In this study, the antibacterial effects of Chinese herbal medicines against Streptococcus iniae in Oreochromis niloticus were investigated by drug sensitiv- ity test. The results indicated that Streptococcus in/ae wa...In this study, the antibacterial effects of Chinese herbal medicines against Streptococcus iniae in Oreochromis niloticus were investigated by drug sensitiv- ity test. The results indicated that Streptococcus in/ae was extremely sensitive to Calla Chinensis, Fructus Hippophae and Fructus Murne, highly sensitive to Sappan Lignum, Pericarpium Granati, Folium Eucalypti and Radix Scutellariae, moderately sensitive to Rh/zoma Coptidis, Radix et Rhizoma Rhei, Flos Caryophyllata, Cortex phellodendri and Rabdosia serra （ Maxim. ） Hara, and insensitive to Herba Portulacae , Herba Houttuyniae , Polygonum hydropiper L. , Herba Menthae , Radix Glycyrrhizae , Pericarpium Citri Reticulatae , Herba Andrographitis and Rhizoma Acori Tatarinowii. Chinese medicinal herbs which Streptococcus iniae was extremely sensitive or moderately sensitive to were selected and prepared into three Chinese herbal medicine formulae for medicated bath of Oreochromis niloticus infected arti- ficially with Streptococcus iniae. The results showed that medicated bath elicited therapeutic effects on infected Oreochromis niloticus. Formula II exhibited the best therapeutic effect with an effective percentage of 90%.展开更多
From the ethyl acetate extract of Murraya koenegii (Rutaceae) leaves, isomahanine (1) and mahanine (2) were isolated that showed antibacterial activity towards Flavobacterium columnare and Streptococcus iniae which ca...From the ethyl acetate extract of Murraya koenegii (Rutaceae) leaves, isomahanine (1) and mahanine (2) were isolated that showed antibacterial activity towards Flavobacterium columnare and Streptococcus iniae which caused columnaris disease and streptococcosis respectively. Isomahanine was found to have the strongest activity against F. columnare (isolate ALM-00-173) and S. iniae (isolate LA94-426) based on 24-h 50% inhibition concentration (IC50) and minimum inhibition concentration (MIC). Although compound (7), a nicotinamide isolated from Amyris texana had the lowest MIC (2.8 ± 0 mg/L) of any of the test compounds against F. columnare, the 24-h IC50 of 14.8 ± 0.6 mg/L was higher than that of isomahanine and subsequently the 24-h IC50 RDC values for (7) were almost a magnitude of order higher than those obtained for isomahanine. Isomahanine also had the strongest activity against S. iniae, with a 24-h IC50 of 1.3 ± 0.1 mg/L and MIC of 3.5 ± 0 mg/L, respectively.展开更多
A pathogenic bacterium （S636）, identified as Streptococcus iniae, was isolated from turbot （Scophthalrnus maximus） in 2005. We immunized turbot with formalin-killed S. iniae four times （on days 1, 14, 21, and 28...A pathogenic bacterium （S636）, identified as Streptococcus iniae, was isolated from turbot （Scophthalrnus maximus） in 2005. We immunized turbot with formalin-killed S. iniae four times （on days 1, 14, 21, and 28） by intraperitoneal inoculation. After each vaccination, we obtained serum samples and isolated the lymphocytes from the peripheral blood, spleen, pronephros, and mesonephros. We measured surface Ig-positive （sIg＋） lymphocytes and serum antibody levels from these organs using flow cytometry and enzyme-linked immunosorbent assay （ELISA）, respectively, using monoclonal antibodies against turbot immunoglohulin. We confirmed that the antibody reacted with both the surface and plasma Ig by confocal laser scanning microscopy and electron microscopy. The percentage of sIg＋ in the lymphocytes increased following each successive vaccination. The mean percentage increased from 31.96% （control） to 37.49%, 38.36%, 42.9%, and 51.63% in the peripheral blood; from 27.09% to 36.63%, 36.81%, 39.28%, and 46.0% in the spleen; from 22.2% to 28.99%, 29.21%, 32.83%, and 41.58% in pronephros; and from 18.12% to 22.17%, 22.45%, 25.69%, and 31.68% in the mesonephros. The ELISA results were consistent with these results. Both the total and specific antibody levels increased with each vaccination. The mean OD value of the specific antibody assay increased from 0.094, to 0.269, 0.283, 0.333, and 0.421; for total antibody the mean OD value increased from 0.133, to 0.292, 0.323, 0.413, and 0.527.展开更多
Streptococcus iniae (S. iniae) is a major pathogen that is capable of resulting severe economic loss to cultured fish. Steadily iron availability from micro-environment is an important virulence factor for pathogens, ...Streptococcus iniae (S. iniae) is a major pathogen that is capable of resulting severe economic loss to cultured fish. Steadily iron availability from micro-environment is an important virulence factor for pathogens, and S. iniae encodes the iron-transporter MtsABC to accomplish heme utilization, but very little was known about the mechanisms involved in regulating and maintaining iron balance in S. iniae. In this study, the role of a putative iron-dependent transcriptional regulator MtsR was investigated, and the results showed that MtsR regulated the expression of iron-transport mtsABC to control iron homeostasis in S. iniae.展开更多
[Objectives] This study aimed to analyze the biological activity and immunogenicity of extracellular products from Streptococcus iniae .[Methods] S. iniae was incubated with brain heart infusion agar medium （BHIA ＋ ...[Objectives] This study aimed to analyze the biological activity and immunogenicity of extracellular products from Streptococcus iniae .[Methods] S. iniae was incubated with brain heart infusion agar medium （BHIA ＋ 4% calf serum） for 60 h. The bacterial liquid was rinsed with PBS, centrifuged, and filtered through microporous filtering film to collect extracellular products （ECPs）.[Results] Extracellular proteinase （ECPase） of S. iniae exhibited amylase, protease, lecitinase, gelatinase, lipase activities and hemolytic activity but had no urease activity. EDTA, DTT and PMSF could reduce ECPase activity to 72.4%, 77.6% and 72.4%, respectively. Cu^2＋ , Ca 2＋ , K^＋ and Mg^2＋ exhibited an inhibitory effect on ECPase activity, whereas Fe^3＋ , Co^2＋ and Mn^2＋ could activate ECPase activity. ECPs had good heat stability and exhibited relatively high activities under alkaline conditions. The optimal temperature for ECPs was 55 ℃. Two-dimensional electrophoresis was performed to analyze the main protein of ECPs. The results indicated that there are 12 main bands of ECPs, and the molecular weights mainly ranged between 28-68 kDa. About 120 protein spots were detected, and the molecular weights mainly ranged between 26-95 kDa. The mouse anti- S. iniae was used for Western-blot analysis of ECPs, and the results showed that there were four proteins, with molecular weights of 26, 37, 95, and 97 kDa, respectively. The pathogenicity assay indicated that ECPs of S. iniae were highly pathogenic to tilapia. The mortality rate of tilapia was enhanced as the concentration of ECPs increased.[Conclusions] This study provided a certain theoretical basis for revealing the pathogenic mechanism of Streptococcus iniae .展开更多
目的:从艾叶中筛选出一种抗无乳链球菌和海豚链球菌的提取物并探究其体外抗菌活性及机制。方法:通过琼脂平板扩散法筛选出体外抗菌效果优良的艾叶提取物,随后测定其对无乳链球菌和海豚链球菌的最低抑菌浓度,通过观测提取物处理后细菌生...目的:从艾叶中筛选出一种抗无乳链球菌和海豚链球菌的提取物并探究其体外抗菌活性及机制。方法:通过琼脂平板扩散法筛选出体外抗菌效果优良的艾叶提取物,随后测定其对无乳链球菌和海豚链球菌的最低抑菌浓度,通过观测提取物处理后细菌生物被膜的形成、表面疏水性、相对电导率及菌体结构来探究其抗菌机制。结果:筛选出的抗菌效果良好的艾叶提取物为艾叶水提取物(Artemisia argyi water extract,AWE),其可通过抑制菌体生物被膜的形成、降低细菌表面疏水率、升高相对电导率而使细胞膜通透性增加,进而破坏细菌细胞膜和菌体结构。结论:AWE为抗菌效果优良的艾叶水提取物,具有作为无乳链球菌和海豚链球菌的天然抗菌剂的潜力。展开更多
基金Supported by Post-award Grant Program from the Department of Science and Technology of Hebei Province(15926620H)Science and Technology Support Program of Qinhuangdao Municipal Science and Technology Bureau(201401A067201402B043)
文摘In this study, the antibacterial effects of Chinese herbal medicines against Streptococcus iniae in Oreochromis niloticus were investigated by drug sensitiv- ity test. The results indicated that Streptococcus in/ae was extremely sensitive to Calla Chinensis, Fructus Hippophae and Fructus Murne, highly sensitive to Sappan Lignum, Pericarpium Granati, Folium Eucalypti and Radix Scutellariae, moderately sensitive to Rh/zoma Coptidis, Radix et Rhizoma Rhei, Flos Caryophyllata, Cortex phellodendri and Rabdosia serra （ Maxim. ） Hara, and insensitive to Herba Portulacae , Herba Houttuyniae , Polygonum hydropiper L. , Herba Menthae , Radix Glycyrrhizae , Pericarpium Citri Reticulatae , Herba Andrographitis and Rhizoma Acori Tatarinowii. Chinese medicinal herbs which Streptococcus iniae was extremely sensitive or moderately sensitive to were selected and prepared into three Chinese herbal medicine formulae for medicated bath of Oreochromis niloticus infected arti- ficially with Streptococcus iniae. The results showed that medicated bath elicited therapeutic effects on infected Oreochromis niloticus. Formula II exhibited the best therapeutic effect with an effective percentage of 90%.
文摘From the ethyl acetate extract of Murraya koenegii (Rutaceae) leaves, isomahanine (1) and mahanine (2) were isolated that showed antibacterial activity towards Flavobacterium columnare and Streptococcus iniae which caused columnaris disease and streptococcosis respectively. Isomahanine was found to have the strongest activity against F. columnare (isolate ALM-00-173) and S. iniae (isolate LA94-426) based on 24-h 50% inhibition concentration (IC50) and minimum inhibition concentration (MIC). Although compound (7), a nicotinamide isolated from Amyris texana had the lowest MIC (2.8 ± 0 mg/L) of any of the test compounds against F. columnare, the 24-h IC50 of 14.8 ± 0.6 mg/L was higher than that of isomahanine and subsequently the 24-h IC50 RDC values for (7) were almost a magnitude of order higher than those obtained for isomahanine. Isomahanine also had the strongest activity against S. iniae, with a 24-h IC50 of 1.3 ± 0.1 mg/L and MIC of 3.5 ± 0 mg/L, respectively.
基金Supported by the National Basic Research Program of China (973 Program, No 2006CB101806)the High Technology Research and Development Program of China (863 Program,No 2006AA100306)the National Natural Science Fundation of China (No 30771648)
文摘A pathogenic bacterium （S636）, identified as Streptococcus iniae, was isolated from turbot （Scophthalrnus maximus） in 2005. We immunized turbot with formalin-killed S. iniae four times （on days 1, 14, 21, and 28） by intraperitoneal inoculation. After each vaccination, we obtained serum samples and isolated the lymphocytes from the peripheral blood, spleen, pronephros, and mesonephros. We measured surface Ig-positive （sIg＋） lymphocytes and serum antibody levels from these organs using flow cytometry and enzyme-linked immunosorbent assay （ELISA）, respectively, using monoclonal antibodies against turbot immunoglohulin. We confirmed that the antibody reacted with both the surface and plasma Ig by confocal laser scanning microscopy and electron microscopy. The percentage of sIg＋ in the lymphocytes increased following each successive vaccination. The mean percentage increased from 31.96% （control） to 37.49%, 38.36%, 42.9%, and 51.63% in the peripheral blood; from 27.09% to 36.63%, 36.81%, 39.28%, and 46.0% in the spleen; from 22.2% to 28.99%, 29.21%, 32.83%, and 41.58% in pronephros; and from 18.12% to 22.17%, 22.45%, 25.69%, and 31.68% in the mesonephros. The ELISA results were consistent with these results. Both the total and specific antibody levels increased with each vaccination. The mean OD value of the specific antibody assay increased from 0.094, to 0.269, 0.283, 0.333, and 0.421; for total antibody the mean OD value increased from 0.133, to 0.292, 0.323, 0.413, and 0.527.
文摘Streptococcus iniae (S. iniae) is a major pathogen that is capable of resulting severe economic loss to cultured fish. Steadily iron availability from micro-environment is an important virulence factor for pathogens, and S. iniae encodes the iron-transporter MtsABC to accomplish heme utilization, but very little was known about the mechanisms involved in regulating and maintaining iron balance in S. iniae. In this study, the role of a putative iron-dependent transcriptional regulator MtsR was investigated, and the results showed that MtsR regulated the expression of iron-transport mtsABC to control iron homeostasis in S. iniae.
基金Supported by Natural Science Foundation of Guangdong Province(2017A030313174)Natural Science Foundation of Guangdong Ocean University(C17379)+2 种基金Undergraduate Innovative and Entrepreneurial Team Project(CCTD201802)Science and Technology Program of Guangdong Province(2015A020209163)Special Fund for Construction of Fishery Port and Development of Fishery Industry of Guangdong Province(A201708A05)
文摘[Objectives] This study aimed to analyze the biological activity and immunogenicity of extracellular products from Streptococcus iniae .[Methods] S. iniae was incubated with brain heart infusion agar medium （BHIA ＋ 4% calf serum） for 60 h. The bacterial liquid was rinsed with PBS, centrifuged, and filtered through microporous filtering film to collect extracellular products （ECPs）.[Results] Extracellular proteinase （ECPase） of S. iniae exhibited amylase, protease, lecitinase, gelatinase, lipase activities and hemolytic activity but had no urease activity. EDTA, DTT and PMSF could reduce ECPase activity to 72.4%, 77.6% and 72.4%, respectively. Cu^2＋ , Ca 2＋ , K^＋ and Mg^2＋ exhibited an inhibitory effect on ECPase activity, whereas Fe^3＋ , Co^2＋ and Mn^2＋ could activate ECPase activity. ECPs had good heat stability and exhibited relatively high activities under alkaline conditions. The optimal temperature for ECPs was 55 ℃. Two-dimensional electrophoresis was performed to analyze the main protein of ECPs. The results indicated that there are 12 main bands of ECPs, and the molecular weights mainly ranged between 28-68 kDa. About 120 protein spots were detected, and the molecular weights mainly ranged between 26-95 kDa. The mouse anti- S. iniae was used for Western-blot analysis of ECPs, and the results showed that there were four proteins, with molecular weights of 26, 37, 95, and 97 kDa, respectively. The pathogenicity assay indicated that ECPs of S. iniae were highly pathogenic to tilapia. The mortality rate of tilapia was enhanced as the concentration of ECPs increased.[Conclusions] This study provided a certain theoretical basis for revealing the pathogenic mechanism of Streptococcus iniae .
文摘目的:从艾叶中筛选出一种抗无乳链球菌和海豚链球菌的提取物并探究其体外抗菌活性及机制。方法:通过琼脂平板扩散法筛选出体外抗菌效果优良的艾叶提取物,随后测定其对无乳链球菌和海豚链球菌的最低抑菌浓度,通过观测提取物处理后细菌生物被膜的形成、表面疏水性、相对电导率及菌体结构来探究其抗菌机制。结果:筛选出的抗菌效果良好的艾叶提取物为艾叶水提取物(Artemisia argyi water extract,AWE),其可通过抑制菌体生物被膜的形成、降低细菌表面疏水率、升高相对电导率而使细胞膜通透性增加,进而破坏细菌细胞膜和菌体结构。结论:AWE为抗菌效果优良的艾叶水提取物,具有作为无乳链球菌和海豚链球菌的天然抗菌剂的潜力。
