The significance of testing for Pseudomonas aeruginosa in recreational seawater beaches.

The occurrence of Pseudomonas aeruginosa and faecal coliforms in Mediterranean sea water from beaches was investigated. Water samples (1,598 in toto) were tested and P. aeruginosa was found in 222 samples (14%). In 31% of samples where P. aeruginosa was detected, faecal coliforms of less than ten bacteria per 100 ml were found. In a group of 98 samples which had > 500 faecal coliforms per 100 ml, 41% had no detectable P. aeruginosa. The inclusion of P. aeruginosa as an additional parameter for approving beaches for recreational activity is recommended.     

Repetitive acceleration swimming performance of brown trout in fresh water and after acute seawater exposure

The effect of acute seawater exposure on repeated swimming performance of brown trout Salmo trutta was investigated by use of a constant acceleration test (CAT). In fresh water, swimming speed was attained regardless of previous exercise, whereas swimming speed in sea water was significantly reduced during consecutive exercise.     

铜绿假单胞菌泳动能力相关新基因的筛选及鉴定

从Mu转座突变子文库中经过表型筛选,得到12株泳动(Swimming motility)能力缺陷的突变子,经Mu转座子插入位点的确认、基因克隆及测序分析发现其中10个突变子中Mu转座子分别插入到10个不同的与鞭毛运动和功能相关的基因中,2个突变子中Mu转座子插入到功能未知的新基因(PA2950和PA5022)中,电镜观察结果表明这2个突变株均具有完整的鞭毛,初步推测这2个基因可能是参与鞭毛泳动的能量代谢、趋化作用或信息传递的新基因。     

Selection experiments reveal trade-offs between swimming and twitching motilities in Pseudomonas aeruginosa

Bacteria possess a range of mechanisms to move in different environments, and these mechanisms have important direct and correlated impacts on the virulence of opportunistic pathogens. Bacteria use two surface organelles to facilitate motility: a single polar flagellum, and type IV pili, enabling swimming in aqueous habitats and twitching along hard surfaces, respectively. Here, we address whether there are trade-offs between these motility mechanisms, and hence whether different environments could select for altered motility. We experimentally evolved initially isogenic Pseudomonas aeruginosa under conditions that favored the different types of motility, and found evidence for a trade-off mediated by antagonistic pleiotropy between swimming and twitching. Moreover, changes in motility resulted in correlated changes in other behaviors, including biofilm formation and growth within an insect host. This suggests environmental origins of a particular motile opportunistic pathogen could predictably influence motility and virulence.     

Synthesis of Pseudomonas aeruginosa lipopolysaccharide core antigens containing 7-O-carbamoyl-L-glycero-alpha-D-manno-heptopyranosyl residues.

The monosaccharide allyl 7-O-carbamoyl-L-glycero-alpha-D-manno- heptopyranoside, the reducing disaccharide 7-O-carbamoyl-L-glycero-alpha-D- manno-heptopyranosyl-(1-->3)-L-glycero-D-manno-heptopyranose and the disaccharides allyl 7-O-carbamoyl-L-glycero-alpha-D-manno-heptopyranosyl-(1-->3)-L-glycero- beta- and alpha-D-manno-heptopyranoside were prepared in good yields. The 7-O-carbamoyl substituent was regioselectively introduced via NH3-NH4HCO3 treatment of a 6,7-O-carbonate group. Glycosylation steps were carried out using Me3SiOTf or BF3.Et2O promoted coupling of allyl alcohol with trichloroacetimidate or fluoride glycosyl donors, respectively. The deprotected allyl glycosides were reacted with cysteamine to afford spacer glycosides which were subsequently linked to bovine serum albumin. The artificial antigens which are related to the dephosphorylated heptose region of the lipopolysaccharide core region from Pseudomonas aeruginosa classified into RNA group I may be used for the characterization of monoclonal antibodies directed against inner core epitopes of human-pathogenic Pseudomonas species.     

Chemotaxis in Pseudomonas aeruginosa.

A chemotaxis system for Pseudomonas aeruginosa was defined by using the method of Adler. Cells were attracted to compounds in the order ammonium chloride greater than amino acids greater than organic acids. Two sugars were assayed and elicited no response. Comparisons with other model systems are discussed.     

Starvation survival of Pseudomonas aeruginosa in sea water before and after adaptation to salinity

The survival of Pseudomonas aeruginosa ATCC 27853 in sea water was minimally influenced by light, temperature and the presence of an associated marine microflora. Pre-adaptation of cells to a salted medium attenuated the initial stress and even permitted their growth but did not modify their long-term survival. The majority of stressed cells were resuscitated in a nutritive medium prepared with sea water. The morphology of the resulting colonies varied considerably depending on the contact time with sea water and the medium used for enumeration of culturable cells.     

Occurrence of Staphylococcus aureus and Pseudomonas aeruginosa in Israeli coastal water.

The occurrence of Pseudomonas aeruginosa and coagulase-positive Staphylococcus aureus in seawater from beaches of central Israel was investigated from June 1983 until June 1985. P. aeruginosa was monitored in 652 samples of seawater from 34 beaches, and S. aureus was monitored in 628 samples. P. aeruginosa was found in 44.8% of samples (6.5% with 1 bacterium per 100 ml of water), and S. aureus was recovered from 60.7% of samples (5.3% with 1 organism per 100 ml), compared with 91.6% of samples with total coliforms (TC) and 82.2% with fecal coliforms (FC). The correlation between the presence of P. aeruginosa to that of TC and FC was 99.1 and 98.3%, respectively, while S. aureus was found in 4.3 and 8% of samples where TC and FC, respectively, were absent. Monitoring of S. aureus as a supplementary indicator in populated beaches is recommended because it will add valuable information on the sanitary quality of the seawater.     

Metagenomic profiling of fresh water lakes at different altitudes in Pakistan

Freshwater lakes play a crucial role in sustainability of ecosystem in the favour of communities flourishing around it. In this study, differential metagenomic evaluation of three freshwater ecosystems in Pakistan was carried out. These included Lakes Keenjhar, Rawal and Saif-ul-Muluk situated at the altitudes 21, 527, 3224 m respectively. Former two lakes serve as water reservoirs for three major cities of Pakistan, while the high-altitude Lake Saif-ul-Muluk is located in a pristine environment at the meeting point of Himalayan and Karakoram ranges. Next generation sequencing (NGS) of metagenomic DNA of microbial communities was carried out using surface water samples from these lakes by Illumina Hi-Seq 2500 sequencing technology. Bioinformatics analysis identified Proteobacteria as the most dominant phylum (58–79%) followed by Planctomycetes (34%), Cyanobacteria (12%) and Bacteroidetes (15%). Lake Saif-ul-Muluk contained highest abundance of bacterial genera including Vibrio, Bordetella, Pseudomonas, Burkholderia and Escherichia; while Microcystis were found to be abundant in Lakes Keenjhar and Rawal. Non-parametric multi-dimensional scaling (NMDS) principle component analysis on genus level revealed that these ecosystems were divergent from each other and from metagenomes of lakes in the Americas. Characterization of virulence factors and antibiotics resistant genes in metagenomic contigs were also identified. Chemical profiling of Lakes Keenjhar and Rawal showed higher concentration of phosphorus which indicated eutrophication in these lakes might be due to Microcystis infestation.     

Risk assessment of adenoviruses detected in treated drinking water and recreational water

AIMS: Human adenoviruses (HAds) have previously been detected in sewage and polluted river and dam water, as well as treated drinking water. The 51 serotypes of HAds cause a wide range of infections with clinical manifestations associated with the gastrointestinal, respiratory and urinary tracts, and the eyes. Water may play a meaningful role in the transmission of many of these HAd serotypes, specifically the enteric HAds which are transmitted via the faecal-oral route. The presence of these viruses in water used for drinking and recreational purposes is considered to constitute a potential health risk. In this study, the risk of infection by the group of HAds previously detected over a period of 1 year in selected drinking water supplies, as well as river and dam water used for recreational purposes, was assessed. METHODS AND RESULTS: Adenoviruses were previously detected in nine of 204 (4.41%) samples of two drinking water supplies (A and B) treated and disinfected according to international specifications, in four of 51 (7.8%) samples of river water and nine of 51 (17.7%) samples of dam water. Application of these previously published results in an exponential risk assessment model indicated an annual risk of infection of 1.01 x 10(-1) and 1.7 x 10(-1) for drinking water supplies A and B, respectively, assuming a daily consumption of 2 l day(-1). The daily risk of infection constituted by HAds in the river water was calculated as 1.71 x 10(-4), and in the dam water as 3.12 x 10(-5), assuming a consumption of 30 ml of water per day. CONCLUSIONS: The risk of infection exceeded the tolerable risk of one infection per 10 000 consumers per year proposed for drinking water. However, the results for river and dam water used for recreational purposes were within the tolerable risk of one infection per 1000 bathers per day proposed for environmental waters used for recreational purposes. SIGNIFICANCE AND IMPACT OF THE STUDY: The study showed that the risk of HAd infection calculated for the drinking water supplies and the recreational water may overestimate the actual risk of infection, as conservative values were assumed for some of the variables. For a more accurate assessment of the potential risk of infection research should at least include a thorough investigation of the water consumption of individuals in South Africa, and the efficiency of recovery of the glass wool adsorption-elution method.     

铜绿假单胞菌PA1550基因对泳动及蹭动的影响

[目的]:研究与铜绿假单胞菌运动能力相关的基因.[方法]:以一株临床分离的铜绿假单胞菌PA68做受体菌,应用人工Mu转座技术建立了库容为2000的突变子文库,从中筛选出泳动能力和蹭动能力丧失或减弱的突变子,通过基因克隆、测序,GenBankBLAST比对测序结果,互补基因表达确定与铜绿假单胞菌运动能力相关的基因.[结果]:突变子Y46在丧失了泳动运动能力的同时,蹭动能力也发生了减弱.在Y46突变子中,Mu转座子插入到功能完全未知的基因PA1550中.对极性效应及PA1550所在操纵子的分析表明,Mu转座子对插入点下游的基因的转录并不造成影响.[结论]:PA1550与铜绿假单胞菌的泳动及蹭动能力有关.     

Purine degradation in Pseudomonas aeruginosa and Pseudomonas testosteroni.

1. Adenine, hypoxanthine, xanthine and guanine are broken down in Pseudomonas aeruginosa and Pseudomonas testosteroni to allantoin by the concerted action of the enzymes adenine deaminase, guanine deaminase, NAD+-dependent xanthine dehydrogenase and uricase. 2. Uric acid is broken down by an unstable, membrane-bound uricase with an unusually low pH optimum. 3. In both strains adenine inhibits growth and xanthine dehydrogenase. A second type of inhibition is manifest only in Ps. testosteroni and concerns the regulation of the biosynthesis of amino acids of the aspartate family. Enzymic studies showed that in this strain aspartate kinase is inhibited by AMP.     

Transduction of a plasmid containing the bacteriophage D3 cos site in Pseudomonas aeruginosa.

Plasmids harboring the cos sequences of bacteriophage D3 can be transferred, by bacteriophage D3, into Pseudomonas aeruginosa by a mechanism which is insensitive to DNase. Transducing activity was separated from the plaque-forming particles by CsCl equilibrium gradient centrifugation. Restriction endonuclease digestion patterns suggest that the transducing particles contain plasmid concatemers.     

Degradation of polychloroaromatic insecticides by Pseudomonas aeruginosa containing biodegradation plasmids

The work was aimed at studying the degradation of DDT, its metabolites and analogs by BS 816 and BS 827 strains constructed on the basis of Pseudomonas aeruginosa 640x strains and carrying biodegradation plasmids pBS2 and pBS3, respectively. DDT and kelthane were degraded by the BS 816 strain at a greater rate than by the parent culture. The investigation of enzymes involved in the oxidation of the aromatic cycle has shown that the plasmid-carrying strains possess the activity of metapyrocatechase and salicylate hydroxylase which is absent in P. aeruginosa 640x. The activity of pyrocatechase increased. In contrast to the parent strain where homogentisate induced only homogentisate oxygenase, this compound induces also metapyrocatechase in the constructed strains.     

Phosphate taxis in Pseudomonas aeruginosa.

Pseudomonas aeruginosa was shown to be attracted to phosphate. The chemotactic response was induced by phosphate starvation. The specificity of chemoreceptors for phosphate was high so that no other tested phosphorus compounds elicited a chemotactic response as strong as that elicited by phosphate. Competition experiments showed that the chemoreceptors for phosphate appeared to be different from those for the common amino acids. Mutants constitutive for alkaline phosphatase showed the chemotactic response to phosphate regardless of whether the cells were starved for phosphate.