A good indicator of the cleanliness of water is the ratio of the num- 

 ber of saprophytic bacteria to their total number expressed in percent 

 (Kuznetsov, 1952; Romanenko, 1971). A summary is presented in Table 2. 



TABLE 2. RATIO OF THE NUMBER OF SAPROPHYTIC BACTERIA TO THEIR TOTAL 

 NUMBER AS AN INDEX OF THE CLEANLINESS OF WATER. 



Ratio, 9T 



Water 



Water-Body 



0.003 or less 

 0.03 



0.3 



3 or greater 



Very clean Lakes Onega, Ladoga, Baikal 



Clean Reservoirs: Rybinskoe, Sheksninskoe 



Ruibyshevskoe 



Dirty Some parts of Volga River 



Very dirty Collectors of waste waters 



Water in which the 

 clean; a ratio of 0.03 

 higher, very dirty. 



ratio is 0.003 percent may be considered exceedingly 

 suggests clean conditions; 0.3, dirty; and 1-3 and 



Content of Bacterial Spores in Waters 



Bacterial populations in water are dominated by non-spore forming bac- 

 teria. The ratio of bacillary forms to other bacterial groups is frequently 

 equal to 1:10. 



In view of some workers, the spore forming bacteria are more often found 

 in the presence of hard to degrade organic substances, e.g., humic compounds, 

 etc. (Kholodnyi, 1957). In fact, spore forming bacteria are more abundant 

 in waters colored by humic substances, and in drainage from peaty grounds. 

 The number of spores is increased in proportion to the vegetative cells. 



Determination of the total number of spore forming bacteria is laborious 

 and a time consuming procedure. The water or sediment to be tested is inocu- 

 lated onto agar plates according to the methods of Koch. It is then neces- 

 sary to wait for some time until the colonies age and begin to produce 

 spores, a microscopic examination of the colonies is performed using pre- 

 ferential staining of the spores (Omelyanski, 1932). 



It is easier to determine the presence of spores in water than it is to 

 enumerate the spore-forming bacteria. For this type of determination, two 

 methods may be used. Both are based on the destruction of the vegetative 

 cells, and subsequent creation of conditions favorable for germination of 

 the spores. 



Method of Heating-- 



A sample of water or sediment, either directly or after dilution, is 

 heated in a water-bath for 10-min. at a temperature of 80 C. Test-tubes 

 with tested water are then cooled and inoculation is made on MPA, or a mix- 



60 



