Four new alkyl aromatics, penixylarins A-D (1-4), along with the known biogenetically related 1,3-dihydroxy-5-(12-hydroxyheptadecyl)benzene (5) and 1,3-dihydroxy-5-(12-sulfoxyheptadecyl)benzene (6), were isolated from a mixed culture of the Antarctic deep-sea-derived fungus Penicillium crustosum PRB-2 and the mangrove-derived fungus Xylaria sp. HDN13-249. UPLC-MS data and an analysis of structural features showed that compounds 1 and 2 were produced by collaboration of the two fungi, while compounds 3-6 could be produced by Xylaria sp. HDN13-249 alone, but in noticeably increased quantities by cocultivation. Compounds 2, 3, 5, and 6 showed antibacterial activity against a panel of strains, and compound 3 possessed potential antituberculosis effects (MIC = 6.25 μM against Mycobacterium phlei).