Browsing by Author "Kruatrachue M."

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    Assessment of dynamic microbial community structure and rhizosphere interactions during bioaugmented phytoremediation of petroleum contaminated soil by a newly designed rhizobox system
    (2022-01-01) Yang K.M.; Poolpak T.; Pokethitiyook P.; Kruatrachue M.; Mahidol University
    To understand the plant (Vigna unguiculata) and plant-growth promoting bacteria (PGPB) (Microcococcus luteus WN01) interactions in crude oil contaminated soil, experiments were conducted based on the newly designed rhizobox system. The rhizobox was divided into three main compartments namely the rhizosphere zone, the mid-zone, and the bulk soil zone, in accordance with the distance from the plant. Plants were grown in these three-chambered pots for 30 days under natural conditions. The plant root exudates were determined by analyzing for carbohydrates, amino acids, and phenolic compounds. The degradation of alkane, polycyclic aromatic hydrocarbons (PAHs), and total petroleum hydrocarbons (TPHs) were quantified by GC-FID. Soil catalase, dehydrogenase, and invertase activities were determined. The microbial community structure was assessed using denaturing gradient gel electrophoresis (DGGE). Results showed that the inoculation of M. luteus WN01 significantly enhanced cowpea root biomass and exudates, especially the phenolic compounds. Bioaugmented phytoremediation by cowpea and M. luteus promoted rhizodegradation of TPH. Cowpea stimulated microbial growth, soil dehydrogenase, and invertase activities and enhanced bacterial community diversity in oil contaminated soil. The rhizosphere zone of cowpea inoculated with M. luteus showed the highest removal efficiency, microbial activities, microbial population, and bacterial community diversity indicating the strong synergic interactions between M. luteus and cowpea.
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    Co-metabolic breakdown of LDPE microplastics in PGPR-Assisted phytoremediation of hydrocarbon-contaminated soil
    (2025-01-01) Mo Yang K.; Poolpak T.; Saengwilai P.; Pokethitiyook P.; Kruatrachue M.; Mo Yang K.; Mahidol University
    A 90-day pot study investigated the effect of low-density polyethylene microplastics (LDPE MPs) on bioaugmented phytoremediation of crude oil-contaminated soil using lemongrass (Cymbopogon flexuosus) and Micrococcus luteus WN01 (PGPR). Plant growth, root morphology, root exudates, microbial population, dehydrogenase activity, residual TPH concentration, and LDPE MP degradation were evaluated. M. luteus significantly increased plant biomass and improved TPH degradation by 79.16% and 64.43%, which were 25.04% and 15.85% higher than uninoculated treatments. M. luteus inoculation still led to higher TPH removal compared to uninoculated treatments despite MP-induced alterations in plant biochemical and morphological traits. GC/MS analysis of lemongrass root exudates showed that M. luteus enriched plants with GABA-associated allelochemicals. FTIR analysis indicated accelerated oxidation of LDPE MPs in planted treatments compared to unplanted ones, evidenced by increased absorbance at characteristic peaks (3620.71 cm−1 O-H stretching, 1651 cm−1 C=O stretching, and 1031.10 cm−1 C-O stretching). This strongly suggests a co-metabolic breakdown of LDPE MPs within the plant rhizosphere (a degradation hotspot). Lemongrass essential oil was not significantly affected by the contaminant or M. luteus. This study highlights the lemongrass-M. luteus association as a promising candidate for the remediation of both petroleum- and MP-contaminated soil, with the added benefit of essential oil production.
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    Glyphosate metabolism in Tetrahymena thermophila: A shotgun proteomic analysis approach
    (2023-03-01) Manan A.; Roytrakul S.; Charoenlappanit S.; Poolpak T.; Ounjai P.; Kruatrachue M.; Yang K.M.; Pokethitiyook P.; Mahidol University
    Glyphosate is one of the most widely used herbicides in the world. However, because of its overuse and resistance to degradation, high levels of glyphosate residues in the environment are reported. Therefore, this study aimed to investigate the effects of glyphosate on proteomic aspects of Tetrahymena thermophila and their uses as bioindicators of freshwater ecosystem. First, an acute toxicity test was performed to determine the median inhibition concentration (IC50). The toxicity test results showed that glyphosate inhibited the growth (proliferation) of T. thermophila. The 96 h-IC50 value of glyphosate was 171 mg L−1. No visible changes in aggregation behavior and cell morphology were observed under glyphosate exposure. In addition, the effects of low and high dose glyphosate concentrations (77.5 mg L−1, 171 mg L−1) on the proteomic changes of T. thermophila was investigated using a label-free shotgun proteomic approach. A total of 3191 proteins were identified, 2791 proteins were expressed in the control, 2651 proteins were expressed in 77.5 mg L−1 glyphosates, and 3012 proteins were expressed in 171 mg L−1 glyphosates. Under glyphosate exposure at both low and high dose glyphosate, 400 unique proteins were upregulated. The majority of these proteins was classified as proteins associated with oxidative stress response and intracellular transport indicating the shifts in the internal metabolism. Proteomics revealed that the glyphosate metabolism by T. thermophila is a multi-step process involving several enzymes, which can be divided into four phases, including modification (phase I), conjugation (phase II), transport (phase III), and degradation (phase IV). The accumulation of various biochemical reactions contributes to overall glyphosate resistance. With the proteomics approach, we have found that T. thermophila was equipped with glyphosate detoxification and degradation mechanisms.
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    In situ bioaugmented phytoremediation of cadmium and crude oil co-contaminated soil by Ocimum gratissimum in association with PGPR Micrococcus luteus WN01
    (2024-01-01) Choden P.; Poolpak T.; Pokethitiyook P.; Yang K.M.; Kruatrachue M.; Choden P.; Mahidol University
    Heavy metals and petroleum oil are the two most important contaminants in the environment. Currently, phytoremediation is regarded as an effective and affordable solution that allows the attenuation of toxic pollutants through the use of plants. Not many studies are carried out regarding the use of aromatic plants capable of remediating soil that is co-contaminated by heavy metal and petroleum hydrocarbons. A pot experiment was conducted to investigate the influence of cadmium-resistant PGPR Micrococcus luteus on the phytoremediation efficiency of Ocimum gratissimum in Cd and petroleum co-contaminated soil. The plants were harvested after 60 days of treatment and their growth and biomass were determined. The accumulation of Cd in plant shoots and roots was determined. The residual petroleum hydrocarbon concentration during the 60 days of the phytoremediation experiment was determined using GC-FID. O. gratissimum with M. luteus showed the highest Cd accumulation (14.05 mg kg−1) and the highest reduction of TPH (46.64%). M. luteus ameliorated contaminant toxicity and promoted biomass production of O. gratissimum. These results demonstrated that O. gratissimum in combination with M. luteus can be efficiently used to remediate Cd and petroleum-co-contaminated soils.
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    Phytoremediation technology for recovery of Ni by Acacia plants in association with Bacillus amyloliquefaciens isolated from E-waste contaminated site
    (2023-01-01) Joradon P.; Poolpak T.; Kruatrachue M.; Yang K.M.; Saengwilai P.; Upatham S.; Pokethitiyook P.; Mahidol University
    Electronic waste (e-waste) illegally disposal in Thailand is becoming more widespread. A sustainable metal recovery technology is needed. A phytotechnology called “phytomining” of metals such as nickel (Ni) is a promising technology providing a sustainable solution to the growing e-waste problems. This study investigated the ability of Acacia species in association with e-waste site isolated, plant growth-promoting rhizobacteria (PGPR), Bacillus amyloliquefaciens. Acacia mangium accumulated higher Ni in their tissues when Ni concentrations in soil were lower than 200 mg kg−1. The inoculation of PGPR B. amyloliquefaciens enhanced Ni uptake and accumulation in the leaves, stem, and root. The results showed that the highest Ni concentration was found in the root ash (825.50 mg kg−1) when inoculated plants were grown in soil containing 600 mg kg−1 Ni. Hence, the Ni recovery process and mass balance were performed on root ashes. The highest Ni recovery was 91.3% from the acid (H2SO4) leachate of the ash of inoculated plant treated with 600 mg kg−1 Ni. This demonstrates the feasibility of PGPR-assisted phytomining from Ni-contaminated soil. Phytomining of Ni from any e-waste contaminated sites using Acacia mangium in combination with B. amyloliquefaciens can promote plant growth and improve the uptake of Ni.
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    Responses of oil degrader enzyme activities, metabolism and degradation kinetics to bean root exudates during rhizoremediation of crude oil contaminated soil
    (2022-01-01) Yang K.M.; Poolpak T.; Pokethitiyook P.; Kruatrachue M.; Saengwilai P.; Mahidol University
    During rhizoremediation process, plant roots secrete the specific exudates which enhance or stimulate growth and activity of microbial community in the rhizosphere resulting in effective degradation of pollutants. The present study characterized cowpea (CP) and mung bean (MB) root exudates and examined their influences on the degradation of total petroleum hydrocarbons (TPHs) and polycyclic aromatic hydrocarbons (PAHs) by the two oil degraders Micrococcus luteus WN01 and Bacillus cereus W2301. The effects of root exudates on soil microbial population dynamic and their enzymes dehydrogenase (DHA), and catechol 2,3 dioxygenase (C23O) activities were assessed. Both root exudates enhanced the degradation by both oil degraders. Cowpea root exudates maximized the removal of TPHs and PAHs by M. luteus WN01. Both bacterial population and DHA increased significantly in the presence of both root exudates. However, the C23O activities were significantly higher in WN01 treated. No significant influence of root exudates was observed on the C23O activities of W2301 treated. By using gas chromatography -mass spectroscopy, the dominant compounds found in cowpea and mung bean root exudates were 4-methoxy-cinnamic acid and terephthalic acid. Found in lower amount were propionic, malonic acid, and citric acid which were associated with enhanced PAHs desorption from soil and subsequent degradation. Novelty statement This is the first study to characterize the low molecular weight organic acids from root exudates of cowpea and mung bean and their influences on hydrocarbon desorption and hence enhancing the biodegradation process. The findings of the present study will greatly contribute to a better understanding of plant-microbe interaction in total petroleum hydrocarbons contaminated soil.
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    Risk assessment and biodegradation potential of PAHs originating from Map Ta Phut Industrial Estate, Rayong, Thailand
    (2022-01-01) Yang K.M.; Poolpak T.; Pokethitiyook P.; Kruatrachue M.; Mahidol University
    Petroleum hydrocarbon contamination is a serious concern across the globe. Here, the capability of native bacterial consortium enriched from sediment samples of Map Ta Phut Industrial Estate (MTPIE), Rayong, Thailand was described. The distribution of PAHs was assessed from the sediment samples collected from MTPIE by GC-FID and the toxic unit (TU) was calculated to assess the potential ecological risk to the surrounding biota. This study investigated the degradation potential and determined the PAH-degrading bacterial cultures by enriching collected sediments in PAHs mixtures (naphthalene, phenanthrene, and pyrene). The TPH degradation capacity of each bacterial consortium was validated in a soil microcosm using aged crude oil-contaminated soil. The MTPIE sediments were highly contaminated with PAHs (843.99-3904.39 ng g-1) and posed extremely high ecological risks to benthic biota (TU > 1). The consortium S5-P most significantly removed naphthalene (90.03%) and phenanthrene (88.14%) while the highest removal of pyrene was achieved by the S3-P consortium. Other consortia only partially degraded the PAHs. The dominant microbes in the consortia were determined using PCR-DGGE, it was found that the PAH degrading consortia were known PAH degraders such as Annwoodia, Bacillus, Brevibacillus, Lysinibacillus, Paracoccus, Rhodococcus, Sphingopyxis, Sulfurovum, and Sulfurimonas species and unknown PAH degraders such as Lithuaxuella species. The consortium S5-P showed the highest degradation capacity, removing 74.99% of TPHs in the soil microcosm. Furthermore, the inoculation of PAH-biodegrading bacterial consortia significantly promoted the catechol-2,3-dioxygenase (C23O) and dehydrogenase (DHA) activities which directly correlated with the degradation efficiency of petroleum hydrocarbons (p < 0.05).