Microbiologically influenced corrosion(MIC)of steel generates a corrosion product film,which can also be called biomineralization film.It is critical to understand the structure of biomineralization film since it domi...Microbiologically influenced corrosion(MIC)of steel generates a corrosion product film,which can also be called biomineralization film.It is critical to understand the structure of biomineralization film since it dominates the corrosion behavior of metal.In this work,Pseudomonas stutzeri(P.stutzeri)was isolated from seawater,and the biomineralization film caused by marine P.stutzeri was characterized by Transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD),etc.The mechanistic effects of the biomineralization film on X80 pipeline steel corrosion were also investigated.The results indicate that the minerals are mainly composed of nano FeOand FeOOH,according to TEM and XRD results.The particle sizes of biominerals are below 10 nm.This work also provides an insight strategy to prepare nanomaterials by MIC caused by P.stutzeri.In addition,P.stutzeri can grow well with COas a carbon source and iron as an electron donor.The corrosion rates(CRs)of specimens are closely related to the structure of biomineralization film.The CRs increase with the decrease of initial cell concentration.P.stutzeri with an initial concentration of 10~7 cells/mL can promote the formation of a compact biomineralization film with a thickness of 145.8±4.8μm,leading to corrosion inhibition with a CR of 0.058±0.008 mm/y.But some corrosion pits can be observed due to the formation of small anodes.Electrochemical impedance spectroscopy(EIS)data show higher impedance values and two time-constants,which imply the formation of a compact biomineralization film.展开更多
A series of polyhydroxyalkanoate(PHA)copolymers consisting of short-chain-length(SCL)and medium-chain-length(MCL)3-hydroxyalkanoate(3HA)monomers were synthesized in the recombinant Ralstonia eutropha PHB - 4 harboring...A series of polyhydroxyalkanoate(PHA)copolymers consisting of short-chain-length(SCL)and medium-chain-length(MCL)3-hydroxyalkanoate(3HA)monomers were synthesized in the recombinant Ralstonia eutropha PHB - 4 harboring a low-substrate-specificity PHA synthase PhaC2Ps from Pseudomonas stutzeri 1317. These polyesters,whose monomer compositions varied widely in chain length,were purified and characterized by acetone fractionation,nuclear magnetic resonance(NMR),gel-permeation chromatography(GPC),and differential scanning calorimetry(DSC).This was the first time that the physical properties of PHA copolymers polymerized by PhaC2Ps were characterized.The results indicated that the variation in MCL 3HA contents did not have an obvious influence on the molecular weights of these PHA copolymers but was effective in changing their physical properties. The variation in the thermal property of PHA copolymers with 3-hydroxyoctanoate(3HO)content was also inves- tigated in this study.展开更多
Synthetic biology promises to simplify the construction of metabolic pathways by assembling the de- tached modules of the whole pathway. This gives new approaches for the microbial production of industrial products su...Synthetic biology promises to simplify the construction of metabolic pathways by assembling the de- tached modules of the whole pathway. This gives new approaches for the microbial production of industrial products such as polyhydroxyalkanoates （PHA）. In this study, to produce poly（3-hydroxybutyrate-co-3-hydroxyhexanoate） （PHBHHx） by Pseudomonas stutzeri 1317 from unrelated carbon sources such as glucose, the phaCl-phaZ-phaC2 operon of P. stutzeri 1317 was knocked out to generate the PHA deficient mutant P. stutzeri 1317LF. Then three modules containing phaCahAReBRe, phaCahBReGep and phaCAhPah were introduced into P. stutzeri 1317LF separately The shake flask results indicated that the precursor supply and PHA synthase activity were the vital factors for the PHBHHx accumulation of P. stutzeri 1317LF. Furthermore, the PHBHHx accumulation of the recombinants from different carbon resources were performed. The highest PHBHHx content was 23.7% （by mass） with 58.6% （by mole） 3HB fraction. These results provide basis for further improving the PHBHHx accumulation of P. stutzeri from unrelated carbon sources.展开更多
Pseudomonas stutzeriA1501, associative and endophytic nitrogen-fixing bacterium showed the capacity of colonization in the rice roots and considered as the good colonizer in the rice plant. The experiment was conducte...Pseudomonas stutzeriA1501, associative and endophytic nitrogen-fixing bacterium showed the capacity of colonization in the rice roots and considered as the good colonizer in the rice plant. The experiment was conducted to study the expression of genes potentiality relevant to the association of nitrogen fixing Pseudomonas stutzeri with host rice and reveal the molecular mechanism by which underlying interaction between bacteria and host rice. The bacteria were shown to be uniformly distributed on the rhizoplane of the root and the density of bacteria was found at the intercellular junction and micro colony developed on the surface of the epidermal cells and on the cellular junctions. Root exudates of rice were the major components of carbon and energy sources for bacteria. RT-PCR analyses of pilK, metE, rpoN and fdhE genes expression of P. stutzeri A1501 were performed at positive and negative (control) conditions. After 1 h, it was found that pilK, metE and rpoN transcription were increased 5.7, 6.4 and 3.4-fold, respectively, whereas in the fdhE gene has no expression. Consequently, after 4 h pilk, fdhE, metE and rpoN were decreased -1.9, -4.4, -0.2 and -0.8-fold, respectively. The gene pilK, expression was up-regulation after 1 h and down-regulation after 4 h that has twitching motility to convey the bacterial cell to point of attachment in to host plant. The gene expressions of the bacteria, pilK, metE, rpoN and fdhE were up- and down-regulated during the influence of root exudates which regulated the colonization of bacteria during plant-microbe interaction.展开更多
Flagellar biosynthesis and motility are subject to a four-tiered transcriptional regulatory circuit in Pseudomonas,and the master regulator FleQ appears to be the highest-level regulator in this hierarchical regulator...Flagellar biosynthesis and motility are subject to a four-tiered transcriptional regulatory circuit in Pseudomonas,and the master regulator FleQ appears to be the highest-level regulator in this hierarchical regulatory cascade.Pseudomonas stutzeri A1501 is motile by a polar flagellum;however,the motility and regulatory mechanisms involved in this process are unknown.Here,we searched the A1501 genome for flagella and motility genes and found that approximately 50 genes,which were distributed in three non-contiguous chromosomal regions,contribute to the formation,regulation and function of the flagella.The non-polar mutation of fleQ impaired flagellar biosynthesis,motility and root colonization but enhanced biofilm formation.FleQ positively regulates the expression of flagellar class Ⅱ-Ⅳ genes,suggesting a regulatory cascade that is coordinated similar to that of the well-known P.aeruginosa.Based on our results,we propose that flagellar genes in P.stutzeri A1501 are regulated in a cascade regulated by FleQ and that flagellum-driven motility properties may be necessary for competitive rhizosphere colonization.展开更多
Pseudomonas stutzeri caused an outbreak of freshwater fish in Luwuk Banggai （tilapia and catfish）, Bali （tilapia）, Jambi （tilapia and catfish） and Tanjung Pinang （catfish）. The study was purposed to comprehens...Pseudomonas stutzeri caused an outbreak of freshwater fish in Luwuk Banggai （tilapia and catfish）, Bali （tilapia）, Jambi （tilapia and catfish） and Tanjung Pinang （catfish）. The study was purposed to comprehensively identify special phenotypic and genotypic characteristics of P. stutzeri isolated from several areas in Indonesia, including its morphometric and biochemical characteristics and molecular variation. Bacteria were isolated from internal organs （kidney, ulcer and eye） of fish. They were then identified using morphology and biochemical test. DNA isolates were entirely extracted, amplified and reversed on 16S rRNA region, and further then were sequenced. Phylogenetic trees of bacteria were constructed using neighbor-joining and maximum-parsimony methods. The colony were similar, such as rod shape （Jambi, Tanjung Pinang, Bali）, bacil shape （Luwuk Banggai）, transparant in tryptic soy agar （TSA） （Luwuk Banggai）, creamy beige in glutamate starch phenol red （GSP） （Bali）, gram negative, motile, no reaction in the oxidative-fermentative test, positive result in catalase and oxidase test, negative in lysine decarboxylase and ornithine decarboxylase test and positive result in indole test; gelatin was degraded （only Bali）, urea was not degraded, no color change in Methyl-red and Voges-proskaeur （MR-VP） test; acid not produce from glucose, inositol or sucrose. Citrate was utilized by some isolates： positive （Jambi, Tanjung Pinang） and negative （Bali, Luwuk Banggai）. Results showed us that isolates of Jambi, Bali and Tanjung Pinang were monophyletic species with P. stutzeri $8 and ZH-1 comparing to gen bank. However, merely phenotypic analysis among Pseudomonas sp. was confused compared to each other.展开更多
基金supported by the National Natural Science Foundation of China(No.51901253)Fundamental Research Funds for the Central Universities(No.19lgzd18)+2 种基金Guangdong Basic and Applied Basic Research Foundation(No.2019A1515011135)the Open Project Program of Beijing Key Laboratory of Pipeline Critical Technology and Equipment for Deepwater Oil&Gas Development(No.BIPT201904)the Open Project Program of Hubei Key Laboratory of Materials Chemistry and Service Failure(No.2020MCF02)。
文摘Microbiologically influenced corrosion(MIC)of steel generates a corrosion product film,which can also be called biomineralization film.It is critical to understand the structure of biomineralization film since it dominates the corrosion behavior of metal.In this work,Pseudomonas stutzeri(P.stutzeri)was isolated from seawater,and the biomineralization film caused by marine P.stutzeri was characterized by Transmission electron microscopy(TEM),scanning electron microscopy(SEM),X-ray diffraction(XRD),etc.The mechanistic effects of the biomineralization film on X80 pipeline steel corrosion were also investigated.The results indicate that the minerals are mainly composed of nano FeOand FeOOH,according to TEM and XRD results.The particle sizes of biominerals are below 10 nm.This work also provides an insight strategy to prepare nanomaterials by MIC caused by P.stutzeri.In addition,P.stutzeri can grow well with COas a carbon source and iron as an electron donor.The corrosion rates(CRs)of specimens are closely related to the structure of biomineralization film.The CRs increase with the decrease of initial cell concentration.P.stutzeri with an initial concentration of 10~7 cells/mL can promote the formation of a compact biomineralization film with a thickness of 145.8±4.8μm,leading to corrosion inhibition with a CR of 0.058±0.008 mm/y.But some corrosion pits can be observed due to the formation of small anodes.Electrochemical impedance spectroscopy(EIS)data show higher impedance values and two time-constants,which imply the formation of a compact biomineralization film.
基金Supported by the National Natural Science Foundation of China （No.30225001, No.20334020）. The authors are very grateful to Prof. A. Steinbiichel of the University of Miinster in Germany for the generous donation of strain R. eutropha PHB 4.
文摘A series of polyhydroxyalkanoate(PHA)copolymers consisting of short-chain-length(SCL)and medium-chain-length(MCL)3-hydroxyalkanoate(3HA)monomers were synthesized in the recombinant Ralstonia eutropha PHB - 4 harboring a low-substrate-specificity PHA synthase PhaC2Ps from Pseudomonas stutzeri 1317. These polyesters,whose monomer compositions varied widely in chain length,were purified and characterized by acetone fractionation,nuclear magnetic resonance(NMR),gel-permeation chromatography(GPC),and differential scanning calorimetry(DSC).This was the first time that the physical properties of PHA copolymers polymerized by PhaC2Ps were characterized.The results indicated that the variation in MCL 3HA contents did not have an obvious influence on the molecular weights of these PHA copolymers but was effective in changing their physical properties. The variation in the thermal property of PHA copolymers with 3-hydroxyoctanoate(3HO)content was also inves- tigated in this study.
基金Supported by the National lqatural Science Foundation of China （31260015）, Natural Science Foundation of Qinghai Province （2012-Z-919Q）, the Extramural Project from State Key Laboratory for Agrobiotechnology （2012SKLAB06-5） and the Research Funds for Young Project of Qinghal University （2011-QYY-1）.
文摘Synthetic biology promises to simplify the construction of metabolic pathways by assembling the de- tached modules of the whole pathway. This gives new approaches for the microbial production of industrial products such as polyhydroxyalkanoates （PHA）. In this study, to produce poly（3-hydroxybutyrate-co-3-hydroxyhexanoate） （PHBHHx） by Pseudomonas stutzeri 1317 from unrelated carbon sources such as glucose, the phaCl-phaZ-phaC2 operon of P. stutzeri 1317 was knocked out to generate the PHA deficient mutant P. stutzeri 1317LF. Then three modules containing phaCahAReBRe, phaCahBReGep and phaCAhPah were introduced into P. stutzeri 1317LF separately The shake flask results indicated that the precursor supply and PHA synthase activity were the vital factors for the PHBHHx accumulation of P. stutzeri 1317LF. Furthermore, the PHBHHx accumulation of the recombinants from different carbon resources were performed. The highest PHBHHx content was 23.7% （by mass） with 58.6% （by mole） 3HB fraction. These results provide basis for further improving the PHBHHx accumulation of P. stutzeri from unrelated carbon sources.
文摘Pseudomonas stutzeriA1501, associative and endophytic nitrogen-fixing bacterium showed the capacity of colonization in the rice roots and considered as the good colonizer in the rice plant. The experiment was conducted to study the expression of genes potentiality relevant to the association of nitrogen fixing Pseudomonas stutzeri with host rice and reveal the molecular mechanism by which underlying interaction between bacteria and host rice. The bacteria were shown to be uniformly distributed on the rhizoplane of the root and the density of bacteria was found at the intercellular junction and micro colony developed on the surface of the epidermal cells and on the cellular junctions. Root exudates of rice were the major components of carbon and energy sources for bacteria. RT-PCR analyses of pilK, metE, rpoN and fdhE genes expression of P. stutzeri A1501 were performed at positive and negative (control) conditions. After 1 h, it was found that pilK, metE and rpoN transcription were increased 5.7, 6.4 and 3.4-fold, respectively, whereas in the fdhE gene has no expression. Consequently, after 4 h pilk, fdhE, metE and rpoN were decreased -1.9, -4.4, -0.2 and -0.8-fold, respectively. The gene pilK, expression was up-regulation after 1 h and down-regulation after 4 h that has twitching motility to convey the bacterial cell to point of attachment in to host plant. The gene expressions of the bacteria, pilK, metE, rpoN and fdhE were up- and down-regulated during the influence of root exudates which regulated the colonization of bacteria during plant-microbe interaction.
基金supported by grants from the National Basic Research(973) Program of China(2015CB755700)the National High-Tech R&D(863) Program of China (2012AA02A703)+2 种基金the National Natural Science Foundation of China(31170081)the Special Fund for Agro-scientific Research in the Public Interest,China(201103007)the Guangdong Innovative and Entrepreneurial Research Team Program,China(2013S033).
文摘Flagellar biosynthesis and motility are subject to a four-tiered transcriptional regulatory circuit in Pseudomonas,and the master regulator FleQ appears to be the highest-level regulator in this hierarchical regulatory cascade.Pseudomonas stutzeri A1501 is motile by a polar flagellum;however,the motility and regulatory mechanisms involved in this process are unknown.Here,we searched the A1501 genome for flagella and motility genes and found that approximately 50 genes,which were distributed in three non-contiguous chromosomal regions,contribute to the formation,regulation and function of the flagella.The non-polar mutation of fleQ impaired flagellar biosynthesis,motility and root colonization but enhanced biofilm formation.FleQ positively regulates the expression of flagellar class Ⅱ-Ⅳ genes,suggesting a regulatory cascade that is coordinated similar to that of the well-known P.aeruginosa.Based on our results,we propose that flagellar genes in P.stutzeri A1501 are regulated in a cascade regulated by FleQ and that flagellum-driven motility properties may be necessary for competitive rhizosphere colonization.
文摘Pseudomonas stutzeri caused an outbreak of freshwater fish in Luwuk Banggai （tilapia and catfish）, Bali （tilapia）, Jambi （tilapia and catfish） and Tanjung Pinang （catfish）. The study was purposed to comprehensively identify special phenotypic and genotypic characteristics of P. stutzeri isolated from several areas in Indonesia, including its morphometric and biochemical characteristics and molecular variation. Bacteria were isolated from internal organs （kidney, ulcer and eye） of fish. They were then identified using morphology and biochemical test. DNA isolates were entirely extracted, amplified and reversed on 16S rRNA region, and further then were sequenced. Phylogenetic trees of bacteria were constructed using neighbor-joining and maximum-parsimony methods. The colony were similar, such as rod shape （Jambi, Tanjung Pinang, Bali）, bacil shape （Luwuk Banggai）, transparant in tryptic soy agar （TSA） （Luwuk Banggai）, creamy beige in glutamate starch phenol red （GSP） （Bali）, gram negative, motile, no reaction in the oxidative-fermentative test, positive result in catalase and oxidase test, negative in lysine decarboxylase and ornithine decarboxylase test and positive result in indole test; gelatin was degraded （only Bali）, urea was not degraded, no color change in Methyl-red and Voges-proskaeur （MR-VP） test; acid not produce from glucose, inositol or sucrose. Citrate was utilized by some isolates： positive （Jambi, Tanjung Pinang） and negative （Bali, Luwuk Banggai）. Results showed us that isolates of Jambi, Bali and Tanjung Pinang were monophyletic species with P. stutzeri $8 and ZH-1 comparing to gen bank. However, merely phenotypic analysis among Pseudomonas sp. was confused compared to each other.
