Anti-bacterial mechanism of baicalin-tobramycin combination on carbapenem-resistant Pseudomonas aeruginosa

BACKGROUND Pseudomonas aeruginosa(P.aeruginosa)is an important cause of nosocomial infections,and contributes to high morbidity and mortality,especially in intensive care units.P.aeruginosa is considered a'critical'category bacterial pathogen by the World Health Organization to encourage an urgent need for research and development of new antibiotics against its infections.AIM To investigate the effectiveness of baicalin combined with tobramycin therapy as a potential treatment method for carbapenem-resistant P.aeruginosa(CRPA)infections.METHODS Polymerase chain reaction(PCR)and RT-PCR were used to detect the expression levels of drug-resistant genes(including VIM,IMP and OprD2)and biofilmrelated genes(including algD,pslA and lasR)in CRPA that confer resistance to tobramycin,baicalin and tobramycin combined with baicalin(0,1/8,1/4,1/2 and 1MIC).RESULTS There was a correlation between biofilm formation and the expression of biofilmrelated genes.In addition,VIM,IMP,OprD2,algD,pslA and lasR that confer biofilm production under different concentrations in CRPA were significantly correlated.The synergistic effect of baicalin combined with tobramycin was a significant down-regulation of VIM,IMP,algD,pslA and lasR.CONCLUSION Baicalin combined with tobramycin therapy can be an effective treatment method for patients with CRPA infection.

Association ofβ-lactam antimicrobial's exposure with carbapenem-resistant Pseudomonas aeruginosa infection:a cumulative meta-analysis

Background:Carbapenems are effective against severe Pseudomonas aeruginosa nosocomial infections.Therefore,carbapenem-resistant Pseudomonas aeruginosa is a serious public health threat.An understanding of the risk of inappropriate exposure to different antimicrobials in resistant Pseudomonas aeruginosa infection could help in elucidating the effective approach towards using antimicrobials in vulnerable patients with CRPA infection.Object:To investigate the association between exposure ofβ-lactam antimicrobials and CRPA infection relative to control patients.Methods:The MEDLINE/PubMed and OVID/Embase databases were used to search case-control and cohort studies in English language which reported antimicrobial exposure as risk factors for CRPA infection.The pooled odds ratios(OR)were calculated using a random-effect and fixed-effect model,and forest plots from a cumulative meta-analysis method were used to better show how pooled OR changed as updated evidence accumulated.Results:A total of 24 studies comprising 7039 participants were included for cumulative meta-analysis.A positive correlation was found between development of CRPA infection and exposure of beta-lactam antimicrobials:carbapenems(OR=7.60,95%CI:3.95 to 14.62,P<0.0001),imipenem(OR=9.81,95%CI:5.56 to 17.33),ampicillin(OR=1.86,95%CI:1.14 to 2.41),piperacillin(OR=2.82,95%CI:1.46 to 2.43),penicillins(OR=1.42,95%CI:0.90 to 2.24),cephalosporins(OR=1.88,95%CI:1.46 to 2.43)andβlactamase inhibitors(OR=1.96,95%CI:1.44 to 2.67).Further,exposure of other antimicrobial agents like quinolone(OR=2.35,95%CI:1.78 to 3.10),ciprofloxacin(OR=2.35,95%CI:1.66 to 3.95),aminoglycoside(OR=2.17,95%CI:1.60 to 2.95),amikacin(OR=3.11,95%CI:2.10 to 4.61),glycopeptides(OR=3.02,95%CI:1.92 to 4.75)and vancomycin(OR=3.26,95%CI:1.48 to 7.18),were also found to be positively associated with development of CRPA infection.Conclusions:Exposure of all kinds ofβ-lactams is significantly associated with development of carbapenemresistant Pseudomonas aeruginosa infection.These findings provide an impetus to take a more active approach while usingβ-lactam antimicrobials in patients with resistant Pseudomonas aeruginosa infections.

Microbiologically influenced corrosion resistance enhancement of coppercontaining high entropy alloy Fe_(x)Cu_(1−x)CoNiCrMn against Pseudomonas aeruginosa

To enhance the microbiologically influenced corrosion(MIC)resistance of FeCoNiCrMn high entropy alloy(HEAs),a series of Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs were prepared.Microstructural characteristics,corrosion behavior(morphology observation and electrochemical properties),and antimicrobial performance of Fe_(x)Cu_((1−x))CoNiCrMn HEAs were evaluated in a medium inoculated with typical corrosive microorganism Pseudomonas aeruginosa.The aim was to identify copper-containing FeCoNiCrMn HEAs that balance corrosion resistance and antimicrobial properties.Results revealed that all Fe_(x)Cu_((1−x))CoNiCrMn(x=1,0.75,0.5,and 0.25)HEAs exhibited an FCC(face centered cubic)phase,with significant grain refinement observed in Fe_(0.75)Cu_(0.25)CoNiCrMn HEA.Electrochemical tests indicated that Fe_(0.75)Cu_(0.25)CoNiCrMn HEA demonstrated lower corrosion current density(i_(corr))and pitting potential(E_(pit))compared to other Fe_(x)Cu_((1−x))CoNiCrMn HEAs in P.aeruginosa-inoculated medium,exhibiting superior resistance to MIC.Anti-microbial tests showed that after 14 d of immersion,Fe_(0.75)Cu_(0.25)CoNiCrMn achieved an antibacterial rate of 89.5%,effectively inhibiting the adhesion and biofilm formation of P.aeruginosa,thereby achieving resistance to MIC.

Molecular investigation of exoU and exoY virulence genes in Pseudomonas aeruginosa collected from hospitalized patients in North of Iran:A descriptive-analytical study

Objective:To investigate the frequency of exoU and exoY genes in patients with Pseudomonas aeruginosa infection.Methods:In this study,100 clinical isolates of Pseudomonas aeruginosa were collected from patients hospitalized in educational-therapeutic hospitals and were identified using standard microbiological tests.Then,the antibiotic resistance pattern of the isolates was determined by the disk agar diffusion method.The bacterial DNAs were extracted by the alkaline lysis method.Finally,the presence of exoU and exoY genes was evaluated by the PCR test.Results:In this study,47%,72%,29%,39%,40%,and 44%of the isolates were non-susceptible to piperacillin,aztreonam,ceftazidime,imipenem,tobramycin,and ciprofloxacin,respectively.In addition,95%and 93%of the clinical isolates carried the exoU and exoY genes.Blood and fecal isolates had both virulence genes,while only one wound isolate had neither genes.Meanwhile,all urinary isolates contained the exoY gene and only one isolate lacked the exoU gene.Also,88 isolates simultaneously had both exoU and exoY genes.Conclusions:High prevalence of exoU and exoY genes in this region indicates a significant role of typeⅢsecretion system in pathogenesis of Pseudomonas aeruginosa.The typeⅢsecretion system may be a suitable target to reduce the pathogenicity of this bacterium.

Evaluation of Azadirachta indica cultivated in Egypt against biofilm formation by Pseudomonas aeruginosa: Insights from molecular docking studies targeting LasR

Background:Azadirachta indica(A.indica),commonly known as neem,is a widely distributed medicinal plant in Asia and Africa and is well known to have a wide spectrum of biological activity.A.indica is considered a skin food that was traditionally used in different cultures to treat a wide range of skin disorders.A.indica was reported to possess antibacterial activity against Pseudomonas aeruginosa(P.aeruginosa)which is considered the most common biofilm model organism.This study aims to investigate the ability of A.indica cultivated in Egypt to inhibit/reduce the biofilm formation by P.aeruginosa.Methods:The microtiter plate assay was used to evaluate the anti-biofilm activity of neem,cultivated in Egypt,leaves against P.aeruginosa as well as the ability to reduce the activity of P.aeruginosa.To investigate the phytocompounds responsible for their bioactivity and to explore potential interactions between their bioactive components and one of the quorum-sensing regulatory proteins of P.aeruginosa involved in biofilm formation,liquid chromatography-mass spectrometric and molecular docking studies were done.Results:Results showed that methanol extract of leaves can reduce the formation of P.aeruginosa biofilm at lower concentrations than those reported in other regions with 1.25 mg/mL as the optimum concentration.The two-way analysis of variance revealed the significance of the extract effect and its concentration on the reduction of biofilm formation(P<0.05).Liquid chromatography-mass spectrometric study revealed the presence of fourteen compounds that belong to limonoids and flavonoids.Molecular docking analysis against LasR,the quorum-sensing regulatory protein,of P.aeruginosa supported these findings.Nimbolinin,a limonoid,has achieved the highest Libdock score of 138.769.Conclusion:It was concluded that A.indica,cultivated in Egypt,leaves can target LasR as a new mechanism of action for biofilm control by A.indica and therefore could be a good source of leads for anti-biofilm medicine.

Efficacy of Pudilan Xiaoyan Oral Liquid in the treatment of pneumonia induced by drug-resistant Pseudomonas aeruginosa

Background:Pudilan Xiaoyan Oral Liquid(PDL)is a Chinese patent medicine with notable pharmacological properties,including anti-inflammatory and antibacterial effects.Drug-resistant Pseudomonas aeruginosa infection is a common and refractory bacterial infection in clinical practice.Due to its high drug resistance,it brings great challenges to treatment.This study aimed to assess the therapeutic efficacy of PDL in a murine model of pneumonia induced by drug-resistant Pseudomonas aeruginosa.Methods:Three different doses of PDL(11 mL/kg/d,5.5 mL/kg/d,2.75 mL/kg/d)were used to observe lung tissue pathology and inflammatory cytokine levels in pneumonia mouse models induced by multidrug-resistant Pseudomonas aeruginosa(MDR-PA).Additionally,the protective efficacy of PDL against mortality in infected mice was evaluated using a death model caused by MDR-PA.Finally sub-MIC concentration of levofloxacin was used to induce drug-resistant mice pneumonia model to evaluate the role of PDL in reversing drug resistance.Experimental data are expressed as mean±standard deviation.Statistical significance was determined by one-way analysis of variance followed by Tukey’s multiple-comparisons test.Results:Treatment effect of PDL on MDR-PA pneumonia:the medium and small doses of PDL can significantly reduce the lung index of multi-drug resistant bacteria infected pneumonia model mice(P<0.05),the lung index inhibition rates for these groups were 55.09%and 58.43%,and improve the degree of lung tissue lesions of mice;The expression of serum cytokines keratinocyte chemoattractant,tumor necrosis factor-αand monocyte chemoattractant protein-1 could be decreased in the three dosage groups of PDL(P<0.01).PDL treatment not only lowered the mortality but also extended the survival duration in mice infected with MDR-PA.It was found after sub-MIC concentration of levofloxacin induced resistance of Pseudomonas aeruginosa to pneumonia in mice.Compared with the model group,the lung index of mice in high and medium PDL doses was significantly reduced(P<0.05),with inhibition rates of 32.16%and 37.73%,respectively.Conclusion:PDL demonstrates protective effects against MDR-PA infection pneumonia,notably decreasing serum inflammatory factor levels.It shows promise in mitigating antibiotic resistance and offers potential for treating pneumonia resulting from Pseudomonas aeruginosa resistance.

β-cyclopiazonic acid binds iron demonstrating siderophorelike activity and promotes growth in Pseudomonas aeruginosa

This chemical study reports a novel siderophore-like compound,β-cyclopiazonic acid(1,β-CPA)extracted from marine fungus Aspergillus flavus.The chemical structure ofβ-CPA was elucidated by a combination of extensive spectroscopic analyses and TDDFT-ECD calculations.The iron-binding ability and CAS assays demonstrate thatβ-CPA is a novel siderophore that features a different chemical structure from those of traditional siderophores.Theβ-CPA has no obvious influence on the growth of bacterium Pseudomonas aeruginosa PAO1.However,its iron chelator could promote the growth of P.aeruginosa PAO1,suggesting that P.aeruginosa employed siderophores to sequester iron,which is vital for their survival.The study provides the physiochemical evaluation ofβ-CPA,an unusual skeletonstructure siderophore,which for the first time,was proven to have the ability to bind iron and affect P.aeruginosa growth.This new discovery of siderophore provides an opportunity for developing novel anti-P.aeruginosa drugs.

Study on the Effect of Shuanghuanglian Powder Needle Combined with Cefoperazone and Sulbactam Sodium on Pseudomonas aeruginosa in Vitro

Objective: To explore the antibacterial activity of combined use of Shuanghuanglian and cefoperazone sulbactam sodium on resistant strains of Pseudomonas aeruginosa. Methods: The Pseudomonas aeruginosa strains which were sensitive and resistant to cefoperazone sulbactam sodium were selected to prepare different test bacterial solutions respectively;The experimental liquid of Shuanghuanglian and Cefoperazone Sulbactam Sodium were prepared separately and set as different test groups and control groups;The Drug Sensitivity Tests of Shuanghuanglian and cefoperazone sulbactam sodium at different concentration gradients which were used alone or used in combination were carried out for different strains with sensitivity and resistance, And use standard entry as a reference control. Result: The results of drug sensitivity test of Shuanghuanglian combined with Cefoperazone-Sulbactam sodium against the resistant strains of Pseudomonas aeruginosa were compared with the results of drug sensitivity test of the two separately used, and the difference was statistically significant (P 〈 0.05) [The drug sensitivity test results of Shuanghuanglian and cefoperazone sulbactam sodium to Pseudomonas aeruginosa resistant strains were statistically significant compared with the drug sensitivity test results of Shuanghuanglian and Cefoperazone Sulbactam Sodium used separately (P 〈 0.05)];There was a dependence between strains and concentration in the effect of the combination of the two drugs. Conclusion: The combination of Shuanghuanglian and cefoperazone sulbactam sodium has synergistic antibacterial or bactericidal effect on Pseudomonas aeruginosa resistant strains. .

Antimicrobial Resistance of Pseudomonas aeruginosa Isolated from Human Infections in N’Djamena, Chad

Background: Urinary Tract infections and pus are major public health problems. The evolution of bacterial resistance to antibiotics makes the treatment of these infections problematic. This is why this study is undertaken to identify and evaluate the resistance of Pseudomonas aeruginosa to antibiotics. Methods: This is a prospective study carried out from December 2020 to November 2021. The germs were isolated on the agar supplemented with cetrimide and identified by the API 20 NE gallery method according to the manufacturer’s protocol. The strains’ resistance profiles were determined by the diffusion method on Mueller-Hinton according to the criteria EUCAST- 2021. Results: A total of 46/1467 (3.13%) Pseudomonas aeruginosa were identified, of which 29/1008 (2.87%) were urinary tract infections and 17/459 (3.70%) were pus. The high resistances were: 97.8% to ceftazidim, 91.3% to aztreonam, 93.5% to cefepim, 82.6% to piperacillin, 58.7% to levofloxacin, 52.2% to amikacin, 47.8% to tazobactam-piperacillin, 47.8% to tobramycin and 43.5% to ciprofloxacin. Low resistance was only 2.2% to fosfomycin, 2.2% to colistin and 15.2% to imipenem. Conclusion: This study reveals the considerable resistance of Pseudomonas aeruginosa to commonly used antibiotics, and thus compromises the empirical treatment practiced in hospitals. This result motivates the need to carry out susceptibility testing of isolates before any prescription of antimicrobials.

Establishment of extensively drug-resistant Pseudomonas aeruginosa pneumonia model in rat

Objective:To establish extensively drug-resistant Pseudomonas aeruginosa(XDR-PA)infection-induced pneumonia model in rats.Methods:Twenty-four male SD rats were randomly divided into blank group,low bacterial group,medium bacterial group,and high bacterial group.The low,medium and high bacterial groups were given intratracheal instillation of 0.1 mL of bacterial suspension(bacterial concentration in turn is 7.5×10^(9),3×10^(10),6×10^(10)CFU/mL),while the blank group were given the same volume of sterile normal saline.After modeling,the general conditions of rats in each group were observed,including mental state,hair,respiration,activity,eating,weight,and the survival curve was drawn.The pathological characteristics of lung tissue and the infiltration of inflammatory cells were observed.Pathogenic identification of each group was carried out by bacterial culture of lung tissue homogenate.Results:The general state of the blank group was normal,and the rats in other groups showed signs of mental depression,bristling,shortness of breath,even oral and nasal bleeding,decreased food intake and activity,and significant weight loss,and different degrees of death within 48 hours,the difference was statistically significant(P<0.05).Pathological results showed that the alveolar structure of rats in the blank group was complete,and the alveolar space was clear without exudation.The lung tissue of the low and medium bacterial groups showed obvious inflammatory cell infiltration,alveolar structure destruction,alveolar septum thickening,interstitial edema,but the pathological damage of the medium group was more severe,with a mortality rate of up to 50%,and the mortality rate of the low bacterial group was 17%.In the high bacterial group,red blood cells,inflammatory cells and a large amount of fibrin-like exudation can be seen in the alveolar space,which has the pathological characteristics of acute respiratory failure,and the mortality rate is as high as 67%.The results of bacterial culture of lung tissue homogenate showed that the blank group had no bacterial colonies,while PA colony growth can be seen in low,medium and high bacterial groups.Conclusion:9 Intratracheal instillation of low bacterial count(0.1 mL of 7.5×10^(9) CFU/mL)XDR-PA bacterial suspension can successfully construct a rat pneumonia model of XDR-PA infection.

Kinetics of Bioremediation of Oil Contaminated Water Dispersed by Environment-Friendly Bacteria (Pseudomonas aeruginosa) and Fungi (Aspergillus niger)

The comparative effectiveness of remediating water polluted with crude oil, using environment-friendly bacteria (Pseudomonas aeruginosa) and fungi (Aspergillus niger) were investigated. The samples were separately treated with Aspergillus niger and Pseudomonas aeruginosa. The bioremediation kinetic efficiency for these systems was studied. At the end of the bioremediation periods, the oil and grease content of the samples decreased from 47.0 mg/L in the untreated sample to 7.0 mg/L after 20 days when inoculated with bacteria while the sample inoculated with fungi decreased to 10.0 mg/L. Post analysis when inoculated with bacteria showed a fall in the value of the biological oxygen demand (BOD) from 73.84 mg/L to 33.28 mg/L after 20 days, while, the fungi inoculated sample showed a reduction from 73.84 mg/L to 38.48 mg/L. The biodegradation process with the bacteria was consistent with the pseudo-first-order model with a rate constant of 0.0891 day-1, while the biodegradation process with the fungi was consistent with the first order reaction model with a rate constant of 0.422 day-1. The degree of degradation after the 20th day of inoculation with Pseudomonas aeruginosa was 85.11%, while with Aspergillus niger was 78.72%. Thus, the results obtained showed that, Pseudomonas aeruginosa performed better than Aspergillus niger. The bioremediation data with fungi fitted the first-order model, while that of the bacteria fitted the pseudo-first-order model. Therefore, the data obtained in this study could be applied in the design of a bioremediation system for potential application to remediation of crude oil polluted water.

Enhancing Accumulation and Penetration Efficiency of Next-Generation Antibiotics to Mitigate Antibiotic Resistance in Pseudomonas aeruginosa PAO1

This study explores the efficacy of advanced antibiotic compounds against P. aeruginosa, focusing on Antibiotic B, an enhanced derivative of Ceftriaxone. The study measured the intracellular uptake of Antibiotic B and introduced a novel adjuvant, Influximax, which augmented its antibacterial activity. Results showed a diminished potential for resistance emergence with Antibiotic B, particularly when used in combination with Influximax. The study suggests that optimizing antibiotic delivery into bacterial cells and leveraging syner-gistic adjuvant combinations can enhance drug resistance combat. .

Analysis of Clinical Characteristics and Risk Factors of Pseudomonas aeruginosa Bloodstream Infection in 55 Cases

Objective: Pseudomonas aeruginosa bloodstream infection presents a severe challenge to hospitalized patients. To investigate the clinical characteristics, risk factors and drug resistance of Pseudomonas aeruginosa bloodstream infection. Methods: Clinical data and laboratory results of patients with Pseudomonas aeruginosa bloodstream infection in the First Affiliated Hospital of Yangtze University from January 2019 to December 2022 were retrospectively analyzed. The factors associated with infection and death were analyzed by univariate analysis. Results: A total of 55 patients were enrolled in this study, The 28-day mortality rate was 14.5%. Univariate analysis showed that high procalcitonin, low albumin, ICU admission, central venous catheterization, indwelling catheter, and mechanical ventilation were associated with death. Multivariate Logistic regression analysis showed that hypoproteinemia and central venous catheters were independent risk factors for death in patients with Pseudomonas aeruginosa bloodstream infection. Conclusions: The drug resistance of P. aeruginosa bloodstream infection is not high, but the fatality rate is high. The combination of hypoalbuminemia after the onset of the disease and the use of central vein catheters can lead to increased mortality, suggesting that clinical identification of high-risk patients as early as possible, reducing the use of catheters, preventing the occurrence of P. aeruginosa bloodstream infection and improving the prognosis.

Prokaryotic Expression of Pseudomonas Aeruginosa Lipase Gene

[Objective] The aim of this study was to investigate the prokaryotic expression of pseudomonas aeruginosa Lipase gene.[Method]Lipase gene was amplified by PCR from the genome DNA of pseudomonas aeruginosa,and its nucleotide sequence was determined.The prokaryotic expression vector of Lipase gene was constructed by the gene recombination technique.The protein expression was induced for 4 hours by IPTG with the final concentration of 1.0 mmol/L,and then SDS-PAGE electrophoresis was analyzed.[Result]The sequence of mature peptides in Lipase gene cloned from pseudomonas aeruginosa had a 99.36% homology with that of pseudomonas aeruginosa lipase submitted in NCBI,so the prokaryotic expression vector of Lipase gene pET32a-Lip was successfully constructed.Furthermore,the results of SDS-PAGE electrophoresis showed that the target gene was expressed highly and effectively.[Conclusion]The cloned pseudomonas aeruginosa lipase with its signal peptide could be normally expressed in E.coli and also used for further study.

铜绿假单胞菌(Pseudomonas aeruginosa)BS-03的诱变育种及产鼠李糖脂类生物表面活性剂的摇瓶工艺初探

采用UV、UV+LiCl对铜绿假单胞菌(Pseudomonasaeruginosa)BS-03的野生菌株进行诱变,筛选出一株糖脂产量较高的菌株LY4,可将产量由41g/L提高至68g/L。并对其摇瓶发酵工艺进行了初步研究,较高产量(893g/L)的适宜发酵条件为植物油6%,尿素02%,一定量的无机盐,34℃,初始pH值为8,搅拌转速200～240r/min,发酵周期2d。

好氧反硝化菌Pseudomonas aeruginosa NO62筛选分离与性质鉴定

从生活污水处理场活性污泥中筛选分离到1株具有好氧反硝化特性的菌株NO62,经过常规生理生化鉴定、Vitek-32细菌鉴定系统鉴定结合16S rDNA鉴定,确定其为铜绿假单胞菌(Pseudomonas aeruginosa)。菌株P.aeruginosa NO62在好氧培养(150 r/min)时在37℃生长最好,但其反硝化活性则在30℃培养时最好。反硝化活性与菌体生长成正相关,在菌体的对数生长期硝态氮迅速被还原成亚硝态氮,继续培养则亚硝态氮浓度也逐渐降低,表明亚硝态氮被进一步还原。通过PCR的方法在NO62的总DNA中也检测到硝酸盐还原酶的编码基因narG。对NO62菌株反硝化活性的研究,可为该菌应用于污水脱氮处理奠定良好的理论基础。

Study on the Phosphorus Metabolism of Microcystis aeruginosa and Adnascent Pseudomonas under Different pH Conditions

[Objective] The study aimed to discuss the effects of pH value on the growth metabolism of Microcystis aeruginosa and the phosphorus metabolism relationship with adnascent Pseudomonas.[Method] By the phosphorus uptake experiment of M.aeruginosa under different pH conditions(8.0-10.0) and the effect experiment on the phosphorus metabolism of M.aeruginosa and adnascent Pseudomonas under different pH conditions(7.0-9.0),the phosphorus uptake of M.aeruginosa in the short time and the growth curve of M.aeruginosa,the change of phosphorus concentration in the water,the change of total phosphorus content in M.aeruginosa in the longer time were measured.[Results] In the short time,pH value had the effects on the absorption phosphorus ability of M.aeruginosa.As pH value rose,the absorption phosphorus ability enhanced.During the longer time,the higher pH value was,the quicker the growth speed of M.aeruginosa was,and the better the growth situation was.M.aeruginosa had the ability of self regulation pH value and could use the phosphorus well in the water which was released from Pseudomonas.In the system of the algae,bacteria and water,the phosphorus in the bacteria played the role of phosphorus source which was released slowly.Though the phosphorus concentration was lower,it was favorable to the growth of algae.[Conclusions] pH value was the factor that affected the circle of the phosphorus element in the system of algae-bacteria-water.

1株铜绿假单胞菌(Pseudomonas aeruginosa)1217石油降解特性及相关基因分析（英文）

从石油污染土壤中分离得到1株石油降解菌1217,经细菌形态学、生理生化及16S rD NA序列分析初步鉴定为铜绿假单胞菌(Pseudomonas aeruginosa)。在温度5~65℃,pH 2~10,盐度0~9%的条件下菌株能很好生长,在以正十二烷、正十八烷、苯、甲苯、二甲苯和萘为唯一碳源的培养基中生长良好。在10℃和30℃条件下培养7 d,对原油的降解率分别为21.57%和15.15%。菌株产生的生物表面活性剂可以将表面张力从72.20 mN/m降至35.14 mN/m。利用特异性PCR扩增,在菌株中检测到烷烃单加氧酶、甲苯双加氧酶、联苯双加氧酶、芳香烃双加氧酶和氧化还原酶基因,并成功克隆出烷烃单加氧酶和芳烃双加氧酶基因,同相关基因比对分析,与铜绿假单胞菌PAO1的相应基因相似度分别为99.91%和99.22%。研究表明,菌株在生物修复和石油烃污染环境中具有潜在的应用价值。

Pseudomonas aeruginosa菌的原油除蜡降黏性能

采用单细胞Raman-D2O同位素标记技术确定了5种原油嗜蜡菌中的优势菌种;考察了其最佳生长条件,并对其代谢产物及其对原油的除蜡降黏性能进行测定。结果表明:优势原油嗜蜡菌种为SS1,属于铜绿假单胞菌属(Pseudomonas aeruginosa);其最佳生长条件为温度36℃、pH值7、NaCl质量浓度5 g/L;该菌种在生长代谢过程中产生糖脂类生物表面活性剂,乳化系数高达63.75%;用该菌种对原油处理120 h后,原油蜡降解率为53.16%,析蜡点及析蜡高峰点均有所降低;在36℃下,其对原油降黏率达到72.84%。

耐有机溶剂蛋白酶高产菌Pseudomonas aeruginosa PT121的发酵条件

优化了耐有机溶剂蛋白酶产生菌株Pseudomonas aeruginosa PT121的产酶发酵条件。通过单因子试验探索了碳源、有机氮源对菌株发酵产酶的影响;通过正交试验对甘油、果糖、胰蛋白胨进行了水平组合优化。正交试验的方差分析表明,培养基中各成分显著性排列顺序为:胰蛋白胨>甘油>果糖。采用优化后培养基发酵72h,发酵液蛋白酶酶活达到12758U/mL,比优化前提高了6.3倍,为现有国内外报道中耐有机溶剂蛋白酶最高发酵产量。