Lysine lactylation as a type of posttranslational modifications (PTMs) is recently associated with chromatin remodeling and gene transcription, but lysine lactylation of histone and non-histone proteins has not yet been studied in Nannochloropsis oceanica. To examine the prevalence and function of lactylation in N. oceanica, protein lactylation modification profiles were tracked after nitrogen deprivation for three days using 4D label-free proteome method. Under nitrogen deprivation (ND) and nitrogen repletion (NR) cultivation conditions, we mapped lactylome of proliferating microalgal cells.