Analysis of Genetic Determinants Involved in Multiresistance in Clinical Strains Isolated from Renal Transplantation Recipients in Guangzhou, China
Lei Shi1), Yali Kou1), Lin Li1) and Shin-ichi Miyoshi2)
1) College of Food and Biological Engineering, South China University of Technology
2) Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University
(Received October 30, 2006)
(Accepted December 25, 2006)
In the present study, we examined the antibiotic sensitivity of 19 bacterial strains [5 coagulase-negative Staphylococcus, 2 methicillin-resistant Staphylococcus aureus (S. aureus), 2 Enterococcus faecium (E. faecium), 5 Escherichia coli (E. coli), 3 Cedecea sp., 1 Klebsiella pneumoniae (K. pneumoniae), and 1 Burkholderia cepacia (B. cepacia)], which were isolated from renal transplantation patients using the Kirby-Bauer method. We also investigated the production of β-lactamase and extended-spectrum β-lactamase (ESBL), and the presence of the integrase gene (intI1) and resistance gene cassette. Among the 19 strains tested, all displayed severe multiresistance, and 12 strains produced β-lactamase, in which 6 strains were ESBL positive. Eleven strains were revealed to possess the class 1 integron; however, neither class 2 nor 3 was detected. Additionally, 3 drug resistance genes, aadA2, dfrA17, and aadA5, were found in some strains. The results indicate that the horizontal transfer of the β-lactamase gene and/or the class 1 integron may contribute significantly to the spread of multiresistant bacteria among renal transplantation patients.
Key words renal transplantation, multiresistance, β-lactamase, integron
Rabu, 20 Februari 2008
Selasa, 19 Februari 2008
Gene Cassette PCR: Sequence-Independent Recovery of Entire Genes from Environmental DNA
Gene Cassette PCR: Sequence-Independent Recovery of Entire Genes from Environmental DNA
H. W. Stokes,1,* Andrew J. Holmes,1,2 Blair S. Nield,1 Marita P. Holley,1,2 K. M. Helena Nevalainen,1 Bridget C. Mabbutt,3 and Michael R. Gillings1,2
Department of Biological Sciences,1 Key Centre for Biodiversity and Bioresources,2 and Department of Chemistry,3 Macquarie University, Sydney, New South Wales 2109, Australia
Received 24 May 2001/Accepted 20 August 2001
The vast majority of bacteria in the environment have yet to be cultured. Consequently, a major proportion of both genetic diversity within known gene families and an unknown number of novel gene families reside in these uncultured organisms. Isolation of these genes is limited by lack of sequence information. Where such sequence data exist, PCR directed at conserved sequence motifs recovers only partial genes. Here we outline a strategy for recovering complete open reading frames from environmental DNA samples. PCR assays were designed to target the 59-base element family of recombination sites that flank gene cassettes associated with integrons. Using such assays, diverse gene cassettes could be amplified from the vast majority of environmental DNA samples tested. These gene cassettes contained complete open reading frames, the majority of which were associated with ribosome binding sites. Novel genes with clear homologies to phosphotransferase, DNA glycosylase, methyl transferase, and thiotransferase genes were identified. However, the majority of amplified gene cassettes contained open reading frames with no identifiable homologues in databases. Accumulation analysis of the gene cassettes amplified from soil samples showed no signs of saturation, and soil samples taken at 1-m intervals along transects demonstrated different amplification profiles. Taken together, the genetic novelty, steep accumulation curves, and spatial heterogeneity of genes recovered show that this method taps into a vast pool of unexploited genetic diversity. The success of this approach indicates that mobile gene cassettes and, by inference, integrons are widespread in natural environments and are likely to contribute significantly to bacterial diversity.
from : http://aem.asm.org
H. W. Stokes,1,* Andrew J. Holmes,1,2 Blair S. Nield,1 Marita P. Holley,1,2 K. M. Helena Nevalainen,1 Bridget C. Mabbutt,3 and Michael R. Gillings1,2
Department of Biological Sciences,1 Key Centre for Biodiversity and Bioresources,2 and Department of Chemistry,3 Macquarie University, Sydney, New South Wales 2109, Australia
Received 24 May 2001/Accepted 20 August 2001
The vast majority of bacteria in the environment have yet to be cultured. Consequently, a major proportion of both genetic diversity within known gene families and an unknown number of novel gene families reside in these uncultured organisms. Isolation of these genes is limited by lack of sequence information. Where such sequence data exist, PCR directed at conserved sequence motifs recovers only partial genes. Here we outline a strategy for recovering complete open reading frames from environmental DNA samples. PCR assays were designed to target the 59-base element family of recombination sites that flank gene cassettes associated with integrons. Using such assays, diverse gene cassettes could be amplified from the vast majority of environmental DNA samples tested. These gene cassettes contained complete open reading frames, the majority of which were associated with ribosome binding sites. Novel genes with clear homologies to phosphotransferase, DNA glycosylase, methyl transferase, and thiotransferase genes were identified. However, the majority of amplified gene cassettes contained open reading frames with no identifiable homologues in databases. Accumulation analysis of the gene cassettes amplified from soil samples showed no signs of saturation, and soil samples taken at 1-m intervals along transects demonstrated different amplification profiles. Taken together, the genetic novelty, steep accumulation curves, and spatial heterogeneity of genes recovered show that this method taps into a vast pool of unexploited genetic diversity. The success of this approach indicates that mobile gene cassettes and, by inference, integrons are widespread in natural environments and are likely to contribute significantly to bacterial diversity.
from : http://aem.asm.org
PCR isolation of catechol 2,3-dioxygenase gene fragments from environmental samples and their assembly into functional genes
PCR isolation of catechol 2,3-dioxygenase gene fragments from environmental samples and their assembly into functional genes
Akiko Okuta, Kouhei Ohnishi and Shigeaki Harayama*
Marine Biotechnology Institute, 3-75-1 Heita, Kamaishi, Iwate 026, Japan
Received 1 December 1997; revised 9 March 1998; accepted 10 March 1998 Available online 16 June 1998.
A. Nakazawa.
Abstract
A method was developed to isolate central segments of catechol 2,3-dioxygenase (C23O) genes from environmental samples and to insert these C23O gene segments into nahH (the structural gene for C23O encoded by catabolic plasmid NAH7) by replacing the corresponding nahH sequence with the isolated segments. To PCR-amplify the central C23O gene segments, a pair of degenerate primers was designed from amino acid sequences conserved among C23Os. Using these primers, central regions of the C23O genes were amplified from DNA isolated from a mixed culture of phenol-degrading or crude oil-degrading bacteria. Both the 5′ and 3′ regions of nahH were also PCR-amplified by using appropriate primers. These three PCR products, the 5′-nahH and 3′-nahH segments and the central C23O gene segments, were mixed and PCR-amplified again. Since the primers for the amplification of the central C23O gene segments were designed so that the 20 nucleotides at both ends of the segments are identical to the 3′ end of the 5′-nahH segment and the 5′ end of the 3′-nahH segment, respectively, the central C23O gene segments could anneal to both the 5′- and 3′-nahH segments. After the second PCR, hybrid C23O genes in the form of (5′-nahH segment—central C23O gene segment—3′-nahH segment) were amplified to full length. The resulting products were cloned into a vector and used to transform Escherichia coli. This method enabled divergent C23O sequences to be readily isolated, and more than 90% of the hybrid plasmids expressed C23O activity. Thus, the present method is useful to create, without isolating bacteria, a library of functional hybrid genes.
from : http://www.sciencedirect.com
Akiko Okuta, Kouhei Ohnishi and Shigeaki Harayama*
Marine Biotechnology Institute, 3-75-1 Heita, Kamaishi, Iwate 026, Japan
Received 1 December 1997; revised 9 March 1998; accepted 10 March 1998 Available online 16 June 1998.
A. Nakazawa.
Abstract
A method was developed to isolate central segments of catechol 2,3-dioxygenase (C23O) genes from environmental samples and to insert these C23O gene segments into nahH (the structural gene for C23O encoded by catabolic plasmid NAH7) by replacing the corresponding nahH sequence with the isolated segments. To PCR-amplify the central C23O gene segments, a pair of degenerate primers was designed from amino acid sequences conserved among C23Os. Using these primers, central regions of the C23O genes were amplified from DNA isolated from a mixed culture of phenol-degrading or crude oil-degrading bacteria. Both the 5′ and 3′ regions of nahH were also PCR-amplified by using appropriate primers. These three PCR products, the 5′-nahH and 3′-nahH segments and the central C23O gene segments, were mixed and PCR-amplified again. Since the primers for the amplification of the central C23O gene segments were designed so that the 20 nucleotides at both ends of the segments are identical to the 3′ end of the 5′-nahH segment and the 5′ end of the 3′-nahH segment, respectively, the central C23O gene segments could anneal to both the 5′- and 3′-nahH segments. After the second PCR, hybrid C23O genes in the form of (5′-nahH segment—central C23O gene segment—3′-nahH segment) were amplified to full length. The resulting products were cloned into a vector and used to transform Escherichia coli. This method enabled divergent C23O sequences to be readily isolated, and more than 90% of the hybrid plasmids expressed C23O activity. Thus, the present method is useful to create, without isolating bacteria, a library of functional hybrid genes.
from : http://www.sciencedirect.com
THE ARIZONA MYCOTA PROJECT
THE ARIZONA MYCOTA PROJECT
Arizona, contrary to what some may think, has more to offer by way of habit than just desert. Rugged mountains, flowing rivers, and expansive forests are also prevalent within the state. These features contribute to a rich diversity of biotic communities. In fact, only a few states, such as California, rival Arizona in this aspect.
In 1990, British mycologist David Hawksworth suggested that only 5% of the Earth's fungal species had been described. Although opinions differ, the Hawksworth estimate is still widely accepted today. The situation is quite similar in Arizona where recent estimates suggest several thousand fungal species that occur in the state have never been recorded. When we consider the diversity of habitats found in Arizona, it is likely that many new records of macrofungi or even new fungal species are awaiting discovery.
Historically, amateur enthusiasts have made numerous contributions to the science of mycology. Recent technological advances, such as GPS units, have enhanced the average citizen's ability to record accurate scientific data, while the advent of digital cameras has greatly improved our ability to capture and transmit images. In the past, it has been proposed that a virtual 'army' of trained mycologist would be needed to truly advance our understanding of the North American fungal flora. However, when considering today's technology and the information that the world wide web has made available to the public, perhaps 'virtual mycologists' can make a significant contribution toward that goal.
The Arizona Mycota Project (AMP) has been created in an attempt to harness this potential resource. This site solicits the help of volunteer contributors, like you, to help advance our knowledge of the Arizona fungal flora (mycota). We encourage persons who have come across interesting fungal finds in the state, to collect specimens and record basic field data OR merely contribute fungal digital images. Specimens of macrofungi sent to AMP will be identified and the field data added to our database. Specimens with significant scientific value will eventually be housed in the University of Arizona's Robert L. Gilbertson Mycological Herbarium. AMP specimens will contribute records of Arizona mycota to the Checklist of Arizona Macrofungi. In addition, AMP images will eventually be linked to the checklist and available for viewing via the World Wide Web.
from : http://www.azfungi.org/amp/
Arizona, contrary to what some may think, has more to offer by way of habit than just desert. Rugged mountains, flowing rivers, and expansive forests are also prevalent within the state. These features contribute to a rich diversity of biotic communities. In fact, only a few states, such as California, rival Arizona in this aspect.
In 1990, British mycologist David Hawksworth suggested that only 5% of the Earth's fungal species had been described. Although opinions differ, the Hawksworth estimate is still widely accepted today. The situation is quite similar in Arizona where recent estimates suggest several thousand fungal species that occur in the state have never been recorded. When we consider the diversity of habitats found in Arizona, it is likely that many new records of macrofungi or even new fungal species are awaiting discovery.
Historically, amateur enthusiasts have made numerous contributions to the science of mycology. Recent technological advances, such as GPS units, have enhanced the average citizen's ability to record accurate scientific data, while the advent of digital cameras has greatly improved our ability to capture and transmit images. In the past, it has been proposed that a virtual 'army' of trained mycologist would be needed to truly advance our understanding of the North American fungal flora. However, when considering today's technology and the information that the world wide web has made available to the public, perhaps 'virtual mycologists' can make a significant contribution toward that goal.
The Arizona Mycota Project (AMP) has been created in an attempt to harness this potential resource. This site solicits the help of volunteer contributors, like you, to help advance our knowledge of the Arizona fungal flora (mycota). We encourage persons who have come across interesting fungal finds in the state, to collect specimens and record basic field data OR merely contribute fungal digital images. Specimens of macrofungi sent to AMP will be identified and the field data added to our database. Specimens with significant scientific value will eventually be housed in the University of Arizona's Robert L. Gilbertson Mycological Herbarium. AMP specimens will contribute records of Arizona mycota to the Checklist of Arizona Macrofungi. In addition, AMP images will eventually be linked to the checklist and available for viewing via the World Wide Web.
from : http://www.azfungi.org/amp/
Effects of the Hot Water Extract and Its Residues of Chlorella Cells on the Growth of Radish Seedlings and the Changes in Soil Microflora
Effects of the Hot Water Extract and Its Residues of Chlorella Cells on the Growth of Radish Seedlings and the Changes in Soil Microflora.
Abstract
The effects of hot water extract and extracted residues of Chlorella cells on the growth of radish seedlings in relation to chages in soil microflora and microbial activity were studied. In particular, actinomycetes spp.isolated from the soil amended with hot water extract of chlorella cells were screened for their productivity of plant growth regulators and antibiotic substances on a plant pathogen, Fusarium oxysporum f.sp.raphani. The hot water extract promoted the growth of 6 species of streptomyces which generally inhabit the soil. The repeated amendment of hot water extract and its residues of chlorella cells to soil promoted the growth of radish seedling and increased the population of actinomycetes and bacteria in soil. The most significant positive correlations were observed between the growth of seedlings and the population of actinomycetes in these soils. Most actinomycetes spp.isolated from the soil amended with hot water extract produced plant growth regulators and also had antagonistic effects on the plant pathogen, Fusarium oxysporum f.sp.raphani. The hot water extract promoted the production of plant growth regulators and the growth of 3 actinomycetes spp.tested. Repeated soil amendment of the hot water extract increased the population of indigenous Fusarium oxysporum f.sp.raphani-antagonists in the soil. These results indicated that the plant growth-promotive effects of the hot water extract and its residues of chlorella cells were due to the increase in the amount of plant growth regulators in soil and the enhancement of soil fungistasis by increasing in the poulation of such profitable actinomycetes in soil.
from : http://ci.nii.ac.jp/naid/110001747407/en/
Abstract
The effects of hot water extract and extracted residues of Chlorella cells on the growth of radish seedlings in relation to chages in soil microflora and microbial activity were studied. In particular, actinomycetes spp.isolated from the soil amended with hot water extract of chlorella cells were screened for their productivity of plant growth regulators and antibiotic substances on a plant pathogen, Fusarium oxysporum f.sp.raphani. The hot water extract promoted the growth of 6 species of streptomyces which generally inhabit the soil. The repeated amendment of hot water extract and its residues of chlorella cells to soil promoted the growth of radish seedling and increased the population of actinomycetes and bacteria in soil. The most significant positive correlations were observed between the growth of seedlings and the population of actinomycetes in these soils. Most actinomycetes spp.isolated from the soil amended with hot water extract produced plant growth regulators and also had antagonistic effects on the plant pathogen, Fusarium oxysporum f.sp.raphani. The hot water extract promoted the production of plant growth regulators and the growth of 3 actinomycetes spp.tested. Repeated soil amendment of the hot water extract increased the population of indigenous Fusarium oxysporum f.sp.raphani-antagonists in the soil. These results indicated that the plant growth-promotive effects of the hot water extract and its residues of chlorella cells were due to the increase in the amount of plant growth regulators in soil and the enhancement of soil fungistasis by increasing in the poulation of such profitable actinomycetes in soil.
from : http://ci.nii.ac.jp/naid/110001747407/en/
Microbial diversity of soil from two hot springs in Uttaranchal Himalaya
Microbial diversity of soil from two hot springs in Uttaranchal Himalaya
Bhavesh Kumar, Pankaj Trivedi, Anil Kumar Mishra, Anita PandeyCorresponding Author Contact Information, E-mail The Corresponding Author and Lok Man S. Palni**
GB Pant Institute of Himalayan Environment and Development, Kosi-Katarmal, Almora, 263 643 Uttaranchal, India
Accepted 13 January 2004. Available online 20 June 2004.
Abstract
Soil samples collected from two hot springs, Soldhar and Ringigad, both located in the Garhwal region of Uttaranchal Himalaya were analysed for their physical, chemical and microbial components. The alkaline pH, total absence of carbon and nitrogen, and high temperature were features common to soil samples from both sites. The Soldhar samples contained higher amounts of Cu, Fe and Mn. Ringigad soil was devoid of Cu, but had much higher phosphate. While the optimum incubation temperature for isolating the maximum microbial counts from soil samples from the two sites was 50°C, microbial growth in broth was also observed when incubated at 80°C. Microscopic examination revealed three types of microbial populations, i.e., bacteria, yeast and filamentous organisms. The soil samples were found to be dominated by spore forming rods. Out of 58 aerobic isolates, 53 were gram positive bacilli. Gram positive anaerobic oval rods were also observed up to 60°C. Soil dilution plates revealed the presence of antagonistic and phosphate solubilizing populations.
Author Keywords: Microbial diversity; Hot springs; Thermophile; Bacilli; Filamentous communities; Uttaranchal Himalaya
from : http://www.sciencedirect.com
Bhavesh Kumar, Pankaj Trivedi, Anil Kumar Mishra, Anita PandeyCorresponding Author Contact Information, E-mail The Corresponding Author and Lok Man S. Palni**
GB Pant Institute of Himalayan Environment and Development, Kosi-Katarmal, Almora, 263 643 Uttaranchal, India
Accepted 13 January 2004. Available online 20 June 2004.
Abstract
Soil samples collected from two hot springs, Soldhar and Ringigad, both located in the Garhwal region of Uttaranchal Himalaya were analysed for their physical, chemical and microbial components. The alkaline pH, total absence of carbon and nitrogen, and high temperature were features common to soil samples from both sites. The Soldhar samples contained higher amounts of Cu, Fe and Mn. Ringigad soil was devoid of Cu, but had much higher phosphate. While the optimum incubation temperature for isolating the maximum microbial counts from soil samples from the two sites was 50°C, microbial growth in broth was also observed when incubated at 80°C. Microscopic examination revealed three types of microbial populations, i.e., bacteria, yeast and filamentous organisms. The soil samples were found to be dominated by spore forming rods. Out of 58 aerobic isolates, 53 were gram positive bacilli. Gram positive anaerobic oval rods were also observed up to 60°C. Soil dilution plates revealed the presence of antagonistic and phosphate solubilizing populations.
Author Keywords: Microbial diversity; Hot springs; Thermophile; Bacilli; Filamentous communities; Uttaranchal Himalaya
from : http://www.sciencedirect.com
Environment, Energy and Forestry
Environment, Energy and Forestry
Taste and Odour
The Guidelines for Canadian Drinking Water Quality 1989 states that drinking water should be inoffensive with respect to both taste and odour. Although taste and odour are not regulated as parameters of health concern, they are perhaps the most important characteristics of drinking water from the point of view of perception. It is next to impossible to convince the public that water is safe to drink if it either tastes or smells bad.
Taste and odour continue to be one of the most difficult issues faced by the water treatment industry. They are a problem, at least intermittently, in most surface water supplies and also in a number of groundwater supplies.
Taste and odour problems may be caused by natural organic matter present in the water, by synthetic chemicals or by some inorganic substances. Some compounds in the first two classes may react with disinfectants such as chlorine to produce tastes and odours that are worse than those in the raw water.
Sources
Taste-causing substances in drinking water are generally inorganic compounds while organic constituents of water are the ones that cause odour problems most frequently -either in themselves or through reaction with disinfectants or oxidation processes.
* Biological Sources
Historically, taste and odour problems in the water treatment industry were associated with algae and decaying vegetation. In addition a class of bacteria known as actinomycetes were linked to taste and odour. The identification of earthy-smelling and musty-smelling compounds were isolated from certain actinomycetes cultures. Many types of algae are common in water supplies and are known as causes of tastes and odours. Both living and dead algae can be responsible for tastes and odours. Although not as common, other bacteria, fungi, zooplankton, nematodes and some amoebae are sometimes responsible for taste and odour.
* Man-Made Sources
Tastes and odours attributed to anthropogenic (man-made) sources can include non-point inputs and municipal and industrial wastewater effluents. Non-point sources may come from direct runoff or from upstream stormwater discharges. This problem can be severe in times of high flow after a prolonged dry or frozen spell, typically in springtime.
* During Treatment
Tastes and odours created during treatment can be caused by either biological activity or the addition of treatment chemicals. The oxidants used in water treatment can remove or reduce tastes and odours but under certain conditions can also cause them.
* In Distribution Systems
There are four sources of tastes and odours in distribution systems:
1. Compounds of biological origin
Tastes and odours of biological origin can be linked to an increase in the number of microorganisms at certain points in the system.
2. Disinfectant residuals and oxidation by-products
Tastes and odours caused by disinfectant residual can be from the residual itself or the reaction on the organic compound.
3. Emissions from pipes and storage facilities
In high concentrations, metals such as lead, copper, zinc and iron can cause tastes on the water as a result of corrosion of the plumbing system.
4. Diffusion of pollutants through synthetic pipes
Some pollutants such as hydrocarbons and phenols may diffuse through plastic piping so care should be given to which way pipes are laid.
* In Household Plumbing
Tastes and odours can be created within ordinary household plumbing. Some examples are metals in high concentrations due to corrosion; hydrogen sulphide forming in hot water tanks; musty odours from inactivity; and odour causing bacteria within certain treatment devices.
Classification and Treatment
It is important to be able to classify an odour that may be detected in drinking water. Classification simplifies odour description, provides a unified terminology, suggests possible sources of odours and may help in choosing the best method of treatment. A taste classification is also required.
The more common descriptors of drinking water odours have been placed in groups. Some of those groups are as follows:
* Group 1 - Earthy/musty/mouldy Most frequently observed;
* May be detected only after addition of chlorine;
* Can be produced by actinomycetes;
* Very low concentrations can lead to complaints.
* Group 2 - Chlorinous High frequency of complaints resulting from chlorination.
* Group 3 - Grass/hay/straw/wood Often associated with algal by-products and sometimes described as decayed vegetation.
* Group 4 - Marshy/swampy/septic/sewage/sulphurous Very offensive;
* May be of natural or anthropogenic origin (sulphur containing compounds).
Treatment
Aeration, filtration, coagulation, oxidation (disinfection), adsorption, and biological treatment are some of the various treatment methods available in assisting in the removal of tastes and odours from the drinking water.
Some of these techniques may be impractical to some situations and can be costly. If oxidation of the water by disinfection and filtering of the water by granular activated carbon (GAC) is not effective in the removal of the tastes and odours, then an alternate source of drinking water should be obtained.
This usually requires construction/ reconstruction of a water well. This frequently involves the installation of additional casing beyond the length (depth) normally required by regulations.
from : http://www.gov.pe.ca/envengfor/index.php3?number=43848&lang=E
Langganan:
Postingan (Atom)
Nature
Spirulina
Mikroalga kaya protein
undersea explorer
