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This work aims to explore the role of cadmium-resistant actinomycetes on promoting plant growth and cadmium uptake in Chlorophytum comosum (Thunb.) Jacques, a spider plant. Actinomycetes isolated from the plant roots in peat swamp forests were screened for their cadmium resistance and the production of indole-3-acetic acid (IAA) and siderophores. The results found that K5PN1 and 11-10SHTh produced high levels of IAA and siderophores, respectively. K5PN1 and 11-10SHTh were identified to be Streptomyces rapamycinicus and Streptomyces cyaneus, respectively. Both strains were able to remove cadmium from aqueous solution and survive under cadmium stress in contaminated soil. The results of pot experiments found that the selected Streptomyces inoculation increased the root and shoot biomass and cadmium accumulation in the root and shoot of C. comosum planted in a cadmium-contaminated soil. The highest cadmium accumulation and translocation ability of cadmium from the root to shoot was found in C. comosum with S. rapamycinicus inoculation. In addition, plant with S. cyaneus inoculation had the highest phytoextraction coefficient and bioaccumulation factor. Our findings concluded that S. rapamycinicus and S. cyaneus stimulated the growth and cadmium uptake in C. comosum, suggesting a combined approach using the selected Streptomyces and C. comosum for phytoremediation of cadmium-polluted soil.

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.

Fifteen plant species-Alternanthera bettzickiana, Drimiopsis botryoides, Aloe vera, Chlorophytum comosum, Aglaonema commutatum, Cordyline fruticosa, Philodendron martianum, Sansevieria hyacinthoides, Aglaonema rotundum, Fittonia albivenis, Muehlenbeckia platyclada, Tradescantia spathacea, Guzmania lingulata, Zamioculcas zamiifolia, and Cyperus alternifolius-were evaluated for the removal efficiency of xylene from contaminated air. Among the test plants, Z. zamiifolia showed the highest xylene removal efficiency. Xylene was toxic to Z. zamiifolia with an LC50 of 3,464 ppm. Higher concentrations of xylene exhibited damage symptoms, including leaf tips turning yellow, holonecrosis, and hydrosis. TEM images showed that a low concentration of xylene vapors caused minor changes in the chloroplast, while a high concentration caused swollen chloroplasts and damage. The effect of photosynthetic types on xylene removal efficiency suggests that a mixture of Z. zamiifolia, S. hyacinthoides, and A. commutatum which represent facultative CAM, CAM, and C3 plants, is the most suitable system for xylene removal. Therefore, for maximum improvement in removing xylene volatile compounds under various conditions, multiple species are needed. The effect of a plant's total leaf area on xylene removal indicates that at lower concentrations of xylene, a small leaf area might be as efficient as a large leaf area.