Transcriptomes of marine denitrifying biofilm co-cultures

Hyphomicrobium nitrativorans strain NL23 and Methylophaga nitratireducenticrescens strain JAM1 are methylotrophic bacteria isolated from the biofilm of a fluidized-bed methanol-fed denitrification reactor. Strain NL23 is capable of complete denitrification but in pure cultures cannot grow under marine conditions; strain JAM1 can reduce nitrate to nitrite, but misses a nitrite reductase to complete denitrification. It grows very well under marine conditions. We performed a biofilm co-culture in biorector with these two strains. As control, a biofilm monoculture with strain NL23 was performed too. The biofilm co-culture/monculture were acclimated with increasing concentration of NaCl to reach marine conditions in the biofilm co-culture (2.75% NaCl) and up to 2% NaCl with the biofilm monoculture (strain NL23). RNA was extracted from the biofilm at different stages of the acclimatation. RNA was also extracted from triplicate pure cultures of strain JAM1 and strain NL23 that were pooled, respectively for sequencing. RNA was extracted from the original biofilm of the denitrification reactor