scholarly journals Bacterial Chemotaxis to Atrazine and Related s-Triazines

2009 ◽  
Vol 75 (17) ◽  
pp. 5481-5488 ◽  
Author(s):  
Xianxian Liu ◽  
Rebecca E. Parales
Keyword(s):  
Cyanuric Acid ◽  
Bacterial Chemotaxis ◽  
Chemotactic Response ◽  
E Coli ◽  
Naturally Occurring ◽  
Catabolic Plasmid ◽  
Herbicide Atrazine ◽  
Degradation Intermediates ◽  
Competition Assays ◽  
Atrazine Degradation

ABSTRACT Pseudomonas sp. strain ADP utilizes the human-made s-triazine herbicide atrazine as the sole nitrogen source. The results reported here demonstrate that atrazine and the atrazine degradation intermediates N-isopropylammelide and cyanuric acid are chemoattractants for strain ADP. In addition, the nonmetabolized s-triazine ametryn was also an attractant. The chemotactic response to these s-triazines was not specifically induced during growth with atrazine, and atrazine metabolism was not required for the chemotactic response. A cured variant of strain ADP (ADP M13-2) was attracted to s-triazines, indicating that the atrazine catabolic plasmid pADP-1 is not necessary for the chemotactic response and that atrazine degradation and chemotaxis are not genetically linked. These results indicate that atrazine and related s-triazines are detected by one or more chromosomally encoded chemoreceptors in Pseudomonas sp. strain ADP. We demonstrated that Escherichia coli is attracted to the s-triazine compounds N-isopropylammelide and cyanuric acid, and an E. coli mutant lacking Tap (the pyrimidine chemoreceptor) was unable to respond to s-triazines. These data indicate that pyrimidines and triazines are detected by the same chemoreceptor (Tap) in E. coli. We showed that Pseudomonas sp. strain ADP is attracted to pyrimidines, which are the naturally occurring structures closest to triazines, and propose that chemotaxis toward s-triazines may be due to fortuitous recognition by a pyrimidine chemoreceptor in Pseudomonas sp. strain ADP. In competition assays, the presence of atrazine inhibited chemotaxis of Pseudomonas sp. strain ADP to cytosine, and cytosine inhibited chemotaxis to atrazine, suggesting that pyrimidines and s-triazines are detected by the same chemoreceptor.

scholarly journals Free calcium transients in chemotactic and non-chemotactic strains of Escherichia coli determined by using recombinant aequorin

1995 ◽  
Vol 306 (3) ◽  
pp. 865-869 ◽  
Author(s):  
N J Watkins ◽  
M R Knight ◽  
A J Trewavas ◽  
A K Campbell
Keyword(s):  
Escherichia Coli ◽  
Bacterial Chemotaxis ◽  
Chemotactic Response ◽  
Calcium Transients ◽  
Free Calcium ◽  
E Coli ◽  
Proposed Model ◽  
Strain Bl21 ◽  
Recombinant Aequorin ◽  
Strain Ab1157

Intracellular Ca2+ has been previously implicated in the chemotactic response of Escherichia coli. However, no correlative measurements of intracellular free Ca2+ have been made during bacterial chemotaxis, essential if this is to be established. In order to monitor internal free Ca2+ in E. coli during challenge with chemotactic agents, the Ca(2+)-activated photoprotein aequorin was expressed in a chemotactic strain (AB1157) and a non-chemotactic strain [BL21(DE3)] of E. coli. Repellents were found to cause an increase (50-150 nM) in intracellular free Ca2+, whereas attractants caused a small but consistent decrease in intracellular free Ca2+. These data are in agreement with the proposed model that an increase in intracellular free Ca2+ causes tumbling. The effect of increasing external Ca2+ on the regulation of intracellular free Ca2+ in both strains was monitored by using aequorin. The resting level of free Ca2+ in E. coli (AB1157) was found to be 100 nM, which agrees with previous data [Gangola and Rosen (1987) J. Biol. Chem. 262, 12570-12574]. As these results also show differences in the regulation of intracellular free Ca2+ between the two strains in the presence of high external Ca2+ concentrations, this may have implications for the effect of high-Ca2+ environments on E. coli.

Bacterial chemotaxis differences inEscherichia coliisolated from different hosts

2008 ◽  
Vol 54 (12) ◽  
pp. 1043-1052 ◽  
Author(s):  
Sijana H. Dzinic ◽  
Marcella Luercio ◽  
Jeffrey L. Ram
Keyword(s):  
Escherichia Coli ◽  
Carbon Sources ◽  
Bacterial Chemotaxis ◽  
Growth Curves ◽  
Chemotactic Response ◽  
Low Density ◽  
Chemotaxis Assay ◽  
E Coli ◽  
Growth Differences ◽  
Chemotactic Behavior

The mechanisms mediating the association between Escherichia coli and specific hosts are unknown. This study investigates the hypothesis that the host-specific associations of E. coli strains are mediated in part by differences in chemotaxis. To test this hypothesis, chemotactic responses of E. coli strains isolated from different host groups (carnivores, herbivores, and omnivores) were tested with various attractants. In low-density agar chemotaxis assays, the average motility of E. coli in response to aspartate, serine, and ribose among the different groups was not significantly different; however, strains from carnivores responded significantly more to aspartate, relative to their responses to serine, in comparison with strains from herbivores, which responded equally or better to serine than to aspartate. The relatively greater chemotactic response of strains from carnivores to aspartate than to serine was confirmed in a subset of strains by capillary chemotaxis assay. Differences in responses to serine and aspartate were not due to growth differences, as determined by comparison of 24 h growth curves with glycerol, aspartate, and serine carbon sources. The differences in chemotactic behavior of E. coli strains isolated from herbivores and carnivores support the hypothesis that host-specific associations of E. coli strains are mediated in part by differences in chemotactic behavior.

scholarly journals Nitrogen Control of Atrazine Utilization in Pseudomonas sp. Strain ADP

2003 ◽  
Vol 69 (12) ◽  
pp. 6987-6993 ◽  
Author(s):  
Vicente García-González ◽  
Fernando Govantes ◽  
Liz J. Shaw ◽  
Richard G. Burns ◽  
Eduardo Santero
Keyword(s):  
Wild Type Strain ◽  
Nitrogen Sources ◽  
Degradation Pathway ◽  
Strong Impact ◽  
Soil Microcosms ◽  
Degradation Rates ◽  
Herbicide Atrazine ◽  
Mutant Derivative ◽  
Nitrogen Repression ◽  
Atrazine Degradation

ABSTRACT Pseudomonas sp. strain ADP uses the herbicide atrazine as the sole nitrogen source. We have devised a simple atrazine degradation assay to determine the effect of other nitrogen sources on the atrazine degradation pathway. The atrazine degradation rate was greatly decreased in cells grown on nitrogen sources that support rapid growth of Pseudomonas sp. strain ADP compared to cells cultivated on growth-limiting nitrogen sources. The presence of atrazine in addition to the nitrogen sources did not stimulate degradation. High degradation rates obtained in the presence of ammonium plus the glutamine synthetase inhibitor MSX and also with an Nas− mutant derivative grown on nitrate suggest that nitrogen regulation operates by sensing intracellular levels of some key nitrogen-containing metabolite. Nitrate amendment in soil microcosms resulted in decreased atrazine mineralization by the wild-type strain but not by the Nas− mutant. This suggests that, although nitrogen repression of the atrazine catabolic pathway may have a strong impact on atrazine biodegradation in nitrogen-fertilized soils, the use of selected mutant variants may contribute to overcoming this limitation.

scholarly journals Microbial Synthesis of Non-Natural Anthraquinone Glucosides Displaying Superior Antiproliferative Properties

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2171 ◽  
Author(s):  
Trang Nguyen ◽  
Ramesh Pandey ◽  
Prakash Parajuli ◽  
Jang Han ◽  
Hye Jung ◽  
...  
Keyword(s):  
Cell Growth ◽  
Biological Activities ◽  
Uterine Cervical Cancer ◽  
Cell Growth Inhibition ◽  
Microbial Synthesis ◽  
E Coli ◽  
Anticancer Effects ◽  
Naturally Occurring ◽  
Spectroscopic Analyses ◽  
Proliferative Assay

Anthraquinones, naturally occurring bioactive compounds, have been reported to exhibit various biological activities, including anti-inflammatory, antiviral, antimicrobial, and anticancer effects. In this study, we biotransformed three selected anthraquinones into their novel O-glucoside derivatives, expressing a versatile glycosyltransferase (YjiC) from Bacillus licheniformis DSM 13 in Escherichia coli. Anthraflavic acid, alizarin, and 2-amino-3-hydroxyanthraquinone were exogenously fed to recombinant E. coli as substrate for biotransformation. The products anthraflavic acid-O-glucoside, alizarin 2-O-β-d-glucoside, and 2-amino-3-O-glucosyl anthraquinone produced in the culture broths were characterized by various chromatographic and spectroscopic analyses. The comparative anti-proliferative assay against various cancer cells (gastric cancer-AGS, uterine cervical cancer-HeLa, and liver cancer-HepG2) were remarkable, since the synthesized glucoside compounds showed more than 60% of cell growth inhibition at concentrations ranging from ~50 μM to 100 μM. Importantly, one of the synthesized glucoside derivatives, alizarin 2-O-glucoside inhibited more than 90% of cell growth in all the cancer cell lines tested.

Null mutation in sspA of Cronobacter sakazakii influences its tolerance to environmental stress

2021 ◽  
Author(s):  
Jie Zhan ◽  
Xin Tan ◽  
Xiaoyuan Wang
Keyword(s):  
Stress Tolerance ◽  
Protein A ◽  
Bacterial Chemotaxis ◽  
Water Concentration ◽  
Acid Tolerance ◽  
Opportunistic Pathogen ◽  
Cronobacter Sakazakii ◽  
Knockout Mutant ◽  
Cellular Survival ◽  
E Coli

Cronobacter sakazakii is a known foodborne opportunistic pathogen that can affect the intestinal health of infants. Despite undergoing complex manufacturing processes and low water concentration in the finished product, infant formula has been associated with Cronobacter infections, suggesting that C. sakazakii’s pathogenicity may be related to its tolerance to stress. In this study, the effect of the stringent starvation protein A (SspA), which plays an important role in E. coli cellular survival under environmental stresses, on the stress tolerance of C. sakazakii BAA894 was investigated by creating an sspA-knockout mutant. The effects of this mutation on the acid, desiccation and drug tolerance were assessed, and results showed that acid tolerance decreased, while desiccation tolerance increased in LB and decreased in M9. Moreover, the MICs of 10 antibiotics in LB medium and 8 antibiotics in M9 medium were determined and compared of the wild-type and ΔsspA. Transcriptome analysis showed that 27.21% or 37.78% of the genes in ΔsspA were significantly differentially expressed in LB or M9 media, the genes relevant to microbial metabolism in diverse environments and bacterial chemotaxis were detailed analyzed. The current study contributes towards an improved understanding of the role of SspA in C. sakazakii BAA894 stress tolerance.

scholarly journals Natural Genetic Transformation of Clinical Isolates of Escherichia coli in Urine and Water

2002 ◽  
Vol 68 (1) ◽  
pp. 440-443 ◽  
Author(s):  
Markus Woegerbauer ◽  
Bernard Jenni ◽  
Florian Thalhammer ◽  
Wolfgang Graninger ◽  
Heinz Burgmann
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Current Knowledge ◽  
Antibiotic Resistance Genes ◽  
Aquatic Environments ◽  
Wild Type ◽  
E Coli ◽  
Naturally Occurring ◽  
Natural Genetic Transformation ◽  
Type Strains

ABSTRACT Transfer of plasmid-borne antibiotic resistance genes in Escherichia coli wild-type strains is possible by transformation under naturally occurring conditions in oligotrophic, aquatic environments containing physiologic concentrations of calcium. In contrast, transformation is suppressed in nitrogen-rich body fluids like urine, a common habitat of uropathogenic strains. Current knowledge indicates that transformation of these E. coli wild-type strains is of no relevance for the acquisition of resistance in this clinically important environment.

scholarly journals Kinetics of atrazine degradation by photocatalytic process in aqueous solution

2003 ◽  
Vol 5 (2) ◽  
pp. 87-93 ◽  
Author(s):  
O. Zahraa ◽  
L. Sauvanaud ◽  
G. Hamard ◽  
M. Bouchy
Keyword(s):  
Aqueous Solution ◽  
Titanium Dioxide ◽  
Salicylic Acid ◽  
Photocatalytic Degradation ◽  
Competitive Adsorption ◽  
Initial Time ◽  
Photocatalytic Process ◽  
Herbicide Atrazine ◽  
Kinetics Of ◽  
Atrazine Degradation

The photocatalytic degradation of the herbicide atrazine has been studied using suspended titanium dioxide as catalyst. The Langmuir-Hinshelwood model is satisfactorily obeyed at initial time and in the course of the reaction. The rate of degradation is found to be enhanced by the addition of persulphate ions. Competitive degradation between atrazine and other pollutants is satisfactorily interpreted as monitored by a competitive adsorption of the reactants. As a consequence, efficient reactants such as salicylic acid and phenol delay atrazine degradation until these compounds are degraded.

scholarly journals An O-Phosphotransferase Catalyzes Phosphorylation of Hygromycin A in the Antibiotic-Producing Organism Streptomyces hygroscopicus

2008 ◽  
Vol 52 (10) ◽  
pp. 3580-3588 ◽  
Author(s):  
Vidya Dhote ◽  
Shuchi Gupta ◽  
Kevin A. Reynolds
Keyword(s):  
Ribosomal Subunit ◽  
Biosynthetic Gene Cluster ◽  
Open Reading Frames ◽  
Streptomyces Hygroscopicus ◽  
Gram Negative Bacteria ◽  
E Coli ◽  
Naturally Occurring ◽  
Insertional Inactivation ◽  
Pathway Regulation ◽  
Reading Frames

ABSTRACT The antibiotic hygromycin A (HA) binds to the 50S ribosomal subunit and inhibits protein synthesis in gram-positive and gram-negative bacteria. The HA biosynthetic gene cluster in Streptomyces hygroscopicus NRRL 2388 contains 29 open reading frames, which have been assigned putative roles in biosynthesis, pathway regulation, and self-resistance. The hyg21 gene encodes an O-phosphotransferase with a proposed role in self-resistance. We observed that insertional inactivation of hyg21 in S. hygroscopicus leads to a greater than 90% decrease in HA production. The wild type and the hyg21 mutant were comparably resistant to HA. Using Escherichia coli as a heterologous host, we expressed and purified Hyg21. Kinetic analyses revealed that the recombinant protein catalyzes phosphorylation of HA (Km = 30 ± 4 μM) at the C-2‴ position of the fucofuranose ring in the presence of ATP (Km = 200 ± 20 μM) or GTP (Km = 350 ± 60 μM) with a k cat of 2.2 ± 0.1 min−1. The phosphorylated HA is inactive against HA-sensitive ΔtolC E. coli and Streptomyces lividans. Hyg21 also phosphorylates methoxyhygromycin A and desmethylenehygromycin A with k cat and Km values similar to those observed with HA. Phosphorylation of the naturally occurring isomers of 5‴-dihydrohygromycin A and 5‴-dihydromethoxyhygromycin A was about 12 times slower than for the corresponding non-natural isomers. These studies demonstrate that Hyg21 is an O-phosphotransferase with broad substrate specificity, tolerating changes in the aminocyclitol moiety more than in the fucofuranose moiety, and that phosphorylation by Hyg21 is one of several possible mechanisms of self-resistance in S. hygroscopicus NRRL 2388.

Fate of Naturally Occurring Escherichia coli O157:H7 and Other Zoonotic Pathogens during Minimally Managed Bovine Feedlot Manure Composting Processes†

2013 ◽  
Vol 76 (8) ◽  
pp. 1308-1321 ◽  
Author(s):  
ELAINE D. BERRY ◽  
PATRICIA D. MILLNER ◽  
JAMES E. WELLS ◽  
NORASAK KALCHAYANAND ◽  
MICHAEL N. GUERINI
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
High Temperatures ◽  
Thermophilic Bacteria ◽  
Foodborne Illness ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Naturally Occurring ◽  
On Farm ◽  
Campylobacter Spp

Reducing Escherichia coli O157:H7 in livestock manures before application to cropland is critical for reducing the risk of foodborne illness associated with produce. Our objective was to determine the fate of naturally occurring E. coli O157:H7 and other pathogens during minimally managed on-farm bovine manure composting processes. Feedlot pen samples were screened to identify E. coli O157:H7–positive manure. Using this manure, four piles of each of three different composting formats were constructed in each of two replicate trials. Composting formats were (i) turned piles of manure plus hay and straw, (ii) static stockpiles of manure, and (iii) static piles of covered manure plus hay and straw. Temperatures in the tops, toes, and centers of the conical piles (ca. 6.0 m3 each) were monitored. Compost piles that were turned every 2 weeks achieved higher temperatures for longer periods in the tops and centers than did piles that were left static. E. coli O157:H7 was not recovered from top samples of turned piles of manure plus hay and straw at day 28 and beyond, but top samples from static piles were positive for the pathogen up to day 42 (static manure stockpiles) and day 56 (static covered piles of manure plus hay and straw). Salmonella, Campylobacter spp., and Listeria monocytogenes were not found in top or toe samples at the end of the composting period, but E. coli O157:H7 and Listeria spp. were recovered from toe samples at day 84. Our findings indicate that some minimally managed composting processes can reduce E. coli O157:H7 and other pathogens in bovine manure but may be affected by season and/or initial levels of indigenous thermophilic bacteria. Our results also highlight the importance of adequate C:N formulation of initial mixtures for the production of high temperatures and rapid composting, and the need for periodic turning of the piles to increase the likelihood that all parts of the mass are subjected to high temperatures.

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