In recent years, microalgae have gained considerable attention due to their potential applications in diverse areas including biofuels, pharmaceuticals, and food and feed additives. One of the key factors that determine microalgae productivity is photosynthetic efficiency. Enhancing photosynthetic efficiency can significantly improve the yield of microalgae and thus make their use in various applications more economically viable.
Photosynthesis is a complex process involving numerous genes and proteins. Overexpression of photosynthesis-related genes has been shown to enhance photosynthetic efficiency in several organisms including plants and algae. In microalgae, some of the key genes involved in photosynthesis include those encoding for the light-harvesting complexes (LHCs), photosystems I and II (PSI and PSII), and enzymes involved in the Calvin cycle.
Recent advancements in genetic engineering techniques have made it possible to overexpress these genes in microalgae. For instance, a study published in the Journal of Biotechnology reported the overexpression of a gene encoding for a key enzyme in the Calvin cycle, Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO), in the microalga Chlamydomonas reinhardtii. This led to an increase in photosynthetic efficiency and biomass production.
Similarly, another study published in Plant Physiology demonstrated the overexpression of a gene encoding for a LHC protein in the diatom Phaeodactylum tricornutum. This resulted in enhanced light harvesting and increased growth rate under different light intensities.
Genetically modified algae also hold promise for improving photosynthetic efficiency. For instance, researchers at Synthetic Genomics and ExxonMobil developed a strain of Nannochloropsis gaditana that overexpresses a gene involved in regulating lipid production. The genetically modified strain showed a twofold increase in lipid content without compromising growth rate.
In another case, scientists at the University of California, San Diego used CRISPR-Cas9 gene-editing technology to knock out non-essential genes in the green alga Chlamydomonas reinhardtii. This resulted in strains with up to 133% higher photosynthetic productivity compared to wild-type strains.
While these studies demonstrate the potential of genetic modifications for enhancing photosynthetic efficiency in microalgae, there are still several challenges that need to be addressed. For instance, overexpression of certain genes can sometimes lead to adverse effects such as reduced growth rate or increased susceptibility to environmental stresses.
Moreover, genetic modifications often result in variable outcomes due to differences in gene expression levels or genetic backgrounds among different strains. Therefore, it is crucial to conduct thorough phenotypic characterizations and stability tests for genetically modified strains before they can be used on a large scale.
In conclusion, overexpression of photosynthesis-related genes holds great promise for enhancing photosynthetic efficiency in microalgae. Recent advancements in genetic engineering techniques have facilitated this process, leading to increased yields and improved economic viability for microalgal applications. However, further research is needed to overcome challenges associated with genetic modifications and ensure stable and consistent performance of genetically modified strains.