A NOTE ON THE THERMODURIC BACTERIAL CONTENT OF FARM WATER SUPPLIES

SUMMARY: Significantly higher thermoduric colony counts were obtained when 5 ml. of water were laboratory pasteurized in 5 ml. of sterile milk or 2 ml. of water were pasteurized in 8 ml. of sterile milk, than when 10 ml. of water were directly pasteurized; 86% of the water samples had higher thermoduric counts after pasteurization in milk. Large differences were not common, only 19% of the ratios being over 5 and 5% over 10. Aerobic sporing rods were dominant in the thermoduric microflora irrespective of the method of pasteurization.     

THE INCIDENCE OF BACTERIUM COLI IN FARM WATER SUPPLIES

SUMMARY: Farm water supplies giving 37° positives in MacConkey's broth within 24 hr. had a much higher incidence of presumptive Bact. coli type I than those which gave 37° positives during the second day of incubation only; presumptive Bact. coli reactions were obtained with 85% of the 7,522 tubes positive in 24 hr. compared with 23% for the 7,593 tubes showing positive reactions during the second day at 37°.     

COLI-AEROGENES BACTERIA IN FARM WATER SUPPLIES

SUMMARY: A series of 825 cultures of coli-aerogenes bacteria isolated at 30° and a series of 735 cultures isolated at 37° from 645 samples of farm water supplies were classified according to the recommendations of the Coliform Sub-Committee of the Society for Applied Bacteriology (Report, 1949). Klebsiella constituted 50% of the cultures isolated at 30°, whereas Escherichia coli I was the dominant type, forming 57%, among the cultures isolated at 37°. It would thus appear that isolation at 30° is as selective for Klebsiella as isolation at 37° is for Escherichia . Coli-aerogenes organisms, mainly 37° negative strains of Citrobacter freundii I and K. cloacae , were found in waters of high sanitary quality derived from protected springs and wells; but the coli-aerogenes microflora of polluted water was dominated by E. coli I, which formed 43% of the isolates at 30° and 76% of those at 37°. The results for a series of fortnightly samples from 11 farm water supplies showed a marked seasonal variation in the incidence of different types isolated at 30°; E. coli I formed a higher proportion in summer than in winter, while 37° negative strains of Klebsiella and Citrobacter formed a higher proportion in winter than in summer.     

THE BACTERIOLOGY OF FARM WATER SUPPLIES: A STUDY OF THE COLONY COUNT IN 72 HOURS AT 22°

SUMMARY: The colony count at 22° of farm water supplies from springs and wells was mainly composed of biochemically inactive, non-pigmented, Gram-negative rods. Water from a stream polluted with farmyard sewage showed a similar dominance of Gram-negative rods, but orange or yellow pigmented colonies were more abundant. There were few 37° positive coli-aerogenes bacteria in either the farm water supplies or the sewage polluted stream, and Bact. coli type I was rare.
A high proportion of the bacteria from farm water supplies fermented milk in 3 days at 22°; a third developed acid, 15% proteolysis and 6.4% ropiness.
Contamination of pure spring water with surface soil from a heavily grazed pasture resulted in a hundredfold increase in colony count with aerobic sporing rods replacing Gram-negative rods as the dominant organisms, but coli-aerogenes bacteria were absent.     

SOME OBSERVATIONS ON THE BACTERIAL CONTENT OF WATER IN WATERCRESS BEDS

SUMMARY: Samples of water flowing into watercress beds had higher bacterial contents during the summer months although this was less marked among samples from deep underground sources. Outlet samples showed higher contents than inlet samples and the bacterial content varied markedly with season, being highest in summer.
The presumptive coli-aerogenes contents at 30°, 37° and 44° also showed a similar seasonal variation among samples from the outlets but the marked inferiority of samples other than from bores was no longer apparent after the water had flowed through the beds. The dominant types were Bact. aerogenes type I, pectate liquefiers, Bact. coli type I, and Intermediate type I.
The importance of the pectate liquefiers was confirmed by plating on pectate gel and by their isolation from these plates and from MacConkey's broth.     

STUDIES OF THE DETERMINATION OF THE BACTERIUM COLI TYPE I CONTENT OF FARM WATER SUPPLIES

SUMMARY: A – comparison of the suitability of brilliant green bile broth and MacConkey's broth at 44° for the detection of Bacterium coli type I in farm water supplies, showed that 83.1% of the samples had no difference in the number of positive tubes at 44°, and only 5 samples (1.7%) had a significantly higher number of positive tubes in MacConkey's broth.
Of 707 strains of coli-aerogenes bacteria isolated from 44° positive tubes of both media, 94.5% were Bact. coli type I. Strains of Bact. coli type II and Bact. aerogenes type I which were 44° positive constituted 3.7% and 0.4% respectively, all of which were indole negative at 44°. In addition there were 10 strains (1.4%) of 44° positive Intermediate type II, 9 of which were indole positive at 44°.
An appreciable number (6.6%) of Bact. coli type I strains failed to give a positive indole reaction in 24 hr at 44°.