Sukh­wan Yoon: "Mi­cro­bial re­duc­tion of ni­trous ox­ide: ..."

Abstract:

Since the first re­ports of the ge­n­omic and physiolo­gical evid­ence of the novel nosZ clade, now termed nosZ clade II, mi­cro­bial re­duc­tion of ni­trous ox­ide (N₂O) has at­trac­ted many in search of en­vir­on­mental tech­no­logy for mit­ig­a­tion of emis­sion of this po­tent green­house gas. Be­gin­ning with the break­through dis­cov­ery re­veal­ing that cer­tain sub­groups of clade II nosZ-pos­sess­ing or­gan­isms have a dis­tin­guished abil­ity to con­sume sub­micro­molar N₂O for util­iz­a­tion as the elec­tron ac­ceptor, we, the past and present mem­bers of En­vir­on­mental Mi­cro­bi­o­logy Labor­at­ory at KAIST, have made sub­stan­tial con­tri­bu­tions in ad­van­cing the physiolo­gical and ge­n­omic un­der­stand­ing of N₂O re­duc­tion, es­pe­cially per­tain­ing to bio­lo­gical ni­tro­gen re­moval (BNR) pro­cesses in the wastewa­ter sec­tor and ni­tro­gen man­age­ment of ag­ri­cul­tural soils. We have veri­fied, via two dis­par­ate av­en­ues of ap­proach, that the clade II nosZ dom­in­ate both gene and tran­script pools of nosZ in ac­tiv­ated sludge mi­cro­bi­o­mes. In a sub­sequent study com­bin­ing cul­ture-based ex­per­i­ments with com­pu­ta­tional ana­lyses of meta­gen­omes and meta­tran­scrip­tomes, we have veri­fied that nanomolar N₂O con­sump­tion can oc­cur in a sus­tain­able man­ner in mi­crooxic en­vir­on­ments and also that the key play­ers be­long to the close re­l­at­ives of the gen­era Dechloromonas and Azospira, the or­gan­isms pre­sumed to be high-af­fin­ity N₂O-re­du­cing or­gan­isms. Ad­di­tion­ally, we have ap­plied these new sci­entific in­sights in de­vel­op­ing a self-sus­tain­ing N₂O biofiltra­tion sys­tem, which can be im­ple­men­ted as a prac­tical ad­dendum to any BNR sys­tems with min­imal al­ter­a­tions to the plant designs. The present­a­tion will provide a brief sum­mary of these sci­entific and tech­no­lo­gical pro­gresses we have con­trib­uted to the field over the past dec­ade, as well as an in­tro­duc­tion of the over­arch­ing re­search dir­ec­tion and long-term plans and ob­ject­ives of our labor­at­ory.