9月19日（周三）上午10:00朱宝利 博士2018年新万博皇马之二十八"Novel microbial processes in carbon and nitrogen biogeochemical cycles: nitrate- and iron(III)-dependent anaerobic oxidation of methane and ‘oxygenic denitrification'"
报告题目：Novel microbial processes in carbon and nitrogen biogeochemical cycles: nitrate- and iron(III)-dependent anaerobic oxidation of methane and ‘oxygenic denitrification'
报告 人：朱宝利 博士
Microbial nitrogen cycling has been intensively investigated for over a century and was thought to be rather well understood.Yet recent discoveries of novel processes and microbes involved in the nitrogen cycle,(e.g.,comammox),have demonstrated that our understanding of the microbial N-cycling may be far from complete.Here I would like to discuss two novel processes that we recently discovered in the carbon and nitrogen cycles,and how these responsible microbes can be applied in wastewater treatment and pollutants degradation.
Aerobic methanotrophs oxidize methane using oxygen as the electron acceptor.Microorganisms using other thermodynamically favorable electron acceptors,such as nitrate/nitrite and oxidized metals,for anaerobic methane oxidation (AOM) were not known for a very long time.Using lab-scale bioreactors,specific enrichment cultures that couple AOM to the reduction of nitrite,nitrate and iron(III) were obtained.The responsible microbes were identified as NC10 bacterium (named Methylomirabilis oxyfera) and archaea (named as AAA),respectively.M.oxyfera is an anaerobe but oxidizes methane with a surprising intra-aerobic pathway,while AAA oxidize methane via reverse methanogenesis and reduce nitrate to ammonia (DNRA).M.oxyfera-like microbes were found to be widespread in the environment and could act as a methane filter to reduce methane emissions.Together with anammox bacteria,M.oxyfera was also successfully applied to simultaneously remove ammonia,methane and nitrite from synthetic wastewater.
In addition,nitric oxide dismutation (NOD) is a peculiar oxygen-forming process.In contrast to canonical NO reduction,via NOD,NO is disproportionated directly into N2 and O2,bypassing the ozone-depleting potent greenhouse gas nitrous oxide.Moreover,the formed O2 theoretically enables microbial aerobic catabolism in anoxic habitats,providing ecophysiological advantage for microbes to thrive on recalcitrant substrates in O2-limited environments.Thus the NOD process could be ecologically important.Specific molecular tools targeting the key gene,encoding NO dismutase (Nod) that catalyze NO dismutation,was developed and we recovered surprisingly high diverse nod genes from various environments,including contaminated aquifers and wastewater treatment plants.This indicates that microbes capable of NOD are diverse and widespread,and they could play significant roles in the environment.However,currently we know very little about the process and these microbes.One of my ongoing projects reveals that NOD microbes could involve in hydrocarbon degradation in a BTEX-contaminated aquifer in Germany.Yet,future research is needed to better understand the process and to be able to apply these extraordinary microbes in bioremediation.