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Oral Sessions
Day 2, June 23（Mon.） 14:55-15:10
Room B (Maesato Center)
- 2B-O2-1455
Bacteria in the atmosphere: Insights into their production and transformation of biological and organic matter in cloud water
(1SEE CityUHK, 2SRI CityUHK, 3SKLMEH)
oTheodora Nah1,2,3, Yushuo Liu1,2, Chee Kent Lim1, Zhiyong Shen1, Patrick Lee1,3
Bacteria are ubiquitous in clouds where they are subjected to a variety of atmospheric stressors, which can affect their survival and energetic metabolism, and hence their microbial activity. I will present findings from our recent investigations on the effect of cloud water pH, exposure to sunlight and hydroxyl (OH) radicals on the survival and energetic metabolism of atmospheric bacteria, and discuss their implications. Our results showed that the energetic metabolism and survival of bacterial strains can strongly depended on the pH. Changes in the bacterial energetic metabolism and survival caused by their exposure to low pH conditions impact the ability of the bacteria to biodegrade organic compounds in clouds. Exposure to OH radicals can lead to bacterial cell damage and lysis, which release biological and organic compounds with molecular weights as larger as >50 kDa. These released compounds will subsequently undergo reactions with OH radicals. Fragmentation reactions play important roles in transforming the composition of the released compounds, cleaving the C-C bonds of the carbon backbones of high molecular weight proteinaceous-like matter. Overall, this study provides new insights into how common atmospheric stressors can affect the roles that bacteria play in producing and transforming organic matter in cloud water.