259 results on '"Mongkolsuk, S."'
Search Results
2. The capability of non-native strains of Bacteroides bacteria to detect bacteriophages as faecal indicators in a tropical area
- Author
-
Sirikanchana, K., Wangkahad, B., and Mongkolsuk, S.
- Published
- 2014
- Full Text
- View/download PDF
3. Single and multiple detections of foodborne pathogens by gold nanoparticle assays
- Author
-
Pissuwan, D, Gazzana, C, Mongkolsuk, S, and Cortie, MB
- Subjects
0304 Medicinal and Biomolecular Chemistry, 0903 Biomedical Engineering, 1007 Nanotechnology ,Nanoscience & Nanotechnology - Abstract
A late detection of pathogenic microorganisms in food and drinking water has a high potential to cause adverse health impacts in those who have ingested the pathogens. For this reason there is intense interest in developing precise, rapid and sensitive assays that can detect multiple foodborne pathogens. Such assays would be valuable components in the campaign to minimize foodborne illness. Here, we discuss the emerging types of assays based on gold nanoparticles (GNPs) for rapidly diagnosing single or multiple foodborne pathogen infections. Colorimetric and lateral flow assays based on GNPs may be read by the human eye. Refractometric sensors based on a shift in the position of a plasmon resonance absorption peak can be read by the new generation of inexpensive optical spectrometers. Surface-enhanced Raman spectroscopy and the quartz microbalance require slightly more sophisticated equipment but can be very sensitive. A wide range of electrochemical techniques are also under development. Given the range of options provided by GNPs, we confidently expect that some, or all, of these technologies will eventually enter routine use for detecting pathogens in food. This article is categorized under: Diagnostic Tools > Biosensing.
- Published
- 2019
4. Biodegradation of 3-chlorobenzoate by Pseudomonas putida 10.2
- Author
-
Chobchuenchom, W., Mongkolsuk, S., and Bhumiratana, A.
- Published
- 1996
- Full Text
- View/download PDF
5. Molecular characterization of iron–sulfur cluster regulator binding motifs in pathogenic bacterium Pseudomonas aeruginosa
- Author
-
Romsang, A., Duang-Nkern, J., and Mongkolsuk, S.
- Published
- 2018
- Full Text
- View/download PDF
6. Roles of genes encoding glutathione biosynthesis against oxidative stress and virulence in Pseudomonas aeruginosa
- Author
-
Wongsaroj, L., Saninjuk, K., Romsang, A., Duang-Nkern, J., Vattanaviboon, P., and Mongkolsuk, S.
- Published
- 2018
- Full Text
- View/download PDF
7. Roles of water quality and disinfectant application on inactivation of fish pathogenic <italic>Streptococcus agalactiae</italic> with povidone iodine, quaternary ammonium compounds and glutaraldehyde.
- Author
-
Mon‐on, N., Surachetpong, W., Mongkolsuk, S., and Sirikanchana, K.
- Subjects
STREPTOCOCCAL diseases ,TILAPIA ,WATER quality ,STREPTOCOCCUS agalactiae ,AMMONIUM compounds - Abstract
Abstract: Streptococcosis is an important bacterial disease in Nile tilapia causing severe economic losses to tilapia aquaculture worldwide. The effects of water quality (low‐ [LS] and high‐level [HS] soiling, to mimic clean or dirty surface conditions and temperatures) and disinfectant application (diluted concentrations and exposure time) were characterized on the inactivation of
Streptococcus agalactiae isolated from diseased tilapia. Five isolates were tested against three commercial disinfectant products with the main ingredients being povidone iodine (Anidine 100™; AD), benzalkonium chloride (Better BKC 80%™; BKC 80), and a mixture of quaternary ammonium compounds and glutaraldehyde (Chloraldehyde™; CR). CR demonstrated highest efficacy toS. agalactiae inactivation, followed by BKC 80 and AD, respectively. Higher‐level soiling, low temperature, diluted concentrations and short exposure time all decreased the disinfectant efficacy. CR and BKC 80 provided more than 5‐log inactivation at 1‐min exposure at 20°C under HS conditions, and also with ten‐fold‐diluted concentrations at 60‐min exposure time at 30°C. However, AD required 10‐min exposure to effectively remove bacteria under LS conditions at 30°C. The results could facilitate aquaculture management planning that leads to operating cost reductions and improvements in biosecurity. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
8. Detection of Indicator Bacteria and Pathogens in Water by Polym Erase Chain Reaction (PCR) and Gene Probe Methods.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Atlas, R. M., Bej, A., Mahbubani, M., Steffan, R., Perlin, M., DiCesare, J., and Haff, L.
- Abstract
Sensitive methods for detecting coliform bacteria, and pathogenic bacteria (Salmonella and Shiqella) in environmental waters that do not require culturing of bacteria were developed by using the polymerase chain reaction (PCR) and gene probes. Cells were collected by filtration and DNA was released by freeze-thaw cycling. PCR amplification of region of lacZ gene was used as a target for detection of total coliform bacteria. A region of the lamB gene was the target for detection of Escherichiacoli, Salmonella and Shigella. A region of the uid gene was used for detection of E. coli and Shigella. Biotin was incorporated during PCR amplification and the biotinylated DNA was detected by using membrane-bound poly-T-tailed capture probes. As little as 1 fg of total DNA and as few as 1 cell per 100 ml were detectable by the PCR-gene probe method. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
9. Recombinant Dna Technology in The Bovine Diseases Control Program and Development of Cattle Industry.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Brockelman, Chariya, Boonsaeng, Vichai, and Tan-ariya, Peerapan
- Abstract
For effective control of the vector-borne bovine diseases, a thorough knowledge of the nature of the infective agents, the vectorial capability, and the susceptibility of the bovine host is required. There is, however, little information on prevalence and transmission of bovine diseases due to the difficulty of identifying infected animals by conventional microscopic examination. Therefore, we have used the novel technology of diagnostic DNA-probes for detection of Babesia infection. The best probe can detect as little as 25 ng of purified Babesia DNA, the equivalent of 0.001% parasitemia. Each of the developed probes are species specific. Research on development of vaccines against other tick-borne diseases is also being pursued. The strategy is to identify surface proteins relevant to protection, clone them, and express gene coding for these proteins and test their effectiveness as protective immunogens in recombinant vaccinia construct. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
10. Analysis of Epitopes in The Cholera Family of Enterotoxins.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Kazemi, Mohsammad, and Finkelstein, Richard A.
- Abstract
It is now over 30 years since the cholera enterotoxin was discovered in India and more than 20 years since it was first purified to homogeneity. Early expectations that, as with diphtheria and tetanus, a toxoid vaccine would solve the cholera problem have not been fulfilled. We are examining the reasons why cholera toxin (CT) vaccines have failed to provide effective immunity. Studies with polyclonal (pAbs) and monoclonal (mAbs) antibodies reveal significant differences among the CTs and CT-related enterotoxins (LTs). All field trials of toxoid vaccines have used CT-1 antigen against the prevailing epitype of CT, usually CT-2. Single amino acid substitutions in the immunodominant B-subunit protein have profound effects on immunological reactivity. We have employed pAbs and mAbs, genetically engineered chimeric B-subunit proteins, checkerboard immunoblotting (CBIB), synthetic peptides and their antisera, and sequential overlapping synthetic hexapeptides representing the B-subunit chain to identify epitopes in the CT family. Reactivity of some, but not all, synthetic hexapeptides with epitope activity with polyclonal antisera can be reduced by pretreatment of the serum with the native toxin protein indicating that certain continuous epitopes are exposed on the surface of the native protein. Interestingly, the holotoxin was more effective in this regard than the native B-subunit pentamer indicating a conformational difference between the two. Human convalescent sera gave diffuse patterns of reactivity with discontinuous (conformational) epitopes. A major tetrapeptide epitope has been identified in a conserved region of the protein. Substitution of amino acids in this region can be permissive or can reduce or eliminate activity. Studies like these may lead to the development of rational synthetic peptide vaccines, but a vaccine composed only of CT antigen can only protect against severe life-threatening diarrhea, not all the diarrhea caused by cholera vibrios. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
11. Applications of a Multicopy Phenotype Approach.
- Author
-
Mongkolsuk, S., Lovett, P. S., and Trempy, J. E.
- Abstract
A multicopy phenotype approach to identify new regulatory proteins is not without drawbacks. Overexpression of an activity is not a "real life" situation for the cell. Hartwell and coworkers remark that this method, even while conveniently providing the cloned wildtype gene for further analysis, might fool the investigator; overexpression of any activity might give the desired phenotype, or lead to cell death (2). However, there are ways to circumvent these problems and the investigator need only realize that, when using a multicopy phenotype approach, the next obvious step after the identification of an activity will be to determine its role, as a single copy function, in the cell. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
12. The Enzyme and Gene of the Thermostable Peroxidase from Bacillus Stearothermophilus.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Loprasert, Suvit, Negoro, Seljl, Urabe, Itaru, and Okada, Hirosuke
- Published
- 1992
- Full Text
- View/download PDF
13. Production of 6-Aminopenicillanic Acid by an Enzymatic Process.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Panbangred, Watanalai, Varavinit, Saiyavit, Vichitsoonthonkul, Taweerat, Udomvaraphunt, Suang, Intrararuangsorn, Suthum, and Meevootlsom, Vithaya
- Published
- 1992
- Full Text
- View/download PDF
14. Molecular Cloning of S-Layer Protein Gene from Bacillus Thuringiensis.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Wiwat, Chanpen, Panbangred, Watanalal, Pantuwatana, Somsak, Mongkolsuk, Skorn, and Bhumiratana, Amaret
- Abstract
Extraction of S-layer protein by treatment with a 6M urea indicated that there appeared to be extra-high molecular weight protein in the extracts obtained from Bacillus thuringiensis subsp. israelensis (B.t.i.) strain 4Q2. The antibody toward this large molecular weight protein was prepared and used for locating of S-layer protein on B.t.i. by using indirect immunofluorescent technique. Immunodiffusion reaction and Western blot analysis confirmed the specificity of the anti-S-layer protein. It was found that the antibody against S-layer protein inhibited the plasmid transfer via the conjugation-like process. The frequency of transfer of plasmid pBC16 was found to be 9.7×10-6 and less than 10-8 in the presence and absence of anti-S-layer antibody, respectively. Using antibody detection technique, S-layer protein gene from B.t.i. strain 4Q2 was cloned in phagemid pKSII and plasmid pUC12 of E.coli DH5α. Three positive clones containing the gene encoding for the S-layer protein were obtained. Two clones had the insert of 5.2 kb, and the other one had an insert of 6.6 kb. The expression of the S-layer protein gene was detected by using Western blot analysis. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
15. Induction of CAT mRNA Translation by Chloramphenicol: an Example of Translational Attenuation.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Lovett, Paul S., Ambulos, Nicholas P., and Rogers, Elizabeth J.
- Abstract
The role of crb-86 in cat-86 induction may be a function of both its complementarity with 16S rRNA and the crb-@#@ encoded peptide. Solving the role of crb. as a gene regulatory device will dissect ribosome function in a manner not possible by conventional methodology much in the same vein as other recently discovered variations of ribosome function (12). [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
16. Translation Initiation from a Cug Codon in Bacillus subtilis.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Ambulos, Nicholas P., and Lovett, Paul S.
- Published
- 1992
- Full Text
- View/download PDF
17. Genetic Analysis of Bacterial Strains Freshly Isolated from Natural Sources.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Holloway, W., Bowen, A., Dharmsthiti, S., Krlshnapillal, V., Morgan, A., Ratnaningsih, E., and Sinclair, M. I.
- Abstract
The increased availability and a variety of recombinant DNA techniques, has provided a route for the genetic analysis of newly isolated bacteria. The data so obtained is essential if the manipulation of metabolic pathways of these strains is to be successful. Three general conclusions are possible. Using genetically well characterized models, effective procedures for the genetic analysis of newly isolated bacteria can be developed. Next, a combination of physical and genetic techniques provides genetic analysis superior to the more traditional procedures. Finally, improved techniques enables whole genome analysis to be applied to a range of organisms. The unveiling of hidden complexities in the manner in which bacteria store their biological information can only contribute to our ability to manipulate them for practical purposes. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
18. Microorganisms For The Introduction Of Chlorinated Aliphatic Hydrocarbons Into The Carbon Cycle.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Leisinger, Thomas
- Published
- 1992
- Full Text
- View/download PDF
19. Molecular Evolution Of Enzymes Toward Nylon-Oligomers, Xenobiotic Compounds.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Okada, Hirosuke, Negoro, Seiji, and Urabe, ltaru
- Published
- 1992
- Full Text
- View/download PDF
20. Tol Plasmid: Organization And Regulation Of Gene Expression.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Nakazawa, Teruko, Tsuda, Masataka, Inouye, Sachiye, and Nakazawa, Atsushi
- Published
- 1992
- Full Text
- View/download PDF
21. Responses of E. coli to DNA Damage and Stress.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Ohta, Toshihiro, Battista, John R., Donnelly, Caroline E., and Walker, Graham C.
- Abstract
Exposure of Escherichia coli to agents that damage DNA or interfere with DNA replication results in the induction of the SOS response. A number of chromosomal genes that are repressed by the LexA protein are transcribed at higher levels and various lysogenic bacteriophage are induced. The RecA protein becomes activated by binding to some intracellular inducing signal, probably single-stranded DNA and then mediates proteolytic cleavage of LexA and bacteriophage repressors by facilitating an otherwise latent capacity of these molecules to autodigest. The products of the SOS-regulated operon umuDC axe required for most UV and chemical mutagenesis. We have shown that the UmuD protein shares homology with the carboxyl-terminal domains of LexA and several bacteriophage repressors and is activated for its role in mutagenesis by a RecA-mediated proteolytic event. Thus the regulation of umuD involves a transcriptional derepression and a posttranslational activation that are mechanistically and evolutionary related. A set of missense mutants of umuD was isolated and shown to encode mutant UmuD proteins that are deficient in RecA-mediated cleavage in vivo but which can be partially cleaved at a higher UV dose. Most of these mutations are dominant to umuD* with respect to UV mutagenesis yet do not interfere with SOS induction. Although both UmuD and UmuD' form homodimers, we have found evidence that they preferentially form heterodimers. These studies of umuD have suggested a role for intact UmuD in the modulation of SOS mutagenesis. Other genetic studies have indicated that the RecA protein plays a third role in mutagenesis besides mediating the cleavage of LexA and UmuD. In addition, we have observed that efficiency of UV mutagenesis is greatly reduced by mutations affecting the groESand groEL heat-shockgenes. These genes encode proteins that function as molecular chaperones which mediate protein folding and protein-protein interaction. It seems possible that they may play a role in the proper assembly of a protein complex required for SOS mutagenesis. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
22. The Potential of White-Rot Fungi in Bioremediation.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Kirk, T. Kent, Lamar, Richard T., and Glaser, John A.
- Abstract
The lignin-degrading enzyme system of white-rot fungi, which are mostly basidiomycetes, has been studied intensively in recent years. The extracellular component of the system is comprised of lignin peroxidase, manganese peroxidase, glyoxal oxidase and certain metabolites. Lignin is fragmented by this system, and the plethora of degradation products taken up by the hyphae and further metabolized by the intracellular system. The intracellular system has received very little research attention. The structural complexity and heterogeneity of lignin show in fact that this enzyme system is so nonspecific that it also degrades a variety of hazardous compounds, including polycyclic aromatics, some polychlorinated biphenyls and dioxins, DDT, and many chlorinated phenols. Using pentachlorophenol (PCP) as a model substrate, we have studied the possibility of using white-rot fungi to remediate soils contaminated with hazardous compounds. Successful laboratory results led to a field study in the summer of 1989. Results showed that the laboratory findings could be duplicated in the field. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
23. Bacterial Heavy Metal Detoxification and Resistance Systems.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Silver, Simon
- Abstract
Bacterial plasmids contain genetic determinants for resistance systems for Hg2+ (and organomercurials), Cd2+, AsO2, AsO43-, CrO42-, TeO32-, Cu2+, Ag+, Co2+, Pb2+, and other metals of environmental concern. In some cases, there is the potential for using genetically engineered microbes for bio-remediation. Recombinant DNA analysis has been applied to mercury, cadmium, zinc, cobalt, arsenic, chromate, tellurium and copper resistance systems. The eight mercury resistance systems that have been sequenced all contain the gene for mercuric reductase, the enzyme that converts toxic Hg2+ ions to less toxic volatile metallic Hg°. Four of these systems also determine the enzyme organomercurial lyase, which cuts the HgC bond and thus detoxifies methylmercury and phenylmercury. Two sequenced Cd2+ resistance determinants govern cellular efflux of Cd2+ assuring a low level of intracellular Cd2+: not an obvious candidate for bioremediation. Cadmium accumulation by bacterial metallothionein or phytochelatin is a potentially useful process, but only preliminary reports have appeared on bacteria producing polythiol polypeptides. For arsenic resistance, a unique efflux ATPase maintains low intracellular As levels. A bacterial AsO2- oxidase has been reported, with the potential of converting more toxic As(III) into less toxic As(V), but this system has not been studied in recent years. For chromate, resistance results from reduced cellular uptake. However, both soluble and membrane-bound Cr(VI) reductase bacterial activities convert more toxic Cr(VI) to less toxic Cr(III) in different bacteria. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
24. Analyzing Pathogen Populations Using Molecular Markers.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Nelson, Rebecca J.
- Abstract
DNA probes are useful markers for studying pathogen population genetics. Repetitive probes may produce characteristic "fingerprints" that identify strains or lineages of asexually-reproducing pathogens. Relatedness among strains can be inferred, giving insight into the processes of race evolution, gene flow, and other aspects of pathogen population biology. Information about pathogen population dynamics may be useful in designing improved strategies for disease management. Knowledge of pathogen lineages can also be used in the selection of diverse tester strains used in screening of breeding material for crop improvement. Different probes may reveal somewhat different information about a population. The specific estimates of diversity obtained for a given population depend on the specific probe employed in the analysis. Probes may vary in the extent to which they reveal RFLP patterns that are associated with pathogenic race. If there is a perfect association between RFLP type and race, a probe may be used to identify race. The extent of association between identified molecular and pathogenic phenotypes depends upon the characteristics of the population tested, of the differential cultivars chosen for virulence analysis, and of the probe and enzyme used for the analysis of RFLP type. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
25. Environmental Control of Microbial Gene Expression and Evolution.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Chakrabarty, A. M.
- Abstract
The survival of microorganisms is dependent on their ability to respond to a changing environment. In the very stressed environment of the CF lung, with salty and dehydrated mucus, the microorganisms need to protect themselves from losing their intracellular water and one way to accomplishing this is to produce an exopolysaccharide capsule with strong gelling properties as a barrier to dehydration. It is interesting that the algD promoter is activated by those environmental factors that are characteristic of the CF disease, which explains why CF patients are particularly vulnerable to infections by mucoid P. aeruginosa. It is also interesting to note that the alginate capsule, which is presumably produced to protect P. aeruginosa from intracellular dehydration, also affords protection The activation of the algD promoter has been measured by measuring catechol 2,3-dioxygenase (C230) activity, since a construct containing the xylE gene placed under the algD promoter was used in these experiments (see ref. 18 and 19). One unit of catechol 2,3-dioxygenase activity is defined as the amount of enzyme oxidizing one mmol of catechol to 2-hydroxymuconic semialdehyde, a product with a molar extinction coefficient of 4.4 × 104 at 375 nm. against antibiotics and antibodies to the detriment of the human patients. When the environment is beset with chlorinated compounds, the immediate response of natural microorganisms is to evolve degradative genes in the form of a plasmid. As a first step, they tend to recruit genes that allow degradation of a structurally analogous non-chlorinated compound, which undergo mutational or recombinational divergence to the appropriate genes whose products have broad substrate specificities to include chlorinated compounds. Such evolutionary processes apparently are not very effective for highly chlorinated compounds for which appropriate enzyme systems have not yet fully developed. In a single incidence of directed evolution, the chromosomal DNA shows the presence of multiple copies of a transposable element near the evolved genes, suggesting that an accelerated process of evolution may bypass the requirement of genetic relatedness of the evolved genes to the genome of the recruiting cells. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
26. The Role of Lectin in Association Between Rice and Nitrogen-Fixing Bacteria.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Chaopongpang, S., Pornpattkul, S., Pitaksutheepong, C., Limpananont, J., Chaisiri, P., and Boonjawat, J.
- Abstract
Lectins are multivalent carbohydrate-binding proteins and glycoproteins. In rice and other cereal crops, lectins are well characterized for their binding specificity to N-acetylglucosamine or its oligomers. Although the natural function of lectin remains unknown, several possible functions of cereal lectins have been proposed including an involvement in plantmicrobial interaction. We found that rice lectins are not exclusively confined to embryo, but also in seedling leaf and root, especially at the root tip, and opening stoma of young leaf, which are preferent adhesion sites of microbes. Lectin contents varied with developmental stage and environmental factors. Different rice varieties contain different amount of lectin and respond differently to inoculation by associative nitrogen-fixing Klebsiella R15 and R17. Better plant growth promotion and associative nitrogen-fixation were observed in high lectin variety. Colonization of bacteria on the root surface increased the root lectin. Our results support for the potential application of nitrogen-fixing Klebsiella for promotion of growth and associative nitrogen fixation in rice, Oryza sativa L. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
27. Molecular Strategies in the Interaction Between Agrobacterium and its Hosts.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Nester, Eugene W., and Gordon, Milton P.
- Abstract
The formation of hyperplasias termed "galls" produced by P.savastanoi and the formation of crown gall tumors by Agrobacterium tumefaciens have a number of features in common, In both cases: the unregulated production of IAA arid cytokintn at the site of-infection is-required for gaii formation. Thus, both compounds, the product of bacteria! genes, are virulence factors in both diseases, and therefore, it is not surprising that the disease symptoms are similar. Further, both violence factors are codecs by genes on large plasmids and have a remarkable degree of homology with each other. However, in Pseudcmonas the genes are constitutively expressed in the bacterium, whereas in Agrobacterium. expression occurs oniy after the genes are integrated into the plant chromosome. Apparently, the structura, component of the gene is prokaryotic in nature whereas the upstream regulatory sequences are eukaryotic and respond to plant transcription and translation machinery. Disease production:by P. savssianos appears to be a much simpler process than that by Agrohacterium. in the former ease, the two phytohormones are synthesized by the bacteria at the site of infection and flying bacteria are necessary for continued symptomatology. On the other hand, Agrobactenaum has evolved a very compfex mechanism.for introducing a piece of its plasmid into plant ceiis where it functions. Consequently, the continuecl growth of the bacteria at the wound site is not necessary for tumor formation. The vir genes of Agrobacte rium apparently do not have a counterpart in .Pseudomonas. although its virulence piasmid has not been subjected to extensive mutagenesis. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
28. Green Revolution and Gene Revolution.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Kung, S. D.
- Published
- 1992
- Full Text
- View/download PDF
29. Structure of Peroxidase Isozyme Genes in Brassica and Their Expression.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Shinmyo, A., Fujiyama, K., Takemura, H., Okada, N., and Takano, M.
- Abstract
We have isolated 5 genomic DNAs (prxC1a. prxC1b. prxC1c. prxC2 and prxC3 @#@) coding for horseradish peroxidase (HRP). All 5 genes consisted of 4 exons and 3 introns, and the positions of introns in the coding regions were same in all genes. Putative promoter sequences and polyadenylation signals were also found. Two peroxidase genes (prxCa and prxEa) of Arabidopsis thaliana which belongs to the same family of horseradish, Brassica.were also cloned. The structures and sequences of the coding regions of prxCa. and prxEa were very similar to prxC1b and prxC3, respectively. Transcripts of all HRP genes were abundant in horseradish cultured cells, but organspecific expression was observed in horseradish plant. prxC1 was expressed in root and stem, C2 in stem, and C3 in root. 5'-Noncoding regions of HRP isozyme genes were joined to β-glucuronidase (GUS) reporter gene and introduced into tobacco protoplast by electroporation. Promoter activity was detected in every construct, especially prxC2 gene showed several times higher activity of CaMV35S promoter. The promoter-GUS fused genes were transferred to tobacco leaf disk using binary vector system with Aqrobacteriumtumefaciens. Strong GUS expression was observed in root of transgenic tobacco, but not in leaf. When callus was induced from leaf, GUS activity enhanced 15 -50 time of that in leaf in all promoter regions as observed in horseradish callus. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
30. Coat Protein Mediated Protection and the Potential for its Application in Agriculture.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Beachy, Roger N.
- Abstract
With the development of techniques for the introduction of foreign genes into plant cells and the regeneration of transgenic plants, a number of different approaches have been taken to attempt to produce resistance to virus diseases. Those most commonly used have been (1) the expression of antisense RNAs; (2) the expression of satellite RNAs and defective interfering RNAs and DNAs; and (3) the expression of genes encoding viral capsid (coat) proteins. Of these the latter has been generally accepted because of its ready application to control a variety of virus diseases in a number of different crops. Because we recently published a review of the current state of the field (Beachy et al, 1990) this brief review will highlight the status of the field. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
31. Expression of the β-1,3-Glucanase Gene in Yeast Hansenula Polymorpha.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Shen, Shi-Hsiang, and Bastien, Lison
- Abstract
The yeast cell wall is composed mainly of glucan, mannoprotein and chitin (1). In most yeasts, the polysaccharide glucan is predominantly β-1,3-linked with some branching via (3-1,6- linkages (2). The glucan network in the yeast cell wall, due to its rigidity, is an essential structure in preventing lysis of the protoplast in a hypotonic environment. Several microorganisms have been reported to produce extracellular enzymes capable of lysing yeast cells (3,4). Analysis of the constituents of these lytic enzyme preparations revealed the presence, among other activities, of β-1,3-glucanases (3,5). When combinedwith athiol reagent, β-1,3-glucanase alone was found to be able to lyse the yeast cell (6). Currently, the most common-used enzyme for digestion of yeast cell walls is an enzyme preparation called Zymolyase, produced from Oerskovia xanthineolytica (5). We have isolated the glucanase gene from this organism and completely determined its sequence (7). [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
32. Recent Advance on Thymidylate Synthase-Dihydrofolate Reductase from Plasmodium falciparum.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Sirawaraporn, Worachart
- Abstract
The coding sequence of bifunctional thymidylate synthase-dihydrofolate reductase (TS-DHFR) from moderate pyrimethamine resistant strain of Plasmodium falciparum was assembled in a pUC expression vector. Insertion of a synthetic oligonucleotide duplex containing a ribosomal binding sequence at 5' upstream to ATG start codon resulted in a recombinant plasmid which expressed catalytically active TS-DHFR in E. coli. The expression of Plasmodium enzyme was demonstrated as follows: First, transformation of a TS-deficient E. coli resulted in genetic complementation of the deficiency and the activities of TS and DHFR were significantly higher than those in control host extracts. Second, TS and DHFR activities copurified upon chromatography with an apparent molecular weight ∼ 110 kDa, a characteristic of protozoan bifunctional enzyme. Third, the enzyme formed a covalent complex with [3H] FdUMP-CH2H4folate, and SDS polyacrylamide gel electrophoresis showed the subunit of the recombinant enzyme to be 67 kDa. Finally, N-terminus sequencing of the 67 kDa protein indicated that the N-terminus was not blocked and the sequences of the first 10 amino acids perfectly matched the reported nucleotide sequence. The recombinant enzyme was purified to homogeneity using 10 formylfolate affinity chromatography followed by FPLC on Mono Q column. Since the coding sequence possesses unique Nco1 and Xba1 sites which flank 243 bp of the DHFR gene that include point mutations thus far linked to pyrimethamine resistance, recombinant plasmids of wild type (3D7) and highly pyrimethamine resistant (7G8) gene were constructed by cassette mutagenesis using Nco1 -Xba1 fragments from the corresponding cloned TS-DHFR genes. Characterization of the purified-recombinant enzymes with regard to their kinetic properties and inhibition by pyrimethamine strongly clearly indicated that point mutations are the molecular basis of pyrimethamine resistance in P. falciparum. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
33. Role of the αA-Crybp1 Site in Lens-Specific Expression of the αA-Crystallin Gene.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Sax, Christina M., Klement, John F., and Piatigorsky, Joram
- Abstract
A heterogeneous group of crystallins comprise 80-90% of the soluble protein of the ocular lens and are responsible for lens transparency (see 30 for review). The two a-crystallins (αA and (αB) are present in all vertebrates, and arose from duplication of a common ancestral gene. The αA gene is expressed in a lens-specific manner, while the αB gene is expressed in numerous tissues (see 24 for review). A combination of transgenic mouse (28), mutagenesis, and cDNA cloning experiments (20) have implicated the αA-CRYBP1 site (5′- GGGAAATCCC-3′ at-66 to-57) in the lens-specific expression of the mouse α-crystallin gene. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
34. Host-Vector System and Reverse Genetics in A Non-Conventional Yeast,Candida maltosa.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Takagi, Masamichi
- Abstract
In Candida maltosa, expression of many genes is induced by the hydrophobic compound, n-alkane, resulting in biogenesis of organelles such as endoplasmic reticulum and peroxisome where n-alkane is metabolized. Host-vector systems are needed in order to investigate this phenomenon at the molecular level. Since C. maltosa does not have plasmids, the isolation of an ARS site from the genome of C maltosa was attempted so as to construct vectors. Several host-vector systems were constructed to promote reverse genetics in this non-conventional yeast as described in our recent papers shown below. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
35. Moveable Elements in The Human Genome: Status of Research.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., Singer, Maxine F., Fanning, Thomas G., Lelbold, Debra M., Swergold, Gary D., and Thayer, Ronald E.
- Abstract
The first moveable DNA elements to be studied at the molecular level were the transposable elements found in prokaryotes. Although several different types are now known, they all share two properties: first, the DNA within the element encodes a gene or genes that are required for transposition, and, second, specific DNA sequences are repeated in inverted orientation at the two ends of the element and are required for transposition. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
36. Modification of Specific Chromosomal Loci in Mammalian Cells by Recombination.
- Author
-
Mongkolsuk, S., Lovett, P. S., Trempy, J. E., and Berg, Paul
- Abstract
Biochemistry and genetics epitomize what is called the reductionist approach to biology; single biological elements (for example, a protein, an enzyme, or a gene) are examined in great detail through a series of narrowly defined questions and experimental protocols. This approach can illuminate many phenotypic characteristics of complex systems, including whole organisms, if those phenotypes are the direct consequence of a single gene's function. [ABSTRACT FROM AUTHOR]
- Published
- 1992
- Full Text
- View/download PDF
37. Effects of exposure times on the toxic response of ammonia oxidizing mixed culture (AOMC) to phenol and chlorinated phenols.
- Author
-
Tantasut, J., Satoh, H., Parkpian, P., and Mongkolsuk, S.
- Subjects
BIOLOGICAL nutrient removal ,PHENOLS ,MIXED culture (Microbiology) ,TOXICITY testing ,AMMONIA & the environment ,WASTEWATER treatment - Abstract
This study investigated the effect of exposure times on the response of ammonia oxidizing mixed culture (AOMC) to phenolic compounds while having the future goal to develop a biosensor using AOMC for toxicity monitoring. AOMC was used instead of purified nitrifying culture because of the ease of culture development. The oxygen utilization rate (OUR) was measured during three exposure periods; 0-15, 25-40 and 50-65 min. It was found that phenolic compounds have a strong inhibitory effect on AOMC. The percentage of OUR reduction increased with higher concentrations and the extended exposure times improved the toxic response of AOMC, especially to the lower concentrations (0.25, 0.50, 1.0 mg/L). Further, AOMC detoxifying mechanisms might result in the reduction of toxic response when the longest exposure time was applied. However, at the higher concentrations (2.5 and 5.0 mg/L), the extended exposure times did not have a critical effect on the response pattern of AOMC, especially for phenol and mono-chlorinated phenols. It was illustrated that AOMC is very sensitive to phenolic compounds and its sensitivity is high enough for the detection of phenolic compounds at the level of effluent standard in Thailand and Japan with a rapid response time of 15 min. To improve the sensitivity of AOMC to low phenolic compound concentrations, an extended exposure time of 25-40 min would be recommended. [ABSTRACT FROM AUTHOR]
- Published
- 2006
- Full Text
- View/download PDF
38. 250. Usnic acid. Part IX. A revised structure for usnolic acid and the resolution of (±)-usnic acid.
- Author
-
Dean, F. M., Halewood, P., Mongkolsuk, S., Robertson, Alexander, and Whalley, W. B.
- Published
- 1953
- Full Text
- View/download PDF
39. Cloning and characterization of ribosomal RNA genes from Opisthorchis viverrini.
- Author
-
Korbsrisate, S., Mongkolsuk, S., Haynes, J. R., Wong, Q., and Sirisinha, S.
- Published
- 1992
- Full Text
- View/download PDF
40. Antibiotic Resistance Genes and crAssphage in Hospital Wastewater and a canal receiving the treatment effluent.
- Author
-
Siri Y, Sresung M, Paisantham P, Mongkolsuk S, Sirikanchana K, Honda R, Precha N, and Makkaew P
- Abstract
Hospital wastewater is a major hotspot for the spread of antimicrobial resistance (AMR) in aquatic ecosystems. This study aimed to investigate the prevalence of antibiotic resistance genes (ARGs) and their correlation with crAssphage in a hospital wastewater treatment plant (HWWTP) and a receiving canal. Water samples were analyzed for 94 ARGs and crAssphage relative to the 16S rRNA using high-throughput quantitative polymerase chain reaction (HT-qPCR). Subsequently, 7 ARGs and crAssphage were selected and quantified using qPCR. The results showed that the detected genes ranged from 85 to 93 out of 94 genes. The raw wastewater (WW) samples had the highest gene diversity compared to the upstream canal, which had less diversity than downstream samples, as determined by HT-qPCR. The bla
GES was the most abundant in WW samples, while qacEΔ1, merA, IS6100, tnpA, and IS26 showed high prevalence throughout the treatment processes. The concentrations of intI1, sul1, blaTEM, blaNDM, blaVIM, tetQ, mcr-1, crAssphage, and 16S rRNA, measured using qPCR, were the highest in WW and significantly reduced in treated water samples. Although some water quality parameters, such as total suspended solids and dissolved oxygen, did not significantly differ before and after treatment, removal efficiency ranged from 0.60 to 3.23 log reduction values (LRV). The highest LRV was observed for the tetQ, whereas the mcr-1 had the lowest of LRV. Strong positive correlations among the absolute concentrations of ARGs and crAssphage were observed (Spearman's rho = 0.6 - 1.0), and biochemical oxygen demand correlated with blaTEM and blaVIM (Spearman's rho = 0.6 and 0.6, respectively). These results indicate that crAssphage and water quality could reflect the distribution of other ARGs throughout the HWWTP. Further studies are needed to underscore the importance of monitoring ARGs and biomarkers such as crAssphage in HWWTPs and their receiving waters to enhance our understanding of ARG distribution., Competing Interests: Declaration of Competing Interest ☒ The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. ☐ The authors declare the following financial interests/personal relationships which may be considered as potential competing interests:, (Copyright © 2024. Published by Elsevier Ltd.)- Published
- 2024
- Full Text
- View/download PDF
41. Risk-based critical concentrations of enteric pathogens for recreational water criteria and recommended minimum sample volumes for routine water monitoring.
- Author
-
Denpetkul T, Pumkaew M, Sittipunsakda O, Srathongneam T, Mongkolsuk S, and Sirikanchana K
- Abstract
Concerns are rising about the contamination of recreational waters from human and animal waste, along with associated risks to public health. However, existing guidelines for managing pathogens in these environments have not yet fully integrated risk-based pathogen-specific criteria, which, along with recent advancements in indicators and markers, are essential to improve the protection of public health. This study aimed to establish risk-based critical concentration benchmarks for significant enteric pathogens, i.e., norovirus, rotavirus, adenovirus, Cryptosporidium spp., Giardia lamblia, Campylobacter jejuni, Salmonella spp., and Escherichia coli O157:H7. Applying a 0.036 risk benchmark to both marine and freshwater environments, the study identified the lowest critical concentrations for children, who are the most susceptible group. Norovirus, C. jejuni, and Cryptosporidium presented lowest median critical concentrations for virus, bacteria, and protozoa, respectively: 0.74 GC, 1.73 CFU, and 0.39 viable oocysts per 100 mL in freshwater for children. These values were then used to determine minimum sample volumes corresponding to different recovery rates for culture method, digital polymerase chain reaction and quantitative PCR methods. The results indicate that for children, norovirus required the largest sample volumes of freshwater and marine water (52.08 to 178.57 L, based on the 5th percentile with a 10 % recovery rate), reflecting its low critical concentration and high potential for causing illness. In contrast, adenovirus and rotavirus required significantly smaller volumes (approximately 0.24 to 1.33 L). C. jejuni and Cryptosporidium, which required the highest sampling volumes for bacteria and protozoa, needed 1.72 to 11.09 L and 4.17 to 25.51 L, respectively. Additionally, the presented risk-based framework could provide a model for establishing pathogen thresholds, potentially guiding the creation of extensive risk-based criteria for various pathogens in recreational waters, thus aiding public health authorities in decision-making, strengthening pathogen monitoring, and improving water quality testing accuracy for enhanced health protection., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
42. Regulation of curcumin reductase curA (PA2197) through sodium hypochlorite and N-ethylmaleimide sensing by TetR family repressor CurR (PA2196) in Pseudomonas aeruginosa.
- Author
-
Duang-Nkern J, Nontaleerak B, Thongphet A, Asano K, Chujan S, Satayavivad J, Sukchawalit R, and Mongkolsuk S
- Subjects
- Promoter Regions, Genetic, Curcumin pharmacology, Binding Sites, Oxidoreductases genetics, Oxidoreductases metabolism, Pseudomonas aeruginosa genetics, Pseudomonas aeruginosa metabolism, Pseudomonas aeruginosa drug effects, Sodium Hypochlorite pharmacology, Bacterial Proteins genetics, Bacterial Proteins metabolism, Gene Expression Regulation, Bacterial drug effects, Repressor Proteins genetics, Repressor Proteins metabolism
- Abstract
Pseudomonas aeruginosa PA2196 is a TetR family transcriptional repressor. In this study, the deletion of the PA2196 gene caused increased expression of the downstream gene curA (PA2197), which encodes for a NADPH-dependent curcumin/dihydrocurcumin reductase. The PA2196 gene was then identified as curR, and a DNA footprinting assay showed that CurR directly bound to the curA promoter at an imperfect 15-bp inverted repeat, 5'-TAGTTGA-C-TGGTCTA-3'. A curA promoter-lacZ fusion assay and site-directed mutagenesis further demonstrated that the identified CurR binding site plays a crucial role in curA repression by CurR. curA transcription was inducible by sodium hypochlorite (NaOCl) and N-ethylmaleimide (NEM) but not by hydrogen peroxide, organic hydroperoxide, or curcumin. The oxidation and alkylation of CurR by NaOCl and NEM, respectively, resulted in the inactivation of its DNA-binding activity, which induced curA expression. Under the tested conditions, the deletion of either curR or curA did not affect the survival of P. aeruginosa under NaOCl stress in the absence or presence of curcumin., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)
- Published
- 2024
- Full Text
- View/download PDF
43. High throughput qPCR unveils shared antibiotic resistance genes in tropical wastewater and river water.
- Author
-
Srathongneam T, Sresung M, Paisantham P, Ruksakul P, Singer AC, Sukchawalit R, Satayavivad J, Mongkolsuk S, and Sirikanchana K
- Subjects
- Genes, Bacterial, Rivers, Drug Resistance, Microbial genetics, Water analysis, Anti-Bacterial Agents pharmacology, Anti-Bacterial Agents analysis, Wastewater
- Abstract
The global challenge posed by rising antimicrobial resistance, and the adoption of a One Health approach, has led to the prioritisation of surveillance for antibiotic resistance genes (ARGs) in various environments. Herein lies an information gap, particularly in the context of Thailand, where there is scarce data on ARG prevalence across diverse environmental matrices and throughout different seasons. This study aimed to fill this void, analysing ARG prevalence by high-throughput qPCR in influent (n = 12) and effluent wastewater (n = 12) and river water (n = 12). The study reveals a substantial and largely uniform presence of ARGs across all water sample types (87 % similarity). Intriguingly, no ARGs were exclusive to specific water types, indicating an extensive circulation of resistance determinants across the aquatic environment. The genes intI1, tnpA, and intI3, part of the integrons and mobile genetic elements group, were detected in high relative abundance in both wastewater and river water samples, suggesting widespread pollution of rivers with wastewater. Additional high-prevalence ARGs across all water types included qepA, aadA2, merA, sul1, qacF/H, sul2, aadB, and ereA. More alarmingly, several ARGs (e.g., bla
VIM , intI3, mcr-1, mexB, qepA, vanA, and vanB) showed higher relative abundance in effluent and river water than in influents, which suggests malfunctioning or inadequate wastewater treatment works and implicates this as a possible mechanism for environmental contamination. Nine genes (i.e., blaCTX-M , blaVIM , emrD, ermX, intI1, mphA, qepA, vanA, and vanB) were recovered in greater relative abundance during the dry season in river water samples as compared to the wet season, suggesting there are seasonal impacts on the efficacy of wastewater treatment practices and pollution patterns into receiving waters. This study highlights the urgency for more effective measures to reduce antibiotic resistance dissemination in water systems., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2024
- Full Text
- View/download PDF
44. Early warning of statewide COVID-19 Omicron wave by sentineled urbanized sewer network monitoring using digital PCR in a province capital city, of Gujarat, India.
- Author
-
Kumar M, Joshi M, Prajapati B, Sirikanchana K, Mongkolsuk S, Kumar R, Gallage TP, and Joshi C
- Subjects
- Humans, SARS-CoV-2 genetics, Polymerase Chain Reaction, India, COVID-19 Testing, RNA, Viral, COVID-19 epidemiology
- Abstract
Wastewater-based epidemiology (WBE) has been implemented globally. However, there remains confusion about the number and frequency of samples to be collected, as well as which types of treatment systems can provide reliable specific details about the virus prevalence in specific areas or communities, enabling prompt management and intervention measures. More research is necessary to fully comprehend the possibility of deploying sentinel locations in sewer networks in larger geographic areas. The present study introduces the first report on wastewater-based surveillance in Gandhinagar City using digital PCR (d-PCR) as a SARS-Cov-2 quantification tool, which describes the viral load from five pumping stations in Gandhinagar from October 2021 to March 2022. Raw wastewater samples (n = 119) were received and analyzed weekly to detect SARS-CoV-2 RNA, 109 of which were positive for N1 or N2 genes. The monthly variation analysis in viral genome copies depicted the highest concentrations in January 2022 and February 2022 (p < 0.05; Wilcoxon signed rank test) coincided with the Omicron wave, which contributed mainly from Vavol and Jaspur pumping stations. Cross-correlation analysis indicated that WBE from five stations in Gandhinagar, i.e., capital city sewer networks, provided two-week lead times to the citywide and statewide active cases (time-series cross-correlation function [CCF]; 0.666 and 0.648, respectively), mainly from individual contributions of the urbanized Kudasan and Vavol stations (CCF; 0.729 and 0.647, respectively). These findings suggest that sewer pumping stations in urbanized neighborhoods can be used as sentinel sites for statewide clinical surveillance and that WBE surveillance using digital PCR can be an efficient monitoring and management tool., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Crown Copyright © 2023. Published by Elsevier B.V. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
45. Quantitative microbial risk assessment of the gastrointestinal risks to swimmers at Southeast Asian urban beaches using site-specific and combined autochthonous and fecal bacteria exposure data.
- Author
-
Denpetkul T, Pumkaew M, Sittipunsakda O, Sresung M, Chyerochana N, Kongprajug A, Rattanakul S, Patarapongsant Y, Mongkolsuk S, and Sirikanchana K
- Subjects
- Humans, Bacteria isolation & purification, Enterococcus isolation & purification, Feces microbiology, Risk Assessment, Southeast Asian People, Urban Population, Swimming, Thailand, Bathing Beaches, Environmental Monitoring methods, Water Microbiology, Gastrointestinal Diseases epidemiology, Gastrointestinal Diseases microbiology, Water Quality, Vibrio parahaemolyticus isolation & purification
- Abstract
Recreational exposure to microbial pollution at urban beaches poses a health risk to beachgoers. The accurate quantification of such risks is crucial in managing beaches effectively and establishing warning guidelines. In this study, we employed a quantitative microbial risk assessment (QMRA) framework to assess marine water quality and estimate the risks associated with Vibrio parahaemolyticus, an autochthonous pathogen that causes gastrointestinal illnesses, and enterococci, a traditional fecal bacteria indicator. The microbial contamination levels of V. parahaemolyticus and enterococci were determined from 48 water samples collected at two beaches in Thailand during dry and wet seasons. The accidentally ingested water volumes were obtained through a survey involving 438 respondents. The probability of illness (P
ill ) was estimated using dose-response models and Monte Carlo simulation. The results revealed that enterococci posed a higher risk of illness than V. parahaemolyticus at all seven study sites. The median combined gastrointestinal (GI) risk from both bacteria at all sites met the US EPA risk benchmark of 0.036 and the 0.05 benchmark set by the WHO, but the 95th percentile risk data at all sites exceeded the benchmarks. This emphasizes the need for the continuous monitoring and management of microbial pollution at these sites. The site-specific exposure data showed higher estimated risks with increased variations compared to the WHO-referenced values, which highlights the significance of locally measured microbial concentrations and survey exposure data to avoid underestimation. Estimating the risks from recreational exposure to waterborne bacteria can inform beach management policies aimed at reducing public health risks to swimmers. The study findings improve the understanding of the risks associated with water recreation activities at Southeast Asian beaches and offer valuable insights for the development of water quality guidelines, which are crucial for the sustainable development of the blue economy., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
46. The redox-sensing mechanism of Agrobacterium tumefaciens NieR as a thiol-based oxidation sensor for hypochlorite stress.
- Author
-
Nontaleerak B, Eurtivong C, Weeraphan C, Buncherd H, Chokchaichamnankit D, Srisomsap C, Svasti J, Sukchawalit R, and Mongkolsuk S
- Subjects
- Agrobacterium tumefaciens genetics, Agrobacterium tumefaciens metabolism, Bacterial Proteins metabolism, Oxidation-Reduction, Cysteine metabolism, Escherichia coli genetics, Disulfides metabolism, Alanine metabolism, DNA metabolism, Hypochlorous Acid pharmacology, Sulfhydryl Compounds
- Abstract
NieR is a TetR family transcriptional repressor previously shown to regulate the NaOCl-inducible efflux pump NieAB in Agrobacterium tumefaciens. NieR is an ortholog of Escherichia coli NemR that specifically senses hypochlorite through the redox switch of a reversible sulfenamide bond between C106 and K175. The amino acid sequence of NieR contains only one cysteine. NieR has C104 and R166, which correspond to C106 and K175 of NemR, respectively. The aim of this study was to investigate the redox-sensing mechanism of NieR under NaOCl stress. C104 and R166 were subjected to mutagenesis to determine their roles. Although the substitution of R166 by alanine slightly reduced its DNA-binding activity, NieR retained its repressor function. By contrast, the DNA-binding and repression activities of NieR were completely lost when C104 was replaced by alanine. C104 substitution with serine only partially impaired the repressor function. Mass spectrometry analysis revealed an intermolecular disulfide bond between the C104 residues of NieR monomers. This study demonstrates the engagement of C104 in the mechanism of NaOCl sensing. C104 oxidation induced the formation of a disulfide-linked dimer that was likely to alter conformation, thus abolishing the DNA-binding ability of NieR and derepressing the target genes., Competing Interests: Declaration of competing interest None., (Copyright © 2023 Elsevier Inc. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
47. Microbial source tracking using molecular and cultivable methods in a tropical mixed-use drinking water source to support water safety plans.
- Author
-
Sresung M, Paisantham P, Ruksakul P, Kongprajug A, Chyerochana N, Gallage TP, Srathongneam T, Rattanakul S, Maneein S, Surasen C, Passananon S, Mongkolsuk S, and Sirikanchana K
- Subjects
- Humans, Animals, Cattle, Swine, Water Pollution analysis, Water Quality, Fresh Water analysis, Feces chemistry, Water Microbiology, Environmental Monitoring methods, Drinking Water analysis
- Abstract
Microbial contamination deteriorates source water quality, posing a severe problem for drinking water suppliers worldwide and addressed by the Water Safety Plan framework to ensure high-quality and reliable drinking water. Microbial source tracking (MST) is used to examine different microbial pollution sources via host-specific intestinal markers for humans and different types of animals. However, the application of MST in tropical surface water catchments that provide raw water for drinking water supplies is limited. We analyzed a set of MST markers, namely, three cultivable bacteriophages and four molecular PCR and qPCR assays, together with 17 microbial and physicochemical parameters, to identify fecal pollution from general, human-, swine-, and cattle-specific sources. Seventy-two river water samples at six sampling sites were collected over 12 sampling events during wet and dry seasons. We found persistent fecal contamination via the general fecal marker GenBac3 (100 % detection; 2.10-5.42 log
10 copies/100 mL), with humans (crAssphage; 74 % detection; 1.62-3.81 log10 copies/100 mL) and swine (Pig-2-Bac; 25 % detection; 1.92-2.91 log10 copies/100 mL). Higher contamination levels were observed during the wet season (p < 0.05). The conventional PCR screening used for the general and human markers showed 94.4 % and 69.8 % agreement with the respective qPCR results. Specifically, in the studied watershed, coliphage could be a screening parameter for the crAssphage marker (90.6 % and 73.7 % positive and negative predictive values; Spearman's rank correlation coefficient = 0.66; p < 0.001). The likelihood of detecting the crAssphage marker significantly increased when total and fecal coliforms exceeded 20,000 and 4000 MPN/100 mL, respectively, as Thailand Surface Water Quality Standards, with odds ratios and 95 % confidence intervals of 15.75 (4.43-55.98) and 5.65 (1.39-23.05). Our study confirms the potential benefits of incorporating MST monitoring into water safety plans, supporting the use of this approach to ensure high-quality drinking water supplies worldwide., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Kwanrawee Sirikanchana reports financial support was provided by Metropolitan Waterworks Authority. Chatsinee Surasen reports a relationship with Metropolitan Waterworks Authority that includes: employment. Somsak Passananon reports a relationship with Metropolitan Waterworks Authority that includes: employment., (Copyright © 2023 Elsevier B.V. All rights reserved.)- Published
- 2023
- Full Text
- View/download PDF
48. Induction of Antimicrobial Resistance of Stenotrophomonas maltophilia by Exposure to Nonlethal Levels of Antibiotics.
- Author
-
Chatree Y, Charoenlap N, Vanitshavit V, Ruangrassamee P, Mongkolsuk S, and Vattanaviboon P
- Subjects
- Humans, Anti-Bacterial Agents pharmacology, Ceftazidime pharmacology, Drug Resistance, Bacterial genetics, Microbial Sensitivity Tests, Ciprofloxacin pharmacology, Stenotrophomonas maltophilia genetics, Gram-Negative Bacterial Infections drug therapy
- Abstract
The effects of the sequential subculture in the presence of a driving force on antimicrobial resistance of Stenotrophomonas maltophilia K279a were investigated. Stationary-phase cells were inoculated into the lysogeny broth medium, with and without antibiotic supplementation, and grown until the stationary phase before being subcultured into the same antibiotic-supplemented medium for six consecutive cycles. Thirty colonies from each cycle and treatment condition were selected and their antibiotic susceptibility profiles were determined. The sequential subculture of K279a for a number of cycles reduced susceptibility to diverse classes of antibiotics, including ciprofloxacin, amikacin, gentamicin, ceftazidime, co-trimoxazole, and chloramphenicol, regardless of the antibiotic used. Supplementation with antibiotics that is, ampicillin, kanamycin, ciprofloxacin, and ceftazidime, at sublethal concentrations significantly accelerated the development rate of strains that reduced susceptibility to other antibiotics. The patterns of reduced susceptibility were different depending on the antibiotic used for supplementation. Thus, without gene transfer, antibiotic-resistant strains of S. maltophilia can readily develop, especially after antibiotic treatments. Whole-genome sequence analysis of the selected antibiotic-resistant mutants identified gene mutations that might be responsible for antimicrobial resistance of S. maltophilia .
- Published
- 2023
- Full Text
- View/download PDF
49. Wastewater monitoring in tourist cities as potential sentinel sites for near real-time dynamics of imported SARS-CoV-2 variants.
- Author
-
Sangsanont J, Rattanakul S, Makkaew P, Precha N, Rukthanapitak P, Sresung M, Siri Y, Kitajima M, Takeda T, Haramoto E, Puenpa J, Wanlapakorn N, Poovorawan Y, Mongkolsuk S, and Sirikanchana K
- Subjects
- Humans, Cities, SARS-CoV-2 genetics, Thailand, Wastewater, Wastewater-Based Epidemiological Monitoring, COVID-19 epidemiology
- Abstract
Wastewater-based epidemiology (WBE) complements the clinical surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its variants' distribution in populations. Many developed nations have established national and regional WBE systems; however, governance and budget constraints could be obstacles for low- and middle-income countries. An urgent need thus exists to identify hotspots to serve as sentinel sites for WBE. We hypothesized that representative wastewater treatment plants (WWTPs) in two international gateway cities, Bangkok and Phuket, Thailand, could be sentineled for SARS-CoV-2 and its variants to reflect the clinical distribution patterns at city level and serve as early indicators of new variants entering the country. Municipal wastewater samples (n = 132) were collected from eight representative municipal WWTPs in Bangkok and Phuket during 19 sampling events from October 2021 to March 2022, which were tested by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) using the US CDC N1 and N2 multiplex and variant (Alpha, Delta, and Omicron BA.1 and BA.2) singleplex assays. The variant detection ratios from Bangkok and Phuket followed similar trends to the national clinical testing data, and each variant's viral loads agreed with the daily new cases (3-d moving average). Omicron BA.1 was detected in Phuket wastewater prior to Bangkok, possibly due to Phuket's WWTPs serving tourist communities. We found that the Omicron BA.1 and BA.2 viral loads predominantly drove the SARS-CoV-2 resurgence. We also noted a shifting pattern in the Bangkok WBE from a 22-d early warning in early 2021 to a near real-time pattern in late 2021. The potential application of tourist hotspots for WBE to indicate the arrival of new variants and re-emerging or unprecedented infectious agents could support tourism-dependent economies by complementing the reduced clinical regulations while maintaining public health protection via wastewater surveillance., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2023
- Full Text
- View/download PDF
50. Monothiol Glutaredoxin Is Essential for Oxidative Stress Protection and Virulence in Pseudomonas aeruginosa.
- Author
-
Saninjuk K, Romsang A, Duang-Nkern J, Wongsaroj L, Leesukon P, Dubbs JM, Vattanaviboon P, and Mongkolsuk S
- Subjects
- Animals, Humans, Virulence, Drosophila melanogaster metabolism, Oxidative Stress, Iron metabolism, Pseudomonas aeruginosa genetics, Pseudomonas aeruginosa metabolism, Glutaredoxins genetics, Glutaredoxins metabolism
- Abstract
Glutaredoxins (Grxs), ubiquitous redox enzymes belonging to the thioredoxin family, catalyze the reduction of thiol-disulfide exchange reactions in a glutathione-dependent manner. A Pseudomonas aeruginosa Δ grxD mutant exhibited hypersensitivity to oxidative stress-generating agents, such as paraquat (PQ) and cumene hydroperoxide (CHP). In vitro studies showed that P. aeruginosa GrxD acts as an electron donor for organic hydroperoxide resistance enzyme (Ohr) during CHP degradation. The ectopic expression of iron-sulfur cluster ([Fe-S]) carrier proteins, including ErpA, IscA, and NfuA, complements the function of GrxD in the Δ grxD mutant under PQ toxicity. Constitutively high expression of iscR , nfuA , tpx , and fprB was observed in the Δ grxD mutant. These results suggest that GrxD functions as a [Fe-S] cluster carrier protein involved in [Fe-S] cluster maturation. Moreover, the Δ grxD mutant demonstrates attenuated virulence in a Drosophila melanogaster host model. Altogether, the data shed light on the physiological role of GrxD in oxidative stress protection and virulence of the human pathogen, P. aeruginosa. IMPORTANCE Glutaredoxins (Grxs) are ubiquitous disulfide reductase enzymes. Monothiol Grxs, containing a CXXS motif, play an essential role in iron homeostasis and maturation of [Fe-S] cluster proteins in various organisms. We now establish that the human pathogen Pseudomonas aeruginosa GrxD is crucial for bacterial virulence, maturation of [Fe-S] clusters and facilitation of Ohr enzyme activity. GrxD contains a conserved signature monothiol motif (C
29 GFS), in which C29 is essential for its function in an oxidative stress protection. Our findings reveal the physiological roles of GrxD in oxidative stress protection and virulence of P. aeruginosa.- Published
- 2023
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.