Dissecting Multiple Arabidopsis CC-NBS-LRR Proteins Structure and Localization

NBS-LRR (nucleotide binding sites and leucine rich repeat) protein plays a crucial role as sentries and as defense activators in plants. The structure and function of NBS-LRR proteins are closely related. Previous articles have announced that the activated ZAR1 (HopZ-Activated Resistance 1) forms a pentamer in the plasma membrane, which is a calcium permeable channel that can trigger plant immune signaling and cell death. However, the structure of galore NBS-LRRs in Arabidopsis is not yet clear. The functional sites of distinct NBS-LRR in cells may vary. In addition, identifying pathogens and activating defense regions may occur in different subcellular compartments. Therefore, dissecting the specific structure and positioning of NBS-LRRs is an indispensable step in understanding their functions. In this article, we exploit AlphaFold to predict the structure of some designed NBS-LRRs, and utilize Agroinfiltration transient expression system, combined with biochemical fractionation, to dissect the localization of these NBS-LRR receptors from Arabidopsis. Structural data indicates that the identified NBS-LRRs share analogous conformation. Membrane fractionation assay demonstrates these NBS-LRRs are mainly associated with the membrane. These data show that the Ca2+-permeable channel activity may be evolutionarily conserved in NBS-LRR of Arabidopsis, and this study provides some reference clues for analyzing the structure and localization patterns of other plant immune receptors.

Study on Distribution of Four Pseudomonas Species in Living Environment Using Multiplex PCR

Purpose: The genus Pseudomonas is a ubiquitous microorganism frequently detected from immunocompromised patients. The inherent resistance to numerous antimicrobial agents contributes to the opportunistic character of this pathogen exhaustive monitoring of this pathogen is considered of critical importance to public health organizations. The reliable identification method able to distinguish genetic close Pseudomonas species is needed, because these organisms are difficult to differentiate by phenotypic or biochemical methods. The purpose of the present study was to design species-specific primers in order to identify and detect four Pseudomonas species which are frequently detected from the human oral cavities, and to investigate the distribution of these organisms in the living environment using a multiplex PCR. Methods: Polymerase chain reaction (PCR) primers were designed based on partial sequences of the rpoD gene of four Pseudomonas species. Swab samples were collected from fifty washstands, and the distribution of Pseudomonas species was investigated using a conventional PCR at genus level and a multiplex PCR at species level. Results: Multiplex PCR method developed in this study was able to distinguish four Pseudomonas species clearly. The genus Pseudomonas was detected from all samples (100%), whereas P. putida, P, aeruginosa, P. stutzeri and P. fluorescens were detected at 44%, 8%, 4% and 2% in fifty swab samples, respectively. Conclusion: Our developed one-step multiplex PCR method is accurate, specific, cost-effective, time-saving, and works without requiring DNA extraction. It was indicated that washstands were the uninhabitable environment for P. putida, P, aeruginosa, P. stutzeri and P. fluorescens.

Thoracic spine infection caused by Pseudomonas fluorescens:A case report and review of literature

BACKGROUND The clinical incidence of spinal infection is gradually increasing,and its onset is insidious,easily leading to missed diagnosis and misdiagnosis,which may lead to serious complications such as nervous system dysfunction,spinal instability and/or deformity,and cause a huge burden on society and families.Early identification of the causative agent and precision medicine will greatly reduce the suffering of patients.At present,the main pathogenic bacteria that cause spinal infection are Staphylococcus aureus,Streptococcus,Pneumococcus,Escherichia coli,and Klebsiella.There are no reports of spinal infection caused by Pseudomonas fluorescens.CASE SUMMARY We report a 32-year-old female patient with spinal infection.She presented with flank pain,initially thought to be bone metastases or bone tuberculosis,and had a family background of tumors.Her clinical features and changes in imaging and laboratory tests led to the suspicion of thoracic spine infection.Histopathology of the lesion showed inflammation,tissue culture of the lesion was negative several times,and the possible pathogen-Pseudomonas fluorescens was found after gene sequencing of the lesion.The patient recovered completely after a full course of antibiotic treatment.CONCLUSION This report increases the range of pathogens involved in spinal infections,highlights the unique advantages of gene sequencing technology in difficult-todiagnose diseases,and validates conservative treatment with a full course of antibiotics for spinal infections without complications.

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.

The NAC Transcription Factor ANAC089 Modulates Seed Vigor through the ABI5-VTC2 Module in Arabidopsis thaliana

Seed viability is an essential feature for genetic resource conservation as well as sustainable crop production.Long-term storage induces seed viability deterioration or seed aging,accompanied by the accumulation of toxic reactive oxygen species(ROS)to suppress seed germination.Controlled deterioration treatment(CDT)is a gen-eral approach for mimicking seed aging.The transcription factor ANAC089 was previously reported to modulate seed primary germination.In this study,we evaluated the ability of ANAC089 to control seed viability during aging.Compared with that in the wild-type line,the mutation of ANAC089 significantly increased H_(2)O_(2),thereby reducing seed viability after CDT,while the overexpression of ANAC089 reduced H_(2)O_(2) and improved seed long-evity,indicating a critical role for ANAC089 in maintaining seed viability through H_(2)O_(2) signaling.A series of stu-dies have shown that ANAC089 targets and negatively regulates the level of ABI5,an important transmitter of abscisic acid(ABA)signals,to affect seed viability after CDT.Furthermore,ABI5 negatively regulated the expres-sion of VTC2,which is involved in the biosynthesis of the antioxidant ascorbic acid and H_(2)O_(2) scavenging.As a result,ANAC089 attenuates the generation of H_(2)O_(2),thereby enhancing seed viability through the ABI5-VTC2 module during the seed aging process.Taken together,our results reveal a novel mechanism by which ANAC089 enhances seed viability by coordinating ABI5 and VTC2 expression,ultimately preventing the overac-cumulation of H_(2)O_(2),which would have led to reduced seed viability.

荧光假单胞菌Pseudomonas fluorescens RN-88抑菌特性研究

本研究旨在利用拮抗菌防治植物病害,为桃的病害生物防治提供更多可行性的方案。以前期筛选获得的一株桃褐腐病拮抗细菌荧光假单胞菌(Pseudomonas fluorescens)RN-88为试验材料,采用杯碟法测定发酵液对桃褐腐菌(Monilinia fructicol)的抑菌活性,并结合抑菌圈法,研究了该菌在pH、温度、紫外线(UV)等不同环境中的稳定性。实验结果表明,细菌RN-88能显著降低桃褐腐病的发病率,其发酵液对褐腐病菌(M.fructicol)的抑制率可达44.69%。在过滤除菌后,相对于高温灭菌,发酵液中抑菌物质的损失较小。在pH 7.5~9.0的碱性溶液中,发酵液的抑菌活性有较好的稳定性,但在酸性溶液(3.0≤pH≤6.5)中处理后,其抑菌能力减弱。发酵液的抑菌率几乎不受温度和紫外线(UV)的影响。Pseudomonas fluorescens RN-88细菌具有较好的环境稳定性,具有开发成桃褐腐病生物拮抗剂的潜在价值,本研究为荧光假单胞菌作为新型生防菌的应用提供了理论依据,同时为实现桃病害的生物防治提供了更多可行性的方案。

酚酸介导下连作茶树根际病原菌Alternaria sp.及其拮抗菌Pseudomonas sp.变化

茶树是我国重要的经济作物,然而长期宿根连作铁观音茶园存在土壤微生物群落结构失衡、病害加重等连作障碍问题,探究铁观音茶树连作障碍形成的分子机制对寻求有效的防控技术具有重要意义。采用微生物分离纯化、平板对峙等方法对铁观音茶树根际病原菌及其拮抗菌进行分离、鉴定,并对不同宿根连作年限(0、1、10、20 a)铁观音茶树根际土壤中的病原菌和拮抗菌数量进行定量分析;同时运用高效液相色谱(HPLC)技术分析不同连作年限根际土壤中酚酸含量变化,并模拟土壤中各酚酸配比,研究酚酸类物质对茶树根际病原菌及其拮抗菌的影响。结果显示,从连作20 a患病铁观音茶树根系分离鉴定到1株病原真菌链格孢菌(Alternaria sp.),并从根际土壤中筛选到1株拮抗菌假单胞菌(Pseudomonas sp.)。荧光定量PCR分析发现,与1 a茶园相比,20 a茶园土壤中的链格孢菌绝对含量显著偏高,而假单胞菌含量却显著偏低。连作茶园根际土壤中共检测到对羟基苯甲酸、香草酸、丁香酸、香兰素、阿魏酸5种酚酸类物质,其平均配比为38∶229∶11∶11∶3。连作条件下酚酸类物质并未在土壤中累积,而是随种植年限的延长呈现出先增加后降低的趋势。模拟试验发现,中低浓度(30~120μmol·L^(-1))的混合酚酸能够显著促进链格孢菌菌丝的生长,单一酚酸对羟基苯甲酸、香草酸和丁香酸在低浓度(30μmol·L^(-1)和60μmol·L^(-1))时也能够显著促进链格孢菌菌丝的生长。对羟基苯甲酸对假单胞菌的生长有抑制作用,并且随着浓度的增加抑制作用增强,混合酚酸以及其他单一酚酸对假单胞菌的生长无明显作用。由此可见,铁观音根系分泌物酚酸类物质对根际土壤关键微生物菌群具有不同的生态效应,是引起微生物群落结构失衡、病害增加等连作障碍问题的重要因素。研究结果为进一步揭示铁观音茶树连作障碍机理提供一些理论依据。

锑氧化菌Pseudomonas sp.AO-1的分离鉴定及其对Sb(III)的氧化性能

采用抗性筛选法从锡矿山筛选出一株锑氧化菌,并利用分子生物学技术对其进行鉴定;考察了其氧化Sb()Ⅲ的性能和氧化次生矿物的特征.结果表明:锑氧化菌属于假单胞菌属(Pseudomonas),将其命名为Pseudomonas sp.AO-1(简称:AO-1);影响AO-1氧化Sb(Ⅲ)的因素主要有溶液pH值、溶解氧和铁锰氧化物(单质铁、FeCl_(3)和MnO_(2))等;AO-1在好氧和缺氧条件下均能氧化Sb(Ⅲ),好氧氧化Sb(Ⅲ)的米门常数Km和最大氧化速率Vmax值分别为393.05µmol/L和0.271µmol/(L·min),体现了较强的锑氧化性;AO-1和铁锰氧化物的耦合作用能促进Sb(Ⅲ)的氧化,且铁锰氧化物促进AO-1氧化Sb(Ⅲ)的速率依次为:FeCl_(3)>MnO_(2)>单质铁;AO-1和铁锰氧化物耦合氧化Sb(Ⅲ)生成含Sb(Ⅴ)的次生矿物,次生矿物会加速Sb(Ⅲ)的氧化以及影响锑在环境中的迁移转化.菌株AO-1的锑氧化性能良好,对于锑的生物化学转化和土壤微生物修复的应用有重要意义.

砷氧化菌Pseudomonas sp.AO-1的分离鉴定及其对As(Ⅲ)的氧化性能研究

随着环境砷污染日趋严重和不断地传播使得人类健康处于高风险之中,修复治理环境中的砷污染刻不容缓。将As(Ⅲ)氧化为As(Ⅴ)是治理砷污染的关键步骤,因此寻找一种经济且绿色的氧化技术成为了研究热点,而微生物氧化As(Ⅲ)被认为是治理砷污染一种绿色经济可行的方法。从湖南锡矿山矿区含砷的土壤中筛选出一株砷氧化菌,并利用分子生物学技术对其进行了鉴定;研究了其对As(Ⅲ)的抗性,不同As(Ⅲ)浓度下的生长特征曲线,不同pH条件下As(Ⅲ)的氧化性能,生长曲线及其氧化动力学。研究结果表明:该菌属于假单胞菌属(Pseudomonas),将其命名为Pseudomonas sp.AO-1(简称:AO-1),其对As(Ⅲ)的抗性达2000 mg·L^(-1),具有较高的抗性;当As(Ⅲ)质量浓度高于100 mg·L^(-1)时,菌株AO-1的生长受到了明显的抑制,其进入对数增殖期的时间延后,稳定期较短,衰亡期提前;pH对菌株AO-1的生长及As(Ⅲ)氧化率有显著的影响,其最适生长pH为7;当pH为3-8时,菌株AO-1氧化As(Ⅲ)的氧化率随pH的升高先提高后减小,pH为7时As(Ⅲ)氧化率到达最大的72.5%;菌株AO-1好氧化氧化As(Ⅲ)的米门常数Km和最大氧化速率Vmax值分别为274.70μmol·L^(-1)和0.31μmol·(L·min)-1,其Km低于一些已研究的菌株,体现菌株AO-1对As(Ⅲ)具有良好的亲和力,也表明了其具有较好的As(Ⅲ)氧化性能。综上,该研究所筛选的菌株AO-1具有良好的耐砷性和As(Ⅲ)氧化性,在水体及土壤砷污染修复与治理中具有的潜在应用价值。

假单胞菌Pseudomonas promysalinigenes RW10S1次级代谢产物研究

目的研究假单胞菌Pseudomonas promysalinigenes RW10S1的次级代谢产物。方法采用MCI柱色谱及半制备高效液相色谱法对发酵产物进行分离纯化,通过HR-ESI-MS、NMR等多种波谱学技术鉴定化合物的化学结构。结果从假单胞菌Pseudomonas promysalinigenes RW10S1的液体发酵物乙酸乙酯萃取部位分离得到了3个化合物,分别鉴定为promysalin(1)、promynicotin(2)、dihydrodeoxypromynicotin(3)。结论化合物2和3为新化合物。

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.

变形假单胞菌(Pseudomonas plecoglossicida)核酸适配体的SELEX筛选

变形假单胞菌(Pseudomonas plecoglossicida)是大黄鱼内脏白点病的主要致病菌。核酸适配体,因其亲和力高、特异性好等多个优点,在微生物检测等多个领域都有较好的应用前景。以变形假单胞菌为靶目标,采用SELEX筛选方法,从高频序列中筛选获得了变形假单胞菌的5个核酸适配体,测定了这些核酸适配体对变形假单胞菌的亲和特异性及其亲和常数(K_(d))和最大亲和力(A_(m)),并对其二级结构进行了分析研究。结果表明,这5个核酸适配体对变形假单胞菌的亲和力是其他非目标菌(嗜水气单胞菌、溶藻弧菌、哈维氏弧菌、大肠杆菌、迟钝爱德华氏菌、铜绿假单胞菌)的10倍以上,体现出了较好的亲和特异性。测定了5个核酸适配体(#1、#2、#3、#4、#5)的K_(d)和A_(m),相应的K_(d)值分别为(25.77±6.11)、(7.14±1.86)、(19.59±3.01)、(83.22±22.45)、(34.31±8.76) nmol/L,A_(m)值分别为(789.23±38.46)、(1392.27±58.03)、(3012.50±106.19)、(1457.99±171.32)、(1070.91±70.16) nmol/L。二级结构模拟发现核酸适配体对靶标的结合能力可能主要与其二级结构中的大中型环有关。相关研究对于变形假单胞菌的快速检测及其病害防控都具有重要意义。

Evaluation of the Bioremediation Potential and Antimicrobial Activity of Pseudomonas and Bacillus Bacteria Isolated from Landfills in Brazzaville, Congo

The pollution of ecosystems as a result of urbanization, industrialization and poor agricultural practices is becoming increasingly alarming. This has a major impact on health and the economy. This pollution causes illness in humans and animals, even at low levels of exposure, leading to endocrine disorders, congenital malformations, cardiovascular disease, nervous system damage and cancer. They are a brake on redevelopment because of the threats they pose, generally causing an anaerobic environment by blocking the diffusion of air into the soil pores, thus affecting the microbial communities living there and preventing the infiltration of water necessary for plant growth. In an ecosystem subjected to various disturbances, changes can be observed in ecosystem structure and function, including loss of aesthetic values, changes in biomass or productivity, and changes in species composition. These include loss of aesthetic values, changes in biomass or productivity, and altered species composition, as a result of habitat loss, disruption of food webs and variations in macro- and micro-climatic environmental conditions. Respect for the environment is becoming a major concern in today’s society. To remedy this, the concept of biological control was used as an alternative, with the selection of microorganisms of bioremediator interest. Twenty (20) isolates, including 10 (50%) from the Pseudomonas genus and 10 (50%) from the Bacillus genus, were isolated from landfills, identified and tested to assess their biofertilization (phosphate solubilization) and depollution (hydrocarbon degradation) potential, and to inhibit the growth of certain microorganisms. The results showed that all Pseudomonas and Bacillus isolates solubilized inorganic phosphate, although this activity was higher in Bacillus. All Bacillus inhibited the growth of all the pathogens included in this study, while Pseudomonas only inhibited the growth of E. coli. With regard to their ability to degrade hydrocarbons, these bacteria all showed exponential growth kinetics in the presence of gasoline. These kinetics evolved as a function of the number of days. The results obtained from this work leave no doubt as to the capacity of microorganisms to be used on a large scale as soil biofertilizers to restore soil integrity and promote sustainable agriculture, but also as biodepollutants to purify ecosystems.

Molecular and genetic regulations of fleshy fruit shape and lessons from Arabidopsis and rice

Fleshy fruit shape is an important external quality trait influencing the usage of fruits and consumer preference.Thus,modification of fruit shape has become one of the major objectives for crop improvement.However,the underlying mechanisms of fruit shape regulation are poorly understood.In this review we summarize recent progress in the genetic basis of fleshy fruit shape regulation using tomato,cucumber,and peach as examples.Comparative analyses suggest that the OFP-TRM(OVATE Family Protein-TONNEAU1 Recruiting Motif)and IQD(IQ67 domain)pathways are probably conserved in regulating fruit shape by primarily modulating cell division patterns across fleshy fruit species.Interestingly,cucumber homologs of FRUITFULL(FUL1),CRABS CLAW(CRC)and 1-aminocyclopropane-1-carboxylate synthase 2(ACS2)were found to regulate fruit elongation.We also outline the recent progress in fruit shape regulation mediated by OFP-TRM and IQD pathways in Arabidopsis and rice,and propose that the OFP-TRM pathway and IQD pathway coordinate regulate fruit shape through integration of phytohormones,including brassinosteroids,gibberellic acids,and auxin,and microtubule organization.In addition,functional redundancy and divergence of the members of each of the OFP,TRM,and IQD families are also shown.This review provides a general overview of current knowledge in fruit shape regulation and discusses the possible mechanisms that need to be addressed in future studies.

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.

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. .

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.

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.

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.

Glucosinolates and Their Hydrolysis Products in Arabidopsis thaliana Influence Performance and Feeding Choice of Pieris rapae and Spodoptera exigua

Glucosinolates and their hydrolysis products, found in plants of the order Brassicales, are well-known for their defensive properties against insect herbivores. Arabidopsis thaliana (Col-0) genetic lines with mutations that modify the type of glucosinolates (i.e. myb28myb29 and cyp79B2cyp79B3 are deficient in the production of aliphatic and indolyl glucosinolates, respectively) make it possible to test for the specific effects of these secondary chemicals on insect herbivores. The Pad3 mutant (deficient in camalexin), which has a role in resistance to pathogens, was also tested. Likewise, the effects of different glucosinolate hydrolysis products can be evaluated using genetically modified (GM) lines of the wild type Col-0 ecotype, which naturally produces isothiocyanates. These GM lines include the nitrile-producing 35S: ESP and the double knockout tgg1tgg2, which virtually lacks hydrolysis products. In both no-choice and choice experiments, the crucifer specialist Pieris rapae was virtually unaffected by differences in the type of glucosinolates or hydrolysis products. In contrast, the generalist insect Spodoptera exigua had statistically significant increases in pupae/adult weight and faster developmental times when reared on mutants deficient in the production of aliphatic and indolyl glucosinolates and their hydrolysis products. There were no differences in the performance of either insect species when reared on wild type Col-0 or Pad3. Results from feeding choice trials showed that Pieris rapae had no statistically significant preference for any of the genetic lines. In contrast, Spodoptera exigua had a significant feeding preference for the double mutant tgg1tgg2. This study provides evidence that variation in the type of glucosinolates and their hydrolysis products can influence insect performance and feeding choices, and that responses are species-specific.