A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting ...A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting toilet by setting post-treatment conditions. The kinetics inactivation of MS2 bacteriophage, selected as indicator for pathogenic viruses were determined during post-treatment at different temperatures (30°C, 40°C and 50°C) with varying moisture contents (50%, 60% and 70%). As a result, the inactivation rates during the post-treatment were 0.093 - 0.020 h-1, 0.025 - 0.088 h1, 0.447 - 0.100 h-1 at 30°C, 40°C and 50°C respectively. The inactivation rate coefficient (k) values of MS2 bacteriophage depended on higher temperature but not on moisture content.展开更多
【目的】为了研究噬菌体整合酶基因在猪链球菌2型(Streptococcus suis type 2,SS2)中的分布情况。【方法】根据噬菌体整合酶基因设计引物,建立了PCR方法,并对扩增产物进行测序。【结果】结果显示,25株SS2致病菌株均扩增出目的片段,非毒...【目的】为了研究噬菌体整合酶基因在猪链球菌2型(Streptococcus suis type 2,SS2)中的分布情况。【方法】根据噬菌体整合酶基因设计引物,建立了PCR方法,并对扩增产物进行测序。【结果】结果显示,25株SS2致病菌株均扩增出目的片段,非毒力株T15、5株其它血清型猪链球菌及兰氏C群猪源链球菌未扩增出目的片段。经丝裂霉素C诱导后,SS2致病菌株出现完全的细胞溶解,而非毒力株T15未出现溶解。SS2致病株HA9801和ZY05719诱导均产生溶原性噬菌体,分别命名为SS2-HA和SS2-ZY,电镜观察,二者均头部呈正六边形,无尾部,其核酸类型为dsDNA,可鉴定为复层噬菌体科(Tectiviridae)的成员。噬菌体SS2-HA和SS2-ZY整合酶基因序列与已报道的SS2噬菌体整合酶基因序列高度同源,显示SS2噬菌体整合酶具有较高的特异性。【结论】从SS2致病株中检出溶原性噬菌体和噬菌体整合酶基因,且噬菌体整合酶基因与SS2溶菌酶释放蛋白(mrp)等7种毒力相关基因有相关性,表明SS2的溶原性噬菌体可能与其致病性有关。展开更多
Pathogenic viruses in drinking water are great threats to public health. Visible-lightdriven photocatalysis is a promising technology for virus inactivation. However, the existing photocatalytic antiviral research stu...Pathogenic viruses in drinking water are great threats to public health. Visible-lightdriven photocatalysis is a promising technology for virus inactivation. However, the existing photocatalytic antiviral research studies have mostly been carried out in single-component systems, neglecting the effect of natural organic matter, which exists widely in actual water bodies. In this paper, electrospun Cu-TiO2 nanofibers were prepared as photocatalysts, and their photocatalytic antiviral performance in the presence of humic acid(HA) was comprehensively studied for the first time. The properties of the reaction mixture were measured during the reaction. In addition, the safety, reliability and stability of photocatalytic disinfection in the mixed system were evaluated. The results showed that the virus removal efficiency decreased with the increase of the HA concentration. The type of reaction solution, such as PBS buffer solution or water, did not affect the removal efficiency noticeably. Under acidic conditions, the electrostatic forces between photocatalysts and viruses were strengthened, leading to higher virus removal efficiency. As the reaction time went on, the pH value in the solution increased first and then tended to be stable, the conductivity remained stable, and the dissolved oxygen increased first and then decreased. The safety test showed that the concentration of Cu ions released into the solution was lower than specified by the international standards. No photoreactivation was observed, and the addition of HA significantly reduced the reutilization efficiency of the photocatalysts.展开更多
Bivalve molluscan shellfish such as oysters are important vectors for the transmission of foodborne pathogens including both viruses and bacteria.Photoinactivation provides a cold-sterilization option against the cont...Bivalve molluscan shellfish such as oysters are important vectors for the transmission of foodborne pathogens including both viruses and bacteria.Photoinactivation provides a cold-sterilization option against the contamination as excited photosensitizers could transfer electronic energy to oxygen molecules producing reactive oxygen species such as singlet oxygen,leading to oxidative damage and death of the pathogens.However,the efficacy of photoinactivation is very often compromised by the presence of food matrix due to the nonselective reactions of short-lived singlet oxygen with organic matter other than the target pathogens.In order to address this issue,we encapsulated a food-grade photosensitizer rose bengal(RB)in alginate microbeads.An extra coating of chitosan effectively prevented the release of RB from the microbeads in seawater,and more importantly,enhanced the selectivity of the photoinactivation via the electrostatic interactions between cationic chitosan and anionic charge of the virus particles(bacteriophage MS2 and Tulane virus)and the Gram-negative bacteria Vibrio parahaemolyticus(V parahaemolyticus).The treatment of oysters with microencapsulated RB resulted in significantly higher reductions of MS2 phage,Tulane virus and V parahaemolyticus than free RB and non-RB carrying microbeads(P<0.05)tested with both in vitro and in vivo experimental set-ups.This study demonstrated a new strategy in delivering comprehensively formulated biochemical sanitizers in bivalve shellfish through their natural filter-feeding activity and thereby enhancing the mitigation efficiency of foodborne pathogen contamination.展开更多
文摘A rural model composting toilet system still had some pathogens in the compost after months of operation and hence requires a post-treatment. The aim of the study was to sanitize compost withdrawn from the composting toilet by setting post-treatment conditions. The kinetics inactivation of MS2 bacteriophage, selected as indicator for pathogenic viruses were determined during post-treatment at different temperatures (30°C, 40°C and 50°C) with varying moisture contents (50%, 60% and 70%). As a result, the inactivation rates during the post-treatment were 0.093 - 0.020 h-1, 0.025 - 0.088 h1, 0.447 - 0.100 h-1 at 30°C, 40°C and 50°C respectively. The inactivation rate coefficient (k) values of MS2 bacteriophage depended on higher temperature but not on moisture content.
文摘【目的】为了研究噬菌体整合酶基因在猪链球菌2型(Streptococcus suis type 2,SS2)中的分布情况。【方法】根据噬菌体整合酶基因设计引物,建立了PCR方法,并对扩增产物进行测序。【结果】结果显示,25株SS2致病菌株均扩增出目的片段,非毒力株T15、5株其它血清型猪链球菌及兰氏C群猪源链球菌未扩增出目的片段。经丝裂霉素C诱导后,SS2致病菌株出现完全的细胞溶解,而非毒力株T15未出现溶解。SS2致病株HA9801和ZY05719诱导均产生溶原性噬菌体,分别命名为SS2-HA和SS2-ZY,电镜观察,二者均头部呈正六边形,无尾部,其核酸类型为dsDNA,可鉴定为复层噬菌体科(Tectiviridae)的成员。噬菌体SS2-HA和SS2-ZY整合酶基因序列与已报道的SS2噬菌体整合酶基因序列高度同源,显示SS2噬菌体整合酶具有较高的特异性。【结论】从SS2致病株中检出溶原性噬菌体和噬菌体整合酶基因,且噬菌体整合酶基因与SS2溶菌酶释放蛋白(mrp)等7种毒力相关基因有相关性,表明SS2的溶原性噬菌体可能与其致病性有关。
基金supported by grants from the National Natural Science Foundation of China(Nos.51778618,51478460)
文摘Pathogenic viruses in drinking water are great threats to public health. Visible-lightdriven photocatalysis is a promising technology for virus inactivation. However, the existing photocatalytic antiviral research studies have mostly been carried out in single-component systems, neglecting the effect of natural organic matter, which exists widely in actual water bodies. In this paper, electrospun Cu-TiO2 nanofibers were prepared as photocatalysts, and their photocatalytic antiviral performance in the presence of humic acid(HA) was comprehensively studied for the first time. The properties of the reaction mixture were measured during the reaction. In addition, the safety, reliability and stability of photocatalytic disinfection in the mixed system were evaluated. The results showed that the virus removal efficiency decreased with the increase of the HA concentration. The type of reaction solution, such as PBS buffer solution or water, did not affect the removal efficiency noticeably. Under acidic conditions, the electrostatic forces between photocatalysts and viruses were strengthened, leading to higher virus removal efficiency. As the reaction time went on, the pH value in the solution increased first and then tended to be stable, the conductivity remained stable, and the dissolved oxygen increased first and then decreased. The safety test showed that the concentration of Cu ions released into the solution was lower than specified by the international standards. No photoreactivation was observed, and the addition of HA significantly reduced the reutilization efficiency of the photocatalysts.
基金supported by the Ministry of Education (MOE)academic research fund (AcRF)TIER 1 Project and the‘Study of important foodborne viruses from relevant foods in Singapore' (R-160-000-A79-114),Singapore。
文摘Bivalve molluscan shellfish such as oysters are important vectors for the transmission of foodborne pathogens including both viruses and bacteria.Photoinactivation provides a cold-sterilization option against the contamination as excited photosensitizers could transfer electronic energy to oxygen molecules producing reactive oxygen species such as singlet oxygen,leading to oxidative damage and death of the pathogens.However,the efficacy of photoinactivation is very often compromised by the presence of food matrix due to the nonselective reactions of short-lived singlet oxygen with organic matter other than the target pathogens.In order to address this issue,we encapsulated a food-grade photosensitizer rose bengal(RB)in alginate microbeads.An extra coating of chitosan effectively prevented the release of RB from the microbeads in seawater,and more importantly,enhanced the selectivity of the photoinactivation via the electrostatic interactions between cationic chitosan and anionic charge of the virus particles(bacteriophage MS2 and Tulane virus)and the Gram-negative bacteria Vibrio parahaemolyticus(V parahaemolyticus).The treatment of oysters with microencapsulated RB resulted in significantly higher reductions of MS2 phage,Tulane virus and V parahaemolyticus than free RB and non-RB carrying microbeads(P<0.05)tested with both in vitro and in vivo experimental set-ups.This study demonstrated a new strategy in delivering comprehensively formulated biochemical sanitizers in bivalve shellfish through their natural filter-feeding activity and thereby enhancing the mitigation efficiency of foodborne pathogen contamination.
