Biomass Conductivity Estimation ofEscherichia Coli

Abstract

The biomass of Escherichia coli is measured from dilutions JO-Il to J0-1 . The effect of 0.05M NazHP04 -C3HsO(COOHh buffer (pH 6.6, 7.2, 7.8) on conductivity is experimentally obtained. The conductance is increasing with higher pH and temperature. A high correlation coefficient between the number of E. coli cells, measured by the conductivity and standard methods is defined (r=+0,911 ). The experimentally received data are comparative to these obtained by the standard microbiological methods. Other factors having influence on conductance are also discussed: cells electrical charge, cells and metabolites aggregation, concentration of different ions, etc. Conductivity appears a highly sensitive and express physical method that could be easily used for experimental needs of biomonitoring, clinical practice and biotechnology.

Continuous, Non-Destructive Detection of Microorganism Growth at Buried Interfaces with Vascularized Polymers

“…Throughout the continuous detection tests, the conductivity followed a trend similar to the growth curve: initial conductivity readings appeared to remain relatively stagnant from the 0 to 4 hour mark; an increase in conductivity was then observed from 4 to 12 h with mark with a peak value of 1.37 ± 0.050 mS/cm; then from the 12 h to 24 h, normalized conductivity decreased to 1.22 ± 0.118 mS/cm and further dropped to 0.568 ± 0.076 mS/cm at the 48 hour time period. A similar trend of increased conductivity during the exponential growth phase and a decrease in conductivity during the death phase was observed by Pavlova et al 32 It was important to note that the residence time the carrier fluid spent in the vascularized polymer was the amount of time between data points. Using the 8 h data point as an example, the carrier fluid experienced 4 h within the vascular channels to collect signals since it was introduced to the system at 4 hours.…”

“…Carrier fluid conductivity measurements were not statistically different between samples with P. aeruginosa surface growth and samples with S. aureus surface growth (p = 0.0604) As with the samples colonized by E. coli, the increase in carrier fluid conductivity of sample vascularized polymers was most likely the result of charged bacterial compound from general bacterial metabolic activity diffusing from the surface into the channels. 32,33 Absorbance measurements of the carrier fluid at 350 nm after 24 h was also measured (Figure 5C). P. aeruginosa exhibited the largest absorbance measurement (1.578 ± 0.133 a.u.…”

“…31 For detecting the compounds produced by bacteria, conductivity has served as a common inexpensive method for monitoring the growth of bacteria as the production of charged metabolites and breakdown of large uncharged molecules from bacterial growth increase a solution's conductivity. 32,33 Advancements in UV-vis spectroscopy have also allowed for the detection of organic compounds such as bacterial metabolites. 34 Additionally, compounds and concentrations produced by bacteria differ between strains.…”

Continuous, Nondestructive Detection of Microorganism Growth at Buried Interfaces with Vascularized Polymers

“…Nevertheless, a significantly higher conductivity was observed from bacteria-containing samples (9.32 ± 0.22 mS/cm) compared to controls (7.86 ± 0.29 mS/cm, p = 0.0003). The increase in carrier fluid conductivity was likely the result of charged molecules created during bacterial growth and metabolism that diffused from the surface into the carrier fluid. , …”

“…coli metabolome indicates a majority of the compounds released are amino acids . To detect the compounds produced by bacteria, conductivity has served as a common inexpensive method for monitoring the growth of bacteria as the production of charged metabolites and breakdown of large uncharged molecules from bacterial growth increase a solution’s conductivity. , Advancements in UV–vis absorbance spectroscopy have also allowed for the detection of organic compounds such as bacterial metabolites . Additionally, compounds and the concentrations at which they are produced by bacteria differ between species.…”