The present study investigated the antioxidant enzyme activities (AEA) of ascorbate peroxidase (APX), catalase (CAT), guaiacol peroxidase (GPX), and superoxide dismutase (SOD) as biomarkers of Cu and Pb stress by using Centella asiatica grown in an experimental hydroponic condition. The results showed (i) higher accumulations of Cu and Pb in the roots of C. asiatica than those in the leaves, (ii) synergistic effects of Cu and Pb stress at higher metal-level exposures, and (iii) Cu and Pb stress triggered the increment of APX, CAT, GPX, and SOD levels in both the leaves and roots of C. asiatica. The increment of four AEA indicated that C. asiatica underwent oxidative stress caused by the production of reactive oxygen species when the plant was exposed to Cu and Pb. In order to prevent damages caused by Cu and Pb stress, the AEA system was heightened in C. asiatica, in which APX, CAT, GPX, and SOD can be used as biomarkers of Pb and Cu stress in the plant.

Polypropylene (PP) is a major environmental problem in Malaysia because it has been ranked the 28th highest plastic polluter in the world (at 56kg per capita per year) in 2021. Landfilling is one of the most common ways of dealing with plastic because leachate may cause increased probability of cancer and neurological impairment in humans. The use of fungi in mycoremediation makes the process eco-friendly. In addition, fungi have a vast hyphal network and broader metabolic competence. The objective of this study was to investigate fungi remediation of PP via the detection of manganese peroxidase and laccase activity in Bushnell Haas Broth (BHB). PP degradation activity was measured via the activity of laccase and manganese peroxidase at a wavelength of 450nm and 610nm, respectively. Of the 17 species of fungi isolated from the Jeram landfill, 12 species of fungi showed growth in BHB with PP as the sole carbon source. Penicillium sp. 1, Aspergillus sp., Penicillium levitum, Talaromyces louisianensis, Aspergillus tamarii, Cunninghamella bertholletiae, Penicillium sp. 2 and Aspergillus niger demonstrated high and longer laccase activity, and these fungi could be considered as potential fungi. P. levitum, P. janthinellum, Penicillium sp, and T. louisianensis have high and longer MnP activity. In summary, P. levitum and T. louisianensis have a high and long duration of MnP and laccase activity in degrading PP, which can be developed and integrated into plastic waste management.

Accumulation of high-density polyethylene (HDPE) plastic in the environment has become a global issue. A substantial amount of HDPE wastes ends up in the mangroves posing a significant menace to the ecology. Mitigation techniques using mycoremediation to treat the HDPE are gaining ground due to its sustainable approach. This study aims to screen and identify fungi isolated from a mangrove located in Kampung Kuala Lukut, Malaysia, that can degrade HDPE. From this study, eight fungi species were shown able to grow on HDPE as a sole carbon source in a Bushnell-Hass Broth culture. The identity of these isolates was confirmed using morphological observation and molecular identification using ITS1 and ITS4 primers. The ability of these eight fungi species to degrade plastic was assessed based on the percentage of weight loss of HDPE and the increment of fungal biomass. Results from this study show Aspergillus niger has the highest biomass increment, but Leptobacillium sp. shows the highest percentage of weight loss of HDPE. Thus, Leptobacillium sp. has the best potential to be developed as an efficient agent to degrade HDPE in an integrated plastic waste management system.