Investigation of frequency and identification of air bacteria during dust storms in Lorestan province

Fine dust includes dust and particles suspended in the air, which reduce visibility and have different origins. The present study aimed to investigate the abundance of air bacteria during micro dust storms in Lorestan province using classical methods.

In this study, sampling was performed in three cities of Lorestan province. Air bacteria were isolated by classical methods, and data analysis was carried out using the Chi-square test. The relationship between the abundance of bacteria and meteorological parameters was investigated and analyzed by Spearman's correlation coefficient test.

The results of the present study demonstrated that 96 colonies grew on the TSA medium. Moreover, %55.2 of these colonies were bacteria, and %44.8 were yeast. Poldakhtar and Khorramabad stations showed the highest (%25) and lowest (%8.33) frequencies. On the R2A medium, 184 colonies grew. In addition, %69 of these colonies were bacteria, and %31 were yeast. Kohdasht and Khorramabad stations had the highest (%34.8) and lowest (%4.3) frequencies. In TSA and R2A environments, the most and least frequently observed isolates were Bacillus and Actinomycetes, and the highest microbial frequency was related to Kohdasht and Poldakhter. According to Spearman's correlation test, there was a direct relationship between the amount of fine dust and the abundance of bacteria (P=0.637, r=0.026), and a significance inverse linear relationship was observed between wind speed and the number of colonies (P=0.048, r = -0.569).

Bacterial abundance was higher in the R2A medium. The dominant bacteria in the TSA environment were Bacillus and Micrococcus, and in the R2A environment, Bacillus and Corynebacterium. The results pointed out that the amount of fine dust and wind speed have an effect on the abundance and diversity of air bacteria.