Enrichment of motile phototrophs by phototaxis v1

This protocol describes a method for enriching motile phototrophs from environmental samples by positive phototaxis, or the ability to move towards light. Samples are collected in the field using sterile equipment, and incubated in water and under lights to bloom phototrophs. Phototaxis is conducted in a sealed glass pasteur pipet filled with 0.15% agar, and wrapped in aluminum foil leaving only the tip exposed. Phototrophs must swim through the agar to reach the illuminated tip, separating them from the rest of the starting sample, and thereby generating an enriched fraction from which the phototrophs can be grown and isolated more easily than from a complex starting sample. This protocol is based on the method described in Sack et al, 1994.