Assimilation and metabolism of formaldehyde by leaves appear unlikely to be of value for indoor air purification

Abstract

Uptake, translocation and metabolism of "%C-labelled formaldehyde in the leaves of Epipremnum aureum (Golden Potho) and Ficus benjamina (Weeping Fig) were investigated. Plants were exposed in light and dark to "%C-formaldehyde (500 µg m −$ ) in gas exposure chambers. The amount of "%C-incorporation into the soluble (waterextractable) and insoluble fractions of leaves, stem sections and roots was determined. The soluble "%C-activity was fractionated by ion exchange chromatography followed by thin-layer chromatography\autoradiography. Approximately 60-70% of the applied "%C-formaldehyde was recovered from the plants. In the light about five times more "%C-formaldehyde was assimilated than in the dark. The amount of "%C-label derived from "%C-formaldehyde, which was incorporated into acid-stable metabolites, was enhanced to an even larger extent in the light. The "%C-activity pattern closely resembled the general labelling spectrum of photosynthates, obtained after a "%CO # exposure. A substantial amount of labelled material, mostly sucrose, was translocated into the stems and roots. Our results suggest that in the light "%C enters the Calvin cycle after an enzymatic two-step oxidation process of "%C-formaldehyde to "%CO # . The activities of the respective enzymes, formaldehyde dehydrogenase and formate dehydrogenase, were determined. Among 27 ' leafy ' indoor decorative plants, a screening experiment revealed no outstanding species with regard to its capacity for metabolism of formaldehyde, and rate of uptake through stomata was too low to justify claims that plants contribute usefully to indoor air purification.

Reducing Indoor Air Pollutants Through Biotechnology

“…Wood et al 2002;Orwell et al 2004). Reported formaldehyde removal rates by plant tissues alone were found to be so low as to be insignificant for IAQ improvement purposes (Schmitz et al 2000), whilst substantial formaldehyde removal has been detected for individual bacterial species associated with an active biofilter (Wang and Zhang 2011), and also for indoor plants when the substrate was also present (Xu et al 2011). The removal of several other contaminants, however, such as CO 2 (Oh et al 2011, Torpy et al 2014, SO x , NO x (Elkiey and Ormrod 1981;Esguerra et al 1983) and ozone (Elkiey and Ormrod 1981) appear to be mostly or wholly plant mediated, and are taken up directly through the stomates (gas exchange pores) of the green shoots, which in most species are open only during daylight hours, and not in the dark.…”

Studies for Absorption of Formaldehyde by Using Foliage on Wild Tomato Species

“…This paper showed that HCHO was absorbed and metabolized in fresh foliage explant by detecting the substances and enzymes involved in HCHO metabolism. In addition to this study, it was indicated that HCHO was metabolized by plant organs such as seeds and leaves by detecting the enzymatic activity related to metabolism of HCHO (Schmitz et al, 2000;Uotila and Koivusalo, 1979). Transgenic plants overexpressing FALDH such as Arabidopsis and golden pothos showed an increased efficiency to take up exog-enous HCHO as compared with wild type plants (Achkor et al, 2003;Tada and Kidu, 2011).…”

“…Moreover, localization of GSH and FALDH showed high activity related to the HCHO metabolism site in the rat liver histochemically (Keller et al, 1990). As for research into HCHO metabolism in plants, 14 C-labelled formaldehyde which was exposed to leaves of golden pothos and weeping fig (Schmitz et al, 2000) and pea seeds (Uotila and Koivusalo, 1979) was reported. In these reports, 14 Clabelled formaldehyde became 14 CO 2 after a two step enzymatic oxidation process by formaldehyde and formate dehydrogenase.…”

A Review of Some Representative Techniques for Controlling the Indoor Volatile Organic Compounds

“…Direct pollutant accumulation or degradation by plants has however been demonstrated to occur during phytoremediation of contaminated soils (Newman and Reynolds, 2004). The ability of plant leaves to directly take up and remove pollutants for air treatment is still however open for debate (Schäffner et al, 2002;Schmitz et al, 2000;Wolverton et al, 1984).…”