Methanococcus maripaludis response to hydrogen limitation

Methanococcus maripaludis is a methanogenic Archaea that conserves energy from molecular hydrogen to reduce carbon dioxide to methane. Chemostat grown cultures limited for hydrogen, phosphate, or leucine were compared to determine the regulatory response to hydrogen limitation. This was done by comparing hydrogen limited cultures to both leucine limited and phosphate limited cultures. Slow and rapid growing samples limited for either hydrogen or phosphate were compared to determine the regulatory effects of growth rate. Keywords: archaea, hydrogen, leucine, phosphate, nutrient limitation, growth rate, methanogen Four biological replicates of hydrogen limited cells grown in chemostats were compared to four biological replicates of leucine limited and phosphate limited chemostat cultures. For growth rate comparisons, two sets were compared, each with three biological replicates of cultures grown at slow and rapid growth rates in chemostats. One set was limited by hydrogen availability at both growth rates, the other by phosphate availability. Each comparison was conducted with a dye swap and each contained two copies of the array, yielding 4 technical replicates for each biological replicate. This yielded a total of 16 replicates for the hydrogen versus leucine and hydrogen versus phosphate comparisons and 12 replicates each for the growth rate comparisons for both hydrogen and phosphate limitation. For growth rate comparisons under phosphate limited conditions a second scanning was done at lower gain set so that no spot reached saturation.