Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance an...Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance and plant growth-promoting traits,was isolated from abandoned mine soil.Strain ME1 exhibited growth at concentrations of Zn up to 250 mg/L,Cd and Pb up to 100 mg/L,and Cr up to 50 mg/L.It had the ability to produce the plant hormone indole-3-acetic acid and siderophores along with 1-aminocyclopropane-1-carboxylic acid deaminase and protease activities.Additionally,it showed antioxidant activity,including catalase and 2,2-diphenyl-1-picryhydrazyl(DPPH)scavenging activities.The optimal conditions for melanin production by ME1 were a pH of 7 and a temperature of 35℃.At 1000 mg/L,ME1-extracted melanin exhibited DPPH radical scavenging activity of(25.040±0.007)%,a sun protection factor of 15.200±0.260,and 19.6%antibacterial activity against the plant pathogen Xanthomonas campestris.Furthermore,its adsorption capacity was(0.235±0.073)mg/g melanin for Zn and(0.277±0.008)mg/g melanin for Ni.In plants of Brassica chinensis grown under conditions of hydroponic cultivation with single heavy metal contamination of Cd,Zn,Pb,or Cr,the removal efficiency of each heavy metal was improved by 0.1–1.8 times after 3 d following inoculation with the strain ME1 compared to the plants grown under the same conditions without inoculation.In addition,ME1 inoculation improved the removal efficiency of each heavy metal by 0.1–1.0 times under multiple heavy metal contamination conditions.These findings suggest that Acinetobacter sp.ME1 could be used to enhance phytoremediation efficiency in heavy metal-contaminated soils.Moreover,the melanin it produces also holds promise in cosmetics,household products,and medical applications due to its photoprotective,antioxidant,and antimicrobial properties.展开更多
A new phenol-degrading bacterium with high biodegradation activity and high tolerance of phenol, strain PD 12, was isolated from the activated sludge of Tianjin Jizhuangzi Wastewater Treatment Facility in China. This ...A new phenol-degrading bacterium with high biodegradation activity and high tolerance of phenol, strain PD 12, was isolated from the activated sludge of Tianjin Jizhuangzi Wastewater Treatment Facility in China. This strain was capable of removing 500 mg phenol/L in liquid minimal medium by 99.6% within 9 h and metabolizing phenol at concentrations up to 1100 mg/L. DNA sequencing and homologous analysis of 16S rRNA gene identified PD12 to be an Acinetobacter sp. Polyvinyl alcohol （PVA） was used as a gel matrix to immobilize Acinetobacter sp. strain PDI2 by repeated freezing and thawing. The factors affecting phenol degradation of immobilized cells were investigated, and the results showed that the immobilized cells could tolerate a high phenol level and protected the bacteria against changes in temperature and pH. Storage stability and reusability tests revealed that the phenol degradation functions of immobilized cells were stable after reuse for 50 times or storing at 4℃ for 50 d. These results indicate that immobilized Acinetobacter sp. strain PD 12 possesses a good application potential in the treatment of phenol-containing wastewater.展开更多
A gram negative bacterium,named JDC-16,which can grow well on the substrate of phthalic acid esters(PAEs) as the sole source of carbon and energy,was isolated from river sludge.Based on the morphology,physiological an...A gram negative bacterium,named JDC-16,which can grow well on the substrate of phthalic acid esters(PAEs) as the sole source of carbon and energy,was isolated from river sludge.Based on the morphology,physiological and biochemical properties and analysis of 16S rRNA gene sequence,it was preliminarily identified belonging to the genus Acinetobacter.The result of substrates utilization range indicates that strain JDC-16 can utilize a variety of phthalates except for diisononyl phthalate(DINP) .The degradation tests using diethyl phthalate(DEP) as the model compound show that the optimal pH and temperature for DEP degradation by Acinetobacter sp.JDC-16 is 8.0 and 35℃,respectively.Meanwhile,degradation kinetics under various initial concentrations of DEP reveals that substrate depletion curves fit well with the modified Gompertz model with high correlation coefficient(R 2 >0.99) .Furthermore,the substrate induction test indicates that DEP-induction can apparently shorten the lag phase and enhance the degradation rate.This work highlights the potential of this isolate for bioremediation of phthalates-contaminated environments.展开更多
Strain EDP3 was isolated from an industrial-activated sludge. It belonged to the gamma group of Pro-teobacteria with an identity of 97.0% to Acinetobacter calcoaceticus according to the 16S rRNA gene sequences. It can...Strain EDP3 was isolated from an industrial-activated sludge. It belonged to the gamma group of Pro-teobacteria with an identity of 97.0% to Acinetobacter calcoaceticus according to the 16S rRNA gene sequences. It can tolerate up to 1000mg·L^-1 phenol at room temperature with a much longer lag phase. This indicates that higher phenol concentration has induced some physiological and genotypic changes in the bacterium. The aim of this study is, therefore, to investigate these responses to phenol concentration variations in strain EDP3. Proteome analysis is conducted by means of a two-dimensional polyacrylamide gel electrophoresis （2D PAGE） and matrix-assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF-MS） was conducted to obtain a deeper insight into the adaptive responses inside the bacterium. Comparative analysis of the proteome profiles of strain EDP3. grown in 400mg·L^-1 and 1000mg·L^-1 phenol allowed us to identify that among all the proteins up-regulated under the higher phenol concentration, oxidative stress proteins were dominant. The synthesis of a heat shock protein, 60000 chaperonin GroEL, was also amplified. In addition, the expression of one membrane protein, adenosine 5＇-triphosphate （ATP）-binding cassette （ABC） type sugar transporter, was found up-regulated. The inhibition of adenosine 5＇-triphosphate （ATP） and RNA/protein synthesis was also observed.展开更多
基金supported by the National Research Foundation of Korea(NRF)grants funded by the Korean government,the Ministry of Science,and the Ministry of Science and Information and Communication Technology(ICT(MSIT))(Nos.2022R1A2C2006615 and RS2023-00217228).
文摘Microorganisms inhabiting soils contaminated with heavy metals produce melanin,a dark brown pigment,as a survival strategy.In this study,a melanin-producing bacterium,Acinetobacter sp.ME1,with heavy metal tolerance and plant growth-promoting traits,was isolated from abandoned mine soil.Strain ME1 exhibited growth at concentrations of Zn up to 250 mg/L,Cd and Pb up to 100 mg/L,and Cr up to 50 mg/L.It had the ability to produce the plant hormone indole-3-acetic acid and siderophores along with 1-aminocyclopropane-1-carboxylic acid deaminase and protease activities.Additionally,it showed antioxidant activity,including catalase and 2,2-diphenyl-1-picryhydrazyl(DPPH)scavenging activities.The optimal conditions for melanin production by ME1 were a pH of 7 and a temperature of 35℃.At 1000 mg/L,ME1-extracted melanin exhibited DPPH radical scavenging activity of(25.040±0.007)%,a sun protection factor of 15.200±0.260,and 19.6%antibacterial activity against the plant pathogen Xanthomonas campestris.Furthermore,its adsorption capacity was(0.235±0.073)mg/g melanin for Zn and(0.277±0.008)mg/g melanin for Ni.In plants of Brassica chinensis grown under conditions of hydroponic cultivation with single heavy metal contamination of Cd,Zn,Pb,or Cr,the removal efficiency of each heavy metal was improved by 0.1–1.8 times after 3 d following inoculation with the strain ME1 compared to the plants grown under the same conditions without inoculation.In addition,ME1 inoculation improved the removal efficiency of each heavy metal by 0.1–1.0 times under multiple heavy metal contamination conditions.These findings suggest that Acinetobacter sp.ME1 could be used to enhance phytoremediation efficiency in heavy metal-contaminated soils.Moreover,the melanin it produces also holds promise in cosmetics,household products,and medical applications due to its photoprotective,antioxidant,and antimicrobial properties.
基金Project supported by the Undergraduate Research Foundation of Nankai University (2004).
文摘A new phenol-degrading bacterium with high biodegradation activity and high tolerance of phenol, strain PD 12, was isolated from the activated sludge of Tianjin Jizhuangzi Wastewater Treatment Facility in China. This strain was capable of removing 500 mg phenol/L in liquid minimal medium by 99.6% within 9 h and metabolizing phenol at concentrations up to 1100 mg/L. DNA sequencing and homologous analysis of 16S rRNA gene identified PD12 to be an Acinetobacter sp. Polyvinyl alcohol （PVA） was used as a gel matrix to immobilize Acinetobacter sp. strain PDI2 by repeated freezing and thawing. The factors affecting phenol degradation of immobilized cells were investigated, and the results showed that the immobilized cells could tolerate a high phenol level and protected the bacteria against changes in temperature and pH. Storage stability and reusability tests revealed that the phenol degradation functions of immobilized cells were stable after reuse for 50 times or storing at 4℃ for 50 d. These results indicate that immobilized Acinetobacter sp. strain PD 12 possesses a good application potential in the treatment of phenol-containing wastewater.
基金Project(30770388) supported by the National Natural Science Foundation of China
文摘A gram negative bacterium,named JDC-16,which can grow well on the substrate of phthalic acid esters(PAEs) as the sole source of carbon and energy,was isolated from river sludge.Based on the morphology,physiological and biochemical properties and analysis of 16S rRNA gene sequence,it was preliminarily identified belonging to the genus Acinetobacter.The result of substrates utilization range indicates that strain JDC-16 can utilize a variety of phthalates except for diisononyl phthalate(DINP) .The degradation tests using diethyl phthalate(DEP) as the model compound show that the optimal pH and temperature for DEP degradation by Acinetobacter sp.JDC-16 is 8.0 and 35℃,respectively.Meanwhile,degradation kinetics under various initial concentrations of DEP reveals that substrate depletion curves fit well with the modified Gompertz model with high correlation coefficient(R 2 >0.99) .Furthermore,the substrate induction test indicates that DEP-induction can apparently shorten the lag phase and enhance the degradation rate.This work highlights the potential of this isolate for bioremediation of phthalates-contaminated environments.
文摘Strain EDP3 was isolated from an industrial-activated sludge. It belonged to the gamma group of Pro-teobacteria with an identity of 97.0% to Acinetobacter calcoaceticus according to the 16S rRNA gene sequences. It can tolerate up to 1000mg·L^-1 phenol at room temperature with a much longer lag phase. This indicates that higher phenol concentration has induced some physiological and genotypic changes in the bacterium. The aim of this study is, therefore, to investigate these responses to phenol concentration variations in strain EDP3. Proteome analysis is conducted by means of a two-dimensional polyacrylamide gel electrophoresis （2D PAGE） and matrix-assisted laser desorption ionization time of flight mass spectrometry （MALDI-TOF-MS） was conducted to obtain a deeper insight into the adaptive responses inside the bacterium. Comparative analysis of the proteome profiles of strain EDP3. grown in 400mg·L^-1 and 1000mg·L^-1 phenol allowed us to identify that among all the proteins up-regulated under the higher phenol concentration, oxidative stress proteins were dominant. The synthesis of a heat shock protein, 60000 chaperonin GroEL, was also amplified. In addition, the expression of one membrane protein, adenosine 5＇-triphosphate （ATP）-binding cassette （ABC） type sugar transporter, was found up-regulated. The inhibition of adenosine 5＇-triphosphate （ATP） and RNA/protein synthesis was also observed.
