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Isolation of cold‐adapted nitrate‐reducing fungi that have potential to increase nitrate removal in woodchip bioreactors
Author(s) -
Aldossari N.,
Ishii S.
Publication year - 2021
Publication title -
journal of applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 1364-5072
DOI - 10.1111/jam.14939
Subject(s) - bioreactor , nitrate , denitrification , nitrite , denitrifying bacteria , nitrate reductase , nitrite reductase , bioaugmentation , chemistry , environmental chemistry , food science , biology , botany , microorganism , nitrogen , bacteria , organic chemistry , genetics
Aims The aim of this study was to obtain cold‐adapted denitrifying fungi that could be used for bioaugmentation in woodchip bioreactors to remove nitrate from agricultural subsurface drainage water. Methods and results We isolated a total of 91 nitrate‐reducing fungal strains belonging to Ascomycota and Mucoromycota from agricultural soil and a woodchip bioreactor under relatively cold conditions (5 and 15°C). When these strains were incubated with 15 N‐labelled nitrate, 29 N 2 was frequently produced, suggesting the occurrence of co‐denitrification (microbially mediated nitrosation). Two strains also produced 30 N 2 , indicating their ability to reduce N 2 O. Of the 91 nitrate‐reducing fungal strains, fungal nitrite reductase gene ( nirK ) and cytochrome P450 nitric oxide reductase gene ( p450nor ) were detected by PCR in 34 (37%) and 11 (12%) strains, respectively. Eight strains possessed both nirK and p450nor , further verifying their denitrification capability. In addition, most strains degraded cellulose under denitrification condition. Conclusions Diverse nitrate‐reducing fungi were isolated from soil and a woodchip bioreactor. These fungi reduced nitrate to gaseous N forms at relatively low temperatures. These cold‐adapted, cellulose‐degrading and nitrate‐reducing fungi could support themselves and other denitrifiers in woodchip bioreactors. Significance and Impact of the Study The cold‐adapted, cellulose‐degrading and nitrate‐reducing fungi isolated in this study could be useful to enhance nitrate removal in woodchip bioreactors under low‐temperature conditions.