HARNESSING PHOTOSYNTHETIC EFFICIENCY OF SYNECHOCOCCUS ELONGATUS PCC 7942 FOR SUSTAINABLE BIOFUEL PRODUCTION: RECENT ADVANCES AND CHALLENGES

The accelerating global energy crisis, combined with an urgent need to curtail greenhouse gas emissions, has positioned photosynthetic microorganisms as compelling platforms for next-generation biofuel production.Among these, Synechococcus elongatus PCC 7942 -a well-characterized, genetically tractable freshwater cyanobacterium -stands out as one of the most intensively studied model systems for harnessing solar energy and atmospheric CO2 to synthesize a diverse portfolio of biofuel molecules.This review provides a comprehensive and critical synthesis of recent advances (2015)(2016)(2017)(2018)(2019)(2020)(2021)(2022)(2023)(2024)(2025)(2026) in the engineering of S. elongatus PCC 7942, covering its photosynthetic machinery, metabolic flux optimization, synthetic biology toolbox, and photobioreactor systems.We compare key cyanobacterial chassis organisms and systematically catalogue biofuel molecules produced in engineered strains, from short-chain alcohols and fatty acids to alkanes and terpenoids.We also examine the persistent bottlenecks -photoinhibition, carbon partitioning, genetic stability, and technoeconomic scalability -that currently limit industrial deployment.The review concludes by proposing an integrated research agenda combining adaptive laboratory evolution,