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The aim: to study the pathogenicity of non-pigmented P. aeruginosa isolates compared to those that synthesize pigment during long-term storage for broiler chickens. Materials and methods. Bacteriological studies were carried out in accordance with generally accepted methods. Initially, P. aeruginosa and other bacterial microflora were isolated from poultry farms, pathological material from poultry. The type of microorganisms was identified using Bergey's identifier. The obtained isolates were examined by morphological characteristics (according to Gram), tincture, cultural, biochemical, pathogenic properties and sensitivity of selected cultures to antibiotics were studied. After the expiration of 3 years, the main biological properties of the isolates were monitored. To establish pathogenic properties, a bioassay was performed on white mice and one-week-old broiler chickens of the Cobb 500 cross (intraperitoneally by washout from daily agar culture at a dose of 0.2 cm³, which corresponds to the previously established LD50). The results. With parenteral infection by washout from agar daily culture of pigmentless isolates at a dose of LD50, chickens died within the first - second day, in this case 87.50 % of the cultures showed pathogenicity. Experimental parenteral infection with washings from a daily culture of pigmented isolates of P. aeruginosa at a dose of LD50 led to the death of one-week-old chickens within 24-48 hours, in this case 75.00 % of the isolates showed pathogenicity. Clinical and pathological signs of infection with pigmented and non-pigmented P. aeruginosa isolates were similar. Conclusions. A comparative analysis of cases of pathogenicity of non-pigmented and pigmented isolates of P. aeruginosa on one-week-old broiler chickens of the Cobb-500 cross was carried out. In the experiment, we found that among the non-pigmented isolates, compared to the pigmented pathogenic isolates, 12.5 % more were detected in chickens. This emphasizes the importance of differential diagnosis for pseudomonosis, because infection with non-pigmented strains often goes undiagnosed [ABSTRACT FROM AUTHOR]

Isolates of Gaeumannomyces spp. obtained from diseased roots of winter wheat showing take-all symptoms were characterized by pathogenicity. All isolates were more pathogenic on wheat and barley than on oat, and were identified as Gaeumannomyces tritici. Most isolates of G. tritici were characterized as middle pathogenic, the pathogenicity of one isolate was higher than those of others, and two isolates showed the lowest pathogenicity. In growth chamber assay, the effect of two Bacillus strains, B. subtilis 16 and B. pumilus 11, on take-all of wheat was studied. Pathogen inoculation was made by isolates of G. tritici of different pathogenicity. It was found that effective biological control depends on take-all severity, which, in turn, co-ordinates with the pathogenicity of fungal isolate. Applying the bacterial cells into the plant growth substrate stimulated the seedling growth when artificial inoculation was performed with a middle pathogenic isolate of G. tritici, and the disease severity was middle. There was no growth promotion by bacterial inoculant at slight disease severity. No stimulating effect was also observed at the high disease severity, where pathogen inoculation was performed with a highly pathogenic isolate of G. tritici. [ABSTRACT FROM AUTHOR]

The aim: to study the pathogenicity of non-pigmented P. aeruginosa isolates compared to those that synthesize pigment during long-term storage for broiler chickens. Materials and methods. Bacteriological studies were carried out in accordance with generally accepted methods. Initially, P. aeruginosa and other bacterial microflora were isolated from poultry farms, pathological material from poultry. The type of microorganisms was identified using Bergey's identifier. The obtained isolates were examined by morphological characteristics (according to Gram), tincture, cultural, biochemical, pathogenic properties and sensitivity of selected cultures to antibiotics were studied. After the expiration of 3 years, the main biological properties of the isolates were monitored. To establish pathogenic properties, a bioassay was performed on white mice and one-week-old broiler chickens of the Cobb 500 cross (intraperitoneally by washout from daily agar culture at a dose of 0.2 cm³, which corresponds to the previously established LD50). The results. With parenteral infection by washout from agar daily culture of pigmentless isolates at a dose of LD50, chickens died within the first - second day, in this case 87.50 % of the cultures showed pathogenicity. Experimental parenteral infection with washings from a daily culture of pigmented isolates of P. aeruginosa at a dose of LD50 led to the death of one-week-old chickens within 24-48 hours, in this case 75.00 % of the isolates showed pathogenicity. Clinical and pathological signs of infection with pigmented and non-pigmented P. aeruginosa isolates were similar. Conclusions. A comparative analysis of cases of pathogenicity of non-pigmented and pigmented isolates of P. aeruginosa on one-week-old broiler chickens of the Cobb-500 cross was carried out. In the experiment, we found that among the non-pigmented isolates, compared to the pigmented pathogenic isolates, 12.5 % more were detected in chickens. This emphasizes the importance of differential diagnosis for pseudomonosis, because infection with non-pigmented strains often goes undiagnosed [ABSTRACT FROM AUTHOR]

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Breeding of wheat cultivar resistant against root diseases is a difficult problem because the lack of evidence about nature of pathogenicity of soil-borne fungi -causal agents of these diseases and their interaction with host plant. The aim of this research was to investigate the character of pathogenicity of Bipolaris sorokiniana, Fusarium spp. и Oculimacula spp. - causal agents of common root rot, Fusarium root rot and eyespot on wheat seedlings under the artificial inoculation with isolates B. sorokiniana, F. oxysporum, F. culmorum, O. acuformis and O. yallundae. It has been revealed that there is significant difference between isolates B. sorokiniana, F. culmorum and F. oxysporum in pathogenicity, which was confirmed by the assessment of root rot severity on inoculated seedlings. Under the artificial inoculation of wheat seedlings with isolates O. acuformis and O. yallundae the severity of eyespot depends significantly on wheat cultivar characteristics. Based on results of our experiments we also suggested the virulence characteristic in B. sorokiniana isolates. Thus, it has been confirmed the specificity of interaction the soil-borne fungi with plant host in every particular pathosystem, that should be considered in breeding programs for resistance against root and stem-base diseases. [ABSTRACT FROM AUTHOR]