230 BIOCHEMISTRY OF BACTERIAL LUMINESCENCE 



nous extracts obtained therefrom, there is an immediate or nearly 

 immediate increase in the level of luminescence to some higher level, 

 v^hich then slowly decays over a period of seconds or minutes to 

 some lower steady state level. When the pressure is released, the exact 

 converse effects occur, i.e., the luminescence drops nearly instanta- 

 neously to a lower level and then slowly rises to the level of lumines- 

 cence obtaining prior to the application of pressure. The most striking 

 modifier of this course of events is the long-chain aldehyde. In the 

 absence of long-chain aldehyde the luminescence is virtually un- 

 affected at suboptimal temperatures by the application or release of 

 pressure. The height of the spike as well as the steady state level 

 under pressure are dependent on aldehyde concentration but not to 

 a marked extent except when aldehyde is completely absent. 



The exact time course of the luminescence also depends on the con- 

 centration of KCF. Suboptimal amounts of this component produce 

 effects which are roughly similar to the course of luminescence in the 

 presence of saturating amounts of the aldehyde, but there are some 

 rather notable differences. Initially, the level of luminescence rises 

 abruptly, as is the case in the system saturated with aldehyde, but it 

 almost immediately decays to a value near to the starting point and 

 then slowly and probably exponentially decreases to a lower level. 



In order to identify the step or steps which react in this manner 

 when pressure is applied, the following experiments were performed. 

 First, in order to determine whether the luminescence "spike" which 

 occurs when pressure is applied is due to the latter steps in the 

 sequence or to earlier ones, we introduced reduced flavins into the 

 pressure chamber, and upon applying and releasing pressure it was 

 noted that the luminescence rose when pressure was applied but no 

 marked decrease to a new steady state was evident above the normal 

 decay of the luminescence when flavin was added (i.e., the flavin dis- 

 appears rather rapidly since it is consumed both by enzymatic reac- 

 tions and by nonenzymatic auto-oxidations ) . Secondly, when the pres- 

 sure was released, the luminescence dropped almost immediately to 

 a new lower level and did not rise subsequently. It was thought that 

 the slow decay and rise might be identified with one of the time 

 constants noted in the rise time experiments discussed earlier, and it 

 was possible to show that the time required for the luminescence to 



