Unravelling anaerobic metabolisms in hypersaline sediment

SOLCHAGA, JI; BUSALMEN, J. P.; NERCESSIAN, D.

Frontiers in microbiology

Frontiers Media SA

Año: 2022

1664-302X

The knowledge on the microbial diversity inhabiting hypersaline sediments is still limited. In particular, existing data about anaerobic hypersaline archaea and bacteria are scarce and refers to a limited number of genera. The approach to obtain existing information has been almost exclusively, attempting to grow every organism in axenic culture on the selected electron acceptor with a variety of electron donors. Here, a different approach has been used to interrogate the microbial community of submerged hypersaline sediment of Salitral Negro, Argentina, aiming at enriching consortia performing anaerobic respiration of different electron acceptor compounds, in which ecological associations can maximize the possibilities of successful growth. Growth of consortia was demonstrated on all offered electron acceptors, including fumarate, nitrate, sulfate, thiosulfate, DMSO and a polarized electrode. Within main findings, Halorubrum and Haloarcula representatives are here shown for the first time growing on lactate, using fumarate or a polarized electrode as the electron acceptor; additionally, they are shown composing sulfate reducing consortia. Halorubrum representatives are for the first time growing in nitrate reducing consortia, probably thanks to reduction of N2O produced by other consortium members. Fumarate respiration is indeed shown for the first time supporting growth of Halanaeroarchaeum and Halorhabdus belonging archaea, as well as growth of Halanaerobium, Halanaerobaculum, Sporohalobacter and Acetohalobium belonging bacteria. Finally, evidence is presented suggesting growth of nanohaloarchaea in anaerobic conditions.