Development of a novel conductance-based technology for environmental bacterial sensing

Shen, Fangxia; Tan, Miaomiao; Xu, Hong; Xu, Zhencheng; Yao, Maosheng

doi:10.1007/s11434-012-5621-1

Cited by 7 publications

(7 citation statements)

References 27 publications

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“…Bacteria and fungi are important contributor to both conductance and total organic carbon [16], [55], [56], [57]. In this work, we also observed significant differences in the conductance levels of the melted snow samples and the outdoor air samples (after DI water extraction).…”

Section: Resultssupporting

confidence: 68%

“…1, no exact correlation between the conductance and bacterial concentration can be drawn (R 2 <0.1). In our another study, we have shown that the bacterial suspension condutance is an exponential function of bacterial concentration for pure bacterial cultures [57]. In a recent study, it was shown that the conductivity of surface snow varied with seasons, and Ca 2+ was found the key ion in determining the conductivity of the surface [33].…”

Section: Resultsmentioning

confidence: 79%

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Are We Biologically Safe with Snow Precipitation? A Case Study in Beijing

Shen

Yao

2013

PLoS ONE

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In this study, the bacterial and fungal abundances, diversities, conductance levels as well as total organic carbon (TOC) were investigated in the snow samples collected from five different snow occurrences in Beijing between January and March, 2010. The collected snow samples were melted and cultured at three different temperatures (4, 26 and 37°C). The culturable bacterial concentrations were manually counted and the resulting colony forming units (CFUs) at 26°C were further studied using V3 region of 16 S rRNA gene-targeted polymerase chain reaction -denaturing gradient gel electrophoresis (PCR-DGGE). The clone library was constructed after the liquid culturing of snow samples at 26°C. And microscopic method was employed to investigate the fungal diversity in the samples. In addition, outdoor air samples were also collected using mixed cellulose ester (MCE) filters and compared with snow samples with respect to described characteristics. The results revealed that snow samples had bacterial concentrations as much as 16000 CFU/ml for those cultured at 26°C, and the conductance levels ranged from 5.6×10−6 to 2.4×10−5 S. PCR-DGGE, sequencing and microscopic analysis revealed remarkable bacterial and fungal diversity differences between the snow samples and the outdoor air samples. In addition, DGGE banding profiles for the snow samples collected were also shown distinctly different from one another. Absent from the outdoor air, certain human, plant, and insect fungal pathogens were found in the snow samples. By calculation, culturable bacteria accounted for an average of 3.38% (±1.96%) of TOC for the snow samples, and 0.01% for that of outdoor air samples. The results here suggest that snow precipitations are important sources of fungal pathogens and ice nucleators, thus could affect local climate, human health and agriculture security.

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Section: Resultssupporting

confidence: 68%

Section: Resultsmentioning

confidence: 79%

Are We Biologically Safe with Snow Precipitation? A Case Study in Beijing

Shen

Yao

2013

PLoS ONE

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“…The cell membrane consisting of a lipid bilayer with many proteins is involved in regulating its metabolic activities, where the lipid molecules are oriented with their polar groups [28,36]. There are two major groups of bacterial membrane types: Gram-positive and Gram-negative.…”

Section: Resultsmentioning

confidence: 99%

“…Likewise, electrical charges on the particles also play a role in their physical depositions in the lung [20][21][22][23]. Additionally, the charge levels and polarity of the bioaerosols can greatly impact their removal efficiencies and detection by electrostatic means [24][25][26][27][28]. While the level of charges results in different amount of electrostatic force imparted on the aerosols, the charge polarity determines the direction of the electrical force.…”

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confidence: 99%

Negatively and positively charged bacterial aerosol concentration and diversity in natural environments

2013

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Bioaerosol charge information is of vital importance for their electrostatic collection. Here, electrostatic means and molecular tools were applied to studying bioaerosol charge dynamics. Positively or negatively charged bioaerosols were collected using an electrostatic sampler operated with a field strength of 1.1 kV cm −1 at a flow rate of 3 L min −1 for 40 min. Those with fewer or no charges bypassing the sampler were also collected using a filter at the downstream of the electrostatic sampler in one environment. The experiments were independently conducted three times in three different environments. The collected bacterial aerosols were cultured directly on agar plates at 26°C, and the colony forming units (CFU) were manually counted. In addition, the CFUs were washed off from the agar plates, and further subjected to polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) for culturable diversity analysis. The results revealed remarkable differences in positively and negatively charged culturable bacterial aerosol concentration and diversity among the studied environments. In the office environment, negatively charged culturable bacterial aerosols appeared to dominate (P = 0.0489), while in outdoor and hotel environments both polarities had similar concentration levels (P = 0.078, P = 0.88, respectively). DGGE patterns for positively charged culturable bacterial aerosols were shown strikingly different from those of negatively charged regardless of the sampling environments. In addition, for each of the environments positively charged culturable bacterial aerosols collected were found to have more band pattern similarity with those positively charged for respective regions of agar plates than those negatively charged, and vice versa. The information developed here is useful for developing efficient electrostatic sampling protocols for bioaerosols. positive charge, negative charge, bacterial aerosol, culturable diversity, PCR, DGGE, gel pattern similarity Citation:Shen F X, Kai W, Yao M S. Negatively and positively charged bacterial aerosol concentration and diversity in natural environments. Chin Sci Bull, 2013, 58: 31693176,

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“…The conductivity value (σ) of Pseudomonas aeruginosa bacterial cells was determined by referring to the conductivity of Escherichia coli (Gramnegative) bacteria, which was at a concentration of 1 x 10 9 -4 x10 9 cfu/ml; the conductivity was 2 x10 -6 -1.4 x 10 -5 mho/m. Meanwhile, the conductivity value (σ) of Staphylococcus epidermidis refers to the conductivity of Bacillus subtilis (Gram-positive), which was at a concentration of 1x 10 8 -8 x10 8 cfu/ml; the conductivity was 0.5 x 10 -5 -5 x10 -5 mho/m (Fangxia et al, 2013). Pockels coefficient r of the cell membrane was 2.6 pm/V (Hajj et al, 2009), lipid refractive index n e was 1.384, water refractive index n a was 1.342, and the number of pores was given the values as expressed by Martinac et al (2008).…”

Section: Variable Values In Modelingmentioning

confidence: 99%

Modeling of Inactivation of Biofilm Composing Bacteria with Low Intensity Electric Field: Prediction of Lowest Intensity and Mechanism

Tirono¹,

Suhariningsih²

2021

JST

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Sterilization using high-intensity electric fields is detrimental to health if safety is inadequate, so it is necessary to study the possibility of sterilization using low-intensity electric fields. This study aims to determine the lowest electric field intensity and treatment time to deactivate the bacteria that make up the biofilms and explain the mechanism of inactivation. The study samples were biofilms from the bacteria Pseudomonas aeruginosa and Staphylococcus epidermidis grown on the catheter. The modeling formula was developed from the Pockels effect and the Weibull distribution with the treatment using a square pulse-shaped electric field with a pulse width of 50 μs and an intensity of 2.0-4.0 kV/ cm. The results showed that the threshold for irreversible electroporation of both samples occurred in the treatment using an electric field with an intensity of 3.5 kV/cm and 3.75 kV/ cm, respectively, where the size and type of Gram of bacteria influenced. Moreover, the time of the treatment had an effect when irreversible electroporation occurred. However, when there was reversible electroporation, the effect of treatment time on the reduction in the number of bacteria was not significant. Also, changes in conductivity affected the reduction in the number of bacteria when reversible electroporation occurred.

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Development of a novel conductance-based technology for environmental bacterial sensing

Cited by 7 publications

References 27 publications

Are We Biologically Safe with Snow Precipitation? A Case Study in Beijing

Are We Biologically Safe with Snow Precipitation? A Case Study in Beijing

Negatively and positively charged bacterial aerosol concentration and diversity in natural environments

Modeling of Inactivation of Biofilm Composing Bacteria with Low Intensity Electric Field: Prediction of Lowest Intensity and Mechanism

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