We report on an ongoing search for biomarkers in the potentially habitable atmospheres of a sample of a dozen Y dwarfs with Teff estimated at around or below 400 K. This work is being carried out using public data from large area optical surveys such as DES and PANStarrs. We focus on a search for g-band emission as an analogue to terrestrial bioluminiscence. The amount of bioluminiscent molecules in the photospheres of Y dwarfs is constrained by the optical to mid infrared colors. Future plans to extend this search using current telescopic facilities and upcoming surveys such as Euclid and Vera Rubin LSST are discussed.