Friends or Foes?: Examining the Mechanisms Driving Interspecies Interactions of Sagebrush-Associated Microbes
Abstract
Plant leaf surfaces host microbial communities that influence plant health and function. The interactions between species of a plant’s microbiome, often via antimicrobial metabolites, impact community structure and host-microbe dynamics. These metabolites can be isolated and harnessed for biocontrol and ecological applications. This research builds on previous work investigating interactions between microbes isolated from the leaves of sagebrush (Artemisia tridentate), where we focused on three isolates: Aureobasidium pullulans, Bacillus amyloliquefaciens, and Cladosporium herbarum. These microbes have demonstrated competitive or antagonistic dynamics when co-cultured. In this study, we aimed to determine the mechanisms and directionality of these antagonistic dynamics. We plated five replicates each of pairwise cultures and monocultures of each microbial species. After two weeks of growth, we extracted metabolites from both monoculture and co-culture plates using ethyl acetate and rotary evaporation, resuspending extracts in methanol with the goal of analyzing microbial metabolic profiles using liquid chromatography-mass spectrometry (LC-MS). To help understand directionality of antagonism, we also grew lawns in triplicate of A. pullulans, B. amyloliquefaciens, and C. herbarum and conducted live culture disk diffusion assays using paper disks saturated in co-culture and monoculture treatments on each lawn. Across all treatments, both monoculture and co-culture treatments containing B. amyloliquefaciens demonstrated antifungal properties against both A. pullulans and C. herbarum, inferring that observed co-culture antagonism was due to B. amyloliquefaciens, which offers potential for its use in both biocontrol and ecosystem practices. Work is ongoing for analysis of our extracted metabolites, which will allow us to connect the chemistry of our microbes to their respective biological functions.
Friends or Foes?: Examining the Mechanisms Driving Interspecies Interactions of Sagebrush-Associated Microbes
Plant leaf surfaces host microbial communities that influence plant health and function. The interactions between species of a plant’s microbiome, often via antimicrobial metabolites, impact community structure and host-microbe dynamics. These metabolites can be isolated and harnessed for biocontrol and ecological applications. This research builds on previous work investigating interactions between microbes isolated from the leaves of sagebrush (Artemisia tridentate), where we focused on three isolates: Aureobasidium pullulans, Bacillus amyloliquefaciens, and Cladosporium herbarum. These microbes have demonstrated competitive or antagonistic dynamics when co-cultured. In this study, we aimed to determine the mechanisms and directionality of these antagonistic dynamics. We plated five replicates each of pairwise cultures and monocultures of each microbial species. After two weeks of growth, we extracted metabolites from both monoculture and co-culture plates using ethyl acetate and rotary evaporation, resuspending extracts in methanol with the goal of analyzing microbial metabolic profiles using liquid chromatography-mass spectrometry (LC-MS). To help understand directionality of antagonism, we also grew lawns in triplicate of A. pullulans, B. amyloliquefaciens, and C. herbarum and conducted live culture disk diffusion assays using paper disks saturated in co-culture and monoculture treatments on each lawn. Across all treatments, both monoculture and co-culture treatments containing B. amyloliquefaciens demonstrated antifungal properties against both A. pullulans and C. herbarum, inferring that observed co-culture antagonism was due to B. amyloliquefaciens, which offers potential for its use in both biocontrol and ecosystem practices. Work is ongoing for analysis of our extracted metabolites, which will allow us to connect the chemistry of our microbes to their respective biological functions.