从大豆土壤中分离纯化得到一株具有卵磷脂和乐果降解能力的菌株Yj1,对该菌株进行鉴定、生长条件优化、酶活性鉴定以及有机磷降解酶的分离纯化。结果表明,Yj1与Serratia marcescens WW4(CP003959.1)的16S r DNA相似度为99%。正交试验对...从大豆土壤中分离纯化得到一株具有卵磷脂和乐果降解能力的菌株Yj1,对该菌株进行鉴定、生长条件优化、酶活性鉴定以及有机磷降解酶的分离纯化。结果表明,Yj1与Serratia marcescens WW4(CP003959.1)的16S r DNA相似度为99%。正交试验对所需培养基进行优化,得到该菌株的最佳生长条件为甘露糖、蛋白胨和p H 8的组合。Yj1菌株在两种磷源条件下,菌株生长量均很低,但72 h内以大豆卵磷脂为磷源时的菌体生长情况优于乐果。以大豆卵磷脂为磷源时酸性磷酸酶、碱性磷酸酶与有机磷降解酶活性明显高于以乐果为磷源时的酶活,且72 h内碱性磷酸酶活性一直都高于酸性磷酸酶和有机磷降解酶。硫酸铵沉淀法结合阳离子交换层析成功从Yj1菌体中分离纯化了有机磷降解酶,SDS-PAGE结果显示纯化的蛋白为单一条带。且阳离子交换层析的提纯倍数是硫酸氨沉淀的5.303倍,硫酸氨沉淀为粗酶的1.416倍。展开更多
A total of 479 bacterial strains were isolated from brine （Bohai, Qinhuangdao City, Hebei Province, China）. Bioassay results indicated that 4 strains named Hal, Hal7, Ha38, and Ha384 had herbicidal activity. And str...A total of 479 bacterial strains were isolated from brine （Bohai, Qinhuangdao City, Hebei Province, China）. Bioassay results indicated that 4 strains named Hal, Hal7, Ha38, and Ha384 had herbicidal activity. And strain Hal had the highest effective herbicidal activity. As a result, this study aims to JdentJfy strain Hal, characterize its physiological and biological activities, evaluate the herbicidal activity of its metabolites, and develop a ＇pesta＇ formulation and assess its effectiveness on Digitaria sanguinalis. Hal was identified as Serratia marcescens based on 16S rDNA sequencing. This strain has a flagellum, a diameter of 0.5 to 0.8 IJm, and a length of 0.9 to 2.0 IJm. The indole test shows positive results, and the catalase enzyme exhibits strong positive reactions. Results further showed that the inhibitory concentration （IC50） of the crude extracts to D. sanguinalis radicula and coleoptile were 3.332 and 2.828 mg mL-1, respectively. Both the suppression of D. sanguinalis and the cell viability of the Hal formulation in ＇pesta＇ were higher when stored at 4℃ than at （25＋2）℃. These results indi- cated that S. marcescens Hal can potentially be used as a biocontrol agent against D. sanguinalis.展开更多
In this study, we characterized strain F9 and evaluated the interaction between strain F9 and hematite by scanning electron microscopy（SEM）, Fourier transform infrared spectrophotometry（FTIR）, zeta potential, flot...In this study, we characterized strain F9 and evaluated the interaction between strain F9 and hematite by scanning electron microscopy（SEM）, Fourier transform infrared spectrophotometry（FTIR）, zeta potential, flotation, and other methods. The results showed that strain F9 belongs to Serratia marcescens. This brevibacterium had CH2, CH3, and hydroxyl groups on its cell wall, which imparted a strong hydrophobic and negative charge. Adsorption of strain F9 reduced the zeta potential of the hematite surface and increased the hydrophobicity of the hematite surface, thereby generating hydrophobic hematite agglomerates. At least four groups on strain F9 interacted with the hematite surface, which contributed to chemical interactions of carboxylic groups and hydrophobic association among hydrophobic hematite particles. The possible use of strain F9 as a bio-collector for hematite flotation was proved.展开更多
A 1 692 bp long chitinase-encoding ch/A gene was cloned from the genomic DNA of Serrat/a marcescens strain C8-8 by PCR, which was speculated to en- code a 563 aa long polypeptide chain with molecular weight of about 6...A 1 692 bp long chitinase-encoding ch/A gene was cloned from the genomic DNA of Serrat/a marcescens strain C8-8 by PCR, which was speculated to en- code a 563 aa long polypeptide chain with molecular weight of about 60.9 kD. Homolog analysis showed that the chiA gene sequence cloned from C8-8 shared the highest similarity with cMA sequences from Serrat/a maresscens strains 141 （ DQ 990373.1 ） and 14041 （ DQ 493896. 1 ）, which reached 99%. Domain analysis showed that N-termlnal （23 aa） of the chiA gene cloned from C8-8 harbored typical signal peptide sequence, while C-telminal harbored the other two domains, in- eluding the PKD region （73 aa） and chitinase catalytic region （387 aa）. The PCR fragment was digested with restriction endonucleases and cloned into plasmid pET28a. The recombinant plasmid pET＇28a-ch/A was firstly transformed into Escherichia coli DI-I5 , and then transformed into expression host E. coli DH3 to express ch/A gene. The recombinant strain DH3 chiA could produce transparent hydrolysis circles on the colloidal chitin plate induced by isopropyl-l-thiogalactopyranoside （IFrG）. SDS-PAGE electrophoresis analysis showed that, a protein with relative molecular weight of about 60 kD was expressed by the recombinant strain DH3 chiA, which was consistent with the except molecular weight. After initial purification, biological activity test showed that the recombinant expression product could hydrolyze chitin, which produced transparent hydrolysis circles on the colloidal chitin plates. Results indicated that chiA gene from Serrat/a marcescens strain C8-8 had biological functions and could be utilized as a potential biological control factor.展开更多
BACKGROUND Healthcare workers(HCWs)are at an increased risk for exposure to infections.Serratia marcescens(S.marcescens)is a gram-negative,opportunistic and nosocomial pathogen belonging to the Enterobacterieae family...BACKGROUND Healthcare workers(HCWs)are at an increased risk for exposure to infections.Serratia marcescens(S.marcescens)is a gram-negative,opportunistic and nosocomial pathogen belonging to the Enterobacterieae family.A few case reports have been published of chorioamnionitis caused by S.marcescens infection.Immunological changes during pregnancy can also affect the risk of infection.However,few studies have examined hospital-acquired bacterial infection in pregnant HCWs.CASE SUMMARY A 33-year-old woman,a resident in anesthesiology,was admitted at 14 wk gestation for fever with chills.She had no medical history other than contact dermatitis of both hands that started from the beginning of the trainee.There was no obvious infection focus and no bacterial growth in blood cultures.She was discharged after 1 wk of empirical antibiotic treatment.At three weeks before the fever started,she had a blister on the site of contact dermatitis on both hands,she applied antibiotic ointment for three days and the blisters had healed.At 19 wk gestation,she had a high fever and was readmitted.Physical examination and image studies were nonspecific and the patient had no other symptoms.S.marcescens grew in blood cultures at 19 wk gestation.Treatment with intravenous antibiotics was started.However,she suffered a miscarriage at 224/7 wk gestation.Pathologically,the amniotic membrane showed chorioamnionitis with a focal infarct.Subsequently,a placenta tissue culture grew S.marcescens.CONCLUSION HCWs can be exposed to pathogens that can cause opportunistic infections such as S.marcescens.Pregnancy affects the immune system,making it susceptible to opportunistic infections.Therefore,pregnant HCWs may require more preventive measures,including hand hygiene and avoid risk factors(ex.wrapping the skin).展开更多
Serratia marcescens has been recognized as an important cause of nosocomial and community-acquired infections. To our knowledge, we describe the first case of S. marcescens rhabdomyolysis, most probably related to acu...Serratia marcescens has been recognized as an important cause of nosocomial and community-acquired infections. To our knowledge, we describe the first case of S. marcescens rhabdomyolysis, most probably related to acute cholecystitis and secondary bacteremia. The condition was successfully managed with levofloxacin. Keeping in mind the relevant morbidity and mortality associated with bacterial rhabdomyolysis, physicians should consider this possibility in patients with suspected or proven bacterial disease. We suggest S. marcescens should be regarded as a new causative agent of infectious rhabdomyolysis.展开更多
The hazelnut weevil(Curculio dieckmanni Faust.)is a major pest of Asian hazel(Corylus heterophylla Fisch.)in China.Dead hazelnut weevil larvae were examined and the associated pathogenic bacterium was identifi ed as S...The hazelnut weevil(Curculio dieckmanni Faust.)is a major pest of Asian hazel(Corylus heterophylla Fisch.)in China.Dead hazelnut weevil larvae were examined and the associated pathogenic bacterium was identifi ed as Serratia marcescens Bizio.This signifi cantly shortened the lifespan of hazelnut weevil.Larval weight was reduced as a function of S.marcescens concentration and exposure time.The structure of infected midgut cells was altered,with necrosis of the wall tissues and many cells becoming dislodged,creating cavities.The S.marcencens strain inhibited digestive enzyme activity and protective enzymes in the midgut of adult hazelnut weevil.Inhibition on S.marcencens strain increased with treatment time.S.marcescens directly destroyed the midgut cells and interfered with digestive and protective enzymes.This decreased the food intake and increased mortality of hazelnut weevil.S.marcescens appears to be an eff ective bacterium for the control of hazelnut weevil but requires further study,including biological formulation development and fi eld application.展开更多
A red-pigmented bacterial strain NS-17 was isolated from soil, and physiological and biochemical characteristics and 16S rDNA analysis established this organism as a strain of Serratia marcescens. The red pigment isol...A red-pigmented bacterial strain NS-17 was isolated from soil, and physiological and biochemical characteristics and 16S rDNA analysis established this organism as a strain of Serratia marcescens. The red pigment isolated from cells of NS-17 was identified as prodigiosin. By analyzing factors affecting the production of prodigiosin, modified medium and culture conditions were set up, and a continuous fermentation method was carried out to take advantage of the mass production of foam during fermentation. Continuous fermentation was achieved in the following conditions: 32℃, 1:1 ventilation ratio, and medium with a nutrient concentration 5-fold higher than that of the fermentation medium (with half the inorganic salt concentration) supplied as a feed medium at a flow rate of 8 mL/min. For the first time of continuous fermentation of Serratia marcescens coupling with foam flotation, a high yield of prodigiosin was obtained. After 56 h of culturing, the total harvest of cells was enhanced 2.33-fold compared to that of batch fermentation, the total amount of prodigiosin was enhanced 2.70-fold compared to that of batch fermentation, and cells and prodigiosin were concentrated in the efflux broth automatically.展开更多
Plants need phosphorus for many physiological activities in a form of phosphate anions. Three different bacterial strains (Bacillus subtilis PH, Serratia marcescens PH1, and Serratia marcescens PH2), recently isolated...Plants need phosphorus for many physiological activities in a form of phosphate anions. Three different bacterial strains (Bacillus subtilis PH, Serratia marcescens PH1, and Serratia marcescens PH2), recently isolated from tomato plant rhizosphere, have high phosphate solubilization index (SI from 2.8 to 3.2) on Pikovskaya agar medium (which contains calcium phosphate). Moreover, phosphate release from calcium in Pikovskaya broth over 5 days is increasing with cell growth for the different isolates. The most efficient phosphate solubilization case is the mixed culture of the 3 strains (OD475 is almost 1). On the other hand, pH values decreased dramatically with time due to organic acids secretion and the maximum acidification level is recoded for Serratia marcescens PH2 (pH = 1.94). Interestingly, the isolates are resistance to important pesticides (oxamyl, thiophanate methyl, and captan) that are commonly used in the sampling area. This resistance is very favorable and increases the persistence of the phosphate solubilizing bacteria in contaminated soils. The isolates are therefore plant symbionts and growth promoting agents.展开更多
Serratia marcescens ECUI010, as an extracellular lipase and a significant catalyst, which had been widely employed to catalyze various chemical reactions such as non-specific, stereo-specific hydrolysis and esterifica...Serratia marcescens ECUI010, as an extracellular lipase and a significant catalyst, which had been widely employed to catalyze various chemical reactions such as non-specific, stereo-specific hydrolysis and esterification for industrial biocatalytic applications, was previously mostly expressed intracellularly as inclusion bodies in Escherichia coli. Denaturation and renaturation of inclusion bodies had a significant influence on the lipase activity. Thereupon, our present work described the secretion expression of gene encoding of this lipase in Pichia pastoris GS 115 and characterization of the recombinant enzyme. Firstly, the obtained lipA gene fragment was introduced into P. pastoris expression vector pPIC9K, the lipA gene without its signal sequence were cloned downstream to the alpha-mating factor signal and expressed in P. pastoris GS115 under the control of AOXI promoter, and the recombinant plasmid pPIC9K-lipA was transformed into P. pastoris strain GS115 by electroporation, and this recombinant P. pastoris were identified by PCR. Then lipase activity was detected on BMMY-tributyrin and olive oil agar plates containing Rhodamine B. Transformants with lipase activity by screening were induced 6 days by methanol, one band of 77 kDa protein could be observed by 10% SDS-PAGE. p-nitrophenyl esters of fatty acids were used as the substrates in an automated activity assay of liquid culture media. The pH and temperature optimum of lipase were pH 8.5 and 40℃ respectively. The stability and effects of metal ions and other reagents were also determined. However, the recombinant fusion intended for secretion was efficiently secreted in a percentage of close to 90% and remained stable even in rich medium at high cell density cultures, yielding values of over 4 U of lipase activity per milliliter of culture media supernatant.展开更多
BACKGROUND Carbapenem-resistant Enterobacteriaceae has become a significant public health concern as hospital outbreaks are now being frequently reported and these organisms are becoming difficult to treat with the av...BACKGROUND Carbapenem-resistant Enterobacteriaceae has become a significant public health concern as hospital outbreaks are now being frequently reported and these organisms are becoming difficult to treat with the available antibiotics.CASE SUMMARY An outbreak of VIM-producing Serratia marcescens occurred over a period of 11 wk(August,1 to October,18)in patients admitted to the adult polyvalent intensive care unit of the University of Campania“Luigi Vanvitelli”located in Naples.Four episodes occurred in three patients(two patients infected,and one patient colonized).All the strains revealed the production of VIM.CONCLUSION After three decades of carbapenem antibiotics use,the emergence of carbapenemresistance in Enterobacteriaceae has become a significant concern and a stricter control to preserve its clinical application is mandatory.This is,to our knowledge,the first outbreak of VIM-producing Serratia marcescens in Europe.Surveillance policies must be implemented to avoid future outbreaks.展开更多
In the continuation of our study on the Serratta marcescens O-antigen, two disaccharides8 and 13, corresponding to the key intermediates of oligosaccharides related to the S. marcescensO10 antigen, were srythesized by...In the continuation of our study on the Serratta marcescens O-antigen, two disaccharides8 and 13, corresponding to the key intermediates of oligosaccharides related to the S. marcescensO10 antigen, were srythesized by the trichloroacetate method. Their structures and compositionswere characterized by H NMR, C NMR, 2D NMR and IR, FAB-MS spectra.展开更多
文摘从大豆土壤中分离纯化得到一株具有卵磷脂和乐果降解能力的菌株Yj1,对该菌株进行鉴定、生长条件优化、酶活性鉴定以及有机磷降解酶的分离纯化。结果表明,Yj1与Serratia marcescens WW4(CP003959.1)的16S r DNA相似度为99%。正交试验对所需培养基进行优化,得到该菌株的最佳生长条件为甘露糖、蛋白胨和p H 8的组合。Yj1菌株在两种磷源条件下,菌株生长量均很低,但72 h内以大豆卵磷脂为磷源时的菌体生长情况优于乐果。以大豆卵磷脂为磷源时酸性磷酸酶、碱性磷酸酶与有机磷降解酶活性明显高于以乐果为磷源时的酶活,且72 h内碱性磷酸酶活性一直都高于酸性磷酸酶和有机磷降解酶。硫酸铵沉淀法结合阳离子交换层析成功从Yj1菌体中分离纯化了有机磷降解酶,SDS-PAGE结果显示纯化的蛋白为单一条带。且阳离子交换层析的提纯倍数是硫酸氨沉淀的5.303倍,硫酸氨沉淀为粗酶的1.416倍。
基金supported by the grants from the National High Technology Research and Development Program of China (2011AA10A206)the China Agriculture Research System (CARS-02)the Science and Technology Support Program of Hebei, China (12220301D)
文摘A total of 479 bacterial strains were isolated from brine （Bohai, Qinhuangdao City, Hebei Province, China）. Bioassay results indicated that 4 strains named Hal, Hal7, Ha38, and Ha384 had herbicidal activity. And strain Hal had the highest effective herbicidal activity. As a result, this study aims to JdentJfy strain Hal, characterize its physiological and biological activities, evaluate the herbicidal activity of its metabolites, and develop a ＇pesta＇ formulation and assess its effectiveness on Digitaria sanguinalis. Hal was identified as Serratia marcescens based on 16S rDNA sequencing. This strain has a flagellum, a diameter of 0.5 to 0.8 IJm, and a length of 0.9 to 2.0 IJm. The indole test shows positive results, and the catalase enzyme exhibits strong positive reactions. Results further showed that the inhibitory concentration （IC50） of the crude extracts to D. sanguinalis radicula and coleoptile were 3.332 and 2.828 mg mL-1, respectively. Both the suppression of D. sanguinalis and the cell viability of the Hal formulation in ＇pesta＇ were higher when stored at 4℃ than at （25＋2）℃. These results indi- cated that S. marcescens Hal can potentially be used as a biocontrol agent against D. sanguinalis.
基金financially supported by the National Natural Science Foundation of China (No. 51074017)
文摘In this study, we characterized strain F9 and evaluated the interaction between strain F9 and hematite by scanning electron microscopy（SEM）, Fourier transform infrared spectrophotometry（FTIR）, zeta potential, flotation, and other methods. The results showed that strain F9 belongs to Serratia marcescens. This brevibacterium had CH2, CH3, and hydroxyl groups on its cell wall, which imparted a strong hydrophobic and negative charge. Adsorption of strain F9 reduced the zeta potential of the hematite surface and increased the hydrophobicity of the hematite surface, thereby generating hydrophobic hematite agglomerates. At least four groups on strain F9 interacted with the hematite surface, which contributed to chemical interactions of carboxylic groups and hydrophobic association among hydrophobic hematite particles. The possible use of strain F9 as a bio-collector for hematite flotation was proved.
基金Supported by Agricultural Science and Technology Innovation Fund of Jiangsu Province.[CX(11)2022]
文摘A 1 692 bp long chitinase-encoding ch/A gene was cloned from the genomic DNA of Serrat/a marcescens strain C8-8 by PCR, which was speculated to en- code a 563 aa long polypeptide chain with molecular weight of about 60.9 kD. Homolog analysis showed that the chiA gene sequence cloned from C8-8 shared the highest similarity with cMA sequences from Serrat/a maresscens strains 141 （ DQ 990373.1 ） and 14041 （ DQ 493896. 1 ）, which reached 99%. Domain analysis showed that N-termlnal （23 aa） of the chiA gene cloned from C8-8 harbored typical signal peptide sequence, while C-telminal harbored the other two domains, in- eluding the PKD region （73 aa） and chitinase catalytic region （387 aa）. The PCR fragment was digested with restriction endonucleases and cloned into plasmid pET28a. The recombinant plasmid pET＇28a-ch/A was firstly transformed into Escherichia coli DI-I5 , and then transformed into expression host E. coli DH3 to express ch/A gene. The recombinant strain DH3 chiA could produce transparent hydrolysis circles on the colloidal chitin plate induced by isopropyl-l-thiogalactopyranoside （IFrG）. SDS-PAGE electrophoresis analysis showed that, a protein with relative molecular weight of about 60 kD was expressed by the recombinant strain DH3 chiA, which was consistent with the except molecular weight. After initial purification, biological activity test showed that the recombinant expression product could hydrolyze chitin, which produced transparent hydrolysis circles on the colloidal chitin plates. Results indicated that chiA gene from Serrat/a marcescens strain C8-8 had biological functions and could be utilized as a potential biological control factor.
基金Supported by a grant of Chonnam National University Hwasun Hospital Research Institute of Clinical Medicine,No.HCRI19012。
文摘BACKGROUND Healthcare workers(HCWs)are at an increased risk for exposure to infections.Serratia marcescens(S.marcescens)is a gram-negative,opportunistic and nosocomial pathogen belonging to the Enterobacterieae family.A few case reports have been published of chorioamnionitis caused by S.marcescens infection.Immunological changes during pregnancy can also affect the risk of infection.However,few studies have examined hospital-acquired bacterial infection in pregnant HCWs.CASE SUMMARY A 33-year-old woman,a resident in anesthesiology,was admitted at 14 wk gestation for fever with chills.She had no medical history other than contact dermatitis of both hands that started from the beginning of the trainee.There was no obvious infection focus and no bacterial growth in blood cultures.She was discharged after 1 wk of empirical antibiotic treatment.At three weeks before the fever started,she had a blister on the site of contact dermatitis on both hands,she applied antibiotic ointment for three days and the blisters had healed.At 19 wk gestation,she had a high fever and was readmitted.Physical examination and image studies were nonspecific and the patient had no other symptoms.S.marcescens grew in blood cultures at 19 wk gestation.Treatment with intravenous antibiotics was started.However,she suffered a miscarriage at 224/7 wk gestation.Pathologically,the amniotic membrane showed chorioamnionitis with a focal infarct.Subsequently,a placenta tissue culture grew S.marcescens.CONCLUSION HCWs can be exposed to pathogens that can cause opportunistic infections such as S.marcescens.Pregnancy affects the immune system,making it susceptible to opportunistic infections.Therefore,pregnant HCWs may require more preventive measures,including hand hygiene and avoid risk factors(ex.wrapping the skin).
文摘Serratia marcescens has been recognized as an important cause of nosocomial and community-acquired infections. To our knowledge, we describe the first case of S. marcescens rhabdomyolysis, most probably related to acute cholecystitis and secondary bacteremia. The condition was successfully managed with levofloxacin. Keeping in mind the relevant morbidity and mortality associated with bacterial rhabdomyolysis, physicians should consider this possibility in patients with suspected or proven bacterial disease. We suggest S. marcescens should be regarded as a new causative agent of infectious rhabdomyolysis.
基金the National Key Research and Development project of China(2016YFC0500308)Special Project for Double First-Class-Cultivation of Innovative Talents(000/41113102)+1 种基金the Natural Science Foundation of Heilongjiang Scientifi c Committee(C2018055)the Application Research Project of Heilongjiang Provincial Forest Industry Administration(sgzjY2014004).
文摘The hazelnut weevil(Curculio dieckmanni Faust.)is a major pest of Asian hazel(Corylus heterophylla Fisch.)in China.Dead hazelnut weevil larvae were examined and the associated pathogenic bacterium was identifi ed as Serratia marcescens Bizio.This signifi cantly shortened the lifespan of hazelnut weevil.Larval weight was reduced as a function of S.marcescens concentration and exposure time.The structure of infected midgut cells was altered,with necrosis of the wall tissues and many cells becoming dislodged,creating cavities.The S.marcencens strain inhibited digestive enzyme activity and protective enzymes in the midgut of adult hazelnut weevil.Inhibition on S.marcencens strain increased with treatment time.S.marcescens directly destroyed the midgut cells and interfered with digestive and protective enzymes.This decreased the food intake and increased mortality of hazelnut weevil.S.marcescens appears to be an eff ective bacterium for the control of hazelnut weevil but requires further study,including biological formulation development and fi eld application.
文摘A red-pigmented bacterial strain NS-17 was isolated from soil, and physiological and biochemical characteristics and 16S rDNA analysis established this organism as a strain of Serratia marcescens. The red pigment isolated from cells of NS-17 was identified as prodigiosin. By analyzing factors affecting the production of prodigiosin, modified medium and culture conditions were set up, and a continuous fermentation method was carried out to take advantage of the mass production of foam during fermentation. Continuous fermentation was achieved in the following conditions: 32℃, 1:1 ventilation ratio, and medium with a nutrient concentration 5-fold higher than that of the fermentation medium (with half the inorganic salt concentration) supplied as a feed medium at a flow rate of 8 mL/min. For the first time of continuous fermentation of Serratia marcescens coupling with foam flotation, a high yield of prodigiosin was obtained. After 56 h of culturing, the total harvest of cells was enhanced 2.33-fold compared to that of batch fermentation, the total amount of prodigiosin was enhanced 2.70-fold compared to that of batch fermentation, and cells and prodigiosin were concentrated in the efflux broth automatically.
文摘Plants need phosphorus for many physiological activities in a form of phosphate anions. Three different bacterial strains (Bacillus subtilis PH, Serratia marcescens PH1, and Serratia marcescens PH2), recently isolated from tomato plant rhizosphere, have high phosphate solubilization index (SI from 2.8 to 3.2) on Pikovskaya agar medium (which contains calcium phosphate). Moreover, phosphate release from calcium in Pikovskaya broth over 5 days is increasing with cell growth for the different isolates. The most efficient phosphate solubilization case is the mixed culture of the 3 strains (OD475 is almost 1). On the other hand, pH values decreased dramatically with time due to organic acids secretion and the maximum acidification level is recoded for Serratia marcescens PH2 (pH = 1.94). Interestingly, the isolates are resistance to important pesticides (oxamyl, thiophanate methyl, and captan) that are commonly used in the sampling area. This resistance is very favorable and increases the persistence of the phosphate solubilizing bacteria in contaminated soils. The isolates are therefore plant symbionts and growth promoting agents.
文摘Serratia marcescens ECUI010, as an extracellular lipase and a significant catalyst, which had been widely employed to catalyze various chemical reactions such as non-specific, stereo-specific hydrolysis and esterification for industrial biocatalytic applications, was previously mostly expressed intracellularly as inclusion bodies in Escherichia coli. Denaturation and renaturation of inclusion bodies had a significant influence on the lipase activity. Thereupon, our present work described the secretion expression of gene encoding of this lipase in Pichia pastoris GS 115 and characterization of the recombinant enzyme. Firstly, the obtained lipA gene fragment was introduced into P. pastoris expression vector pPIC9K, the lipA gene without its signal sequence were cloned downstream to the alpha-mating factor signal and expressed in P. pastoris GS115 under the control of AOXI promoter, and the recombinant plasmid pPIC9K-lipA was transformed into P. pastoris strain GS115 by electroporation, and this recombinant P. pastoris were identified by PCR. Then lipase activity was detected on BMMY-tributyrin and olive oil agar plates containing Rhodamine B. Transformants with lipase activity by screening were induced 6 days by methanol, one band of 77 kDa protein could be observed by 10% SDS-PAGE. p-nitrophenyl esters of fatty acids were used as the substrates in an automated activity assay of liquid culture media. The pH and temperature optimum of lipase were pH 8.5 and 40℃ respectively. The stability and effects of metal ions and other reagents were also determined. However, the recombinant fusion intended for secretion was efficiently secreted in a percentage of close to 90% and remained stable even in rich medium at high cell density cultures, yielding values of over 4 U of lipase activity per milliliter of culture media supernatant.
文摘BACKGROUND Carbapenem-resistant Enterobacteriaceae has become a significant public health concern as hospital outbreaks are now being frequently reported and these organisms are becoming difficult to treat with the available antibiotics.CASE SUMMARY An outbreak of VIM-producing Serratia marcescens occurred over a period of 11 wk(August,1 to October,18)in patients admitted to the adult polyvalent intensive care unit of the University of Campania“Luigi Vanvitelli”located in Naples.Four episodes occurred in three patients(two patients infected,and one patient colonized).All the strains revealed the production of VIM.CONCLUSION After three decades of carbapenem antibiotics use,the emergence of carbapenemresistance in Enterobacteriaceae has become a significant concern and a stricter control to preserve its clinical application is mandatory.This is,to our knowledge,the first outbreak of VIM-producing Serratia marcescens in Europe.Surveillance policies must be implemented to avoid future outbreaks.
文摘In the continuation of our study on the Serratta marcescens O-antigen, two disaccharides8 and 13, corresponding to the key intermediates of oligosaccharides related to the S. marcescensO10 antigen, were srythesized by the trichloroacetate method. Their structures and compositionswere characterized by H NMR, C NMR, 2D NMR and IR, FAB-MS spectra.
