一株耐高氨氮菌株的筛选及脱氮性能研究

硝化反硝化生物脱氮被认为是目前有效的氨氮废水处理技术之一,其关键是高效脱氮微生物的筛选。本研究从养猪厂污水处理池中筛选异养硝化好氧反硝化细菌,并探究其生长性能和脱氮性能。结果筛选出一株异养硝化好氧反硝化细菌Acinetobacter junii YQ-1,当温度为30℃、转速为200 r/min、初始pH值为8、接种量为2.0%(V/V)、培养时间为48 h时,菌株YQ-1具有最高的菌体密度(OD_(595)=0.999),且脱氮效果最好。在最佳生长条件下,当初始氨氮浓度、亚硝态氮和硝态氮浓度均为200 mg/L时,菌株YQ-1在48 h对这3种形式氮素的降解率分别达到89.73%、63.51%和70.19%。且当氨氮浓度为1000 mg/L时,菌株YQ-1仍能较好地生长,其生长情况符合BidoseResp模型,培养基中化学需氧量(Chemical Oxygen Demand,COD)变化情况符合ExpDec2模型,培养基中化学需氧量(Chemical Oxygen Demand,COD)的减少速率与菌株YQ-1的生长速率呈正相关关系。本研究为异养硝化好氧反硝化菌处理高浓度氨氮污水的实际应用提供了参考。

典型微塑料对异养硝化-好氧反硝化菌的影响特性研究

以HN-AD中的不动杆菌属Acinetobacter sp.TAC-1为对象,探究了不同种类、粒径和浓度的典型微塑料对其生长活性及脱氮性能的影响。经研究发现:聚丙烯(PP)与聚氯乙烯(PVC)对TAC-1的生长和脱氮性能表现出轻微促进作用,最大分别提高了6.99%和5.7%,而PS对其有一定的抑制作用,最高减小了13.22%,PE则对菌株的影响不显著;在粒径控制条件下,PS组中,100 nm粒径促进了菌株生长但抑制了脱氮效果,30μm粒径抑制了生长但对脱氮无影响。在PP影响下,几乎所有粒径都促进了菌株的生长和脱氮能力;在5μm条件下菌株生长最好,但对脱氮能力促进最强的是100 nm和30μm,其TN去除率分别达到80.61%和77.72%;PE和PVC粒径对菌株生长和脱氮效果均有微弱的促进作用,但不受粒径大小影响。浓度控制实验中,PS浓度为1.0~2.0 g/L时会抑制菌株生长和脱氮效果,浓度增大为2.5 g/L时促进菌体生长和强化脱氮作用,增加了2.3%;PP、PE、PVC浓度对菌株生长和脱氮效果影响不显著。研究结果可为理解微塑料与高氨氮废水共污染环境中的脱氮过程提供参考,对相关污染水体的治理与处理具有指导意义。

Establishment of a Multiplex Detection Method for Common Bacteria in Blood Based on Human Mannan-Binding Lectin Protein-Conjugated Magnetic Bead Enrichment Combined with Recombinase-Aided PCR Technology

Objective Recombinase-aided polymerase chain reaction(RAP)is a sensitive,single-tube,two-stage nucleic acid amplification method.This study aimed to develop an assay that can be used for the early diagnosis of three types of bacteremia caused by Staphylococcus aureus(SA),Pseudomonas aeruginosa(PA),and Acinetobacter baumannii(AB)in the bloodstream based on recombinant human mannanbinding lectin protein(M1 protein)-conjugated magnetic bead(M1 bead)enrichment of pathogens combined with RAP.Methods Recombinant plasmids were used to evaluate the assay sensitivity.Common blood influenza bacteria were used for the specific detection.Simulated and clinical plasma samples were enriched with M1 beads and then subjected to multiple recombinase-aided PCR(M-RAP)and quantitative PCR(qPCR)assays.Kappa analysis was used to evaluate the consistency between the two assays.Results The M-RAP method had sensitivity rates of 1,10,and 1 copies/μL for the detection of SA,PA,and AB plasmids,respectively,without cross-reaction to other bacterial species.The M-RAP assay obtained results for<10 CFU/mL pathogens in the blood within 4 h,with higher sensitivity than qPCR.M-RAP and qPCR for SA,PA,and AB yielded Kappa values of 0.839,0.815,and 0.856,respectively(P<0.05).Conclusion An M-RAP assay for SA,PA,and AB in blood samples utilizing M1 bead enrichment has been developed and can be potentially used for the early detection of bacteremia.

Epidemiology of carbapenem-resistant Acinetobacter baumannii colonization in neonatal intensive care units:A systematic review and meta-analysis

BACKGROUND The rising prevalence of carbapenem-resistant Acinetobacter baumannii(CRAB)in neonatal intensive care units(NICUs)represents an escalating challenge in healthcare settings,particularly in managing hospital-acquired infections(HAIs).Studies across various World Health Organization regions have documented a significant incidence of CRAB-related HAIs,with rates as high as 41.7 cases per 1000 patients in ICUs,accounting for 13.6%of all HAIs.These infections pose a doubled mortality risk compared to infections with carbapenem-susceptible Acinetobacter baumannii.A particularly concerning aspect of CRAB colonization is its asymptomatic nature,enabling its transmission through healthcare workers(HCWs)or the NICU environment to vulnerable neonates with developing immune systems.AIM To explore the prevalence of CRAB colonization in NICUs,focusing on neonates,healthcare workers,and the environmental samples,to enhance epidemiological understanding and inform targeted interventions.METHODS We conducted according to PRISMA 2020 checklist guidelines,a comprehensive literature search across multiple databases including MEDLINE(Ovid),EMBASE(Ovid),Global Health(Ovid),Web of Science,and Global Index Me-dicus.Studies were selected based on predetermined criteria,primarily involving neonates,HCWs,and environmental swabs,using culture or molecular methods to detect CRAB colonization.We excluded studies that did not specifically focus on NICUs,were duplicates,or lacked necessary data.The study selection and quality assessment were conducted independently by two reviewers.Data extraction involved collecting comprehensive details about each study.Our statistical analysis used a random-effects model to calculate the pooled prevalence and confidence intervals,stratifying results by regional location.We assessed study heterogeneity using Cochran's Q statistic and I²statistic,with regression tests employed to evaluate potential publication bias.RESULTS We analyzed 737 records from five databases,ultimately including 13 studies from ten countries.For neonates,the pooled prevalence was 4.8%(95%CI:1.1%to 10.5%)with the highest rates observed in South-East Asia(10.5%;95%CI:2.4%to 23.3%).Among HCWs,a single Indian study reported a 3.3%prevalence.Environmental samples showed a prevalence of 2.3%(95%CI:0%to 9.3%),with the highest rates in South-East Asia(10%;95%CI:4.2%to 17.7%).Significant heterogeneity was found across studies,and no publication bias was detected.CONCLUSION This systematic review highlights a significant prevalence of CRAB colonization in neonates across various regions,particularly in South-East Asia,contrasting with lower rates in high-income countries.The study reveals a gap in research on HCWs colonization,with only a single study from India reporting moderate prevalence.Environmental samples indicate moderate levels of CRAB contamination,again higher in South-East Asia.These findings underscore the need for more extensive and focused research on CRAB colonization in NICUs,including exploring the roles of HCWs and the environment in transmission,understanding antimicrobial resistance patterns,and developing effective prevention measures.

Dissemination of carbapenem-non-susceptible Acinetobacter baumannii isolates collected from educational hospitals in Qazvin province of Iran

Background:Acinetobacter baumannii(A.baumannii)is known as an opportunistic pathogen related to health-care-associated infection that has a high antibiotic resistance potential,notably against carbapenems that are widely used to combat A.baumannii infections.This study aimed to detect oxacillin-hydrolyzing(OXA)carbapenemases and metallo-β-lactamases(MBL)among carbapenem-resistant A.baumannii isolated strains and to determine their clonal relationship by repetitive extragenic palindromic PCR(rep-PCR).Methods:In the present study,a total of 211 non-repetitive isolates of A.baumannii were collected from Qazvin educational hospitals(2016–2017).The disk diffusion method was used to investigate the antibiotic susceptibility of studied strains,followed by the detection of MBL and OXA-type genes using polymerase chain reaction(PCR)and sequencing methods.The rep-PCR method assessed the clonal relationship of carbapenem-non-susceptible A.baumannii isolates.Result:The obtained results showed that 87.2%and 86.7%of isolates were non-susceptible to imipenem and meropenem.The blaOXA-24(93.5%)was the most frequent gene,followed by the blaOXA-23(4.34%),blaIMP-1(1.63%),and blaVIM-1(0.54%).Meanwhile,blaOXA-58 and blaOXA-143 genes were not found.81.5%and 66.1%of isolates contained ISAba1 upstream of the blaOXA-23 and blaOXA-58 genes,respectively.Rep-PCR results revealed the carbapenem non-susceptible isolates belonged to three distinct clones:A 171(81%),B 34(16.1%),and C 6(2.8%).Conclusions:The results indicated a high prevalence of carbapenem-non-susceptible A.baumannii,with the emergence of the blaOXA-24 gene as the most common gene and the notable prevalence of MBL genes.These results revealed the need for appropriate therapeutic and infection control strategies and monitoring susceptibility patterns for controlling A.baumannii infections.

Clinical Efficacy and Safety Analysis of Tigecycline in the Treatment of Acute Exacerbation of Chronic Obstructive Pulmonary Disease Combined with Multidrug-Resistant Acinetobacter baumannii Infection

Objective:To study the clinical efficacy and safety of tigecycline in the treatment of acute exacerbation of chronic obstructive pulmonary disease(COPD)combined with multidrug-resistant Acinetobacter baumannii infection.Methods:113 patients with acute exacerbation of COPD combined with multidrug-resistant Acinetobacter baumannii infection were recruited between January 2021 and January 2023,and given tigecycline treatment.The total effective rate,lung function indexes,related biochemical index levels,and the incidence rate of adverse reactions were observed after the treatment.Results:After the treatment,100 patients were cured,1 case with apparent effect,2 cases were effective,10 cases were ineffective,and the total effective rate was 91.15%.The post-treatment CRP(21.22±3.35 mg/L),PCT(3.18±1.11 ng/L),CRE(76.36±9.24μmol/L),and ALT(37.76±6.99 U/L)were significantly improved as compared to the pre-treatment(P<0.05).After treatment,10 cases of vomiting(8.85%),13 cases of nausea(11.50%),4 cases of diarrhea(3.53%),1 case of abdominal pain(0.88%),and 2 cases of allergy(1.77%)were observed in 113 patients.Conclusion:Tigecycline therapy for patients with acute exacerbation of COPD combined with multidrug-resistant Acinetobacter baumannii infection not only has significant therapeutic efficacy but also has a high degree of safety.

Study on Distribution of Acinetobacter baumannii Complex in Dental Hospital Using Multiplex PCR

Purpose: In recent years, multidrug-resistant Acinetobacter baumannii has appeared and caused outbreaks of hospital infections all over the world. Close monitoring of this pathogen and other A. baumanii complex species is considered of critical importance to public health organizations. The reliable identification method able to distinguish A. baumannii from genetically close Acinetobacter species is needed, because these species are unable to be differentiated by phenotypic or biochemical methods. The purpose of the present study was to design species-specific primers in order to identify and detect A. baumanii complex species, and Acinetobacter lwoffii which is frequently detected from the human specimens, and to investigate the distribution of these organisms in dental hospital using a multiplex PCR. Methods: Polymerase chain reaction (PCR) primers were designed based on partial sequences of the 16S ribosomal RNA (16S rRNA) gene and DNA gyrase subunit B (gyrB) of each species of A. baumanii complex species. Swab samples were collected from ten dental spittoon units in dental hospital, and the distribution of A. baumanii complex species was investigated using a multiplex PCR. Results: These primers were able to distinguish each species of A. baumanii complex species clearly. A. baumanii and A. calcoaceticus were detected at 20.0% and 10.0% in ten swab samples, respectively. On the other hand, A. nosocomialis, A. lowffii, and A. pittii were detected from no sample. Conclusion: Our developed one-step multiplex PCR method is accurate, specific, cost-effective, time-saving, and worked without requiring DNA extraction.

Colistin Resistance Profiles, Molecular Investigation of mcr-1 and mcr-2 Plasmid Genes and Investigation of Carbapenemase Production in Pseudomonas and Acinetobacter Strains

Background and Purpose: The reintroduction of colistin as a last resort treatment against multi-resistant Gram-negative bacilli, is currently challenged by the emergence of colistin-resistant bacteria. The aim of this study was to assess the susceptibility of Pseudomonas and Acinetobacter strains to colistin, to identify carbapenemase production, and to investigate the plasmid genes involved in colistin resistance and carbapenemase production. Methodology: In order to establish the susceptibility profiles of 17 strains of Pseudomonas and Acinetobacter to colistin, their Minimum Inhibitory Concentrations (MICs) were determined using the liquid microdilution method. The possible production of carbapenemases was investigated with the modified Carbapenem Inactivation Method (mCIM). The search for genes encoding carbapenemases (blaOXA, blaIMP, blaCarba) and those responsible for plasmid resistance to colistin (mcr-1 and mcr-2) was performed by conventional PCR. Results and Conclusion: Ninety-four percent (94%) (16/17) of the strains were resistant to colistin. Intraspecies distribution was 50% (8/16), 31% (5/16), 13% (2/16) and 6% (1/16) for Acinetobacter baumannii, Pseudomonas aeruginosa, Pseudomonas luteola, and Pseudomonas fluorescens, respectively. Twenty-nine percent (29%) (6/17) of the strains produced carbapenemases. No mcr-1 and mcr-2 plasmid genes were detected. On the other hand, 17.6% (3/17) of the strains possessed the carbapenemase genes distributed as follows: Carba type (60%), OXA type (40%) and IMP type (0%). The results of this study highlight a high resistance to colistin in strains belonging to the genera Acinetobacter and Pseudomonas, and some of these strains produce carbapenemases.

Phenotypic Characterization and Prevalence of Carbapenemase-Producing Acinetobacter baumanii Isolates in Four Health Facilities in Cameroon

Background and Objective: Nowadays, the clinical utility of carbapenems is threatened by the emergence of resistant bacteria, favored by its increasing use. According to the WHO, Acinetobacter baumannii: nosocomial infection agent, tops the list of priority antibiotic-resistant pathogens, considered to be the riskiest for humans. This study sought to determine the prevalence of carbapenemase-producing Acinetobacter baumannii strains in four health facilities in the Center and Littoral regions of Cameroon and the associated risk factors. Materials and Method: An analytical cross-sectional study was conducted over a six-month period from January to June 2022. All suspicious A. baumanii isolates obtained from pathological samples at the bacteriology laboratory of the different health facilities were systematically collected and re-identified. Re-identification and antimicrobial susceptibility Testing (AST) were performed using the VITEK 2 System and the Kirby-Bauer method according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Detection and phenotypic characterization of carbapenemases was performed according to adequate standard procedures. Results: A total of 168/226 clinical isolates of Acinetobacter baumannii were confirmed after re-identification, among which 52.69% derived from male patients, 55.09% from participants aged between 10 - 39 years old, and 46.71% from pus samples. A very high resistance rates to all families of antibiotics was noted, except to colistin (10.2%). 40.12% of these isolates produced carbapenemase, represented by 62.69% of class B and 37.31% of class A. Carbapenemase production was observed only at HMR1, Centre region and at Laquintinie hospital, Littoral region with 53.33% and 50% respectively, even if there is no significant difference (P = 0.81). In addition, frequent hospitalisation was significantly associated to the production of carbapenemase among A. baumanii (Adjusted-OR = 16.53, P-value 0.0001). Conclusion: This study highlighted the emergence of carbapenemase-producing Acinetobacter baumannii which is increasingly growing. Continuous drug-resistant monitoring and preventive measures could help to prevent and curb the dissemination of A. baumanii resistance genes, especially in health settings.

Causative bacteria of ventilator-associated pneumonia in intensive care unit in Bahrain:Prevalence and antibiotics susceptibility pattern

BACKGROUND Ventilator-associated pneumonia(VAP)is defined as pneumonia that occurs two calendar days following endotracheal intubation or after that.It is the most common infection encountered among intubated patients.VAP incidence showed wide variability between countries.AIM To define the VAP incidence in the intensive care unit(ICU)in the central gove-rnment hospital in Bahrain and review the risk factors and the predominant bacterial pathogens with their antimicrobial susceptibility pattern.METHODS The research was a prospective cross-sectional observational study over six months from November 2019 to June 2020.It included adult and adolescent patients(>14 years old)admitted to the ICU and required intubation and mechanical ventilation.VAP was diagnosed when it occurred after 48 h after endotracheal intubation using the clinical pulmonary infection score,which considers the clinical,laboratory,microbiological,and radiographic evidence.RESULTS The total number of adult patients admitted to the ICU who required intubation and mechanical ventilation during the study period was 155.Forty-six patients developed VAP during their ICU stay(29.7%).The calculated VAP rate was 22.14 events per 1000 ventilator days during the study period,with a mean age of 52 years±20.Most VAP cases had late-onset VAP with a mean number of ICU days before the development of VAP of 9.96±6.55.Gram-negative contributed to most VAP cases in our unit,with multidrug-resistant Acinetobacter being the most identified pathogen.CONCLUSION The reported VAP rate in our ICU was relatively high compared to the international benchmark,which should trigger a vital action plan for reinforcing the implementation of the VAP prevention bundle.

Risk Factors Associated with MDR and CR Acinetobacter baumannii Carriage among ICU Patients Hospitalized at MOI Teaching and Referral Hospital, Kenya

Background: Multi-drug resistant and Carbapenem-Resistant Acinetobacter baumannii (CRAB) infections present a significant challenge in hospital ICU settings worldwide and the threat posed is worse in developing countries including Kenya. Despite the limited treatment options, there is inadequate comprehensive data on factors associated with MDR and CR Acinetobacter baumannii carriage among ICU patients hospitalized at hospitals. This study therefore aimed to address this gap and determined risk factors associated with MDR and CR Acinetobacter baumannii carriage among ICU patients hospitalized at MOI Teaching and Referral Hospital, Kenya. Methods: Through cross-sectional study design, a total of 132 ICU admitted patients were purposively enrolled in this study between July 2019 and July 2020. Demographic and risk factors associated with MDR and CR Acinobacter baumannii were collected using structured questionnaire. Descriptive statistics and bivalent analysis were used for data analysis obtained. Level of statistical significance was 95% confidence interval (CI) for all analysis. Results: Bivariable analysis showed that employed participants were 3.4 times more likely to have A. baumannii compared to the unemployed (cOR = 3.38, 95%, CI: 1.09 - 10.43, p = 0.035). Patients who were having high BMI were likely to be infected by A. baumannii compared to those who had normal/low BMI (aOR = 11.2, 95%, CI: 3.57 - 21.11, p = 0.004). Those who were aged ≥ 50 years were 21 times more likely to be carbapenem-resistant Acinetobacter baumannii, COR = 21.0, 95% CI: 1.83 - 240.52, p = 0.011. Those who stayed in ICU for more than 30 days were 16 times more likely to be carbapenem-resistant Acinetobacter baumannii compared to those who had been admitted (COR = 16.0, 95% CI: 1.45 - 176.45, p = 0.019). Conclusion: Increased length of hospital stay, obesity and marital status were the factors found to be significantly associated with A. baumannii infections among ICU admitted patients. On the other hand, gender, age, level of education, occupation, referral status and presence of infection were found to have no significant association with A. baumannii infections among ICU admitted patients. All patients admitted to the intensive care units should be screened for colonization with A. baumannii, owing to the poor treatment outcomes associated with carriage of this multidrug resistant pathogen. Proper infection control in the ICU settings should be upheld to mitigate the spread of A. baumannii in the intensive care units.

Clinical Distribution and Drug Resistance of Acinetobacter baumannii in a Hospital from 2019 to 2021

Objective:To analyze the clinical distribution and drug resistance of Acinetobacter baumannii(AB)and provide reference for the treatment of AB infection.Methods:AB isolated from clinical specimens of Huaihua First People’s Hospital from 2019 to 2021 were collected and identified by VITEK 2 Compact,an automated microbial identification and susceptibility testing system,in which drug sensitivity test was also performed.Excel was used for statistical analysis.Results:Among the 1,311 AB strains,81.16%(1,064 strains)were from sputum samples,and the departments with the highest detections rates of AB were neurosurgery(24.33%),intensive care(15.48%)and infectious disease(11.44%).The drug sensitivity test showed that the resistance rate of 1,311 AB strains to compound sulfamethoxazole and amikacin was 28.38%and 20.54%,respectively,and the resistance rate to 10 other kinds of common antibiotics was more than 40%.Conclusion:The 1,311 AB strains isolated were widely distributed in clinical settings and had strong resistance to commonly used antibiotics.Therefore,it is necessary to strengthen the monitoring of pathogens and drug resistance,formulate reasonable and effective infection control measures,and ensure that antibiotics are used in a reasonable manner.

好氧反硝化菌Acinetobacter sp.A3生长及脱氮特性影响因素的研究

好氧反硝化菌具有同步硝化反硝化的特性,在黑臭水体生物氧化处理方面备受关注。以一株从生物接触氧化反应器生物膜上分离出的好氧反硝化菌(Acinetobacter sp. A3)为研究对象,在好氧条件下研究了氮源、碳氮比(C/N)、初始pH和培养温度对Acinetobacter sp. A3菌生长及脱氮特性的影响。实验结果表明,以氨氮(NH+4-N)为氮源时,菌株生长速度更快。C/N对菌株的生长速率、细胞最高产量和脱氮效果有明显影响。增加C/N,氨氮(NH+4-N)去除速率和去除率不断提高,而硝态氮(NO-3-N)去除速率和去除率在C/N为4时达到最大。菌株在pH为7~9,温度为30~35℃时生长最快。

好氧异养硝化菌Acinetobacter sp. YY-5的分离鉴定及脱氮机理

通过异养硝化培养基获得一株高效脱氮细菌,并通过形态学特征、生理生化反应及16S rDNA同源性比较对筛得菌株进行了鉴定;分别以NO3--N和NO2--N为唯一氮源,通过对脱氮过程中各种含氮代谢物的定量及对脱氮相关基因氨单加氧酶基因(amoA)、羟胺氧化酶基因(hao)、周质硝酸盐还原酶亚基基因(napA)的扩增及测序比较,对该菌株的生理途径及脱氮机理进行了研究.结果表明,高效脱氮细菌YY-5不能发生好氧反硝化,但能在3d内将氨氮由95.23mg/L降解至1.29mg/L,降解率达到98.6%,同时未发现亚硝酸盐氮、硝酸盐氮积累;对该菌主要代谢气体产物进行检测,发现CO2和N2明显增多,无N2O生成;经鉴定,初步判定该菌为不动杆菌属,命名为Acinetobacter sp. YY-5;从该菌基因组中均能扩增出amoA、hao、napA等基因,其中napA与hao基因与已报道的napA与hao基因进行Blast比较,发现具有较大差别.

一株菲降解细菌的分离鉴定及其特性

通过选择性富集培养,从沈抚灌区石油污染土壤中分离到1株菲降解细菌.试验证明该菌株能以菲为唯一碳源和能源生长.经形态学、生理生化鉴定和16SrRNA基因序列比对分析,确定该菌株属于不动杆菌属,命名为Acinetobactersp.L2.系统发育进化分析发现,L2菌株与Acinetobactersp.DG880[AY258108]亲源关系最近.L2菌株培养7d后对菲的降解率达96·3%.邻苯二酚2,3-双加氧酶活力测定表明,L2菌株可能含有菲降解基因.

牛蛙腹水病病原鉴定和药敏试验

从患病牛蛙(Rana catesbeiana)肝脏、四肢、腹水等组织划线分离,共获得3株菌,通过对菌落形态观察、革兰氏染色镜检及生理生化鉴定,确认其理化性质一致,均为洛菲不动杆菌(Acinetobacter lwoffi)。采取腹部注射和浸泡两种不同方式人工感染试验均证实该菌存在致病性,药敏试验表明,分离菌株W2011-01对左氟沙星、美洛培南、哌拉西林/他唑巴坦、妥布霉素、复方新诺明、庆大霉素等18种药物敏感,对呋喃妥因、环丙沙星、沙拉沙星、乙酰螺旋霉素、青霉素、杆菌肽、痢特灵、利福平、氨苄西林、强力霉素耐药。

异育银鲫(Carassius auratus gibelio)源醋酸钙不动杆菌表型及分子鉴定

采用常规的培养特征、理化特性及分子生物学的方法,对从濒死异育银鲫(Carassius auratus gibelio)血液中分离到的菌株SY-1进行了致病性、表型生物学、分子生物学及药敏试验的系统研究。结果表明,该菌株在盐度5—30、pH6—8,温度10—42℃的LB液体培养基中均能生长,具有脲酶。该菌株16SrRNA基因序列(Gen Bank登录存取号:JX164201,长度1435bp)与其它不动杆菌属菌的16SrRNA基因同源性相似性在99%—100%之间,构建系统发育树确定该菌株为醋酸钙不动杆菌(Acinetobacter calcoaceticus)。人工回感可导致异育银鲫死亡。药敏试验结果显示:对恩诺沙星、强力霉素、萘啶酸、复方新诺明、氧氟沙星等10种抗生素敏感;对羧苄青霉素、诺氟沙星、大观霉素、卡那霉素、四环素等14种抗生素中度敏感;对氨苄西林、苯唑西林、林可霉素、万古霉素、氟苯尼考等15种抗生素耐药。

Acinetobacter sp. XA05和Sphingomonas sp. FG03苯酚生物降解特性研究

从活性污泥和苯酚污染的土壤中分离出来两个菌株,分别编号为XA05和FG03.通过16S rRNA基因序列分析表明,XA05属于Acinetobacter sp.,而FG03属于Sphingomonas sp..将XA05和FG03在以不同浓度的苯酚作为唯一碳源的基础培养液中培养,结果显示,在初始苯酚浓度分别为800 mg/L和1000 mg/L时,作用45 h和60 h后,XA05和FG03对苯酚的去除率分别是99.5%、78.3%和97.6%、68.1%.两个菌株按1:1的体积比混合后,当苯酚的初始浓度分别为800 mg/L和1000 mg/L时,作用35 h和60 h后,苯酚去除率分别为99.8%,97.2%.XA05和FG03的苯酚降解动力学研究表明,在Haldane’s模型中,XA05和FG03都有较高的KS和KSI值.

低温贫营养好氧反硝化细菌SY13的反硝化特性

从底泥中分离出1株低温贫营养好氧反硝化细菌SY13,经常规生理生化鉴定和16SrDNA测序,鉴定出细菌SY13属于Acinetobacter sp.。考察了温度、pH、C/N比及接种量对菌株SY13硝酸盐还原活性的影响,初始硝酸盐浓度为15mg/L左右,温度为15℃时低温贫营养好氧反硝化细菌SY13的硝酸盐去除率为49.26%,在中性环境适应性较强,pH值为7.0时72h的硝氮去除率达到58.08%,随着C/N比不断增加,菌株SY13硝酸盐的去除效果逐渐增强,接种量为10%时,菌株SY13培养72 h后的硝氮去除率可达到59.62%。

固定化Acinetobacter sp. XA05和Sphingomonas sp. FG03降解苯酚

从活性污泥和受苯酚污染的土壤中分离出的菌株XA05和FG03均具有很强的苯酚生物降解能力。16srDNA序列分析表明,XA05和FG03菌株分别属于不动杆菌属(Acinetobacter sp.)和鞘氨醇单胞菌属(Sphin-gomonas sp.)。实验结果表明,在苯酚初始质量浓度为800.0mg/L、培养时间为35h的条件下,自由悬浮细胞和固定化细胞的苯酚降解率均高于95.0%。