PJ-161 (JTK):

Effect of heterotrophic bacteria on growth of a marine ammonia-oxidizing archaeon

Ammonia-oxidizing archaea (AOA) belonged to Thaumarchaeota play significant roles in the first step of nitrification and are abundant in various environments. Up to date, effect of heterotrophic bacteria on the growth and activity of marine AOA are not investigated yet. A marine ammonia-oxidizing archaeon designated strain DDS1 was isolated from a deep seawater. In this study, interaction between strain DDS and co-occurring heterotrophs was investigated using four common marine heterotrophs: Pseudoalteromoans sp. PA2, Pseudoalteromonas sp. PA13, Leeuwenhoekiella sp. LB, Sulfitobacter sp. SB. While yeast extract (0.001%) was inhibitory to archaeal growth, growth of strain DDS1 was recovered by inoculation of one of the heterotrophic bacteria. This indicates that heterotrophic bacteria can remove organic chemicals of yeast extract which are toxic to strain DDS1. Although growth of strain DDS1 was not affected by inclusion of a single substrate (glucose or aspartic acid), it was inhibited by inoculation of a bacterial strain to the medium. This indicates that bacterial growth might affect archaeal growth by production of metabolites. To better understanding of the marine AOA and extant heterotrophic bacteria, more extensive survey of marine bacteria using various substrates in the context of marine ecology is required.

keywords:ammonia-oxidizing archaeon,Thaumarchaeota,heterotrophic bacteria ,interation,marine