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

Abstract

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,

Particle precipitation by bipolar corona discharge ion winds

“…Indeed, although more investigations are requested, several recent publications [30,31] showed that electrostatic field would damage the culturability of collected bio-particles (bacteria, fungi and other cellular derivatives) due to the excessively charged stress. Furthermore, the particle collection by unipolar charge systems causes a significant difference compared with real results in monitoring a collection due to the intrinsic charge of bioparticles.…”

“…Furthermore, the particle collection by unipolar charge systems causes a significant difference compared with real results in monitoring a collection due to the intrinsic charge of bioparticles. It is up to the charge polarities of particles and generator, the error could be up to 50% as represented in [30].…”

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“…Consistent with this, Yao and Mainelis (2006) reported that airborne microorganisms encountered in indoor and outdoor environments carried either net negative or net positive charges. Results obtained by Shen, Wei, and Yao (2013) also showed that the positively and negatively charged culturable bacterial aerosol concentration and diversity varied with sampling environment. After dispersal in a field environment, the microorganisms gradually return to their natural charge state, which depends on their cell structure (Lee et al, 2004).…”