This paper deals with the 0 groups of citrate utilizing variants of Escherichia coli (Cit+ E. Coli) isolated from cattle, the production of colicin, hemolysin, K99 antigen, heat stable enterotoxin, and the isolation of plasmid DNA. Among 42 Cit + E. Coli, 12 strains were 020, 9 strains 08, 5 strains 045, 3 strains 0115, 1 strain 064, 1 strain 0139 and remaining strains (11) were untypable. Thirty-nine(81.3%)out of 48 Cit + E. Coli produced colicin and 13(27.0%) produced hemolysin. Of 12 cit + E. coli bearing K99 antigen, 6(50.0%) produced heat stable enterotoxin. In gel electrophoresis for the isolation of plasmid DNA, the number of plasmids varied from 1 to 7 in 10 Cit+ E. Coli. Its molecular weight ranged from 2 to 50 Mdalton, and 50 Mdalton plasmid commonly existed in all strains

The prevalence of diarrhea caused by enterotoxigenic Escherichia coli was surveyed on 445 calves in 6 farms which were located in the central part of Korea. The incidence of enterotoxigenic Escherichia coli in calves with diarrhea was investigated by detecting the K99 and F41 antigens from the isolated strains of Escherichia coli. The incidence of colibacillosis in calves was 23.3%. Of 238 strains of Escherichia coli isolated from calves with diarrhea, 73 strains (30.6%) were proved possessing the K99 antigen by mannose-resistant hemagglutination (MRHA) using horse red blood cells and 79(33.1%) possessing F41 antigens by MRHA using guinea-pig red blood cells

In the conditions of the Republic of Belarus there was created an adhesive antigen on the basis of bacterial suspension of Escherichia which were separated from culture media by means of purification and concentration on membranes UMP-300 and UMP-5 that made it possible to obtain a cleaned-up preparation the specific activity of which was in 2-4 higher that of the unpurified one. In course of the study there was developed a method of purification and concentration of adhesive Escherichia antigens with the help of membrane technology. There were obtained biologically active adhesive antigens E.coli K88, K99, F41, 987P; there were selected the ultrafiltration membranes providing the optimal selectivity and productivity of the process; there were studied the influence of some factors on the process of adhesins concentration by means of ultrafiltration method. During the experiments there was analysed the agglutinating activity of antigents prepared by different methods.