Micro-organisms of Maple Sap 591 



Conclusions 



Among the 42 strains of green fluorescent bacteria selected 

 from several hundred strains which had been isolated from 

 maple sap, there were 32 strains of the liquefaciens and 9 strains 

 of the non-liquefaciens varieties of Ps. fluorescens. The studies 

 included one strain which was never more than doubtfully fluo- 

 rescent which, for this and other reasons, should not properly be 

 regarded as a member of the fluorescent group. The 9 strains 

 of the non-liquefaciens variety showed a delayed liquefaction of 

 gelatin in from 50 days to 5 months when cultivated in a moist 

 chamber at 20 C. Peptonization of milk by these strains was 

 also long delayed.commencing in from 30 days to 3 months. 



Critical comparative studies of 7 representative strains of 

 green fluorescent sap bacteria and 6 so-called species Ps. alba. 

 Ps. fluorescens, Ps. longa, Ps. mesenterica, Ps. tenuis, and Ps. 

 putrida show that no sharp line of differentiation can be drawn 

 between these forms. Of the known "species,"' Ps. alba, Ps. 

 longa, and Ps. putrida fail to liquefy gelatin in 6 months time. 

 while in the case of Ps. mesenterica and Ps. tenuis a delayed 

 liquefaction occurs. In the latter named strain liquefaction first 

 appears 4 months after inoculation. 



It is believed that the fluorescent sap bacteria as well as 

 the so called species, Ps. alba, J's. longa, Ps. mesenterica, Ps. 

 tenuis, and Ps. putrida should properly be recognized as -trains 

 of the liquefaciens and non-liquefaciens varieties of Ps. fluores- 

 cens. 



