scholarly journals MazEF-rifampicin interaction suggests a mechanism for rifampicin induced inhibition of persisters

2020 ◽  
Author(s):  
Cyrus Alexander ◽  
Ankeeta Guru ◽  
Pinkilata Pradhan ◽  
Sunanda Mallick ◽  
Nimai Charan Mahanandia ◽  
...  
Keyword(s):  
Batch Culture ◽  
Treatment Time ◽  
Cell Formation ◽  
Live Cells ◽  
Natural Phenomenon ◽  
Bacterial Strains ◽  
Bacterial Persistence ◽  
Death Phase ◽  
Resistant Strains ◽  
Persistent Bacteria

Abstract Background: Persistence is a natural phenomenon whereby a subset of a population of isogenic bacteria either grow slow or become dormant conferring them with the ability to withstand various stresses including antibiotics. In a clinical setting bacterial persistence often leads to the recalcitrance of various infections increasing the treatment time and cost. Additionally, some studies also indicate that persistence can also pave way for the emergence of resistant strains. In a laboratory setting this persistent phenotype is enriched in nutritionally deprived environments. Consequently, in a batch culture the late stationary phase is enriched with persistent bacteria. The mechanism of persister cell formation and its regulation is not well understood. Toxin-antitoxin (TA) systems have been implicated to be responsible for bacterial persistence and rifampicin is used to treat highly persistent bacterial strains. The current study tries to explore a possible interaction between rifampicin and the MazEF TA system that furthers the former’s success rate in treating persistent bacteria. Results: In the current study we found that the population of bacteria in the death phase of a batch culture consists of metabolically inactive live cells resembling persisters, which showed higher membrane depolarization as compared to the log phase bacteria. We also observed an increase in the expression of the MazEF TA modules in this phase. Since rifampicin is used to kill the persisters, we assessed the interaction of rifampicin with MazEF complex. We showed that rifampicin moderately interacts with MazEF complex with 1:1 stoichiometry.Conclusion: Our study suggests that the interaction of rifampicin with MazEF complex might play an important role in inhibition of persisters.

scholarly journals MazEF-rifampicin interaction suggests a mechanism for rifampicin induced inhibition of persisters

2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Cyrus Alexander ◽  
Ankeeta Guru ◽  
Pinkilata Pradhan ◽  
Sunanda Mallick ◽  
Nimai Charan Mahanandia ◽  
...  
Keyword(s):  
Batch Culture ◽  
Treatment Time ◽  
Cell Formation ◽  
Live Cells ◽  
Natural Phenomenon ◽  
Bacterial Strains ◽  
Bacterial Persistence ◽  
Death Phase ◽  
Resistant Strains ◽  
Persistent Bacteria

Abstract Background Persistence is a natural phenomenon whereby a subset of a population of isogenic bacteria either grow slow or become dormant conferring them with the ability to withstand various stresses including antibiotics. In a clinical setting bacterial persistence often leads to the recalcitrance of various infections increasing the treatment time and cost. Additionally, some studies also indicate that persistence can also pave way for the emergence of resistant strains. In a laboratory setting this persistent phenotype is enriched in nutritionally deprived environments. Consequently, in a batch culture the late stationary phase is enriched with persistent bacteria. The mechanism of persister cell formation and its regulation is not well understood. Toxin-antitoxin (TA) systems have been implicated to be responsible for bacterial persistence and rifampicin is used to treat highly persistent bacterial strains. The current study tries to explore a possible interaction between rifampicin and the MazEF TA system that furthers the former’s success rate in treating persistent bacteria. Results In the current study we found that the population of bacteria in the death phase of a batch culture consists of metabolically inactive live cells resembling persisters, which showed higher membrane depolarization as compared to the log phase bacteria. We also observed an increase in the expression of the MazEF TA modules in this phase. Since rifampicin is used to kill the persisters, we assessed the interaction of rifampicin with MazEF complex. We showed that rifampicin moderately interacts with MazEF complex with 1:1 stoichiometry. Conclusion Our study suggests that the interaction of rifampicin with MazEF complex might play an important role in inhibition of persisters.

scholarly journals MazEF-rifampicin interaction suggests a mechanism for rifampicin induced inhibition of persisters

2020 ◽  
Author(s):  
Cyrus Alexander ◽  
Ankeeta Guru ◽  
Pinkilata Pradhan ◽  
Sunanda Mallick ◽  
Nimai Charan Mahanandia ◽  
...  
Keyword(s):  
Batch Culture ◽  
Treatment Time ◽  
Cell Formation ◽  
Live Cells ◽  
Natural Phenomenon ◽  
Bacterial Strains ◽  
Bacterial Persistence ◽  
Death Phase ◽  
Resistant Strains ◽  
Persistent Bacteria

Abstract Background: Persistence is a natural phenomenon whereby a subset of a population of isogenic bacteria either grow slow or become dormant conferring them with the ability to withstand various stresses including antibiotics. In a clinical setting bacterial persistence often leads to the recalcitrance of various infections increasing the treatment time and costs. Additionally, some studies also indicate that persistence can also pave way for the emergence of resistant strains. In a laboratory setting this persistent phenotype is enriched in nutritionally deprived environments. Consequently, in a batch culture the late stationary phase is enriched with persistent bacteria. The mechanism of persister cell formation and its regulation is not well understood. Toxin-antitoxins (TA) systems have been implicated to be responsible for bacterial persistence and rifampicin is used to treat highly persistent bacterial strains. The current study tries to explore a possible interaction between rifampicin and the MazEF TA system that furthers the former’s success rate in treating persistent bacteria. Results: In the current study we found that the population of bacteria in the death phase of a batch culture consists of metabolically inactive live cells resembling persisters, which showed higher membrane depolarization as compared to the log phase bacteria. We also observed an increase in the expression of the MazEF TA modules in this phase. Since rifampicin is used to kill the persisters, we assessed the interaction of rifampicin with MazEF complex. We showed that rifampicin moderately interacts with MazEF complex with 1:1 stoichiometry.Conclusion: Our study suggests that the interaction of rifampicin with MazEF complex might play an important role in inhibition of persisters.

scholarly journals MazEF-rifampicin Interaction Suggests a Mechanism for Rifampicin Induced Inhibition of Persisters

2020 ◽  
Author(s):  
Cyrus Alexander ◽  
Ankeeta Guru ◽  
Sunanda Mallick ◽  
Nimai Charan Mahanandia ◽  
Bharat Bhushan Subudhi ◽  
...  
Keyword(s):  
Treatment Time ◽  
Cell Formation ◽  
Live Cells ◽  
Natural Phenomenon ◽  
Bacterial Strains ◽  
Late Stationary Phase ◽  
Bacterial Persistence ◽  
Death Phase ◽  
Resistant Strains ◽  
Persistent Bacteria

Abstract Background: Persistence is a natural phenomenon whereby a subset of a population of isogenic bacteria either grow slow or become dormant conferring them with the abilityto withstand various stresses including antibiotics.In a clinical setting bacterial persistence often leads to the recalcitrance of various infectionsincreasing the treatment time and costs.Additionally, some studies also indicate that persistence can also pave way for the emergence of resistant strains. In a laboratory setting this persistent phenotype is enriched in nutritionally deprived environments. Consequently, in a batch culture the late stationary phase is enriched with persistent bacteria. The mechanism of persister cell formation and its regulation is not well understood. Toxin-antitoxins (TA) systems have been implicated to be responsible for bacterial persistence and rifampicin is used to treat highly persistent bacterial strains. The current study tries to explore a possible interaction between rifampicin and the MazEFTA system that furthers the former’s success rate in treating persistent bacteria.Results: In the current study we found that the population of bacteria in the death phase of a batch cultureconsists of metabolically inactive live cells resembling persisters, which showed higher membrane depolarization as compared to the log phase bacteria. We also observed an increase in the expression of the MazEF TA modules in this phase. Since rifampicin is commonly used to kill the persisters, we assessed the interaction of rifampicin with MazEF complex. We showed that rifampicin directly interacts with MazEF complex.Conclusion: Our study suggests that the interaction of rifampicin with MazEF complex might play an important role in inhibition of persisters.

Removal of Toxic Volatile Compounds in Batch Culture Prolongs Stationary Phase and Delays Death of Escherichia coli

2021 ◽  
Author(s):  
Melisa G. Osborne ◽  
Christopher J. Geiger ◽  
Christopher H. Corzett ◽  
Karin E. Kram ◽  
Steven E. Finkel
Keyword(s):  
Escherichia Coli ◽  
Life Cycle ◽  
Stationary Phase ◽  
Volatile Compounds ◽  
Batch Culture ◽  
Future Research ◽  
Bacterial Strains ◽  
Batch Cultures ◽  
Death Phase

The mechanisms controlling entry into and exit from death phase in the bacterial life cycle remain unclear. While bacterial growth studies in batch cultures traditionally focus on the first three phases during incubation, two additional phases, death phase and long-term stationary phase, are less understood. Although there are a number of stressors that arise during long-term batch culture, including nutrient depletion and the accumulation of metabolic toxins such as reactive oxidative species, their roles in cell death are not well-defined. By manipulating environmental conditions of Escherichia coli incubated in long-term batch culture through chemical and mechanical means, we investigated the role of volatile metabolic toxins in modulating the onset of death phase. Here, we demonstrate that with the introduction of substrates with high binding affinities for volatile compounds, toxic byproducts of normal cell metabolism, into the headspace of batch cultures, cells display prolonged stationary phase and delayed entry into death phase. Addition of these substrates allows cultures to maintain a high cell density for hours to days longer than cultures incubated under standard growth conditions. A similar effect is observed when the gaseous headspace in culture flasks is continuously replaced with sterile air, mechanically preventing the accumulation of metabolic byproducts in batch cultures. We establish that toxic compound(s) are produced during exponential phase, demonstrate that buildup of toxic byproducts influence entry into death phase, and present a novel tool for improving high density growth in batch culture that may be used in future research, industrial, or biotechnology applications. IMPORTANCE Bacteria, such as Escherichia coli , are routinely used in the production of biomaterials because of their efficient and sustainable capacity for synthesis of bioproducts. Industrial applications of microbial synthesis typically utilize cells in stationary phase, when cultures have the greatest density of viable cells. By manipulating culture conditions to delay the transition from stationary phase to death phase, we can prolong stationary phase on a scale of hours to days, thereby maintaining the maximum density of cells that would otherwise quickly decline. Characterization of the mechanisms that control entry into death phase for the model organism Escherichia coli not only deepens our understanding of the bacterial life cycle, but also presents an opportunity to enhance current protocols for batch culture growth and explore similar effects in a variety of widely used bacterial strains.

4H-1,3-Benzothiazin-4-one a Promising Class Against MDR/XDR-TB

2019 ◽  
Vol 19 (8) ◽  
pp. 567-578 ◽  
Author(s):  
Marcus Vinicius Nora de Souza ◽  
Thais Cristina Mendonça Nogueira
Keyword(s):  
Treatment Time ◽  
Public Health Problem ◽  
New Drugs ◽  
Global Public Health ◽  
Synthesis Mechanism ◽  
Highly Active ◽  
Latent Disease ◽  
Resistant Strains ◽  
Chemical Class ◽  
Global Public Health Problem

Nowadays, tuberculosis (TB) is an important global public health problem, being responsible for millions of TB-related deaths worldwide. Due to the increased number of cases and resistance of Mycobacterium tuberculosis to all drugs used for the treatment of this disease, we desperately need new drugs and strategies that could reduce treatment time with fewer side effects, reduced cost and highly active drugs against resistant strains and latent disease. Considering that, 4H-1,3-benzothiazin-4-one is a promising class of antimycobacterial agents in special against TB-resistant strains being the aim of this review the discussion of different aspects of this chemical class such as synthesis, mechanism of action, medicinal chemistry and combination with other drugs.

scholarly journals Biosorption potential and molecular characterization of metal resistant autochthonous microbes from tannery solid waste

2021 ◽  
Author(s):  
Hajira Younas ◽  
Aisha Nazir ◽  
Zakia Latif ◽  
Janice E Thies ◽  
Muhammad Shafiq ◽  
...  
Keyword(s):  
Solid Waste ◽  
Its Region ◽  
Metal Resistance ◽  
Molecular Techniques ◽  
Bacterial Strains ◽  
Fungal Strains ◽  
Resistant Strains ◽  
Tannery Solid Waste ◽  
Clean Metal

This study encompasses isolation and screening of heavy metal-resistant fungal and bacterial strains from tannery solid waste (TSW). Twelve fungal strains and twenty-five bacterial strains were isolated from TSW. The growth of fungal strains was observed against different heavy metals ranging from 10 mg L -1 to 1050 mg L -1 and the growth of bacteria was observed in metal concentrations ranging from 10 mg L -1 to 1200 mg L -1 . Five multi-metal resistant fungal isolates belonging to the genus Trichoderma and ten bacterial isolates belonging to the genus Bacillus showed good metal resistance and biosorption potential. They were identified through molecular techniques, fungi based on ITS region ribotyping, and bacteria based on 16S rRNA ribotyping. The fungal strains were characterized as T. hamatum (TSWF-06), T. harzianum (TSWF-11), T. lixii (TSWF-02) and T. pseudokoningii (TSWF-03, TSWF-10). The bacterial strains were characterized as Bacillus xiamenensis (TSW-02), B. velezensis (TSW-05), B. piscis (TSW-06), B. safensis (TSW-10), B. subtilis (TSW-14, TSW-15, TSW-17) B. licheniformis (TSW-19), B. cereus (TSW-20) and B. thuringiensis (TSW-22). The fungal strains namely, T. pseudokoningii (TSWF-03) and T. harzianum proved to be two multi-metal resistant strains with good biosorption efficiency. Unlike fungi, bacterial strains showed metal specific resistance. The strains Bacillus xiamenensis , B. subtilis (TSW-14) and B. subtilis (TSW-15) showed good biosorption efficiency against Cr, B. safensis against Cu, B. piscis and B. subtilis (TSW-17) against Pb and B. licheniformis and B. thuringiensis against Zn. The autochthonous fungal and bacterial strains can therefore be employed to clean metal contaminated environments.

Antibiotic survey ofLactococcus lactisstrains to six antibiotics by Etest, and establishment of new susceptibility-resistance cut-off values

2007 ◽  
Vol 74 (3) ◽  
pp. 262-268 ◽  
Author(s):  
Ana Belén Flórez ◽  
Morten Danielsen ◽  
Jenni Korhonen ◽  
Joanna Zycka ◽  
Atte von Wright ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Inhibitory Concentration ◽  
Tetracycline Resistance ◽  
Large Collection ◽  
Bacterial Strains ◽  
Resistance Determinants ◽  
Resistant Strains ◽  
Geographical Locations ◽  
S Genes ◽  
Acquired Antibiotic Resistance

In order to establish cut-off values forLactococcus lactisto six antibiotics to distinguish susceptible and intrinsically resistant strains from those having acquired resistances, the minimum inhibitory concentration (MIC) of tetracycline, erythromycin, clindamycin, streptomycin, chloramphenicol and vancomycin was determined in 93 differentLc. lactisstrains using the Etest. These bacterial strains were originally isolated from dairy and animal sources in widely separated geographical locations. Cut-offs were defined on the basis of the distribution of the MICs frequency of the studied antibiotics, which in the absence of acquired determinants should approach to a normal statistical distribution. In general, the new cut-off values proposed in this study are higher than previously defined (European Commission, 2005. The EFSA Journal 223, 1–12). Based on these new values, all the strains tested were susceptible to erythromycin, chloramphenicol and vancomycin, and 79 susceptible to all six antibiotics. However, 11 strains (around 12%) were considered resistant to tetracycline (six of which had been identified after screening of a large collection of lactococci strains for tetracycline resistance) and five (5·4%) resistant to streptomycin. Of these, two fish isolates proved to be resistance to both tetracycline and streptomycin. From the tetracycline resistant strains,tet(M) and mosaictet(L/S) genes were amplified by PCR, demonstrating they harboured acquired antibiotic resistance determinants.

scholarly journals Effect of milk chocolate supplementation with lyophilised Lactobacillus cells on its attributes

2010 ◽  
Vol 28 (No. 5) ◽  
pp. 392-406 ◽  
Author(s):  
D. Żyżelewicz ◽  
E. Nebesny ◽  
I. Motyl ◽  
Z. Libudzisz
Keyword(s):  
Ambient Temperature ◽  
High Temperatures ◽  
Functional Food ◽  
Lactobacillus Casei ◽  
Probiotic Bacteria ◽  
Live Cells ◽  
Bacterial Cells ◽  
Bacterial Strains ◽  
Milk Chocolate ◽  
Live Bacterial Cells

Manufacturing of novel foodstuffs supplemented with live probiotic bacteria has recently been intensively investigated. The supplementation of confectionery with probiotics is troublesome since some unit technological processes are conducted at high temperatures and the products are usually stored at ambient temperature. Our group has developed a method of the production of milk chocolate, sweetened with either sucrose or isomalt and aspartame, containing 32, 36, or 40 g/100 g fat, and supplemented with live cells of probiotic bacterial strains: Lactobacillus casei and paracasei. This new milk chocolate displayed the same sensory properties as the reference, probiotic-free chocolate. The number of live bacterial cells was maintained at the functional level of 10<sup>6</sup> &divide; 10<sup>8</sup> cfu/g after keeping for 12 months irrespective of the temperature. The highest number of live probiotic bacteria survived in the chocolate kept at 4&deg;C. Thus the product can be regarded as functional food.

scholarly journals Phytochemical Study and Antibacterial and Antibiotic Modulation Activity of Punica granatum (Pomegranate) Leaves

Scientifica ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Amine Trabelsi ◽  
Mohamed Amine El Kaibi ◽  
Aïmen Abbassi ◽  
Amira Horchani ◽  
Leila Chekir-Ghedira ◽  
...  
Keyword(s):  
Antibacterial Properties ◽  
Punica Granatum ◽  
Diffusion Method ◽  
Bacterial Strains ◽  
Leaf Extracts ◽  
Phytochemical Study ◽  
E Coli ◽  
Microdilution Method ◽  
Resistant Strains

This study aimed to determine phytochemical contents, antibacterial properties, and antibiotic modulating potential of Punica granatum leaf extracts: hexane, chloroform, ethyl acetate, ethanol, and aqueous extracts as well as an extract enriched with total oligomer flavonoids (TOFs). The TOF extract contained the highest value of phenols and flavonoids. Rutin, luteolin, gallic acid, and ellagic acid were determined by HPLC analysis of this extract. The antibacterial activity was assayed by the disc diffusion method and microdilution method against Staphylococcus aureus and Escherichia coli standard ATCC strains and clinical isolates resistant strains. The TOF extract was the most active against all tested strains. The checkerboard method was used for the determination of synergy between two antibiotics (amoxicillin and cefotaxime) and P. granatum leaf extracts. The best synergistic interaction was found with TOF extract combined with amoxicillin for penicillin-resistant E. coli and penicillin-resistant S. aureus. These results can be assigned to tannins, flavonoids, and phenolic acids found in P. granatum leaf extracts. Pomegranate leaf extracts or active compounds isolated from these extracts could be used to fight the emergence and spread of resistant bacterial strains.

scholarly journals A High-Content Live-Cell Viability Assay and Its Validation on a Diverse 12K Compound Screen

2017 ◽  
Vol 22 (9) ◽  
pp. 1120-1130 ◽  
Author(s):  
Jeanne Chiaravalli ◽  
J. Fraser Glickman
Keyword(s):  
High Throughput ◽  
Treatment Time ◽  
Cell Structure ◽  
Relative Size ◽  
Extended Period ◽  
Cell Number ◽  
Cytotoxicity Assay ◽  
Live Cells ◽  
Cell Viability Assay ◽  
Viability Assay

We have developed a new high-content cytotoxicity assay using live cells, called “ImageTOX.” We used a high-throughput fluorescence microscope system, image segmentation software, and the combination of Hoechst 33342 and SYTO 17 to simultaneously score the relative size and the intensity of the nuclei, the nuclear membrane permeability, and the cell number in a 384-well microplate format. We then performed a screen of 12,668 diverse compounds and compared the results to a standard cytotoxicity assay. The ImageTOX assay identified similar sets of compounds to the standard cytotoxicity assay, while identifying more compounds having adverse effects on cell structure, earlier in treatment time. The ImageTOX assay uses inexpensive commercially available reagents and facilitates the use of live cells in toxicity screens. Furthermore, we show that we can measure the kinetic profile of compound toxicity in a high-content, high-throughput format, following the same set of cells over an extended period of time.

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