Zeta Potential of Escherichia Coli DH5α Grown in Different Growth Media

2021 ◽  
Vol 05 (04) ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Escherichia Coli ◽  
Zeta Potential ◽  
Growth Media

Genetics and regulation of peptidase N in Escherichia coli K-12

1982 ◽  
Vol 152 (2) ◽  
pp. 848-854
Author(s):  
M T McCaman ◽  
A McPartland ◽  
M R Villarejo
Keyword(s):  
Escherichia Coli ◽  
Constitutive Expression ◽  
Growth Cycle ◽  
Growth Media ◽  
Chromosome Loss ◽  
E Coli ◽  
Cell Enzyme ◽  
Nutritional Needs ◽  
K 12 ◽  
Type Strains

Escherichia coli K-12 strains contain a cytoplasmic activity, peptidase N, capable of hydrolyzing alanine-p-nitroanilide. Mutations in the structural gene for the enzyme, pepN, were mapped, and the properties of mutant strains were examined. The pepN locus lay between ompF and asnS at approximately 20.8 min on the E. coli chromosome. Loss of peptidase N activity through mutation had no apparent effect on the growth rate or nutritional needs of the cell. Enzyme levels in wild-type strains were constant throughout the growth cycle and were constitutive in all of the growth media tested. Starvation for carbon, nitrogen, or phosphate also did not alter enzyme levels. Constitutive expression of peptidase N is consistent with the idea that the enzyme plays a significant role in the degradation of intracellularly generated peptides.

scholarly journals Strain improvement of Escherichia coli K-12 for recombinant production of deuterated proteins

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Vinardas Kelpšas ◽  
Claes von Wachenfeldt
Keyword(s):  
Escherichia Coli ◽  
Structural Biology ◽  
Strain Improvement ◽  
Growth Media ◽  
Genomic Changes ◽  
E Coli ◽  
Recombinant Production ◽  
High Concentrations ◽  
Neutron Protein Crystallography ◽  
K 12

AbstractDeuterium isotope labelling is important for structural biology methods such as neutron protein crystallography, nuclear magnetic resonance and small angle neutron scattering studies of proteins. Deuterium is a natural low abundance stable hydrogen isotope that in high concentrations negatively affect growth of cells. The generation time for Escherichia coli K-12 in deuterated medium is substantially increased compared to cells grown in hydrogenated (protiated) medium. By using a mutagenesis plasmid based approach we have isolated an E. coli strain derived from E. coli K-12 substrain MG1655 that show increased fitness in deuterium based growth media, without general adaptation to media components. By whole-genome sequencing we identified the genomic changes in the obtained strain and show that it can be used for recombinant production of perdeuterated proteins in amounts typically needed for structural biology studies.

scholarly journals Activation of Toxin-Antitoxin System Toxins Suppresses Lethality Caused by the Loss of σEin Escherichia coli

2015 ◽  
Vol 197 (14) ◽  
pp. 2316-2324 ◽  
Author(s):  
Yasushi Daimon ◽  
Shin-ichiro Narita ◽  
Yoshinori Akiyama
Keyword(s):  
Escherichia Coli ◽  
Stress Responses ◽  
Ectopic Expression ◽  
Growth Media ◽  
Content Type ◽  
E Coli ◽  
Envelope Stress ◽  
Genes Encoding ◽  
Σ Factor ◽  
Mutant Forms

ABSTRACTσE, an alternative σ factor that governs a major signaling pathway in envelope stress responses in Gram-negative bacteria, is essential for growth ofEscherichia colinot only under stressful conditions, such as elevated temperature, but also under normal laboratory conditions. A mutational inactivation of thehicBgene has been reported to suppress the lethality caused by the loss of σE.hicBencodes the antitoxin of the HicA-HicB toxin-antitoxin (TA) system; overexpression of the HicA toxin, which exhibits mRNA interferase activity, causes cleavage of mRNAs and an arrest of cell growth, while simultaneous expression of HicB neutralizes the toxic effects of overproduced HicA. To date, however, how the loss of HicB rescues the cell lethality in the absence of σEand, more specifically, whether HicA is involved in this process remain unknown. Here we showed that simultaneous disruption ofhicAabolished suppression of the σEessentiality in the absence ofhicB, while ectopic expression of wild-type HicA, but not that of its mutant forms without mRNA interferase activity, restored the suppression. Furthermore, HicA and two other mRNA interferase toxins, HigB and YafQ, suppressed the σEessentiality even in the presence of chromosomally encoded cognate antitoxins when these toxins were overexpressed individually. Interestingly, when the growth media were supplemented with low levels of antibiotics that are known to activate toxins,E. colicells with no suppressor mutations grew independently of σE. Taken together, our results indicate that the activation of TA system toxins can suppress the σEessentiality and affect the extracytoplasmic stress responses.IMPORTANCEσEis an alternative σ factor involved in extracytoplasmic stress responses. Unlike other alternative σ factors, σEis indispensable for the survival ofE. colieven under unstressed conditions, although the exact reason for its essentiality remains unknown. Toxin-antitoxin (TA) systems are widely distributed in prokaryotes and are composed of two adjacent genes, encoding a toxin that exerts harmful effects on the toxin-producing bacterium itself and an antitoxin that neutralizes the cognate toxin. Curiously, it is known that inactivation of an antitoxin rescues the σEessentiality, suggesting a connection between TA systems and σEfunction. We demonstrate here that toxin activation is necessary for this rescue and suggest the possible involvement of TA systems in extracytoplasmic stress responses.

Proflavine binding and release by sensitive and resistant Bacillus subtilis

1970 ◽  
Vol 16 (10) ◽  
pp. 973-981
Author(s):  
Gy. Barabas ◽  
B. M. Mehta ◽  
D. J. Kushner
Keyword(s):  
Escherichia Coli ◽  
Bacillus Subtilis ◽  
Organic Acids ◽  
Resistant Strain ◽  
Binding Capacity ◽  
Sensitive Strain ◽  
Growth Media ◽  
Sodium Salts ◽  
Salts Of Organic Acids ◽  
Resistant Cells

Proflavine binding of a sensitive strain of Bacillus subtilis and of a resistant strain derived from it was compared. Proflavine was bound very rapidly and more was bound at 0 °C than at 37 °C. Boiling increased the proflavine-binding capacity at 37 °C of sensitive but not of resistant cells. The binding capacity of sensitive and resistant cells suspended in buffer was the same; this was also true in various growth media. If cells were able to grow in the presence of proflavine their proflavine content decreased.Bound proflavine was released when cells were treated with growth media or with the salts of growth media. Sodium salts of organic acids also caused a release. This effect seemed due to their Na+ content, and was somewhat higher for resistant than for sensitive cells. The mechanism of proflavine resistance in B. subtilis is probably different from that of Escherichia coli, which is thought to depend on an energy-driven release of bound proflavine.

scholarly journals Different Cellular Origins and Functions of Extracellular Proteins from Escherichia coli O157:H7 and O104:H4 as Determined by Comparative Proteomic Analysis

2016 ◽  
Vol 82 (14) ◽  
pp. 4371-4378 ◽  
Author(s):  
Nazrul Islam ◽  
Attila Nagy ◽  
Wesley M. Garrett ◽  
Dan Shelton ◽  
Bret Cooper ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Medium ◽  
Foodborne Pathogen ◽  
The United States ◽  
Extracellular Proteins ◽  
Growth Media ◽  
Environmental Matrices ◽  
Content Type ◽  
E Coli ◽  
Relative Abundances

ABSTRACTExtracellular proteins play important roles in bacterial interactions with the environmental matrices. In this study, we examined the extracellular proteins fromEscherichia coliO157:H7 and O104:H4 by tandem mass spectrometry. We identified 500 and 859 proteins from the growth media ofE. coliO157:H7 and O104:H4, respectively, including 371 proteins common to both strains. Among proteins that were considered specific toE. coliO157:H7 or present at higher relative abundances in O157:H7 medium, most (57 of 65) had secretion signal sequences in their encoding genes. Noticeably, the proteins included locus of enterocyte effacement (LEE) virulence factors, proteins required for peptidyl-lipoprotein accumulation, and proteins involved in iron scavenging. In contrast, a much smaller proportion of proteins (37 of 150) that were considered specific to O104:H4 or presented at higher relative abundances in O104:H4 medium had signals targeting them for secretion. These proteins included Shiga toxin 2 subunit B and O104:H4 signature proteins, including AAF/1 major fimbrial subunit and serine protease autotransporters. Most of the abundant proteins from the growth medium ofE. coliO104:H4 were annotated as having functions in the cytoplasm. We provide evidence that the extensive presence of cytoplasmic proteins inE. coliO104:H4 growth medium was due to biological processes independent of cell lysis, indicating alternative mechanisms for this potent pathogen releasing cytoplasmic contents into the growth milieu, which could play a role in interaction with the environmental matrices, such as pathogenesis and biofilm formation.IMPORTANCEIn this study, we compared the extracellular proteins from two of the most prominent foodborne pathogenicE. coliorganisms that have caused severe outbreaks in the United States and in Europe.E. coliO157:H7 is a well-studied Shiga toxigenic foodborne pathogen of the enterohemorrhagic pathotype that has caused numerous outbreaks associated with various contaminated foods worldwide.E. coliO104:H4 is a newly emerged Shiga toxigenic foodborne pathogen of the enteroaggregative pathotype that gained notoriety for causing one of the most deadly foodborne outbreaks in Europe in 2011. Comparison of proteins in the growth medium revealed significant differences in the compositions of the extracellular proteins for these two pathogens. These differences may provide valuable information regarding the cellular responses of these pathogens to their environment, including cell survival and pathogenesis.

scholarly journals Análise Microbiológica em Aparelhos de Celular de Acadêmicos e Professores da Universidade de Cuiabá (UNIC) Campus Primavera do Leste – MT

UNICIÊNCIAS ◽  
2019 ◽  
Vol 23 (2) ◽  
pp. 105
Author(s):  
Vivian Tallita Pinheiro de Santana ◽  
Phelipe Magalhães Duarte ◽  
Uvleique Alves Fernandes ◽  
Gabriel Moreno Damião ◽  
Amanda Lourença Da Silva
Keyword(s):  
Escherichia Coli ◽  
Staphylococcus Aureus ◽  
Staphylococcus Epidermidis ◽  
Cell Phones ◽  
Control Measures ◽  
Growth Media ◽  
Staphylococcus Lugdunensis ◽  
Nutrient Culture ◽  
Microbiological Agents ◽  
Staphylococcus Spp

Rápidos, portáteis e acessíveis, os aparelhos celulares foram incorporados às atividades e rotinas diárias da população. Diante de tal intimidade, esses aparelhos também passaram a se constituir em um meio de crescimento para agentes microbiológicos comensais e acidentais. Medidas de controle como a adoção de boas práticas de higiene são imprescindíveis para a diminuição da carga microbiológica e, por consequência, decréscimo dos riscos de transmissão destes agentes ao homem, principalmente em imunodeprimidos. Dessa forma, o presente trabalho objetivou identificar os micro-organismos presentes em aparelhos celulares de acadêmicos e professores da Universidade de Cuiabá (UNIC), Campus Primavera do Leste – MT, através de amostragens obtidas de 24 aparelhos de telefones celulares de voluntários. Foram realizadas coletas para cada um dos aparelhos celulares disponibilizados pelos voluntários, através de um swab de transporte. Este foi deslizado na parte externa do aparelho, cobrindo toda a área da tela, conectores e alto-falante e, em seguida, inseridos em meio Stuart e remetidos ao laboratório. Do total de amostras coletadas, 19 (79,1%) apresentaram crescimento bacteriano em meio de cultura nutritivo. Os micro-organismos isolados foram Staphylococcus aureus em seis amostras (31,6%), Staphylococcus lugdunensis em outras seis (31,6%), Staphylococcus epidermidis em três (15,8%), Staphylococcus spp. em três (5,8%) e Escherichia coli em uma (5,2%) das amostras. Diante dos resultados obtidos se pôde constatar que os aparelhos celulares podem atuar como meio de multiplicação microbiológica, assim se deve adotar medidas preventivas de higiene e antissepsia das mãos e destes aparelhos, a fim de evitar a proliferação e veiculação de micro-organismos por meio destes. Palavras-chave: Telefone Celular. Staphylococcus aureus.  Escherichia coli. AbstractFast, portable and affordable, mobile phones have been incorporated into the daily activities and routines of the population. Faced with such intimacy, these devices have also become a growth medium for commensal and accidental microbiological agents. Control measures such as the adoption of good hygiene practices are essential to reduce the microbiological load and, consequently, decrease the risks of transmission of these agents to humans, especially in immunosuppressed ones. Thus, the present work aimed to identify the microorganisms present in cell phones of academics and professors of the University of Cuiabá (UNIC), Campus Primavera do Leste - MT, through samples obtained from 24 cell phones of volunteers. The samples  were collected for each of the mobile devices made available by the volunteers through a transport swab. This was slid on the external part of the device, covering the entire display area, connectors and speaker, then inserted into Stuart medium and sent to the lab. Of the total samples collected, only 19 (79.1%) showed bacterial growth in nutrient culture medium. Microorganisms isolated from growth media were Staphylococcus aureus in six samples (31.6%), Staphylococcus lugdunensis in six (31.6%), Staphylococcus epidermidis in three (15.8%), Staphylococcus spp. in three (5.8%) and Escherichia coli in one (5.2%) of the samples. Given the results obtained, it can be seen that cell phones can act as a means of microbiological multiplication, so preventive measures of hygiene and antisepsis of  hands should be adopted, in order to prevent the proliferation and spread of microorganisms through them . Keyword: Cell Phone. Staphylococcus aureus.  Escherichia coli. 

scholarly journals Comparation Between Mac conkey and Coconut Water Medium as a Growth Medium for Escherichia coli

2021 ◽  
Vol 3 (1) ◽  
pp. 19-25
Author(s):  
Endah Prayekti ◽  
Suliati Suliati ◽  
Dwi Agustin Wulandari
Keyword(s):  
Escherichia Coli ◽  
Growth Medium ◽  
Coconut Water ◽  
Growth Media ◽  
Water Medium ◽  
E Coli ◽  
Commercial Media ◽  
Randomized Design ◽  
Significant Difference ◽  
Water Media

Escherichia coli is the bacteria that can cause diarrhea in humans and often used as a parameter of stool environmental pollution. Culture of E. coli from the sample often requires Mac Conkey as commercial media which is able to distinguish it from other bacteria in the Enterobacteriaceae group. Commercial media such as Mac Conkey certainly has a price that is quite expensive because of its ability as a growth medium for Enterobacteriaceae. Therefore, in the study tested natural ingredients that can be used for growth media, such as coconut water. The purpose of this study was to compare the ability of Mac Conkey media and coconut water to support the growth of E. coli. This research is an experimental study with a completely randomized design. The concentration of coconut water tested was 0%, 20%, 40%, 60%, 80%, and 100%. The results showed that at the concentration of coconut water 20% to 60% the number of E. coli colonies on coconut water media was slightly below the Mac Conkey Agar media, while in coconut water a concentration of 80% showed a greater number of colonies than Mac Conkey. The Mann Whitney test showed a significant difference between the number of colonies on 80% coconut water media and Mac Conkey Agar, which was equal to 0.004 (p < 0.05). Based on these results, coconut water has the potential to be used as a growth medium for E. coli.

scholarly journals Development of a semi-defined medium for high cell density cultivation of Escherichia coli in shake flask culture system

2015 ◽  
Author(s):  
Wenfa Ng ◽  
Yen-Peng Ting
Keyword(s):  
Escherichia Coli ◽  
Cell Density ◽  
Yeast Extract ◽  
High Cell Density ◽  
Growth Media ◽  
Buffer System ◽  
High Cell ◽  
High Cell Density Cultivation ◽  
E Coli ◽  
Carbon And Nitrogen

Microbes in environmental studies should be cultured in growth media with characteristics as close to their original habitat as possible, and which also allows a high cell density to be attained for providing enough cells in subsequent experiments. This in-progress report describes the formulation of a medium with an environmentally-relevant composition, and which also affords aerobic high cell density cultivation of Escherichia coli DH5α in shake flasks. The formulated medium comprises four components: a buffer system (K2HPO4: 12.54 g/L and KH2PO4: 2.31 g/L), vitamins (yeast extract: 12.0 g/L), salts (NaCl: 5.0 g/L and MgSO4: 0.24 g/L), and carbon and nitrogen sources (D-Glucose: 6.0 g/L and NH4Cl: 1.5 g/L). Notable characteristics of this medium were: high capacity phosphate buffer system (89 mM phosphate); 1:1 molar ratio between D-Glucose and NH4Cl; and yeast extract providing trace elements and a secondary carbon and nitrogen source. Growth experiments revealed that an OD600nm of 9 was attained after 24 hours of cultivation at 37 oC. This phase of growth was largely fuelled by glucose and NH4Cl. After 48 hours, the OD600nm reached 11, which was fuelled by the mixture of carbohydrates, lipids and proteins in yeast extract. Broth’s pH varied between 5.5 and 7.8 during cultivation, which was in the range conducive for growth of E. coli. In comparison, the OD600nm of E. coli reached 1.4, 3.2, and 9.2 for three commonly used complex media; Nutrient Broth, LB Lennox, and Tryptic Soy Broth, respectively, over 48 hours under identical culture conditions. In addition, the formulated medium was able to maintain a large viable cell population for a longer period of time (three days) relative to Tryptic Soy Broth. Thus, preliminary data suggested that the formulated medium holds potential for use as a high cell density aerobic growth medium for Gram-negative bacteria.

scholarly journals Overlapping stimulons arising in response to divergent stresses in Escherichia coli

2021 ◽  
Author(s):  
Huijing Wang ◽  
GW McElfresh ◽  
Nishantha Wijesuriya ◽  
Adam Podgorny ◽  
Andrew D Hecht ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Stress Responses ◽  
Differential Expression Analysis ◽  
Stringent Response ◽  
Coli Strain ◽  
Growth Media ◽  
Overflow Metabolism ◽  
Rna Seq ◽  
E Coli

Cellular responses to stress can cause a similar change in some facets of fitness even if the stresses are different. Lactose as a sole carbon source for Escherichia coli is an established example: too little causes starvation while excessive lactose import causes toxicity as a side-effect. In an E. coli strain that is robust to osmotic and ionic differences in growth media, B REL606, the rate of antibiotic-tolerant persister formation is elevated in both starvation-inducing and toxicity-inducing concentrations of lactose in comparison to less stressful intermediate concentrations. Such similarities between starvation and toxification raise the question of how much the global stress response stimulon differs between them. We hypothesized that a common stress response is conserved between the two conditions, but that a previously shown threshold driving growth rate heterogeneity in a lactose-toxifying medium would reveal that the growing fraction of cells in that medium to be missing key stress responses that curb growth. To test this, we performed RNA-seq in three representative conditions for differential expression analysis. In comparison to nominally unstressed cultures, both stress conditions showed global shifts in gene expression, with informative similarities and differences. Functional analysis of pathways, gene ontology terms, and clusters of orthogonal groups revealed signatures of overflow metabolism, membrane component shifts, and altered cytosolic and periplasmic contents in toxified cultures. Starving cultures showed an increased tendency toward stringent response-like regulatory signatures. Along with other emerging evidence, our results show multiple possible pathways to stress responses, persistence, and possibly other phenotypes. These results suggest a set of overlapping responses that drives emergence of stress-tolerant phenotypes in diverse conditions.

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