PJB-2017-597
FORMALDEHYDE ASSIMILATION AND METABOLIC CONVERSION BY TAMBA BLACK SOYBEAN ROOTS FROM HCHO TREATMENT SOLUTIONS
YONG MIN
Abstract
It has been shown that plant roots have considerable contribution to formaldehyde (HCHO) removal in bioreactors, which is associated with HCHO absorption or assimilation by roots. This study investigated HCHO assimilation and metabolic conversion by the roots of Tamba black soybean treated in 2, 4 and 6 mM HCHO solutions. The results showed that the contribution (77.8%, 65.5% and 75.5%) of HCHO assimilation by living roots to HCHO removal were significantly greater than that of the HCHO adsorption by dead roots at 48 h. The evidence suggested the presence of active enzymes for HCHO metabolism in RB roots. 13C-NMR analyses indicated that the H13CHO absorbed by RB roots was first oxidized to H13COOH, which was then mainly converted to oxalate, glycine (Gly), asparagine (Asn), glutamine (Gln) and serine (Ser) in subsequent metabolism during the early period (0-4 h) of 2 mM H13CHO treatment. The metabolic pathways for generation of these organic acids mediated the HCHO assimilation in RB roots during this period. During the late stage (4-48 h), these organic acids were converted to malate, citrate, isocitrate and glucose through their later metabolism in RB roots. The metabolic conversion of HCHO efficiently accelerated the HCHO assimilation in RB roots during the late treatment stage. Inhibition of citrate and isocitrate production by cyclosporin A decreased the HCHO assimilation in RB roots to some extent. The metabolic pathways of HCHO conversion were postulated based on the results of 13C-NMR analysis.
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