Updated project metadata. Halorubrum lacusprofundi is an important member of Deep Lake in Antarctica, representing ~10% of the lake population (DeMaere et al., 2013). Deep Lake is in the Vestfold Hills, East Antarctica (68°33’36.8S, 78°11’48.7E) and is 36 m deep, monomictic, and perennially cold (down to -20°C) (DeMaere et al., 2013; Williams et al., 2014; Tschitschko et al., 2015; Tschitschko et al., 2016). In this project, using quantitative proteomics (8-plex iTRAQ labeling), proteins, pathways and cellular processes important for biofilm formation were determined for Hrr. lacusprofundi. The data provided a new level of understanding about molecular mechanisms and regulatory networks involved in adaptation of Hrr. lacusprofundi to biofilm formation. DeMaere, M. Z., Williams, T. J., Allen, M. A., Brown, M. V., Gibson, J. A., Rich, J., et al. (2013) High level of intergenera gene exchange shapes the evolution of haloarchaea in an isolated Antarctic lake. Proc Natl Acad Sci USA 110: 16939-16944. Tschitschko, B., Williams, T. J., Allen, M. A., Páez-Espino, D., Kyrpides, N., Zhong, L., et al. (2015) Antarctic archaea–virus interactions: metaproteome-led analysis of invasion, evasion and adaptation. ISME J 9: 2094-2107. Tschitschko, B., Williams, T. J., Allen, M. A., Zhong, L., Raftery, M. J., and Cavicchioli, R. (2016) Ecophysiological distinctions of haloarchaea from a hypersaline Antarctic lake determined using metaproteomics. Appl Environ Microbiol 82: 3165 – 3173. Williams, T. J., Allen, M. A., DeMaere, M. Z., Kyrpides, N. C., Tringe, S. G., Woyke, T., and Cavicchioli, R. (2014) Microbial ecology of an Antarctic hypersaline lake: genomic assessment of ecophysiology among dominant haloarchaea. ISME J 8: 1645-1658.