Publication: Response of Microalgae to Repeated Exposure to Glufosinate Ammonium and Temperatures Stress.
| dc.contributor.author | YEO BANN SIANG | |
| dc.date.accessioned | 2023-10-06T15:24:59Z | |
| dc.date.available | 2023-10-06T15:24:59Z | |
| dc.date.issued | 2020 | |
| dc.description.abstract | Glufosinate ammonium is a widely used herbicide in agricultural practice. Studies have proven glufosinate is harmful to non-target organism such as microalgae. One-time exposure practiced in laboratory toxicity does not reflect the effects of glufosinate on microalgae as agrochemical inputs in environment occurred in pulses. Moreover, increase in global temperature would cause much changes in biological and chemical processes of microalgae. In this study, the effects of increased temperature and repeated exposure of glufosinate on microalgae, namely Chlorella sp. and Pseudokirchnerilla subcapitata were investigated based on growth, pigment content and oxidative stress responses. Glufosinate uptake by microalgae was assessed by high performance liquid chromatograph (HPLC). The morphology of microalgae was observed under transmission electron microscopy (TEM). Preliminary toxicity testing showed the effective concentrations 25% (EC25) for Chlorella sp. and P. subcapitata were 120 and 43 μg mL-1, respectively. Photosynthetic parameters such as Fv/Fm, α, rETRmax, Ek and NPQ were found gradually decreased with the increase of glufosinate concentrations and temperatures in P. subcapitata at both 28 and 33oC. In repeated exposure, the microalgae were repeatedly exposed to glufosinate for 5 cycles (15 days, 3 days per cycle) at 28 and 33oC. Microalgae were then treated with a range of glufosinate concentration from 0 to 200 μg mL-1. There was slight decrease in specific growth rate (μ) of both repeated exposure of glufosinate (REG) and control Chlorellla sp. with the increase of glufosinate concentration at 28 and 33oC. However, no notable changes in μ of REG P. subcapiata at 33oC. Inconsistent trends of chlorophyll a (chl a) and carotenoids (car) were found in control and REG Chlorella sp. at 28 and 33oC. In P. subcapitata, there was no clear trend for chl a except lower chl a with higher glufosinate in control P. subcapitata at 33oC. High car was found at 200 μg mL-1 in both control and REG P. subcapitata at 28 and 33oC. High ROS production and lipid peroxidation level were found in both control and REG microalgae at 33oC. Significantly high ROS and lipid peroxidation levels were found in 50 and 200 μg mL-1 of glufosinate in control Chlorella sp. and P. subcapitata respectively as compared to the REG microalgae at same concentrations. High catalase (CAT) activities were found in control and REG culture treated with high concentration of glufosinate despite inconsistent trend was observed in both microalgae at 28 and 33oC. However, irregular SOD trend was found in the both control and REG Chlorella sp. and P. subcapitata at 28 and 33oC. TEM results show damaged thylakoid, lipid droplet and starch granules were found in both control and REG microalgae. Increased of glufosinate accumulation was found in control and REG Chlorella sp. and P. subcapitata at 28 and 33oC, except REG P. subcapitata with 200 μg mL-1 at 33oC. Conclusively, Chlorella sp. and P. subcapitata were found adapted to toxicity of glufosinate as well as temperature stress after repeatedly exposed to glufosinate. Low accumulation of glufosinate was observed in Chlorella sp. and P. subcapitata despite the increase of glufosinate concentration and temperature stress. of glufosinate concentration from 0 to 200 μg mL-1. There was slight decrease in specific growth rate (μ) of both repeated exposure of glufosinate (REG) and control Chlorellla sp. with the increase of glufosinate concentration at 28 and 33oC. However, no notable changes in μ of REG P. subcapiata at 33oC. Inconsistent trends of chlorophyll a (chl a) and carotenoids (car) were found in control and REG Chlorella sp. at 28 and 33oC. In P. subcapitata, there was no clear trend for chl a except lower chl a with higher glufosinate in control P. subcapitata at 33oC. High car was found at 200 μg mL-1 in both control and REG P. subcapitata at 28 and 33oC. High ROS production and lipid peroxidation level were found in both control and REG microalgae at 33oC. Significantly high ROS and lipid peroxidation levels were found in 50 and 200 μg mL-1 of glufosinate in control Chlorella sp. and P. subcapitata respectively as compared to the REG microalgae at same concentrations. High catalase (CAT) activities were found in control and REG culture treated with high concentration of glufosinate despite inconsistent trend was observed in both microalgae at 28 and 33oC. However, irregular SOD trend was found in the both control and REG Chlorella sp. and P. subcapitata at 28 and 33oC. TEM results show damaged thylakoid, lipid droplet and starch granules were found in both control and REG microalgae. Increased of glufosinate accumulation was found in control and REG Chlorella sp. and P. subcapitata at 28 and 33oC, except REG P. subcapitata with 200 μg mL-1 at 33oC. Conclusively, Chlorella sp. and P. subcapitata were found adapted to toxicity of glufosinate as well as temperature stress after repeatedly exposed to glufosinate. Low accumulation of glufosinate was observed in Chlorella sp. and P. subcapitata despite the increase of glufosinate concentration and temperature stress.of glufosinate concentration from 0 to 200 μg mL-1. There was slight decrease in specific growth rate (μ) of both repeated exposure of glufosinate (REG) and control Chlorellla sp. with the increase of glufosinate concentration at 28 and 33oC. However, no notable changes in μ of REG P. subcapiata at 33oC. Inconsistent trends of chlorophyll a (chl a) and carotenoids (car) were found in control and REG Chlorella sp. at 28 and 33oC. In P. subcapitata, there was no clear trend for chl a except lower chl a with higher glufosinate in control P. subcapitata at 33oC. High car was found at 200 μg mL-1 in both control and REG P. subcapitata at 28 and 33oC. High ROS production and lipid peroxidation level were found in both control and REG microalgae at 33oC. Significantly high ROS and lipid peroxidation levels were found in 50 and 200 μg mL-1 of glufosinate in control Chlorella sp. and P. subcapitata respectively as compared to the REG microalgae at same concentrations. High catalase (CAT) activities were found in control and REG culture treated with high concentration of glufosinate despite inconsistent trend was observed in both microalgae at 28 and 33oC. However, irregular SOD trend was found in the both control and REG Chlorella sp. and P. subcapitata at 28 and 33oC. TEM results show damaged thylakoid, lipid droplet and starch granules were found in both control and REG microalgae. Increased of glufosinate accumulation was found in control and REG Chlorella sp. and P. subcapitata at 28 and 33oC, except REG P. subcapitata with 200 μg mL-1 at 33oC. Conclusively, Chlorella sp. and P. subcapitata were found adapted to toxicity of glufosinate as well as temperature stress after repeatedly exposed to glufosinate. Low accumulation of glufosinate was observed in Chlorella sp. and P. subcapitata despite the increase of glufosinate concentration and temperature stress. | en_US |
| dc.identifier.uri | https://hdl.handle.net/20.500.14377/32086 | |
| dc.language.iso | en | en_US |
| dc.publisher | International Medical University | en_US |
| dc.subject | Ammonium Compounds | en_US |
| dc.subject | Microalgae | en_US |
| dc.subject | Herbicides | en_US |
| dc.subject | Chlorella | en_US |
| dc.subject | Catalase | en_US |
| dc.subject | Microscopy, Electron, Transmission | en_US |
| dc.subject | Chromatography, High Pressure Liquid | en_US |
| dc.title | Response of Microalgae to Repeated Exposure to Glufosinate Ammonium and Temperatures Stress. | en_US |
| dc.type | Thesis | |
| dspace.entity.type | Publication |