Acid, alkali, heat-shock, KNO3 and control pretreatment methods applied to anaerobic sludge were evaluated for their ability to selectively enrich the marine hydrogen-producing mixed microflora. Sea-water culture medi...Acid, alkali, heat-shock, KNO3 and control pretreatment methods applied to anaerobic sludge were evaluated for their ability to selectively enrich the marine hydrogen-producing mixed microflora. Sea-water culture medium was used as the substrate. The hydrogen yield of pretreated microflora was higher than that of the un-pretreated control (P < 0.05). Among the pretreatment methods studied, heat-shock pretreatment yielded the greatest hydrogen production, which was 14.6 times that of the control. When the effect of initial pH on hydrogen production of heat-shock pretreated samples was studied, hydrogen was produced over the entire pH range (pH 4 - 10). The hydrogen yield peaked at initial pH 8 (79 mL/g sucrose) and then steadily decreased as the initial pH increased. Sucrose con-sumption was high at neutral initial pH. During the process of hydrogen production, pH decreased gradually, which indicated that the acquired microflora consisted of acidogenic bacteria.展开更多
Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin,and extracellular serine...Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin,and extracellular serine protease(i.e.,aerA,hlyA,and ahpA,respectively).These genes were investigated using polymerase chain reaction(PCR)with specific primers for each gene.And the pathogenicities to Carrassius auratus ibebio of these strains were also assayed.PCR results demonstrated that the distribution patterns of aerA,hlyA,and ahpA were different in these strains.6/9 of A.hydrophila strains were aerA positive,8/9 of strains hlyA positive,7/9 of strains ahpA positive,respective-ly.However,the assay for pathogenesis showed that two strains(A.hydrophila XS91-4-1 and C2)were strong virulent,two strains(A.hydrophila ST78-3-3 and 58-20-9)avirulent and the rest middle virulent was to the fish.In conclusion,there are significant correlation between the distribution pattern of the three virulence genes and the patho-genicity to Carrassius auratus ibebio.All strong virulent A.hydrophila strains were aerA+hlyA+ahpA+genotype,and all aerA+hlyA+ahpA+strains were virulent.Strains with the genotype of aerA−hlyA−ahpA+have middle pathogenicity.In the present study,we found for the first time that all A.hydrophila isolated from the ahpA positive were virulent to Carrassius auratus ibebio.Additionally,there was a positive correlation between the virulence of A.hydrophila and the presence of aerA and ahpA.展开更多
基金Supported by the National High Technology Research and Development Program of China (Grant No. 2006AA05Z112)
文摘Acid, alkali, heat-shock, KNO3 and control pretreatment methods applied to anaerobic sludge were evaluated for their ability to selectively enrich the marine hydrogen-producing mixed microflora. Sea-water culture medium was used as the substrate. The hydrogen yield of pretreated microflora was higher than that of the un-pretreated control (P < 0.05). Among the pretreatment methods studied, heat-shock pretreatment yielded the greatest hydrogen production, which was 14.6 times that of the control. When the effect of initial pH on hydrogen production of heat-shock pretreated samples was studied, hydrogen was produced over the entire pH range (pH 4 - 10). The hydrogen yield peaked at initial pH 8 (79 mL/g sucrose) and then steadily decreased as the initial pH increased. Sucrose con-sumption was high at neutral initial pH. During the process of hydrogen production, pH decreased gradually, which indicated that the acquired microflora consisted of acidogenic bacteria.
基金This work was supported by the Science Innovation Project of Institute of Hydrobiology,Chinese Academy of Sciences(No.220317).
文摘Nine strains of Aeromonas hydrophila isolated from diseased fish or soft-shelled tortoise were tested for the presence of three virulence genes including the genes encoding aerolysin,hemolysin,and extracellular serine protease(i.e.,aerA,hlyA,and ahpA,respectively).These genes were investigated using polymerase chain reaction(PCR)with specific primers for each gene.And the pathogenicities to Carrassius auratus ibebio of these strains were also assayed.PCR results demonstrated that the distribution patterns of aerA,hlyA,and ahpA were different in these strains.6/9 of A.hydrophila strains were aerA positive,8/9 of strains hlyA positive,7/9 of strains ahpA positive,respective-ly.However,the assay for pathogenesis showed that two strains(A.hydrophila XS91-4-1 and C2)were strong virulent,two strains(A.hydrophila ST78-3-3 and 58-20-9)avirulent and the rest middle virulent was to the fish.In conclusion,there are significant correlation between the distribution pattern of the three virulence genes and the patho-genicity to Carrassius auratus ibebio.All strong virulent A.hydrophila strains were aerA+hlyA+ahpA+genotype,and all aerA+hlyA+ahpA+strains were virulent.Strains with the genotype of aerA−hlyA−ahpA+have middle pathogenicity.In the present study,we found for the first time that all A.hydrophila isolated from the ahpA positive were virulent to Carrassius auratus ibebio.Additionally,there was a positive correlation between the virulence of A.hydrophila and the presence of aerA and ahpA.
