Indoor formaldehyde removal by three species of Chlorphytum Comosum under the long-term dynamic fumigation system

Endophyte-assisted non-host plant Tillandsia brachycaulos enhance indoor formaldehyde removal

This study investigated the use of endophyte-assisted Tillandsia brachycaulos to enhance formaldehyde removal in indoor environments. A formaldehyde-degrading endophyte from the root of Epipremnum aureum, Pseudomonas plecoglossicida, was identified and used for inoculation. Among the inoculation methods, spraying proved to be the most effective, resulting in a significant 35 % increase in formaldehyde removal after 36 hours. The results of the light exposure experiment (3000 Lux) demonstrate that an increase in light intensity reduces the efficiency of the Tillandsia brachycaulos-microbial system in degrading formaldehyde. In a 15-day formaldehyde fumigation experiment at 2 ppm in a normal indoor environment, the inoculated Tillandsia brachycaulos exhibited removal efficiency ranging from 42.53 % to 66.13 %, while the uninoculated declined from 31.62 % to 3.17 %. The Pseudomonas plecoglossicida (referred to as PP-1) became the predominant bacteria within the Tillandsia brachycaulos after fumigation. Moreover, the endophytic inoculation effectively increased the resistance and tolerance of Tillandsia brachycaulos to formaldehyde, as evidenced by lower levels of hydroxyl radical, malondialdehyde (MDA), free protein, and peroxidase activity (POD), as well as higher chlorophyll content compared to uninoculated Tillandsia brachycaulos. These findings indicate that the combination of endophytic bacteria and Tillandsia brachycaulos has significant potential for improving indoor air quality.

Obtainment and Inoculation of Acinetobacter pittii Strain JJ-2, and Combined Action with Plants for Formaldehyde and CO2 Removal: A Research Study

A formaldehyde-degrading bacterium JJ-2 was isolated from the rhizosphere of Chlorophytum and identified as Acinetobacter pittii by colony morphology and 16S rDNA sequence analysis. Further studies showed that under optimal conditions, JJ-2 could maintain activity for six cycles at an initial formaldehyde concentration of 450 mg L-1. At the same time, the complete degradation time was shortened from 12 to 6 h. When the JJ-2 strain was inoculated into sterile soil, the surface spray method had the best effect, and the removal efficiency of 5 ppm formaldehyde increased by 22.63%. In an actual potted plants system colonized with strain JJ-2, the first and second fumigations (without re-inoculation) increased removal by 1.36 times and 0.92 times during the day and 1.27 times and 2.07 times at night. In addition, in the second fumigation, the plant-bacteria combined system was 693.63 ppm and the plant system was 715.34 ppm, effectively reducing the CO2 concentration. This study provides an economical, ecological, and efficient approach to improve the combined system of plants and bacteria to remove gaseous formaldehyde from indoor air, with a positive impact on carbon neutrality.

Evaluating the antioxidative defense response of selected indoor plants against benzene and formaldehyde

Volatile organic compounds (VOCs) such as formaldehyde and benzene are among the key contributors to indoor air pollution. The current situation of environmental pollution is alarming, especially indoor air pollution is becoming a challenge as affecting plants and humans. VOCs are known to adversely affect indoor plants by causing necrosis and chlorosis. In order to withstand these organic pollutants, plants are naturally equipped with an antioxidative defense system. The current research study aimed to evaluate the combined effect of formaldehyde and benzene on the antioxidative response of selected indoor C3 plants including Chlorophytum comosum, Dracaena mysore, and Ficus longifolia. After the combined application of different levels (0, 0; 2, 2; 2, 4; 4, 2; and 4, 4 ppm) of benzene and formaldehyde respectively, in an airtight glass chamber, the enzymatic and non-enzymatic antioxidants were analyzed. Analysis of total phenolics showed a significant increase (10.72 mg GAE/g) in F. longifolia; C. comosum (9.20 mg GAE/g); and D. mysore (8.74 mg GAE/g) compared to their respective controls as 3.76, 5.39, and 6.07 mg GAE/g. Total flavonoids (724 µg/g) were reported in control plants of F. longifolia which were increased to 1545.72 µg/g from 724 µg/g (in control) followed by 322.66 µg/g in D. mysore (control having 167.11 µg/g). Total carotenoid content also increased in D. mysore (0.67 mg/g) followed by C. comosum (0.63 mg/g) in response to increasing the combined dose compared to their control plants having 0.62 and 0.24 mg/g content. The highest proline content was exhibited by D. mysore (3.66 μg/g) as compared to its respective control plant (1.54 μg/g) under a 4 ppm dose of benzene and formaldehyde. A significant increase in enzymatic antioxidants including total antioxidants (87.89%), catalase (59.21 U/mg of protein), and guaiacol peroxidase (52.16 U/mg of protein) was observed in the D. mysore plant under a combined dose of benzene (2 ppm) and formaldehyde (4 ppm) with respect to their controls. Although experimental indoor plants have been reported to metabolize indoor pollutants, the current findings indicate that the combined application of benzene and formaldehyde is also affecting the physiology of indoor plants as well.

Overexpression of CcFALDH from spider plant (Chlorophytum comosum) enhances the formaldehyde removing capacity of transgenic gloxinia (Sinningia speciosa)1

Formaldehyde can cause leukemia and nasopharyngeal cancer in humans, and is a major indoor air pollutant. In this study, to improve the ability of flowering plants to purify formaldehyde, we cloned the CcFALDH gene encoding formaldehyde dehydrogenase (FALDH) from the spider plant (Chlorophytum comosum), which encodes 379 amino acids with the alcohol dehydrogenase (ADH) structural domain, and used it to transform the flowering plant gloxinia (Sinningia speciosa). The FALDH activity of transgenic gloxinia was 1.8-2.7 times that of wild-type (WT) with a considerable increase in formaldehyde stress tolerance. The activities of the antioxidant enzymes SOD, POD, and CAT of transgenic gloxinia were 1.5-2.0 times those of the WT under formaldehyde stress; H₂O₂, O^2-, and MDA contents were markedly lower than those in WT. Liquid formaldehyde and gaseous formaldehyde were metabolized at 2.1-2.8 and 2.1-2.7 times higher rates in transgenic gloxinia than in WT. Our findings indicate that overexpression of CcFALDH can enhance the capacity of flowering plants to metabolize formaldehyde, which provides a new strategy to tackle the indoor formaldehyde pollution problem.

Phytoremediation of indoor formaldehyde by plants and plant material

Formaldehyde evolves from various household items and is of environmental and public health concern. Removal of this contaminant from the indoor air is of utmost importance and currently, various practices are in the field. Among these practices, indoor plants are of particular importance because they help in controlling indoor temperature, moisture, and oxygen concentration. Plants and plant materials studied for the purpose have been reviewed hereunder. The main topics of the review are, mechanism of phytoremediation, plants and their benefits, plant material in formaldehyde remediation, and airtight environmental and health issues. Future research in the field is also highlighted which will help new researches to plan for the remediation of formaldehyde in indoor air. The remediation capacity of several plants has been tabulated and compared, which gives easy access to assess various plants for remediation of the target pollutant. Challenges and issues in the phytoremediation of formaldehyde are also discussed.Novelty statement: Phytoremediation is a well-known technique to mitigate various organic and inorganic pollutants. The technique has been used by various researchers for maintaining indoor air quality but its efficiency under real-world conditions and human activities is still a question and is vastly affected relative to laboratory conditions. Several modifications in the field are in progress, here in this review article we have summarized and highlighted new directions in the field which could be a better solution to the problem in the future.

Indoor formaldehyde removal by three species of Chlorophytum comosum under dynamic fumigation system: part 2-plant recovery

Spider plants (Chlorophytum comosum) are known to be among the most common easy mountable indoor plants capable of purifying indoor air by absorbing carbon monoxide, formaldehyde, xylene, and many other hazardous gases. In addition, these plants are non-toxic and safe for pets and children. This project is focused on the investigation of the spider plants' capability of the formaldehyde purification under laboratory-controlled parameters of the indoor air environment. Two scenarios including employment of fresh plants as well as recovered ones damaged by 7-day exposure of formaldehyde were considered. A special attention was made to the investigation of physiological indexes of the plant leaves after damage, and whether the spider plant could be reused after its recovery. The physiological characteristics of the recovery period of potted Chlorophytum comosum immediately after 7 days of fumigation with formaldehyde were studied. Eight physiological indexes of leaves including chlorophyll, free protein, relative conductivity, MDA (malondialdehyde, lipid peroxidation), SOD (superoxide dismutase), POD (peroxidase), T-AOC (total antioxidant capacity), and stomata were selected to monitor plants' recovery processes. The results of 30-day experimental runs showed that three species of spider plants were mostly recovered within 15 days. Repeated 7-day fumigation of plants, conducted to study their ability to effectively clean the air after regeneration, confirmed such ability; the efficiency at the first day was similar to the performance of the fresh plant. However, from the second day, the efficiency was dropped by 35-50% and remained at these levels for the rest of the exercise.