Identification of denitrifying rhizobacteria from bentgrass and bermudagrass golf greens.
OBJECTIVE
As high rates of nitrogen fertilization are used in turfgrass management, there is a great potential for nitrogen loss. Research on identification of denitrifiers in turfgrass has been limited. Therefore, the aim was to identify denitrifier species and genes from turfgrass roots.


RESULTS
Rhizobacteria were isolated from roots of bentgrass and bermudagrass in sand-based United States Golf Association (USGA) golf greens and used for denitrification biochemical analysis. Seventeen per cent (34 isolates) were identified as denitrifiers, 47% were classified as nitrate-reducers and 36% were nondenitrifiers. Identification of species of the denitrifiers was performed by chromatography fatty acid methyl ester (GC-FAME) and16S rDNA analyses. Bacillus and Pseudomonas were the major turfgrass denitrifiers. The two methods showed a 60% agreement at the genus level. Nitrite reductase genes nirK and nirS were detected in 74 and 15% of the denitrifiers, respectively, but not in nondenitrifiers. The nosZ gene encoding nitrous oxide reductase was detected in all the denitrifiers, but also in some nondenitrifiers.


CONCLUSIONS
To our knowledge, this is the first report for identification of denitrifiers and denitrification-related genes associated with turfgrass roots.


CONCLUSIONS
These results provide valuable data for future denitrification studies that seek to improve turfgrass nitrogen management for maximum efficiency.
Wang
G
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Department of Crop and Soil Environmental Science, Clemson University, Clemson, SC, USA.
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D001407:Bacillus / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D002849:Chromatography, Gas / Q000379:methods; D003580:Cytochromes; D003576:Electron Transport Complex IV / Q000235:genetics; D005227:Fatty Acids; D005308:Fertilizers; D005798:Genes, Bacterial / Q000235:genetics; D006055:Golf; D009572:Nitrite Reductases / Q000235:genetics; D009584:Nitrogen / Q000378:metabolism*; D010088:Oxidoreductases / Q000235:genetics; D010802:Phylogeny; D006109:Poaceae / Q000382:microbiology*; D016133:Polymerase Chain Reaction / Q000379:methods; D011549:Pseudomonas / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000032:analysis
D003580:Cytochromes; D005227:Fatty Acids; D005308:Fertilizers; D012336:RNA, Ribosomal, 16S; D010088:Oxidoreductases; D009572:Nitrite Reductases; C028123:nitrite reductase (NO-forming); C052695:nitrite reductase, copper-containing; C022763:nitrous oxide reductase; D003576:Electron Transport Complex IV; D009584:Nitrogen