科研之友
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摘要
Short exposures of Bacillus spores to nutrient germinants can commit spores to germinate when germinants are removed or their binding to the spores%26apos; nutrient germinant receptors (GRs) is inhibited. Bacillus subtilis spores were exposed to germinants for various periods, followed by germinant removal to prevent further commitment. Release of spore dipicolinic acid (DPA) was then measured by differential interference contrast microscopy to monitor germination of multiple individual spores, and spores did not release DPA after 1 to 2 min of germinant exposure until similar to 7 min after germinant removal. With longer germinant exposures, percentages of committed spores with times for completion of DPA release (T-release) greater than the time of germinant removal (T-b) increased, while the time T-lag - T-b, where T-lag represents the time when rapid DPA release began, was decreased but rapid DPA release times (Delta T-release = T-release - T-lag) were increased; Factors affecting average Trelease values and the percentages of committed spores were germinant exposure time, germinant concentration, sporulation conditions, and spore heat activation, as previously shown for commitment of spore populations. Surprisingly, germination of spores given a 2nd short germinant exposure 30 to 45 min after a 1st exposure of the same duration was significantly higher than after the 1st exposure, but the number of spores that germinated in the 2nd germinant exposure decreased as the interval between germinant exposures increased up to 12 h. The latter results indicate that spores have some memory, albeit transient, of their previous exposure to nutrient germinants.
- 出版日期2014-7
