Span 20 at 10 g/l induced dispersed mycelial growth of Blakeslea trispora, and significantly increased beta-carotene production to 2.16 g/l. Without surfactant only 0.15 g beta-carotene/l was produced. Other non-ionic surfactants composed of the same hydrophilic part as Span 20 and the hydrophobic fatty acids of Spans, including lauric acid (C-12), neither induced dispersed growth of the microorganism nor increased beta-carotene production.