An experiment in enzyme evolution studies with Pseudomonas aeruginosa amidase

1988 ◽  
Vol 8 (2) ◽  
pp. 103-120 ◽  
Author(s):  
Patricia H. Clarke ◽  
Robert Drew
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Control System ◽  
Experimental Evolution ◽  
Positive Control ◽  
Enzyme Evolution ◽  
Regulator Protein ◽  
Hydrolysis Of

The regulation of amidase synthesis in P. aeruginosa is under positive control. This review describes the experimental evolution of amidase and its regulator protein for the hydrolysis of novel substrates and experiments to elucidate the mechanism of the control system.

scholarly journals GES-2, a Class A β-Lactamase fromPseudomonas aeruginosa with Increased Hydrolysis of Imipenem

2001 ◽  
Vol 45 (9) ◽  
pp. 2598-2603 ◽  
Author(s):  
Laurent Poirel ◽  
Gerhard F. Weldhagen ◽  
Thierry Naas ◽  
Christophe De Champs ◽  
Michael G. Dove ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Amino Acid ◽  
Amino Acid Change ◽  
Blood Cultures ◽  
Class A ◽  
Omega Loop ◽  
Cephalosporin Resistance ◽  
Lactamase Gene ◽  
Hydrolysis Of

ABSTRACT Pseudomonas aeruginosa GW-1 was isolated in 2000 in South Africa from blood cultures of a 38-year-old female who developed nosocomial pneumonia. This isolate harbored a self-transferable ca. 100-kb plasmid that conferred an expanded-spectrum cephalosporin resistance profile associated with an intermediate susceptibility to imipenem. A β-lactamase gene, bla GES-2, was cloned from whole-cell DNA of P. aeruginosa GW-1 and expressed in Escherichia coli. GES-2, with a pI value of 5.8, hydrolyzed expanded-spectrum cephalosporins, and its substrate profile was extended to include imipenem compared to that of GES-1, identified previously in Klebsiella pneumoniae. GES-2 activity was less inhibited by clavulanic acid, tazobactam and imipenem than GES-1. The GES-2 amino acid sequence differs from that of GES-1 by a glycine-to-asparagine substitution in position 170 located in the omega loop of Ambler class A enzymes. This amino acid change may explain the extension of the substrate profile of the plasmid-encoded β-lactamase GES-2.

Enhancing enzymatic hydrolysis of coconut husk through Pseudomonas aeruginosa AP 029/GLVIIA rhamnolipid preparation

2017 ◽  
Vol 237 ◽  
pp. 20-26 ◽  
Author(s):  
Cynthia Kérzia Costa de Araújo ◽  
Alan de Oliveira Campos ◽  
Carlos Eduardo de Araújo Padilha ◽  
Francisco Canindé de Sousa Júnior ◽  
Ruthinéia Jéssica Alves do Nascimento ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Enzymatic Hydrolysis ◽  
Coconut Husk ◽  
Hydrolysis Of

scholarly journals ANTIBACTERIAL RESISTANCE PATTERN OF PSEUDOMONAS AERUGINOSA ISOLATED FROM CLINICAL SAMPLES AT A GENERAL HOSPITAL IN PADANG, WEST SUMATRA, INDONESIA

2017 ◽  
Vol 10 (8) ◽  
pp. 158
Author(s):  
Rustini Rustini ◽  
Jamsari Jamsari ◽  
Marlina Marlina ◽  
Nasrul Zubir ◽  
Yori Yuliandra
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Bacterial Resistance ◽  
Clinical Sample ◽  
Opportunistic Pathogen ◽  
Positive Control ◽  
Diffusion Method ◽  
Clinical Samples ◽  
Resistance Pattern ◽  
Tract Infections ◽  
Almost All

Objectives: Pseudomonas aeruginosa is an opportunistic pathogen that has an innate resistance to some antibiotics. This bacterium is one of the mostcommon causes of nosocomial infections that include surgical wound infections, burns, and urinary tract infections. The bacteria have been reportedlyresistant to many antibiotics and have developed multidrug resistance (MDR). The objective of the study was to determine the resistance pattern ofP. aeruginosa isolated from clinical samples of patients against some major antibiotics.Methods: Isolates of P. aeruginosa were obtained from clinical sample of urine, sputum, swabs, pus, feces, and blood and cultured in cetrimide agar. P.aeruginosa ATCC 27853 was used as a positive control. The antibacterial susceptibility testing was conducted against 13 antibiotics: Ceftazidime, cefotaxime,ceftriaxone, cefoperazone, ciprofloxacin, levofloxacin, ofloxacin, gentamicin, amikacin, piperacillin, ticarcillin, meropenem, and imipenem. The examinationwas carried out using agar diffusion method of Kirby-Bauer and following the standards from Clinical and Laboratory Standards Institute (CLSI).Results: The results showed that bacterial resistance was established against all tested antibiotics. The highest number of resistance was shownagainst ceftriaxone (44.21%), whereas the most susceptibility was exhibited against amikacin (only 9.47% of resistance). MDR P. aeruginosa (MDRPA)was detected on almost all clinical samples tested, except the feces. The sample with the highest percentage of MDRPA was the pus.Conclusion: The study concludes that the most effective antibiotic against P. aeruginosa is amikacin (91.51%), whereas the most resistance is exhibited to ceftriaxone (43.16%).

scholarly journals Effects of Biosurfactants on Enzymatic Saccharification and Fermentation of Pretreated Softwood

Molecules ◽  
2020 ◽  
Vol 25 (16) ◽  
pp. 3559 ◽  
Author(s):  
Alfredo Oliva-Taravilla ◽  
Cristhian Carrasco ◽  
Leif J. Jönsson ◽  
Carlos Martín
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Pseudomonas Aeruginosa ◽  
Enzymatic Hydrolysis ◽  
Enzymatic Saccharification ◽  
Horse Chestnut ◽  
Yeast Growth ◽  
Cellulose Conversion ◽  
Enzymatic Hydrolysis Of Cellulose ◽  
Hydrolysis Of Cellulose ◽  
Hydrolysis Of

The enzymatic hydrolysis of cellulose is inhibited by non-productive adsorption of cellulases to lignin, and that is particularly problematic with lignin-rich materials such as softwood. Although conventional surfactants alleviate non-productive adsorption, using biosurfactants in softwood hydrolysis has not been reported. In this study, the effects of four biosurfactants, namely horse-chestnut escin, Pseudomonas aeruginosa rhamnolipid, and saponins from red and white quinoa varieties, on the enzymatic saccharification of steam-pretreated spruce were investigated. The used biosurfactants improved hydrolysis, and the best-performing one was escin, which led to cellulose conversions above 90%, decreased by around two-thirds lignin inhibition of Avicel hydrolysis, and improved hydrolysis of pretreated spruce by 24%. Red quinoa saponins (RQS) addition resulted in cellulose conversions above 80%, which was around 16% higher than without biosurfactants, and it was more effective than adding rhamnolipid or white quinoa saponins. Cellulose conversion improved with the increase in RQS addition up to 6 g/100 g biomass, but no significant changes were observed above that dosage. Although saponins are known to inhibit yeast growth, no inhibition of Saccharomyces cerevisiae fermentation of hydrolysates produced with RQS addition was detected. This study shows the potential of biosurfactants for enhancing the enzymatic hydrolysis of steam-pretreated softwood.

scholarly journals Stability and stabilization of linear positive systems on time scales

Positivity ◽  
2020 ◽  
Vol 24 (5) ◽  
pp. 1361-1372
Author(s):  
Zbigniew Bartosiewicz
Keyword(s):  
Control System ◽  
Linear System ◽  
Time Scale ◽  
Sufficient Conditions ◽  
Positive Control ◽  
Positive Systems ◽  
The Matrix ◽  
Exponentially Stable ◽  
Stability And Stabilization ◽  
Necessary And Sufficient

Abstract It is shown that a positive linear system on a time scale with a bounded graininess is uniformly exponentially stable if and only if the characteristic polynomial of the matrix defining the system has all its coefficients positive. Then this fact is used to find necessary and sufficient conditions of positive stabilizability of a positive control system on a time scale.

scholarly journals Phosphorylcholine Phosphatase: A Peculiar Enzyme of Pseudomonas aeruginosa

2011 ◽  
Vol 2011 ◽  
pp. 1-12 ◽  
Author(s):  
Carlos Eduardo Domenech ◽  
Lisandro Horacio Otero ◽  
Paola Rita Beassoni ◽  
Angela Teresita Lisa
Keyword(s):  
Gene Expression ◽  
Pseudomonas Aeruginosa ◽  
Adaptive Response ◽  
Metal Ion ◽  
Coordination Geometry ◽  
Choline Metabolism ◽  
Inhibitory Site ◽  
Closed Structure ◽  
Phosphorylcholine Phosphatase ◽  
Hydrolysis Of

Pseudomonas aeruginosa synthesizes phosphorylcholine phosphatase (PchP) when grown on choline, betaine, dimethylglycine or carnitine. In the presence of Mg2+ or Zn2+, PchP catalyzes the hydrolysis of p-nitrophenylphosphate (p-NPP) or phosphorylcholine (Pcho). The regulation of pchP gene expression is under the control of GbdR and NtrC; dimethylglycine is likely the metabolite directly involved in the induction of PchP. Therefore, the regulation of choline metabolism and consequently PchP synthesis may reflect an adaptive response of P. aeruginosa to environmental conditions. Bioinformatic and biochemistry studies shown that PchP contains two sites for alkylammonium compounds (AACs): one in the catalytic site near the metal ion-phosphoester pocket, and another in an inhibitory site responsible for the binding of the alkylammonium moiety. Both sites could be close to each other and interact through the residues 42E, 43E and 82YYY84. Zn2+ is better activator than Mg2+ at pH 5.0 and it is more effective at alleviating the inhibition produced by the entry of Pcho or different AACs in the inhibitory site. We postulate that Zn2+ induces at pH 5.0 a conformational change in the active center that is communicated to the inhibitory site, producing a compact or closed structure. However, at pH 7.4, this effect is not observed because to the hydrolysis of the [Zn2+L2−1L20(H2O)2] complex, which causes a change from octahedral to tetrahedral in the metal coordination geometry. This enzyme is also present in P. fluorescens, P. putida, P. syringae, and other organisms. We have recently crystallized PchP and solved its structure.

scholarly journals Evolution of Cost-Free Resistance under Fluctuating Drug Selection in Pseudomonas aeruginosa

mSphere ◽  
2017 ◽  
Vol 2 (4) ◽  
Author(s):  
Anita H. Melnyk ◽  
Nicholas McCloskey ◽  
Aaron J. Hinz ◽  
Jeremy Dettman ◽  
Rees Kassen
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Antibiotic Treatment ◽  
Experimental Evolution ◽  
Public Health Problem ◽  
Content Type ◽  
Compensatory Evolution ◽  
High Fitness ◽  
Treatment Conditions ◽  
Resistant Strains

ABSTRACT Antibiotic resistance is a global problem that greatly impacts human health. How resistance persists, even in the absence of antibiotic treatment, is thus a public health problem of utmost importance. In this study, we explored the antibiotic treatment conditions under which cost-free resistance arises, using experimental evolution of the bacterium Pseudomonas aeruginosa and the quinolone antibiotic ciprofloxacin. We found that intermittent antibiotic treatment led to the evolution of cost-free resistance and demonstrate that compensatory evolution is the mechanism responsible for cost-free resistance. Our results suggest that discontinuous administration of antibiotic may be contributing to the high levels of antibiotic resistance currently found worldwide. Antibiotic resistance evolves rapidly in response to drug selection, but it can also persist at appreciable levels even after the removal of the antibiotic. This suggests that many resistant strains can both be resistant and have high fitness in the absence of antibiotics. To explore the conditions under which high-fitness, resistant strains evolve and the genetic changes responsible, we used a combination of experimental evolution and whole-genome sequencing to track the acquisition of ciprofloxacin resistance in the opportunistic pathogen Pseudomonas aeruginosa under conditions of constant and fluctuating antibiotic delivery patterns. We found that high-fitness, resistant strains evolved readily under fluctuating but not constant antibiotic conditions and that their evolution was underlain by a trade-off between resistance and fitness. Whole-genome sequencing of evolved isolates revealed that resistance was gained through mutations in known resistance genes and that second-site mutations generally compensated for costs associated with resistance in the fluctuating treatment, leading to the evolution of cost-free resistance. Our results suggest that current therapies involving intermittent administration of antibiotics are contributing to the maintenance of antibiotic resistance at high levels in clinical settings. IMPORTANCE Antibiotic resistance is a global problem that greatly impacts human health. How resistance persists, even in the absence of antibiotic treatment, is thus a public health problem of utmost importance. In this study, we explored the antibiotic treatment conditions under which cost-free resistance arises, using experimental evolution of the bacterium Pseudomonas aeruginosa and the quinolone antibiotic ciprofloxacin. We found that intermittent antibiotic treatment led to the evolution of cost-free resistance and demonstrate that compensatory evolution is the mechanism responsible for cost-free resistance. Our results suggest that discontinuous administration of antibiotic may be contributing to the high levels of antibiotic resistance currently found worldwide.

scholarly journals Evolution of Ecological Diversity in Biofilms of Pseudomonas aeruginosa by Altered Cyclic Diguanylate Signaling

2016 ◽  
Vol 198 (19) ◽  
pp. 2608-2618 ◽  
Author(s):  
Kenneth M. Flynn ◽  
Gabrielle Dowell ◽  
Thomas M. Johnson ◽  
Benjamin J. Koestler ◽  
Christopher M. Waters ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Experimental Evolution ◽  
Ecological Diversity ◽  
Chronic Infections ◽  
Daily Cycle ◽  
Content Type ◽  
Dna Mismatch ◽  
Community Function ◽  
Evolutionary Forces ◽  
Intracellular Signal

ABSTRACTThe ecological and evolutionary forces that promote and maintain diversity in biofilms are not well understood. To quantify these forces, threePseudomonas aeruginosapopulations were experimentally evolved from strain PA14 in a daily cycle of attachment, assembly, and dispersal for 600 generations. Each biofilm population evolved diverse colony morphologies and mutator genotypes defective in DNA mismatch repair. This diversity enhanced population fitness and biofilm output, owing partly to rare, early colonizing mutants that enhanced attachment of others. Evolved mutants exhibited various levels of the intracellular signal cyclic-di-GMP, which associated with their timing of adherence. Manipulating cyclic-di-GMP levels within individual mutants revealed a network of interactions in the population that depended on various attachment strategies related to this signal. Diversification in biofilms may therefore arise and be reinforced by initial colonists that enable community assembly.IMPORTANCEHow biofilm diversity assembles, evolves, and contributes to community function is largely unknown. This presents a major challenge for understanding evolution during chronic infections and during the growth of all surface-associated microbes. We used experimental evolution to probe these dynamics and found that diversity, partly related to altered cyclic-di-GMP levels, arose and persisted due to the emergence of ecological interdependencies related to attachment patterns. Clonal isolates failed to capture population attributes, which points to the need to account for diversity in infections. More broadly, this study offers an experimental framework for linking phenotypic variation to distinct ecological strategies in biofilms and for studying eco-evolutionary interactions.

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