kDa) from Streptococcus iniae QMA0131 was expressed in Escherichia coli and biochemically characterized. SinHL is a strictly HA-specific and exolytic hyaluronate lyase that does not degrade CSs and can produce a desired low-molecular-weight HA from high-molecular-weight HA (HMW-HA, 1.52 × 106 Da) under controlled reaction times. The correlation between the 26 residues within the −4 to +2 subsites of the catalytic cleft and enzyme activity was confirmed by alanine-scanning mutagenesis. The carbohydrate-binding module of SinHL facilitated its activity and preference for HMW-HA without alteration of substrate specificity. Molecular dynamics simulations revealed that the narrower catalytic cleft and the smaller cavity adjacent to the catalytic residue Y558 only allowed the glycosidic oxygen O4 of HA to approach Y558, which may determine the substrate specificity for HA of SinHL.
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Biology-Basel
·
2025
·Vol. 14
·期 8
·986
·
IF 3.5
Yanjian Yang,Guanrong Zhang,Ruilong Xu,Yiyang Deng,Zequan Mo,Yanwei Li,Xueming Dan
Simple SummaryStreptococcus iniae(S. iniae) is a major aquaculture pathogen causing significant economic losses. While infections show seasonal patterns tied to water temperature, the mechanisms behind its thermal adaptation remain unclear. This study explored the proteomic changes inS. iniaeat different temperatures and their effects on immune responses in yellowfin seabream (Acanthopagrus latus,A. latus). Results demonstrated that elevated temperatures markedly upregulated bacterial virulence factor expression, resulting in significantly higher host mortality rates. Furthermore, thermal stress enhances the destruction of key immune functions of the host byS. iniae, including immune cell survival, ROS production, and phagocytic activity. These findings provide novel insights into the heat-regulated immune evasion strategies ofS. iniae, offering valuable theoretical foundations for developing temperature-aware disease management protocols in aquaculture systems.Streptococcus iniae(S. iniae) is a globally significant aquatic pathogen responsible for severe economic losses in aquaculture. While theS. iniaeinfection often exhibits distinct seasonal patterns strongly correlated with water temperature, there is limited knowledge regarding the temperature-dependent immune evasion strategies ofS. iniae. Our results demonstrated a striking temperature-dependent virulence phenotype, with significantly higherA. latusmortality rates observed at high temperature (HT, 33 °C) compared to low temperature (LT, 23 °C). Proteomic analysis revealed temperature-dependent upregulation of key virulence factors, including streptolysin S-related proteins (SagG, SagH), antioxidant-related proteins (SodA), and multiple capsular polysaccharide (cps) synthesis proteins (cpsD, cpsH, cpsL, cpsY). Flow cytometry analysis showed that HT infection significantly reduced the percentage of lymphocyte and myeloid cell populations in the head kidney leukocytes ofA. latus, which was associated with elevatedcaspase-3/7expression and increased apoptosis. In addition, HT infection significantly inhibited the release of reactive oxygen species (ROS) but not nitric oxide (NO) production. UsingS. iniaecps-deficient mutant, Δcps, we demonstrated that the cps is essential for temperature-dependent phagocytosis resistance inS. iniae, as phagocytic activity against Δcps remained unchanged across temperatures, while NS-1 showed significantly reduced uptake at HT. These findings provide new insights into the immune evasion ofS. iniaeunder thermal regulation, deepening our understanding of the thermal adaptation of aquatic bacterial pathogens.
研究领域:
微生物学
·
鱼类免疫学
·
分子病理学
·
水产养殖疾病防控
·
宿主-病原体相互作用
·
环境微生物适应
·
蛋白质组学
·
先天免疫
✓ 已验证
产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）