Impact of Relative Humidity and Collection Media on Mycobacteriophage D29 Aerosol

Abstract

This study was conducted to evaluate the effect of aerosol generation, methods of sampling, storage conditions, and relative humidity on the culturability of the mycobacteriophage D29. The lytic phage D29 can kill Mycobacterium tuberculosis, and the phage aerosol can be treated as a potential tool for tuberculosis treatment. The culturability of D29 was tested using a test chamber designed for the bioaerosols research against three spray liquids (deionized water, phosphate-buffered saline [PBS], and normal saline), four collection media (suspension medium [SM], nutrient broth, PBS, and deionized water), two sampling systems (the all-glass impinger AGI-30 and the Biosampler) and across a range of humidities (20 to 90%). The effect of storage conditions on the culturability of collected sample was also evaluated for the AGI-30 impinger. The results proved that viable phage D29 particles generated by deionized water were approximately 30-and 300-fold higher than PBS and normal saline, respectively. As collection media, SM buffer and nutrient broth were observed to yield a higher number of plaques compared to PBS and deionized water. No difference was observed in collection efficiency between AGI-30 and Biosampler with two detection methods (culture-based technique and real-time PCR). The culturability of collected D29 in SM buffer or nutrient broth can be maintained up to 12 h irrespective of storage temperature. Relative humidity was found to strongly influence airborne D29 culturability which is 2-to 20-fold higher in low humidity (25%) than medium (55%) or high (85%) humidity. This research will help identify the optimal means for the application of D29 aerosol in animal inhalation experiments.

Improving the collection efficiency of the liquid impinger for ultrafine particles and viral aerosols by applying granular bed filtration

“…As estimated by QRT-PCR, the mean collection efficiency of PRRSV were 0.02188, 0.01585 and 0.009333 for the SKC BioSampler (12.5 lpm), AGI30 (12.5 lpm) and AGI4 (6 lpm), respectively. Because the recovery rate of viruses with PCR method is much higher than that with culture method (Liu et al, 2012), and perhaps this may be the reason why collection efficiency reported by Hermann et al (2006) is greater than ours. Furthermore, the composition of sampling liquid and spray liquid aerosolized and relative humidity can also significantly affect the collection efficiency of liquid impinge for viral aerosols (Hermann et al, 2006;Liu et al, 2012).…”

Assessment of the risk of infectious aerosols leaking to the environment from BSL-3 laboratory HEPA air filtration systems using model bacterial aerosols

“…The aerosolization and collection processes can inactivate or kill some microorganisms. Microorganisms are subjected to numerous stresses during the aerosol generation and collection processes within a device (Liu et al, 2012). Maintaining their integrity and activity depends on the nature of the nebulizers, samplers, and media.…”

Characterization of a Lytic Bacteriophage vB_EfaS_PHB08 Harboring Endolysin Lys08 against Enterococcus faecalis Biofilms

“…The supernatants were filtered using a 0.22 μm membrane (Millex–GP, USA) to remove bacteria. After that, 300 μL of the filtrates mixed with 300 μL of the indicator bacterium in exponential growth phase was poured on the double-layer plate, and then incubated at 37 °C for 12 h. A single plaque was picked and then was resuspended in sterile SM buffer (100 mM NaCl, 8.5 mM MgSO 4 ·7H2O, 50 mM Tris-Cl (pH 7.5), and 0.01% gelatin) [ 32 ]. Thereafter, four rounds of phage purification assays were performed by using the double-layer ager method as described previously [ 31 ].…”