Atmospheric bacterial profile and suspended particulate matter of Lahore city [Pakistan]

Air of ten different localities of Lahore was sampled with the help of Hi- volume sampler for 15 minute by using Whatman glass microfiber filter papers. A piece of 4x4cm2 of each filter was then suspended in sterile water and processed for enumeration of bacteria on nutrient, EMB and mannitol salt agar media. Plates of these media were also exposed directly to the atmospheres of sampling areas. It was found that air of the city harboured high to considerable profiles of viable bacteria corresponding to the amount and size distribution of suspended particulate matter (SPM). The agar plates directly exposed to the atmosphere indicated that the number of colony forming units (CFU) of bacteria including coliform and Staphylococcus aureus in general, followed the higher and lower values of concentration and size of SPM respectively. Atmosphere of Ravi Chowk depicted more than 600 value of CFU, while the lowest figure, 35 appeared on the plate exposed in the Quaid-e-Azam Campus of the University of the Punjab. Surprisingly, these areas also expressed highest and lowest counts for the S. aureus i.e. 385 and 3 CFU. Concentrations of SPM mug/m3 for the Ravi Chowk and Quaid-e-Azam campus areas measured 240.53 and 3.16, respectively. Amongst the coliform, CFU values of E. coli represented the highest figures and ranged from 8 to 125 for the different study areas. CFU obtained for water immersed SPM reflected a range of 134x10 to 101x10 4x4cm2 of the air filter on nutrient agar for different study areas. The CFU values on EMB and mannitol salt agar media ranged from 300x10 to 45x10 and nothing to 182x10, respectively for different urban locations. These results are suggestive that besides other toxicological effects of the atmospheric SPM of an industrial city with heavy traffic load, they should also be considered seriously in the spreading of various types of bacteria including pathogens. The study indicates importance of size and mass distribution of airborne particles and correlates these attributes to microbial types and densities to be disseminated.