Degradation of 2,5-dimethylpyrazine by Rhodococcus erythropolis strain DP-45 isolated from a waste gas treatment plant of a fishmeal processing company.
A bacterium, strain DP-45, capable of degrading 2,5-dimethylpyrazine (2,5-DMP) was isolated and identified as Rhodococcus erythropolis. The strain also grew on many other pyrazines found in the waste gases of food industries, like 2,3-dimethylpyrazine (2,3-DMP), 2,6-dimethylpyrazine (2,6-DMP), 2-ethyl-5(6)-dimethylpyrazine (EMP), 2-ethylpyrazine (EP), 2-methylpyrazine (MP), and 2,3,5-trimethylpyrazine (TMP). The strain utilized 2,5-DMP as sole source of carbon and nitrogen and grew optimally at 25 degrees C with a doubling time of 7.6 h. The degradation of 2,5-DMP was accompanied by the growth of the strain and by the accumulation of a first intermediate, identified as 2-hydroxy-3,6-dimethylpyrazine (HDMP). The disappearance of HDMP was accompanied by the release of ammonium into the medium. No other metabolite was detected. The degradation of 2,5-DMP and HDMP by strain DP-45 required molecular oxygen. The expression of the first enzyme in the pathway was induced by 2,5-DMP and HDMP whereas the second enzyme was constitutively expressed. The activity of the first enzyme was inhibited by diphenyliodonium (DPI), a flavoprotein inhibitor, methimazole, a competitive inhibitor of flavin-containing monooxygenases, and by cytochrome P450 inhibitors, 1-aminobenzotriazole (ABT) and phenylhydrazine (PHZ). The activity of the second enzyme was inhibited by DPI, ABT, and PHZ. Sodium tungstate, a specific antagonist of molybdate, had no influence on growth and consumption of 2,5-DMP by strain DP-45. These results led us to propose that a flavin-dependent monooxygenase or a cytochrome P450-dependent monooxygenase rather than a molybdenum hydroxylase catalyzed the initial hydroxylation step and that a cytochrome P450 enzyme is responsible for the transformation of HDMP in the second step.
Rappert
Sugima
S
Institute of Technical Biocatalysis, Technical University Hamburg-Harburg, Denickestr. 15, 21071 Hamburg, Germany.
Li
Renjie
R
Kokova
Mariya
M
Antholz
Mathias
M
Nagorny
Stephanie
S
Francke
Wittko
W
Müller
Rudolf
R
D000818:Animals; D001673:Biodegradation, Environmental; D002244:Carbon / Q000737:chemistry; D005399:Fishes; D005415:Flavins / Q000737:chemistry; D019649:Food Industry / Q000379:methods; D005740:Gases; D007220:Industrial Waste; D009584:Nitrogen / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry; D010659:Phenylhydrazines / Q000737:chemistry; D011719:Pyrazines / Q000737:chemistry* / Q000378:metabolism; D012240:Rhodococcus / Q000378:metabolism*; D013696:Temperature; D014230:Triazoles / Q000737:chemistry
D005415:Flavins; D005740:Gases; D007220:Industrial Waste; D010659:Phenylhydrazines; D011719:Pyrazines; D014230:Triazoles; C030299:phenylhydrazine; C033020:1-aminobenzotriazole; D002244:Carbon; D009584:Nitrogen; D010100:Oxygen; C075524:2,5-dimethylpyrazine