Low Oxygen

How do low concentrations of oxygen affect the structuring and function of microbial communities? 

The focus on low O2 arises from the simple recognition that wherever microbes gather, respiration will create zones where O2 consumption outpaces its diffusion.  Microbes in the ocean’s oxygen minimum zone, aggregates of soil, or biofilms all experience low oxygen conditions and yet microbes are typically studied under atmospheric levels of O2 or strictly anoxic conditions.  Additionally, the large intestine is full of these micro-oxic zones.  The bacteria in our GI tract never experience atmospheric conditions, but are frequently exposed to low levels of oxygen.  We clearly need to know more about life under low oxygen.  

Efficiency vs. Power

How important is metabolic efficiency in the evolution and ecology of microbes?

Efficiency, the number of progeny produced per unit of substrate consumed, is the second topic that has captured our attention.  The capacity for rapid growth, a hallmark of many microbes, confers an advantage in nutrient-rich environments, but microbes in nature are more often nutrient limited – conditions that should favor growth efficiency.  We are testing the hypotheses that there is a tradeoff between growth rate and growth efficiency and working to identify mechanistic underpinnings of efficiency.  One way that we like to think about this tradeoff is the difference between a sports car and a scooter.  The sports car is able to go fast (high power), but it burns a lot of fuel in the process (low efficiency).  The scooter, on the other hand, is not as fast, but can get much more mileage from the same amount of gas.

The Michigan Microbiome Project

How can we manipulate human microbiomes to promote health?

The Michigan Microbiome Project is focused on investigating the human microbiome in a collection of cohorts.  Currently, we are investigating the effects of resistant starch and fiber in the GI tracts of an undergraduate cohort at the University of Michigan. The is a cohort examining the effects of the microbiome on weight loss and maintenance, and we will soon launch a new cohort investigating clinical outcomes in Graft vs. Host Disease in light of fiber supplementation to the gut microbiome.  More information about the Michigan Microbiome Project can be found here.