Cyanobacteria are photosynthetic microorganisms that can both produce glucose using solar energy (autotrophy) and import glucose or other organic compounds from their surroundings (mixotrophy/heterotrophy) (Cohen and Gurevitz, 2006; Stebegg et al., 2023; Muñoz-Marín et al., 2024). (A) Simplified overview of the glucose degradation pathways found in cyanobacteria: the Embden–Meyerhof–Parnas (EMP, red), Entner–Doudoroff (ED, green), and oxidative pentose phosphate (OPP, blue) pathways and their shared intermediates. (B) Comparison of protein costs* vs energy production (per molecule of glucose) (ATP, NADH, NADPH) for the EMP and ED pathways. Previously, researchers proposed that some cyanobacteria can use a third route for degrading glucose, the Entner-Doudoroff (ED) pathway (Chen et al., 2016). Now, in eLife, Kirstin Gutekunst and colleagues – including Ravi Ojha and Marius Theune as joint first authors – report new insights into the glucose metabolite pathways of cyanobacteria (Ojha et al., 2026).