Heterologous Expression of Cyanobacterial Cyanase Gene (CYN) in Microalga Chlamydomonas reinhardtii for Bioremediation of Cyanide Pollution

Abstract

Recombinant DNA technology offered the creation of new combinations of DNA segments that are not found together in nature. The present study aimed to produce an ecofriendly bioremediation model to remediate cyanide pollution from a polluted marine system. Cyanide is a known toxic compound produced through natural and anthropogenic activities. An Agrobacterium-tumefaciens-mediated genetic transformation technique was used to generate transformed Chlamydomonas reinhardtii using plant expression vector pTRA-K-cTp carries isolated coding sequence of the cyanobacterial cyanase gene (CYN) isolated from Synechococcus elongatus (PCC6803). qRT-PCR analysis showed the overexpression of CYN in transgenic C. reinhardtii, as compared with the respective wild type. Growth parameters and biochemical analyses were performed under cyanide stress conditions using transgenic and wild C. reinhardtii for evaluating the effect of the presence of the cyanobacterial cyanase gene in algae. The transgenic C. reinhardtii strain (TC. reinhardtii-2) showed promising results for cyanide bioremediation in polluted water samples. Cyanide depletion assays and algal growth showed a significant resistance in the transgenic type against cyanide stress, as compared to the wild type. Genetically modified alga showed the ability to phytoremediate a high level of potassium cyanide (up to150 mg/L), as compared to the wild type. The presence of the CYN gene has induced a protection response in TC. Reinhardtii-2, which was shown in the results of growth parameter analyses. Therefore, the present study affirms that transgenic C. reinhardtii by the CYN coding gene is a potential effective ecofriendly bioremediator model for the remediation of cyanide pollutants in fresh water.

A synthetic biology approach for the treatment of pollutants with microalgae

“…Ibuot et al (Ibuot et al, 2017) also noted, however, that despite the overexpression of crMTP4, increasing Cd tolerance and uptake compared to wild type, the genetically modified C. reinhardtii still showed lower levels of Cd tolerance and accumulation than naturally adapted chlorophyte algae strains. C. reinhardtii has also demonstrated remediation of chemical pollutants, such as potassium cyanide (Sobieh et al, 2022), phenols (Nazos et al, 2020) and fluroxypyr (Zhang et al, 2011).…”

“…Again, C. reinhardtii has seen the most usage for these studies. Sobieh et al (Sobieh et al, 2022) utilised Agrobacterium to incorporate the cyanobacterial cyanase gene into C. reinhardtii. The transgenic strain demonstrated significant increases in resistance to cyanide toxicity and the ability to phytoremediate up to 150 mg/L of potassium cyanide.…”

“…The transgenic strain demonstrated significant increases in resistance to cyanide toxicity and the ability to phytoremediate up to 150 mg/L of potassium cyanide. Sobieh et al (Sobieh et al, 2022) propose that the engineered strain could be an effective treatment system for industrial cyanide containing wastewater. Ismaiel et al (Ismaiel et al, 2019) utilised C. reinhardtii as a chassis for the glutathione-S-transferase enzyme using Agrobacterium-mediated transformation.…”

Significance and Applications of the Microalgae Chlamydomonas and its Bacterial Consortia

“…Some of the pollutants removed by biotransformation by C. reinhardtii include polystyrene [82], polycyclic aromatic hydrocarbons such as benz(a)anthracene [83], organophosphorus pesticide such as trichlorfon [84], microplastics as bisphenol A [85], antiinflammatory as ibuprofen [86], and antibiotics as sulfadiazine [87]. Genetically modified C. reinhardtii expressing the cyanase gene from Synechococcus elongatus showed the ability to remediate high levels of potassium cyanide, up to 150 mg/L [88]. These findings underscore the ability of Chlamydomonas to eliminate different substances, highlighting their role in environmental processes and potential applications in bioremediation.…”