Document Type : ORIGINAL RESEARCH ARTICLE

Authors

• M. Iqhrammullah ^{1, 2}
• S. Saudah ^{3, 4}
• M. Monalisa ^{5, 6}
• F. Fahrurrozi ¹
• S.A. Akbar ⁷
• S.S. Lubis ⁸

¹ Research Center for Marine and Land Bioindustry National Research and Innovation Agency, North Lombok 83756, Indonesia

² Postgraduate Program of Public Health, Universitas Muhammadiyah Aceh, Banda Aceh 23123, Indonesia

³ Faculty of Education and Teacher Training, Universitas Serambi Mekkah, Banda Aceh, 23245, Indonesia

⁴ Master Program of Biology, Universitas Serambi Mekkah, Banda Aceh, 23245, Indonesia

⁵ Department of Agribusiness, Faculty of Agriculture, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia

⁶ Aceh Climate Change Initiative, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia

⁷ Faculty of Marine and Fisheries, Department of Aquaculture, Universitas Syiah Kuala, Banda Aceh 23111, Indonesia

⁸ Faculty of Science and Technology, Biology Departement, Ar-Raniry State Islamic University, Banda Aceh 23111, Indonesia

Abstract

BACKGROUND AND OBJECTIVES: The presence of heavy metals, specifically cadmium, in the environment poses significant threats to both ecological systems and human health. However, microalgae have shown potential in addressing this issue through their ability to absorb cadmium and produce valuable biomass, making them a promising solution for bioremediation. Among the various microalgae species, Chlorella vulgaris stands out as a suitable candidate due to its potential for biodiesel production and its capacity to effectively absorb cadmium. Therefore, the main objective of this study is to assess the toxicity of cadmium on Chlorella vulgaris cells using network meta-analysis as a methodology.
METHODS: A comprehensive search was conducted on Scopus, Scilit, Google Scholar, and Web of Science to identify relevant studies published from 1 January 1990 to 16 January 2024. Only studies that reported the cell number of Chlorella vulgaris as a result of cadmium exposure were considered for inclusion. The collected data were then subjected to Bayesian frequentist network meta-analysis, utilizing standardized mean difference and a 95 percent confidence interval as measures of effect size. Additionally, a linear regression analysis was performed to examine the dose-dependent impact of cadmium toxicity.
FINDINGS: Dose-dependent toxic effects of cadmium on Chlorella vulgaris were evident (R-square of more than 0.90), particularly at a concentration of 1 part per million, deemed as the maximum tolerable threshold. Prolonged exposure revealed a concentration-dependent reduction in cell viability, suggesting potential lifespan shortening. A comparison of growth stimulants, gibberellic acid and brassinolide (standard means differences of 1.7 and 3.8, respectively), in mitigating cadmium toxicity indicated the latter superior effectiveness in sustaining microalgal survivability. The presence of high nitrogen and low phosphorous levels was found to be significantly associated with a reduction in Chlorella vulgaris cells due to cadmium exposure.
CONCLUSION: This research has provided conclusive proof of the harmful effects of cadmium on Chlorella vulgaris through the implementation of Bayesian frequentist network meta-analysis, offering valuable insights for environmental management practices. The findings reveal concentration-dependent effects of cadmium toxicity. The survivability of Chlorella vulgaris is determined by the compositions of macronutrients nitrogen and phosphorous. Comparative analyses highlight the superior protective effect of brassinolide over gibberellic acid in mitigating cadmium toxicity. Overall, the findings highlight the potential of Chlorella vulgaris in both bioremediation of heavy metals and biomass production.

Graphical Abstract

Highlights

• The Bayesian network frequentist meta-analysis confirmed that the cadmium toxicity against Chlorella vulgaris is concentration-dependent;
• A concentration of cadmium of 1 ppm is the maximum tolerable threshold as suggested by the linear regression on dose-response analysis;
• Exposure to cadmium could induce the alteration of metabolites biosynthesis of the Chlorella vulgaris;
• Addition of gibberellic acid or brassinolide could attenuate the toxicity of cadmium in Chlorella vulgaris.

Keywords

• Bioremediation
• Cadmium
• Chlorella vulgaris
• Growth
• Heavy metals

Main Subjects

• Environmental bioremediation and measurement

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©2024 The author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit: 

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