A bacterium that relies solely on fermentation for energy generation uses glycolysis exclusively.
There are two plausible explanations for the lack of fluorescence observed under UV light: (1) The bacterial DNA within the pellet was not adequately isolated, leading to no fluorescence detection, or (2) After three hours of IPTG induction and G3 labeling, IPTG may not have bound effectively to the bacterial DNA to show any response when exposed to UV.