A bacterial strain that utilized o-chloronitrobenzene (o-CNB) as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identifi...A bacterial strain that utilized o-chloronitrobenzene (o-CNB) as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology, physiological, and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32℃. At these conditions, the strain degraded 85% of o-CNB at a starting concentration of 1.1 mmol/L in 42 h. o-Chloroaniline was identified as the major metabolite with high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The study showed that o-CNB degradation by Pseudomonas putida OCNB-1 was initiated by aniline dioxyenase, nitrobenzene reductase and catechol-l,2- dioxygenase.展开更多
Filamentous bacteria(FB)overgrowth is an important cause of sludge bulking in wastewater treatment plants(WWTPs).However,to date,methods for the cultivation and preservation of isolated FB in the laboratory have not b...Filamentous bacteria(FB)overgrowth is an important cause of sludge bulking in wastewater treatment plants(WWTPs).However,to date,methods for the cultivation and preservation of isolated FB in the laboratory have not been completely described.Furthermore,research on whether FB can function as phosphorus accumulating organisms(PAOs)is limited.In this study,a pure strain,a Pseudomonas putida PAO-1(P.putida PAO-1)isolate with phosphorus removal functions was isolated from the biofilm of an alternating anaerobic/aerobic biofilter(AABF),and its physiological characteristics were studied.Nitrate or nitrite could be used by the strain P.putida PAO-1 as electron acceptors for denitrification during phosphorus anoxic uptake,and 0.63 mg NO-3-N was consumed to reduce 1 mg soluble orthophosphate(SOP)by P.putida PAO-1.The strain P.putida PAO-1 consumed phosphorus within the optimal pH range of 6 to 8 and the temperature range of 25℃to 35℃.Cell deformity was a main morphological trait of the strain P.putida PAO-1,and it could elongate(with an elongation rate of 300%-500%)when it was subjected to oligotrophic or high-salt stress(15 g·L-1 NaCl).The findings in this study provide a microbiological reference for understanding the special characteristics of a denitrifying PAO.展开更多
Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well doc...Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.展开更多
Hypocrellins are major bioactive perylenequinones from Shiraia fruiting bodies and have been developed as efficient photosensitizers for photodynamic therapy.Pseudomonas is the second dominant genus inside Shiraia fru...Hypocrellins are major bioactive perylenequinones from Shiraia fruiting bodies and have been developed as efficient photosensitizers for photodynamic therapy.Pseudomonas is the second dominant genus inside Shiraia fruiting bodies,but with less known actions on the host fungus.In this work,the effects of bacterial volatiles from the Shiraia-associated Pseudomonas on fungal hypocrellin production were investigated.Pseudomonas putida No.24 was the most active to promote significantly accumulation of Shiraia perylenequinones including hypocrellin A(HA),HC,elsinochrome A(EA)and EC.Headspace analysis of the emitted volatiles revealed dimethyl disulfide as one of active compounds to promote fungal hypocrellin production.The bacterial volatiles induced an apoptosis in Shiraia hyphal cell,which was associated with the generation of reactive oxygen species(ROS).ROS generation was proved to mediate the volatile-induced membrane permeability and up-regulation of gene expressions for hypocrellin biosynthesis.In the submerged volatile co-culture,the bacterial volatiles stimulated not only HA content in mycelia,but also HA secretion into the medium,leading to the enhanced HA production to 249.85 mg/L,about 2.07-fold over the control.This is the first report on the regulation of Pseudomonas volatiles on fungal perylenequinone production.These findings could be helpful to understand the roles of bacterial volatiles in fruiting bodies and also provide new elicitation method using bacterial volatiles to stimulate fungal secondary metabolite production.展开更多
Microbial secondary metabolites represent a rich source of valuable compounds with a variety of applications in medicine or agriculture.Effective exploitation of this wealth of chemicals requires the functional expres...Microbial secondary metabolites represent a rich source of valuable compounds with a variety of applications in medicine or agriculture.Effective exploitation of this wealth of chemicals requires the functional expression of the respective biosynthetic genes in amenable heterologous hosts.We have previously established the TREX system which facilitates the transfer,integration and expression of biosynthetic gene clusters in various bacterial hosts.Here,we describe the yTREX system,a new tool adapted for one-step yeast recombinational cloning of gene clusters.We show that with yTREX,Pseudomonas putida secondary metabolite production strains can rapidly be constructed by random targeting of chromosomal promoters by Tn5 transposition.Feasibility of this approach was corroborated by prodigiosin production after yTREX cloning,transfer and expression of the respective biosynthesis genes from Serratia marcescens.Furthermore,the applicability of the system for effective pathway rerouting by gene cluster adaptation was demonstrated using the violacein biosynthesis gene cluster from Chromobacterium violaceum,producing pathway metabolites violacein,deoxyviolacein,prodeoxyviolacein,and deoxychromoviridans.Clones producing both prodigiosin and violaceins could be readily identified among clones obtained after random chromosomal integration by their strong color-phenotype.Finally,the addition of a promoter-less reporter gene enabled facile detection also of phenazine-producing clones after transfer of the respective phenazine-1-carboxylic acid biosynthesis genes from Pseudomonas aeruginosa.All compounds accumulated to substantial titers in the mg range.We thus corroborate here the suitability of P.putida for the biosynthesis of diverse natural products,and demonstrate that the yTREX system effectively enables the rapid generation of secondary metabolite producing bacteria by activation of heterologous gene clusters,applicable for natural compound discovery and combinatorial biosynthesis.展开更多
Bacillus subtilis N-2 which was isolated from natto,produced lipopeptides using soybean meal as a substrate.This work aimed to purify,identify,and determine the antibacterial mechanism of lipopeptides produced by B.su...Bacillus subtilis N-2 which was isolated from natto,produced lipopeptides using soybean meal as a substrate.This work aimed to purify,identify,and determine the antibacterial mechanism of lipopeptides produced by B.subtilis N-2.The fermented product obtained by solid-state fermentation was subjected to water extraction,acid precipitation,and methanol extraction.Fractions were separated and collected using a two-step ultrafiltration method and then identified by LC-MS/MS.Mass spectrometry characterization revealed the presence of four variants of iturin A that differed according to the p-amino fatty acid chain from C14 to C17 as well as the amino acid positions.A new lipopeptide(m/z 1070.3)was identified and its structure was different from the previously reported lipopeptides.The lipopeptides were shown to inhibit the growth of an isolate of Pseudomonas putida,a common pathogen in decaying fish,by changing membrane permeability.These results suggest that the lipopeptides from B.subtilis N-2 could be used as a biocontrol agent in aquaculture.展开更多
Acute bacterial meningitis(ABM)is the medical emergency which warrants an early diagnosis and an aggressive therapy.Despite the availability of the potent newer antibiotics,the mortality caused by ABM and its complica...Acute bacterial meningitis(ABM)is the medical emergency which warrants an early diagnosis and an aggressive therapy.Despite the availability of the potent newer antibiotics,the mortality caused by ABM and its complications remain high in India,ranging from 16%to 32%.The aim of this case report is to present the rare isolation of Pseudomonas putida from cerebrospinal fluid sample.Besides this,the author also emphasizes the importance of correctly identifying the organism and thus the selection of the most accurate antibiotic from the susceptibility profile to allow for early recovery and to improve the patient outcome and survival.展开更多
A Pseudomonas strain(named as P.PAO-1) with phosphorous removal function was isolated and characterized.A new method of two-stage cultivation was applied to the strain to induce the synthesis of intracellular polyhydr...A Pseudomonas strain(named as P.PAO-1) with phosphorous removal function was isolated and characterized.A new method of two-stage cultivation was applied to the strain to induce the synthesis of intracellular polyhydroxylbutyrate(PHB) in the cells.In the first stage,bacterial cells were enriched under a high carbon source condition;in the second stage,the bacteria cells were cultivated under the nutrient-imbalanced conditions with the carbon source-regulated medium.As a result,the PHB content of strain P.PAO-1 reached 22.8% compared with the normal 7.41% in the non-acclimated strain.This change had led to the rising of P uptake from 1 to 25 mg·L^(-1).When added the strain P.PAO-1into the activated sludge(with the addition proportion of 1:1),the ratio of biological phosphorus removal increased by 14.9%under the normal alternating anaerobic/aerobic conditions with low-carbon consumption.The results demonstrated that the isolated pure culture strain P.PAO-1 belonged to the functional group of poly-P accumulating microorganism.When cultured by the two-stage cultivation method,the initial accumulation of PHB in the strain cells could be achieved and the phosphorous removal capacity of strain P.PAO-1 could be induced subsequently.When applied to the wastewater,strain P.PAO-1 performed phosphorus removal from the wastewater with or without the addition of activated sludge.展开更多
Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhiz...Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhizobacteria (PGPR) on garlic (Allium sativum L.) growth and biochemical contents. Garlic cloves were inoculated with 3 kinds of PGPRs, Pseudomonas putida (KX574857), Pseudomonas stutzeri (Kx574858) and Bacillus cereus (ATCC14579) at 10<sup>8</sup> cells/mL prior to sowing. Under natural conditions, plants were grown in the net house. The PGPR significantly enhanced % germination, leaf and root growth and their biomass also increased the diameter of bulb and fresh and dry weight. The flavonoids, phenolics, chlorophyll, protein and sugar content were also significantly increased due to PGPR inoculation. The Pseudomonas stutzeri was found most effective for producing longer leaves with moderate sugar, high flavonoids (129%) and phenolics (263%) in bulb over control (Tap). The Pseudomonas putida exhibited a maximum increase in bulb diameter and bulb biomass with maximum phenolics and flavonoid contents.展开更多
The survival adaptation of bacteria in saline soil is poor.The bilayer microcapsules were prepared by secondary embedding of monolayer sodium alginate(NaAlg)-bentonite(Bent)-sodium carboxy-methylcellulose(CMC)microcap...The survival adaptation of bacteria in saline soil is poor.The bilayer microcapsules were prepared by secondary embedding of monolayer sodium alginate(NaAlg)-bentonite(Bent)-sodium carboxy-methylcellulose(CMC)microcapsules wrapped with plant growth promoting rhizobacteria(PGPR)Pseudomonas putida Rs-198 by chitosan solution to promote the synergistic effect of bilayer microen-capsulation and PGPR.The characterization of the Rs-198 bilayer microcapsules showed that the amino and carboxyl groups were cross-linked and a thin layer of chitosan was formed on the outside of the microcapsule.The bilayer microcapsule(Ch-d)with a chitosan concentration of 0.8 wt%and pH 6 showed a slow release of bacteria with a maximum release of 6.06 × 10^(9) cfu/g on the 7th day.The viable bacteria of Ch-d increased by 4.42%after 60 days of storage compared with monolayer microcapsules.The 0.9 wt%L-cysteine,10 wt%glycerinum,10 wt%trehalose and 12 wt%soluble starch were added as bacterial protective agents during the process of preparing the Ch-d lyophilized bacterial inoculant(Ch-d LBI).Pot experiments showed that Ch-d LBI exhibited better growth promotion of Capsicum annuum L.under salt stress.Therefore,the bilayer microcapsule as slow-release bacterial inoculant is a potential alternative for sustainable agriculture.展开更多
基金supported by the National Natural Sci- ence Foundation of China (No. 50278036)the National Hi-Tech Research and Development Program (863) of China (No. 2006AA06Z378)
文摘A bacterial strain that utilized o-chloronitrobenzene (o-CNB) as the sole carbon, nitrogen and energy sources was isolated from an activated sludge collected from an industrial waste treatment plant. It was identified as Pseudomonas putida based on its morphology, physiological, and biochemical characteristics with an automatic biometrical system and the 16S rRNA sequence analysis. Microcosm study showed that the biodegradation of o-CNB was optimized at culture medium pH 8.0 and 32℃. At these conditions, the strain degraded 85% of o-CNB at a starting concentration of 1.1 mmol/L in 42 h. o-Chloroaniline was identified as the major metabolite with high performance liquid chromatography (HPLC) and gas chromatography-mass spectrometry (GC-MS). The study showed that o-CNB degradation by Pseudomonas putida OCNB-1 was initiated by aniline dioxyenase, nitrobenzene reductase and catechol-l,2- dioxygenase.
基金National Natural Science Foundation of China(No.21777024)National Key Research and Development Project,China(No.2019YFC0408503)。
文摘Filamentous bacteria(FB)overgrowth is an important cause of sludge bulking in wastewater treatment plants(WWTPs).However,to date,methods for the cultivation and preservation of isolated FB in the laboratory have not been completely described.Furthermore,research on whether FB can function as phosphorus accumulating organisms(PAOs)is limited.In this study,a pure strain,a Pseudomonas putida PAO-1(P.putida PAO-1)isolate with phosphorus removal functions was isolated from the biofilm of an alternating anaerobic/aerobic biofilter(AABF),and its physiological characteristics were studied.Nitrate or nitrite could be used by the strain P.putida PAO-1 as electron acceptors for denitrification during phosphorus anoxic uptake,and 0.63 mg NO-3-N was consumed to reduce 1 mg soluble orthophosphate(SOP)by P.putida PAO-1.The strain P.putida PAO-1 consumed phosphorus within the optimal pH range of 6 to 8 and the temperature range of 25℃to 35℃.Cell deformity was a main morphological trait of the strain P.putida PAO-1,and it could elongate(with an elongation rate of 300%-500%)when it was subjected to oligotrophic or high-salt stress(15 g·L-1 NaCl).The findings in this study provide a microbiological reference for understanding the special characteristics of a denitrifying PAO.
基金supported by the National Natural Science Foundation of China (Nos.41991332,41977323 and 42090063)the National Institutes of Health (No.R35 GM136211)。
文摘Arsenic is a ubiquitous environmental pollutant.Microbe-mediated arsenic biotransformations significantly infuence arsenic mobility and toxicity.Arsenic transformations by soil and aquatic organisms have been well documented,while little is known regarding effects due to endophytic bacteria.An endophyte Pseudomonas putida ARS1 was isolated from rice grown in arsenic contaminated soil.P.putida ARS1 shows high tolerance to arsenite(As(Ⅲ))and arsenate(As(V)),and exhibits efficient As(V)reduction and As(Ⅲ)effux activities.When exposed to 0.6 mg/L As(V),As(V)in the medium was completely converted to As(Ⅲ)by P.putida ARS1 within 4 hr.Genome sequencing showed that P.putida ARS1 has two chromosomal arsenic resistance gene clusters(arsRCBH)that contribute to efficient As(V)reduction and As(Ⅲ)effux,and result in high resistance to arsenicals.Wolffia globosa is a strong arsenic accumulator with high potential for arsenic phytoremediation,which takes up As(Ⅲ)more efficiently than As(V).Co-culture of P.putida ARS1 and W.globosa enhanced arsenic accumulation in W.globosa by 69%,and resulted in 91%removal of arsenic(at initial concentration of 0.6 mg/L As(V))from water within 3 days.This study provides a promising strategy for in situ arsenic phytoremediation through the cooperation of plant and endophytic bacterium.
基金the National Natural Science Foundation of China(No.82073955 and 81773696)the Priority Academic Program Development of the Jiangsu Higher Education Institutes(PAPD).
文摘Hypocrellins are major bioactive perylenequinones from Shiraia fruiting bodies and have been developed as efficient photosensitizers for photodynamic therapy.Pseudomonas is the second dominant genus inside Shiraia fruiting bodies,but with less known actions on the host fungus.In this work,the effects of bacterial volatiles from the Shiraia-associated Pseudomonas on fungal hypocrellin production were investigated.Pseudomonas putida No.24 was the most active to promote significantly accumulation of Shiraia perylenequinones including hypocrellin A(HA),HC,elsinochrome A(EA)and EC.Headspace analysis of the emitted volatiles revealed dimethyl disulfide as one of active compounds to promote fungal hypocrellin production.The bacterial volatiles induced an apoptosis in Shiraia hyphal cell,which was associated with the generation of reactive oxygen species(ROS).ROS generation was proved to mediate the volatile-induced membrane permeability and up-regulation of gene expressions for hypocrellin biosynthesis.In the submerged volatile co-culture,the bacterial volatiles stimulated not only HA content in mycelia,but also HA secretion into the medium,leading to the enhanced HA production to 249.85 mg/L,about 2.07-fold over the control.This is the first report on the regulation of Pseudomonas volatiles on fungal perylenequinone production.These findings could be helpful to understand the roles of bacterial volatiles in fruiting bodies and also provide new elicitation method using bacterial volatiles to stimulate fungal secondary metabolite production.
基金The scientific activities of the Bioeconomy Science Center were financially supported by the Ministry of Innovation,Science and Research of the German federal state of North Rhine-Westphalia MIWF within the framework of the NRW Strategieprojekt BioSC(No.313/323-400-00213).
文摘Microbial secondary metabolites represent a rich source of valuable compounds with a variety of applications in medicine or agriculture.Effective exploitation of this wealth of chemicals requires the functional expression of the respective biosynthetic genes in amenable heterologous hosts.We have previously established the TREX system which facilitates the transfer,integration and expression of biosynthetic gene clusters in various bacterial hosts.Here,we describe the yTREX system,a new tool adapted for one-step yeast recombinational cloning of gene clusters.We show that with yTREX,Pseudomonas putida secondary metabolite production strains can rapidly be constructed by random targeting of chromosomal promoters by Tn5 transposition.Feasibility of this approach was corroborated by prodigiosin production after yTREX cloning,transfer and expression of the respective biosynthesis genes from Serratia marcescens.Furthermore,the applicability of the system for effective pathway rerouting by gene cluster adaptation was demonstrated using the violacein biosynthesis gene cluster from Chromobacterium violaceum,producing pathway metabolites violacein,deoxyviolacein,prodeoxyviolacein,and deoxychromoviridans.Clones producing both prodigiosin and violaceins could be readily identified among clones obtained after random chromosomal integration by their strong color-phenotype.Finally,the addition of a promoter-less reporter gene enabled facile detection also of phenazine-producing clones after transfer of the respective phenazine-1-carboxylic acid biosynthesis genes from Pseudomonas aeruginosa.All compounds accumulated to substantial titers in the mg range.We thus corroborate here the suitability of P.putida for the biosynthesis of diverse natural products,and demonstrate that the yTREX system effectively enables the rapid generation of secondary metabolite producing bacteria by activation of heterologous gene clusters,applicable for natural compound discovery and combinatorial biosynthesis.
基金supported by the National Key R&D Program of China(2017YFC1600703)the National Natural Science Foundation of China(31471657).
文摘Bacillus subtilis N-2 which was isolated from natto,produced lipopeptides using soybean meal as a substrate.This work aimed to purify,identify,and determine the antibacterial mechanism of lipopeptides produced by B.subtilis N-2.The fermented product obtained by solid-state fermentation was subjected to water extraction,acid precipitation,and methanol extraction.Fractions were separated and collected using a two-step ultrafiltration method and then identified by LC-MS/MS.Mass spectrometry characterization revealed the presence of four variants of iturin A that differed according to the p-amino fatty acid chain from C14 to C17 as well as the amino acid positions.A new lipopeptide(m/z 1070.3)was identified and its structure was different from the previously reported lipopeptides.The lipopeptides were shown to inhibit the growth of an isolate of Pseudomonas putida,a common pathogen in decaying fish,by changing membrane permeability.These results suggest that the lipopeptides from B.subtilis N-2 could be used as a biocontrol agent in aquaculture.
文摘Acute bacterial meningitis(ABM)is the medical emergency which warrants an early diagnosis and an aggressive therapy.Despite the availability of the potent newer antibiotics,the mortality caused by ABM and its complications remain high in India,ranging from 16%to 32%.The aim of this case report is to present the rare isolation of Pseudomonas putida from cerebrospinal fluid sample.Besides this,the author also emphasizes the importance of correctly identifying the organism and thus the selection of the most accurate antibiotic from the susceptibility profile to allow for early recovery and to improve the patient outcome and survival.
基金National Natural Science Foundation of China(No.51478099)Scientific Research Foundation for Returned Overseas Chinese Scholars,China(No.SEM-11W11329)Natural Science Foundation of Shanghai,China(No.16ZR1402000)
文摘A Pseudomonas strain(named as P.PAO-1) with phosphorous removal function was isolated and characterized.A new method of two-stage cultivation was applied to the strain to induce the synthesis of intracellular polyhydroxylbutyrate(PHB) in the cells.In the first stage,bacterial cells were enriched under a high carbon source condition;in the second stage,the bacteria cells were cultivated under the nutrient-imbalanced conditions with the carbon source-regulated medium.As a result,the PHB content of strain P.PAO-1 reached 22.8% compared with the normal 7.41% in the non-acclimated strain.This change had led to the rising of P uptake from 1 to 25 mg·L^(-1).When added the strain P.PAO-1into the activated sludge(with the addition proportion of 1:1),the ratio of biological phosphorus removal increased by 14.9%under the normal alternating anaerobic/aerobic conditions with low-carbon consumption.The results demonstrated that the isolated pure culture strain P.PAO-1 belonged to the functional group of poly-P accumulating microorganism.When cultured by the two-stage cultivation method,the initial accumulation of PHB in the strain cells could be achieved and the phosphorous removal capacity of strain P.PAO-1 could be induced subsequently.When applied to the wastewater,strain P.PAO-1 performed phosphorus removal from the wastewater with or without the addition of activated sludge.
文摘Garlic is a most important medicinal herb belonging to the family Liliaceae. Both its leaves and bulb are edible. The current study was based on evaluating the growth promoting potential of plant growth promoting rhizobacteria (PGPR) on garlic (Allium sativum L.) growth and biochemical contents. Garlic cloves were inoculated with 3 kinds of PGPRs, Pseudomonas putida (KX574857), Pseudomonas stutzeri (Kx574858) and Bacillus cereus (ATCC14579) at 10<sup>8</sup> cells/mL prior to sowing. Under natural conditions, plants were grown in the net house. The PGPR significantly enhanced % germination, leaf and root growth and their biomass also increased the diameter of bulb and fresh and dry weight. The flavonoids, phenolics, chlorophyll, protein and sugar content were also significantly increased due to PGPR inoculation. The Pseudomonas stutzeri was found most effective for producing longer leaves with moderate sugar, high flavonoids (129%) and phenolics (263%) in bulb over control (Tap). The Pseudomonas putida exhibited a maximum increase in bulb diameter and bulb biomass with maximum phenolics and flavonoid contents.
基金supported by the National Natural Science Foundation of China(grant No.U1803332,22278325)Xi'an Science and Technology Plan Project Agricultural Technology R&D Project(grant No.21NYYF0030,22NYYF037)+2 种基金the Scientific Research Plan for Local Special Service of Shaanxi Provincial Education Department(grant No.20JC014)Preferential Funding Projects for Scientific and Technological Activities of Overseas Scholar(grant No.2020018)Key Research and Development Program of Xianyang City(grant No.S2021ZDYF-NY-0024)。
文摘The survival adaptation of bacteria in saline soil is poor.The bilayer microcapsules were prepared by secondary embedding of monolayer sodium alginate(NaAlg)-bentonite(Bent)-sodium carboxy-methylcellulose(CMC)microcapsules wrapped with plant growth promoting rhizobacteria(PGPR)Pseudomonas putida Rs-198 by chitosan solution to promote the synergistic effect of bilayer microen-capsulation and PGPR.The characterization of the Rs-198 bilayer microcapsules showed that the amino and carboxyl groups were cross-linked and a thin layer of chitosan was formed on the outside of the microcapsule.The bilayer microcapsule(Ch-d)with a chitosan concentration of 0.8 wt%and pH 6 showed a slow release of bacteria with a maximum release of 6.06 × 10^(9) cfu/g on the 7th day.The viable bacteria of Ch-d increased by 4.42%after 60 days of storage compared with monolayer microcapsules.The 0.9 wt%L-cysteine,10 wt%glycerinum,10 wt%trehalose and 12 wt%soluble starch were added as bacterial protective agents during the process of preparing the Ch-d lyophilized bacterial inoculant(Ch-d LBI).Pot experiments showed that Ch-d LBI exhibited better growth promotion of Capsicum annuum L.under salt stress.Therefore,the bilayer microcapsule as slow-release bacterial inoculant is a potential alternative for sustainable agriculture.