Cellular fatty acid composition of rod and coccus forms of Arthrobacter globiformis, A.crystallopoietes and A.nicotianae isolated from the water fern Azolla

Seven strains of Arthrobacter globiformis, and one each of A. crystallopoietes and A. nicotianae, isolated from the water fern Azolla, were cultured for 2–3 d at 30 °C on Pseudomonas Agar F to obtain rods and for 5 d to obtain cocci, then analysed for total cellular fatty acids. In rods, saturated iso‐ and anteiso‐branched 13–19 carbon fatty acids averaged 85% of the total in A. globiformis, 81% in A. crystallopoietes, and 97% in A. nicotianae. Minor components included unsaturated branched chains, hydroxy and cyclopropane fatty acids. Fatty acid composition of A. globiformis was similar to that of A. crystallopoietes but different from that of A. nicotianae. Saturated straight chains in A. nicotianae averaged 1·5% of the total compared with 14–16% in A. globiformis/crystallopoietes, and anteiso‐15:0 constituted 73% of the total in A. nicotianae compared with 18–19% in the other species. Composition of cocci was different from that of rods in A. globiformis and A. crystallopoietes. As cells changed from rods to cocci, percentages of saturated and unsaturated straight chains decreased and saturated iso‐ and anteiso‐branched chains increased. In A. nicotianae there were no significant differences in the fatty acids between rods and cocci.