Study On Seasonal Change Of Culturable Airborne Microbial Concentration And Diversity In The Edge Region Of Laohugou NO.12 Glacier, Qilian Mountain

Airborne microorganisms have traditionally been linked to air quality and health hazards to humans. With the intensification of global climate change, there is a growing awareness to realize that airborne microbes may also have a potentially important role in the process related to atmospheric physics and chemistry. Some remote high-alpine glacier areas have become the hot-area to study the climate effect of air microorganisms due to less affected by anthropogenic factors and the similarity between its atmospheric environmental conditions and the upper atmosphere. In this study, the seasonal change of culturable airborne microbial concentration and diversity in the edge region of Laohugou NO.12 Glacier, Qilian Mountain were investigated by using culture-dependent and molecular biological identification methods. The relationships between environmental factors and the seasonal change of culturable airborne microbial concentration and diversity were examined. The results obtained in the study were summarized as follows:The concentrations of culturable airborne bacteria were higher in colder months (June and October) and lower in warmer months (July and August). The highest concentration of bacteria was in June (32.1±6.74 cfu m-3), followed by October (31.5±5.9 cfu m-3), then August (19.3±3.7 cfu m-3) and September (13.3±2.1 cfu m-3), the lowest concentration were found in July (11.9±2.4 cfu m-3), and that the variations of culturable fungal concentrations were not very obvious. In June, July and October, the diurnal distribution of culturable airborne bacterial concentration was afternoon > evening > morning, While in August and September, the diurnal distribution of culturable airborne bacterial concentration was evening > afternoon > morning. And for airborne fungi, the diurnal distribution was evening > afternoon > morning in June, July, August and September, While the diurnal distribution was afternoon > evening > morning in October. Total 17 bacterial genera and 8 fungal genera were isolated from the air samples. The dominant bacterial genera were Arthrobacter. Bacillus. Acinetobacter and Planomicrobium. while the dominant fungal genera were Alternaria, Davidiella. Aspergillus and Choiromyces. Most of the microorganisms recovered from the air sample were highly similar to the species which commonly found in cold environments. The diversity of culturable airborne microorganisms in different months varied significantly as well as the diurnal diversity. Meteorological factors have a very important effect on the seasonal change of culturable airborne microbial concentration and diversity. Temperature was positively associated with culturable micorbial concentrations, while the correlations between culturable micorbial concentrations and relative humidity were negative. Positive correlations between culturable bacterial concentrations and wind speed were also observed. Culturable fungal concentrations increased with higher wind speed in June and October, while negative correlations between culturable fungal concentrations and wind speed were found in July, August and September. And the diurnal distributions of culturable airborne microbial concentration and diversity are closely related to the daily climate change cycle.In summery, the distributions of culturable airborne microbial concentration and diversity in the edge region of Laohugou NO.12 Glacier, Qilian Mountain were unique. Meteorological conditions were the main factors which affect the distributions of culturable airborne microbial concentration and diversity. This study provided theoretical basis for the further explore of the climatic effects and geographic distribution patterns of airborne microorganisms in high altitude areas.