scholarly journals The Physiological Responses of Escherichia coli Triggered by Phosphoribulokinase (PrkA) and Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase (Rubisco)

2020 ◽  
Vol 8 (8) ◽  
pp. 1187
Author(s):  
En-Jung Liu ◽  
I-Ting Tseng ◽  
Yi-Ling Chen ◽  
Ju-Jiun Pang ◽  
Zhi-Xuan Shen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacterial Growth ◽  
Physiological Responses ◽  
Lactate Production ◽  
Reducing Power ◽  
Glucose Consumption ◽  
Redox Balance ◽  
Bisphosphate Carboxylase ◽  
E Coli ◽  
Co2 Recycling

Phosphoribulokinase (PrkA) and ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) have been proposed to create a heterologous Rubisco-based engineered pathway in Escherichia coli for in situ CO2 recycling. While the feasibility of a Rubisco-based engineered pathway has been shown, heterologous expressions of PrkA and Rubisco also induced physiological responses in E. coli that may compete with CO2 recycling. In this study, the metabolic shifts caused by PrkA and Rubisco were investigated in recombinant strains where ppc and pta genes (encodes phosphoenolpyruvate carboxylase and phosphate acetyltransferase, respectively) were deleted from E. coli MZLF (E. coli BL21(DE3) Δzwf, ΔldhA, Δfrd). It has been shown that the demand for ATP created by the expression of PrkA significantly enhanced the glucose consumptions of E. coli CC (MZLF Δppc) and E. coli CA (MZLF Δppc, Δpta). The accompanying metabolic shift is suggested to be the mgsA route (the methylglyoxal pathway) which results in the lactate production for reaching the redox balance. The overexpression of Rubisco not only enhanced glucose consumption but also bacterial growth. Instead of the mgsA route, the overproduction of the reducing power was balanced by the ethanol production. It is suggested that Rubisco induces a high demand for acetyl-CoA which is subsequently used by the glyoxylate shunt. Therefore, Rubisco can enhance bacterial growth. This study suggests that responses induced by the expression of PrkA and Rubisco will reach a new energy balance profile inside the cell. The new profile results in a new distribution of the carbon flow and thus carbons cannot be majorly directed to the Rubisco-based engineered pathway.

Effect of Tannins on the In Vitro Growth of Escherichia coli O157:H7 and In Vivo Growth of Generic Escherichia coli Excreted from Steers

2007 ◽  
Vol 70 (3) ◽  
pp. 543-550 ◽  
Author(s):  
BYENG R. MIN ◽  
WILLIAM E. PINCHAK ◽  
ROBIN C. ANDERSON ◽  
TODD R. CALLAWAY
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Bacterial Growth ◽  
Escherichia Coli O157 ◽  
Tannin Extract ◽  
Bacterial Growth Rate ◽  
Linear Effect ◽  
E Coli

The effect of commercially available chestnut and mimosa tannins in vitro (experiment 1) or in vivo (experiment 2) on the growth or recovery of Escherichia coli O157:H7 or generic fecal E. coli was evaluated. In experiment 1, the mean growth rate of E. coli O157:H7, determined via the measurement of optical density at 600 nm during anaerobic culture in tryptic soy broth at 37°C, was reduced (P < 0.05) with as little as 400 μg of either tannin extract per ml of culture fluid. The addition of 200, 400, 600, 800, and 1,200 μg of tannins per ml significantly (P < 0.01) reduced the specific bacterial growth rate when compared with the nontannin control. The specific growth rate decreased with increasing dose levels up to 800 μg of tannins per ml. Bacterial growth inhibition effects in chestnut tannins were less pronounced than in mimosa tannins. Chestnut tannin extract addition ranged from 0 to 1,200 μg/ml, and a linear effect (P < 0.05) was observed in cultures incubated for 6 h against the recovery of viable cells, determined via the plating of each strain onto MacConkey agar, of E. coli O157:H7 strains 933 and 86-24, but not against strain 6058. Similar tests with mimosa tannin extract showed a linear effect (P < 0.05) against the recovery of E. coli O157:H7 strain 933 only. The bactericidal effect observed in cultures incubated for 24 h with the tannin preparations was similar, although it was less than that observed from cultures incubated for 6 h. When chestnut tannins (15 g of tannins per day) were infused intraruminally to steers fed a Bermuda grass hay diet in experiment 2, fecal E. coli shedding was lower on days 3 (P < 0.03), 12 (P = 0.08), and 15 (P < 0.001) when compared with animals that were fed a similar diet without tannin supplementation. It was concluded that dietary levels and sources of tannins potentially reduce the shedding of E. coli from the gastrointestinal tract.

scholarly journals Phenotypic Detection of Plasmid-Mediated Colistin Resistance in Enterobacteriaceae

2019 ◽  
Vol 58 (3) ◽  
Author(s):  
Edgar Gonzales Escalante ◽  
Katherine Yauri Condor ◽  
Jose A. Di Conza ◽  
Gabriel O. Gutkind
Keyword(s):  
Escherichia Coli ◽  
Klebsiella Pneumoniae ◽  
Serratia Marcescens ◽  
Bacterial Growth ◽  
Screening Test ◽  
Colistin Resistance ◽  
Content Type ◽  
E Coli

ABSTRACT The aim of this work was to evaluate an easy-to-perform assay based upon inhibition of mobile colistin resistance (MCR) activity by EDTA. We included 92 nonrelated isolates of Enterobacteriaceae (74 Escherichia coli, 17 Klebsiella pneumoniae, and 1 Serratia marcescens). Our proposed method is based on a modification of the colistin agar-spot screening test (CAST), a plate containing 3 μg/ml colistin, by adding an extra plate of colistin agar-spot supplemented with EDTA (eCAST). Bacterial growth was evaluated after 24 h of incubation at 35°C. All the colistin-resistant isolates showed development on the CAST plates. Colistin-resistant K. pneumoniae without mcr-1 and S. marcescens also grew on the eCAST plates. In contrast, colistin-resistant MCR-producing E. coli was not able to grow in eCAST plates. The combined CAST/eCAST test could provide a simple and easy-to-perform method to differentiate MCR-producing Enterobacteriaceae from those in which colistin resistance is mediated by chromosomal mechanisms.

scholarly journals Pyruvate Formate Lyase and Acetate Kinase Are Essential for Anaerobic Growth of Escherichia coli on Xylose

2004 ◽  
Vol 186 (22) ◽  
pp. 7593-7600 ◽  
Author(s):  
Adnan Hasona ◽  
Youngnyun Kim ◽  
F. G. Healy ◽  
L. O. Ingram ◽  
K. T. Shanmugam
Keyword(s):  
Escherichia Coli ◽  
Minimal Medium ◽  
High Capacity ◽  
Redox Balance ◽  
Anaerobic Growth ◽  
Acetate Kinase ◽  
Anaerobic Conditions ◽  
Pyruvate Formate Lyase ◽  
E Coli ◽  
Xylose Transport

ABSTRACT During anaerobic growth of bacteria, organic intermediates of metabolism, such as pyruvate or its derivatives, serve as electron acceptors to maintain the overall redox balance. Under these conditions, the ATP needed for cell growth is derived from substrate-level phosphorylation. In Escherichia coli, conversion of glucose to pyruvate yields 2 net ATPs, while metabolism of a pentose, such as xylose, to pyruvate only yields 0.67 net ATP per xylose due to the need for one (each) ATP for xylose transport and xylulose phosphorylation. During fermentative growth, E. coli produces equimolar amounts of acetate and ethanol from two pyruvates, and these reactions generate one additional ATP from two pyruvates (one hexose equivalent) while still maintaining the overall redox balance. Conversion of xylose to acetate and ethanol increases the net ATP yield from 0.67 to 1.5 per xylose. An E. coli pfl mutant lacking pyruvate formate lyase cannot convert pyruvate to acetyl coenzyme A, the required precursor for acetate and ethanol production, and could not produce this additional ATP. E. coli pfl mutants failed to grow under anaerobic conditions in xylose minimal medium without any negative effect on their survival or aerobic growth. An ackA mutant, lacking the ability to generate ATP from acetyl phosphate, also failed to grow in xylose minimal medium under anaerobic conditions, confirming the need for the ATP produced by acetate kinase for anaerobic growth on xylose. Since arabinose transport by AraE, the low-affinity, high-capacity, arabinose/H+ symport, conserves the ATP expended in pentose transport by the ABC transporter, both pfl and ackA mutants grew anaerobically with arabinose. AraE-based xylose transport, achieved after constitutively expressing araE, also supported the growth of the pfl mutant in xylose minimal medium. These results suggest that a net ATP yield of 0.67 per pentose is only enough to provide for maintenance energy but not enough to support growth of E. coli in minimal medium. Thus, pyruvate formate lyase and acetate kinase are essential for anaerobic growth of E. coli on xylose due to energetic constraints.

Reduction of Listeria monocytogenes and Escherichia coli O157:H7 Numbers on Vacuum-Packaged Fresh Beef Treated with Nisin or Nisin Combined with EDTA†

1999 ◽  
Vol 62 (10) ◽  
pp. 1123-1127 ◽  
Author(s):  
SHANSHAN ZHANG ◽  
AZLIN MUSTAPHA
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Bacterial Growth ◽  
Escherichia Coli O157 ◽  
E Coli ◽  
Key Factor ◽  
Vacuum Package ◽  
And Storage

Nisin or nisin combined with EDTA was used to treat fresh beef. Beef cubes (2.5 by 2.5 by 2.5 cm) that were inoculated with approximately 7 log CFU/ml of Listeria monocytogenes Scott A or Escherichia coli O157:H7 505 B were dipped in the following solutions: (i) H2O, (ii) HCl, (iii) nisin, (iv) EDTA, or (v) nisin combined with EDTA, respectively, for 10 min each, with an exception of one set of control beef samples without treatment. Beef samples were then drip-dried for 15 min, vacuum packaged, and stored at 4°C for up to 30 days. The pH on beef after different treatments was not a key factor in preventing bacterial growth. Treatment with nisin or with nisin combined with EDTA reduced the population of L. monocytogenes by 2.01 and 0.99 log CFU/cm2 as compared to the control, respectively, under the conditions of vacuum package and storage at 4°C for up to 30 days. However, the effect of nisin and nisin combined with EDTA against E. coli O157:H7 505 B was marginal at 1.02 log CFU/cm2 and 0.8 log CFU/cm2 reductions, respectively.

scholarly journals Restriction of bacterial growth by inhibition of polyamine biosynthesis by using monofluoromethylornithine, difluoromethylarginine and dicyclohexylammonium sulphate

1982 ◽  
Vol 208 (2) ◽  
pp. 435-441 ◽  
Author(s):  
A J Bitonti ◽  
P P McCann ◽  
A Sjoerdsma
Keyword(s):  
Escherichia Coli ◽  
Ornithine Decarboxylase ◽  
Bacterial Growth ◽  
Active Site ◽  
Bacterial Infections ◽  
Polyamine Biosynthesis ◽  
E Coli ◽  
Subsequent Investigation ◽  
Generation Times ◽  
Viable Approach

Bacterial growth was measurably slowed by a combination of drugs which inhibit polyamine-biosynthetic enzymes. Addition of DL-alpha-monofluoromethylornithine, which was shown to inactivate irreversibly ornithine decarboxylase extracted from Escherichia coli (Ki = 0.36 mM) and Pseudomonas aeruginosa (Ki = 0.30 mM), DL-alpha-difluoromethylarginine and dicyclohexylammonium sulphate to cultures of E. coli or P. aeruginosa resulted in a 40 and 70% increase in generation times (decreased growth rates) respectively, which was completely reversed by the addition of 0.1 mM-putrescine plus 0.1 mM-spermidine to the medium. Decreased intracellular polyamine concentrations correlated with increased generation times; putrescine concentration was decreased by 70% in E. coli and 80% in P. aeruginosa, while spermidine concentration was decreased by 50% in E. coli and 95% in P. aeruginosa. Subsequent investigation of the inactivation of the ornithine decarboxylase by monofluoromethylornithine indicated that it was active-site directed, as the normal substrate ornithine slowed the rate of inhibition. Specific interference with polyamine biosynthesis may be a viable approach to control of some bacterial infections.

scholarly journals UJI AKTIVITAS ANTIBAKTERI EKSTRAK DAN FRAKSI SPONS Leucetta chagosensis DARI PERAIRAN PULAU MANTEHAGE SULAWESI UTARA TERHADAP PERTUMBUHAN BAKTERI Staphylococcus aureus DAN Escherichia coli

PHARMACON ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 834
Author(s):  
Eunike Pelealu ◽  
Defny S. Wewengkang ◽  
Surya Sumantri Abdullah
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Bacterial Growth ◽  
Pathogenic Bacteria ◽  
Inhibition Zone ◽  
Disk Diffusion ◽  
E Coli ◽  
Activity Test ◽  
Escherichia Coli Bacteria ◽  
Metabolite Content

ABSTRACTSponges are one of the biota components that make up coral reefs which are quite widely distributed. The metabolite content in the sponge can ward off and inhibit the pathogenic bacteria that interfere with it. This study aims to determine the activity of inhibiting bacterial growth from the extract and fraction of Leucetta chagosensis sponge against the growth of Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli bacteria. The samples were extracted using the maceration method with 95% ethanol solvent and then fractionated using 3 solvents with different polarity levels, namely methanol, n-hexane and chloroform. Activity test using the disk diffusion agar method of Kirby and Bauer. Only the MeOH fraction was able to inhibit the growth of E. coli bacteria with an average inhibition zone of 6.88 mm. Whereas for S.aureus bacteria extracts and all fractions showed activity to inhibit bacterial growth with an average inhibition zone of EtOH (6.61 mm), CHCI3 (6.68 mm), n-hexane (7.83 mm) and MeOH (8.00 mm), respectively. All activities that are shown are categorized as weak (weak).Keywords: Antibacterial, Leucetta chagosensis, Staphylococcus aureus, Escherichia coli ABSTRAKSpons merupakan salah satu komponen biota penyusun terumbu karang yang penyebarannya cukup luas. Kandungan metabolit yang ada di dalam spons dapat menangkal dan menghambat bakteri patogen pengganggunya.  Penelitian ini bertujuan untuk melihat aktivitas menghambat pertumbuhan bakteri dari ekstrak dan fraksi spons Leucetta chagosensis. terhadap pertumbuhan bakteri Gram positif Staphylococcus aureus dan Gram negatif Escherichia coli. Sampel di ekstraksi menggunakan metode maserasi dengan pelarut etanol 95% lalu di fraksinasi dengan menggunakan 3 pelarut dengan tingkat kepolaran yang berbeda yaitu metanol, n-heksan dan kloroform. Uji aktivitas menggunakan metode disk diffusion agar Kirby dan Bauer.  Hanya fraksi MeOH yang mampu menghambat pertumbuhan bakteri E.coli dengan zona hambat rata-rata 6,88 mm. Sedangkan terhadap bakteri S.aureus ekstrak dan semua fraksi menunjukan aktifitas menghambat pertumbuhan bakteri dengan rata-rata zona hambat masing-masing EtOH (6,61 mm), CHCl3 (6,68 mm), n-Heksan (7,83 mm), dan MeOH (8,00 mm). Semua aktivitas yang ditunjukan dikategorikan lemah (weak).Kata kunci : Antibakteri, Leucetta chagosensis, Staphylococcus aureus,  Escherichia coli

scholarly journals Aerobic and Anaerobic Microbiology of Surgical-Site Infection Following Spinal Fusion

1999 ◽  
Vol 37 (3) ◽  
pp. 841-843 ◽  
Author(s):  
Itzhak Brook ◽  
Edith H. Frazier
Keyword(s):  
Escherichia Coli ◽  
Spinal Fusion ◽  
Bacterial Growth ◽  
Anaerobic Bacteria ◽  
Surgical Site Infections ◽  
Aerobic Bacteria ◽  
Site Infection ◽  
E Coli ◽  
Naval Hospital ◽  
Aerobic And Anaerobic

The aerobic and anaerobic microbiology of surgical-site infections (SSI) following spinal fusion was retrospectively studied. This was done by reviewing the clinical and microbiological records at the Naval Hospital in Bethesda, Md., from 1980 to 1992. Aspirates of pus from 25 infection sites showed bacterial growth. Aerobic bacteria only were recovered from 9 (36%) specimens, anaerobic bacteria only were recovered from 4 (16%), and mixed aerobic and anaerobic bacteria were recovered from 12 (48%). Sixty isolates were recovered: 38 aerobes (1.5 isolates per specimen) and 22 anaerobes (0.9 isolate per specimen). The predominant aerobes were Escherichia coli(n = 8) and Proteus sp. (n = 7). The predominant anaerobes wereBacteroides fragilis group (n = 9) andPeptostreptococcus sp. (n = 6) isolates. An increase in recovery of E. coli and B. fragilis was noted in patients with bowel or bladder incontinence. This study highlights the polymicrobial nature of SSI and the importance of anaerobic bacteria in SSI following spinal fusion.

scholarly journals Environmental Growth Conditions Influence the Ability of Escherichia coli K1 To Invade Brain Microvascular Endothelial Cells and Confer Serum Resistance

1998 ◽  
Vol 66 (12) ◽  
pp. 5692-5697 ◽  
Author(s):  
Julie L. Badger ◽  
Kwang Sik Kim
Keyword(s):  
Escherichia Coli ◽  
Endothelial Cells ◽  
Blood Brain Barrier ◽  
Bacterial Growth ◽  
Growth Conditions ◽  
Brain Barrier ◽  
Microvascular Endothelial Cells ◽  
Serum Resistance ◽  
Brain Microvascular Endothelial Cells ◽  
E Coli

ABSTRACT A major limitation to advances in prevention and therapy of neonatal meningitis is our incomplete understanding of the pathogenesis of this disease. In an effort to understand the pathogenesis of meningitis due to Escherichia coli K1, we examined whether environmental growth conditions similar to those that the bacteria might be exposed to in the blood could influence the ability ofE. coli K1 to invade brain microvascular endothelial cells (BMEC) in vitro and to cross the blood-brain barrier in vivo. We found that the following bacterial growth conditions enhanced E. coli K1 invasion of BMEC 3- to 10-fold: microaerophilic growth, media buffered at pH 6.5, and media supplemented with 50% newborn bovine serum (NBS), magnesium, or iron. Growth conditions that significantly repressed invasion (i.e., 2- to 250-fold) included iron chelation, a pH of 8.5, and high osmolarity. More importantly, E. coli K1 traversal of the blood-brain barrier was significantly greater for the growth condition enhancing BMEC invasion (50% NBS) than for the condition repressing invasion (osmolarity) in newborn rats with experimental hematogenous meningitis. Of interest, bacterial growth conditions that enhanced or repressed invasion also elicited similar serum resistance phenotype patterns. This is the first demonstration that bacterial ability to enter the central nervous system can be affected by environmental growth conditions.

Real-Time Bioluminescence Analysis of Escherichia coli O157:H7 Survival on Livestock Meats Stored Fresh, Cold, or Frozen

2018 ◽  
Vol 81 (11) ◽  
pp. 1906-1912 ◽  
Author(s):  
SEONG B. PARK ◽  
SHECOYA B. WHITE ◽  
CHRISTY S. STEADMAN ◽  
CLAY A. CAVINDER ◽  
SCOTT T. WILLARD ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Real Time ◽  
Bacterial Growth ◽  
Room Temperature ◽  
Storage Conditions ◽  
Escherichia Coli O157 ◽  
Production Environment ◽  
Real Time Monitoring ◽  
E Coli ◽  
C Storage

ABSTRACT Foodborne bacteria such as Escherichia coli O157:H7 can cause severe hemorrhagic colitis in humans following consumption of contaminated meat products. Contamination with pathogenic bacteria is frequently found in the food production environment, and adequate household storage conditions of purchased foods are vital for illness avoidance. Real-time monitoring was used to evaluate bacterial growth in ground horse, beef, and pork meats maintained under various storage conditions. Various levels of E. coli O157:H7 carrying the luxCDABE operon, which allows the cells to emit bioluminescence, were used to inoculate meat samples that were then stored at room temperature for 0.5 day, at 4°C (cold) for 7 or 9 days, or −20°C (frozen) for 9 days. Real-time bioluminescence imaging (BLI) of bacterial growth was used to assess bacterial survival or load. Ground horse meat BLI signals and E. coli levels were dose and time dependent, increasing during room temperature and −20°C storage, but stayed at low levels during 4°C storage. No bacteria survived in the lower level inoculum groups (101 and 103 CFU/g). With an inoculum of 107 CFU/g, pork meats had higher BLI signals than did their beef counterparts, displaying decreased BLI signals during 7 days storage at 4°C. Both meat types had higher BLI signals in the fat area, which was confirmed with isolated fat tissues in the beef meat. Beef lean and fat tissues contrasted with both pork fat and lean tissues, which had significantly higher BLI signals and bacterial levels. BLI appears to be a useful research tool for real-time monitoring of bacterial growth and survival in various stored livestock meats. The dependence of E. coli O157:H7 growth on meat substrate (fat or lean) and storage conditions may be used as part of an effective antibacterial approach for the production of safe ground horse, beef, and pork meats.

scholarly journals Escherichia coli Strains Engineered for Homofermentative Production of d-Lactic Acid from Glycerol

2010 ◽  
Vol 76 (13) ◽  
pp. 4327-4336 ◽  
Author(s):  
Suman Mazumdar ◽  
James M. Clomburg ◽  
Ramon Gonzalez
Keyword(s):  
Escherichia Coli ◽  
Lactic Acid ◽  
Lactate Dehydrogenase ◽  
Cell Mass ◽  
Lactate Production ◽  
Fumarate Reductase ◽  
Glycerol Metabolism ◽  
E Coli ◽  
Fuels And Chemicals ◽  
Microaerobic Conditions

ABSTRACT Given its availability and low price, glycerol has become an ideal feedstock for the production of fuels and chemicals. We recently reported the pathways mediating the metabolism of glycerol in Escherichia coli under anaerobic and microaerobic conditions. In this work, we engineer E. coli for the efficient conversion of glycerol to d-lactic acid (d-lactate), a negligible product of glycerol metabolism in wild-type strains. A homofermentative route for d-lactate production was engineered by overexpressing pathways involved in the conversion of glycerol to this product and blocking those leading to the synthesis of competing by-products. The former included the overexpression of the enzymes involved in the conversion of glycerol to glycolytic intermediates (GlpK-GlpD and GldA-DHAK pathways) and the synthesis of d-lactate from pyruvate (d-lactate dehydrogenase). On the other hand, the synthesis of succinate, acetate, and ethanol was minimized through two strategies: (i) inactivation of pyruvate-formate lyase (ΔpflB) and fumarate reductase (ΔfrdA) (strain LA01) and (ii) inactivation of fumarate reductase (ΔfrdA), phosphate acetyltransferase (Δpta), and alcohol/acetaldehyde dehydrogenase (ΔadhE) (strain LA02). A mutation that blocked the aerobic d-lactate dehydrogenase (Δdld) also was introduced in both LA01 and LA02 to prevent the utilization of d-lactate. The most efficient strain (LA02Δdld, with GlpK-GlpD overexpressed) produced 32 g/liter of d-lactate from 40 g/liter of glycerol at a yield of 85% of the theoretical maximum and with a chiral purity higher than 99.9%. This strain exhibited maximum volumetric and specific productivities for d-lactate production of 1.5 g/liter/h and 1.25 g/g cell mass/h, respectively. The engineered homolactic route generates 1 to 2 mol of ATP per mol of d-lactate and is redox balanced, thus representing a viable metabolic pathway.

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