Microfabricated Device for Impedance-Based Detection of Bacterial Metabolism

2002 ◽  
Vol 729 ◽  
Author(s):  
Rafael Gómez ◽  
Michael R. Ladisch ◽  
Arun K. Bhunia ◽  
Rashid Bashir
Keyword(s):  
Complex Impedance ◽  
Ionic Species ◽  
Bacterial Metabolism ◽  
Live Cells ◽  
Bacterial Cells ◽  
Detection Level ◽  
Experimental Conditions ◽  
Minimum Detection Level ◽  
On Chip ◽  
Live Bacterial Cells

AbstractWe present the use of a microfabricated device for impedance-based detection of a few live bacterial cells. Impedance-based detection relies on measuring changes in the AC impedance of two electrodes immersed in a liquid were the bacteria are cultured, caused by the release of ionic species by metabolizing bacterial cells. Rapid detection of a few cells (1 to 10) is possible if the cells are confined into a volume on the order of nanoliters. A microfluidic biochip prototype has been fabricated to test this miniaturized assay. The conductance of the bacterial suspensions is extracted from measuring their complex impedance in a 5.27 nl chamber in the biochip, at several frequencies between 100 Hz and 1 MHz. Measurements on suspensions of the bacteria Listeria innocua, Listeria monocytogenes, and Escherichia coli in a low conductivity buffer demonstrate that, under the current experimental conditions, the minimum detection level is between 50 and 200 live cells, after two hours of off-chip incubation. Work is in progress to develop techniques for selective capture of bacteria inside the chip, and to minimize background changes in impedance during on-chip incubation.

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 Artificial Cell Therapy: New Strategies for the Therapeutic Delivery of Live Bacteria

2005 ◽  
Vol 2005 (1) ◽  
pp. 44-56 ◽  
Author(s):  
Satya Prakash ◽  
Mitchell Lawrence Jones
Keyword(s):  
Oral Delivery ◽  
Therapeutic Potential ◽  
Immobilized Cells ◽  
Genetically Engineered ◽  
Live Cells ◽  
Bacterial Cells ◽  
Artificial Cells ◽  
Artificial Cell ◽  
Wide Range ◽  
Live Bacterial Cells

There has been rapid growth in research regarding the use of live bacterial cells for therapeutic purposes. The recognition that these cells can be genetically engineered to synthesize products that have therapeutic potential has generated considerable interest and excitement among clinicians and health professionals. It is expected that a wide range of disease modifying substrates such as enzymes, hormones, antibodies, vaccines, and other genetic products will be used successfully and will impact upon health care substantially. However, a major limitation in the use of these bacterial cells is the complexity of delivering them to the correct target tissues. Oral delivery of live cells, lyophilized cells, and immobilized cells has been attempted but with limited success. Primarily, this is because bacterial cells are incapable of surviving passage through the gastrointestinal tract. In many occasions, when given orally, these cells have been found to provoke immunogenic responses that are undesirable. Recent studies show that these problems can be overcome by delivering live bacterial cells, such as genetically engineered cells, using artificial cell microcapsules. This review summarizes recent advances in the therapeutic use of live bacterial cells for therapy, discusses the principles of using artificial cells for the oral delivery of bacterial cells, outlines methods for preparing suitable artificial cells for this purpose, addresses potentials and limitations for their application in therapy, and provides insight for the future direction of this emergent and highly prospective technology.

scholarly journals Dead bacterial absorption of antimicrobial peptides underlies collective tolerance

2019 ◽  
Vol 16 (151) ◽  
pp. 20180701 ◽  
Author(s):  
Fan Wu ◽  
Cheemeng Tan
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Peptides ◽  
Mathematical Modelling ◽  
Dynamic Process ◽  
Bacterial Strain ◽  
Live Cells ◽  
Bacterial Cells ◽  
Tolerance Mechanisms ◽  
Cytoplasmic Membranes ◽  
Live Bacterial Cells

The collective tolerance towards antimicrobial peptides (APs) is thought to occur primarily through mechanisms associated with live bacterial cells. In contrast to the focus on live cells, we discover that the LL37 antimicrobial peptide kills a subpopulation of Escherichia coli , forming dead cells that absorb the remaining LL37 from the environment. Combining mathematical modelling with population and single-cell experiments, we show that bacteria absorb LL37 at a timing that coincides with the permeabilization of their cytoplasmic membranes. Furthermore, we show that one bacterial strain can absorb LL37 and protect another strain from killing by LL37. Finally, we demonstrate that the absorption of LL37 by dead bacteria can be reduced using a peptide adjuvant. In contrast to the known collective tolerance mechanisms, we show that the absorption of APs by dead bacteria is a dynamic process that leads to emergent population behaviour.

scholarly journals Intracellular absorption underlies collective bacterial tolerance towards an antimicrobial peptide

2018 ◽  
Author(s):  
Fan Wu ◽  
Cheemeng Tan
Keyword(s):  
Mathematical Modeling ◽  
Escherichia Coli ◽  
Antimicrobial Peptide ◽  
Live Cells ◽  
Bacterial Cells ◽  
Tolerance Mechanisms ◽  
Intracellular Space ◽  
Cytoplasmic Membranes ◽  
New Directions ◽  
Live Bacterial Cells

AbstractThe collective tolerance towards antimicrobial peptides (APs) is thought to occur primarily through mechanisms associated with live bacterial cells. In contrast to the focus on live cells, we discover that the LL37 antimicrobial peptide kills Escherichia coli, forming a subpopulation of dead cells that absorbs the remaining LL37 into its intracellular space. Combining mathematical modeling with population and single-cell experiments, we show that bacteria absorb LL37 at a timing that coincides with the permeabilization of their cytoplasmic membranes. Furthermore, we show that one bacterial strain can absorb LL37 and protect another strain from killing by LL37. Finally, we demonstrate that the intracellular absorption of LL37 can be reduced using a peptide adjuvant. In contrast to the existing collective tolerance mechanisms, we show that the dead-bacterial absorption of APs is a dynamic process that leads to emergent population behavior, and the work suggests new directions to enhance the efficacy of APs.

Real-time monitoring and inhibition of the activity of carbapenemase in live bacterial cells: application to screening of β-lactamase inhibitors

2020 ◽  
Vol 44 (46) ◽  
pp. 20334-20340
Author(s):  
Han Gao ◽  
Ying Ge ◽  
Min-Hao Jiang ◽  
Cheng Chen ◽  
Le-Yun Sun ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Real Time ◽  
Bacterial Cells ◽  
Real Time Monitoring ◽  
Live Bacterial Cells

Antibiotic resistance mediated by β-lactamases including metallo-β-lactamases (MβLs) has become an emerging threat.

scholarly journals Recent Development of Rapid Antimicrobial Susceptibility Testing Methods through Metabolic Profiling of Bacteria

Antibiotics ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 311
Author(s):  
Chen Chen ◽  
Weili Hong
Keyword(s):  
Antimicrobial Susceptibility ◽  
Metabolic Profiling ◽  
Bacterial Infections ◽  
Susceptibility Testing ◽  
Antimicrobial Susceptibility Testing ◽  
Bacterial Metabolism ◽  
Resistant Bacteria ◽  
Bacterial Cells ◽  
Inappropriate Use ◽  
Key Factor

Due to the inappropriate use and overuse of antibiotics, the emergence and spread of antibiotic-resistant bacteria are increasing and have become a major threat to human health. A key factor in the treatment of bacterial infections and slowing down the emergence of antibiotic resistance is to perform antimicrobial susceptibility testing (AST) of infecting bacteria rapidly to prescribe appropriate drugs and reduce the use of broad-spectrum antibiotics. Current phenotypic AST methods based on the detection of bacterial growth are generally reliable but are too slow. There is an urgent need for new methods that can perform AST rapidly. Bacterial metabolism is a fast process, as bacterial cells double about every 20 to 30 min for fast-growing species. Moreover, bacterial metabolism has shown to be related to drug resistance, so a comparison of differences in microbial metabolic processes in the presence or absence of antimicrobials provides an alternative approach to traditional culture for faster AST. In this review, we summarize recent developments in rapid AST methods through metabolic profiling of bacteria under antibiotic treatment.

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