Networked Speaker Series #29

March 18, 2021

Megan Mullis, Texas A&M Corpus Christi

Outwit, Outplay, Outlast: A microbial tale of survival within the marine deep subsurface


Microbes play fundamental roles in ecosystem function through mediating biogeochemical cycles, yet we know very little about how microbes interact and what drives community diversity. The marine deep subsurface hosts a massive reservoir of microbial biomass that can be actively surviving (or even thriving) harsh conditions, such as high pH, low nutrients, or extreme temperatures. There are various methods to analyze microbial community diversity and functionality within the marine subsurface including culture-independent and -dependent methods. The studies presented here utilize this two-pronged approach to investigate microbial diversity, functionality, and specific survival mechanisms within two marine subsurface environments. The Mariana Forearc sediments were sampled through use of the International Ocean Discover Program Expedition 366 from December 2016 – February 2017. Sediments were extracted for total RNA as a proxy for microbial activity and sequenced using Illumina NovaSeq. These metatranscriptomes were analyzed for microbial diversity and metabolic capabilities and indicates microbial life is persisting through partial denitrification (nirKS) and anaerobic methane oxidation (pmoABC). The western flank of the Mid-Atlantic Ridge (commonly referred to as North Pond) sediments were sampled via push cores aboard the R/V Atlantis in October 2017. We utilized a novel method of high-throughput single-cell sorting using Fluorescence Activated Cell Sorting (FACS) to cultivate individual cells from shallow North Pond sediments. Individual cells from sediment slurries were sorted into a modified artificial seawater medium and extracted for whole genome sequencing using Illumina MiSeq. I will present novel methodology and genome characterizations from Idiomarina abyssalis strain KJE, Marinobacter salarius strain NP2017, and Marinobacter salarius strain AT3901.

Speaker Biography

I attended the University of Southern Mississippi as an undergraduate and received my Bachelor’s in Marine Biology. I began my Ph.D. in Marine Biology with Dr. Brandi Kiel Reese at Texas A&M University – Corpus Christi in August of 2016 and anticipate graduation in summer of 2021. I am very interested in microbial survival and competition through use of secondary metabolites. If I am not in the lab or on my computer for science, I am usually watching a movie (most likely Lord of the Rings), at the beach, or harassing my two cats to play with me.



Networked Speaker Series