b. Colony planting (1 μl, ca 105 cells) on the colony background of bacteria (0, 1, or 2 days old). Insets: CDK inhibitor controls. c. Simple cases of elongated plantings. d. Ring-colony encounters. Mutual influencing of a colony and a ring planted in different time intervals. All colonies are shown at day 7; bar = 1 cm. We have also confirmed the previously described phenomenon of “”ghost”" colonies [23], originally documented on a different strain. Briefly,

colonies planted at the background of multiple (hundreds) colonies became inhibited, or even “”dissolved”" on the background (Figure 3b). This is the case even in synchronous cultures if, at the beginning, the background is represented by at least about 100 colony-forming units. Such a background can keep at bay a plant as dense as 100 000 cells, preventing its development towards a colony. The effect is more profound when background Selleck Pifithrin �� colonies are older. With

this information in mind, we return to ring colonies. A colony was planted into the center of a ring colony of greater diameter, or a ring Oligomycin A chemical structure colony was blotted around a growing F colony. Both bodies represent a “”background”" to each other, depending on the succession of plating. Results in Figure 3d show that the synchronous planting of both structures leads to disruption of the structure of the central colony, but no change in the structure of the ring. Colonies planted on the background of older rings became inhibited. On the for other hand, when the ring is planted around an older colony, it develops into a typical structure, only with more profound reddening of the inner rim – again confirming that a developing colony can perceive the presence and layout of its neighbors. Long-distance interactions between colonies and maculae To examine the putative long-distance signals between bacterial bodies, colonies (F) were planted to the vicinity of maculae of two different Serratia clones (F, R) or an unrelated bacterial strain (E. coli). Maculae and colonies either shared the same agar plate, or were separated by a septum. When F colonies were planted in varying distances from an F macula (Figure 4a), the closer was the macula to a

colony, the quicker the reddening of that colony. At the same time, the colony deviated from its typical structure to an extent inversely related to its distance from the macula. The graph in Figure 4a shows that the transition point between aberrant and standard patterns lies approximately 15 to 20 mm from the macula, corresponding roughly to the diameter of adult F colonies. This breakdown of the colony structure was not observed with the Serratia isolate characterized previously ([23]; data not shown). The Fw macula exhibited weaker effects than its F counterpart, and elicited the loss of structure only when older (not shown). Figure 4 F colony development in the presence of macula. a. F-colonies planted simultaneously with an F-macula (12 cm dish).