GREEN FLUORESCENT BACTERIA FROM WATER 91 



reagent was added to the tubes and control tubes, and com- 

 parison made in a colorimeter used for determining ammonia in 

 water analysis. 



Fifty-two of the 100 cultures produced ammonia in ten days 

 at 37 °C. Plain nutrient broth cultures were often tested for 

 ammonia production, and all strains were found to produce 

 ammonia. The plain broth cultures were alkaline to phenol- 

 phthalein. 



Vitality of fluorescent bacteria 



The members of this group seem to be able to resist very 

 unfavorable conditions. No special experiments have been 

 made, but much evidence from a number of sources is available. 



Broth suspensions of B. pyocyaneus were suspended in the 

 Urbana septic tank and daily counts made. The number of bac- 

 teria increased regularly until the end of the period, which indi- 

 cates that this bacterium is able to live in such an environment. 



It has been noticed that tubes of supposedly sterile culture 

 media which spoiled were often infected with bacteria of this 

 group. Thus it is apparent that these bacteria are able to 

 resist high temperatures for short periods. It is well known 

 among physicians that once a hospital is infected with B. pyo- 

 cyaneus, it is disinfected with great difficulty. 



Cultures of these bacteria live for a long time on laboratory 

 media. Agar slants which have been allowed to dry for six 

 months at room temperature were found to support living flu- 

 orescent bacteria. Cultures of strains 22 and 37 were left for 

 a year and a half with infrequent transfers and in each case 

 good growth was secured from the old cultures. These cul- 

 tures did however lose some of their pigment-producing property. 



Rettger and Sherrick (1911) report an example of resistance 

 by a member of this group. They state that an old culture of 

 B. pyocyaneus began to lose its property of producing the green 

 pigment. An agar slant of this bacterium was placed on the 

 top of an incubator in April and left until October. When 

 examined at this time the agar was dried to a hard mass and it 

 was thought unlikely that any living bacteria were present. 



