[Erwinia amylovora--the fire blight pathogen of trees in Ukraine].

Niduses of fire blight of fruit and ornamental trees have been found in the Kyiv and Vinnitsa regions of Ukraine. Pathogen Erwinia amylovora was isolated between April and October. The pathogen was often accompanied by bacteria Pseudomonas syringae pv. syringae. Artificial infection with a mixture of bacteria E. amylovora and P. syringae pv. syringae accelerates and enhances the disease process in the laboratory.

[Polyvalence of bacteriophages isolated from fruit trees, affected by bacterial fire blight].

Phage populations appearing as a result of a pathogenic process caused by Erwinia amylovora have been discovered and described. They accompany bacterial fire blight development in the process of quince, pear and apple trees vegetation in Zakarpattya region of Ukraine. Phage isolates of the affected pear and quince include polyvalent virulent phages able to develop on bacterial strains associated with plants--E. amylovora. E. "horticola" and Pantoea agglomerans. E. amylovora isolated from the plant tissues affected by the fire blight and detected at the same time as phages proved to be resistant to the viral infection. It is hard to explain now this characteristic however it was noticed that resistance to phages can change drastically in case of dissociation, lysogenization and mutagenesis of erwinia in laboratory conditions. Phage population study shows that they are heterogeneous and can obviously include not only polyvalent but also specific viruses. Further studies of biology and molecular genetics of pure lines of isolated phages will help to get closer to understanding the place and role of bacteriophages in the complicated network of relations between bacterial pathogens and plants.

[Properties of pectolitic phytopathogenic bacteria isolates obtained in Ukraine].

Bacteria obtained from potato tubers having symptoms of soft rot and grown in different regions of Ukraine are identified as Pectobacterium carotovorum subsp. carotovorum. These bacteria strains are able to produce bacteriocines. Their killer activity in respect of P. carotovorum and Esherichia coli has been studied. The sensitivity to bactericines has been shown. Purified fractions of bacteriocines having high molecular weight (MCTV) have been obtained. The difference in composition of proteins from phage tails as compared to the ones in P. carotovorum J2 has been studied by the method of electrophoresis. It was found that the composition of MCTV major proteins of studied isolates mostly corresponds to P. carotovorum J2. The set of enzyme minor fractions has some different compositions as compared to P. carotovorum J2. It has been hypothesized that this difference is responsible for killer specificity.

[Electron microscopy and restriction analysis of bacteriophages isolated from quince and pear with symptoms of fire blight].

Phage populations of isolates from quince and pear affected with fire blight disease were studied using electron microscopy, restriction analysis and both agarose gel electrophoresis of particles and host range scoping method. The isolate from quince (pMA1) comprises at least three phage populations and two phage variants that can be detected on different bacterial indicators. After titration of this isolate on Erwinia amylovora the bacteriophage KEY of B1 morphotype with the genome size of 82.4 kb was identified. The isolate pMA1 also includes a unique phage population 4*, which can be identified on the test bacteria Pantoea agglomerans (Pag) g150. Two analogous populations being also present in the isolate pMA1 that appeared to be close phage variants with almost identical Hpal-restriction patterns can be identified using Pag g157 and 9/7-1. The situation is similar in the case of phage isolates from pear, pMG. Three phage populations identified in it using three different indicators represent the same phage of C1 morphotype (TT10-27) with a genome size of 71.4 kb. At least two other phage populations were also detected in the same isolate using P. agglomerans 9/7-2 as an indicator. A model system allowing the most efficient analysis of the isolates for the presence of different phage populations and phage variants in plants infected by fire blight disease has been developed. It provides for using three indicator enterobacterial species closely associated with the plants: E. amylovora, Erwinia "horticola" and Pagglomerans and ignoring of the phage cloning procedure.

[Study of population dissociation of collection strains of Erwinia carotovora]. / Izuchenie populiatsionnoi dissotsiatsii kollektsionnykh shtammov Erwinia carotovora.

Unusual dissociants of Erwinia carotovora subsp. atroseptica (EAT) population that emerge with high frequency (18-94%) during long-term storage of cultures were found. The dissociants (Poe-phenotype) differ from parental forms by slow growth and long development of the colour of colonies on EMB agar though they are not Lac-mutants. More than 60% of Poe-mutants of strain EAT 39A are characterized by 8- and 150-fold decrease of stability to erythromycin and oleandomicin, correspondingly. They are also sensitive to colicin-like carotovoricin, which is induced by mytomicin C, to carotovoricin of initial strain EAT 39A and to autocin, which they produce themselves during induction. A multiple phenotype of these dissociants (dissociants of the second type) is labeled: PoeOmSErSBnSAu. Its appearance as well as the appearance of pure Poe-variants is not associated with usual mutations and a loss of residential plasmids by cells. Population dissociants of the both types--Poe and PoeApSOmS--were also obtained from E. carotovora subsp. carotovora (J2) during growth at supraoptimal temperature. Poe-variants are more often observed in representatives of subspecies atroseptica than carotovora and can be useful when studying pathogeneity of these practically important erwinias.

[Adsorbed receptors for Erwinia carotovor subsp. carotovora macromolecular bacteriocins]. / Izuchenie adsorbtsionnykh retseptorov makromolekuliarnykh bakteriotsinov Erwinia carotovora subsp. carotovora.

Study of nature of receptors for macromolecular bacteriocins Erwinia carotovora subsp. carotovora has shown that lipopolysaccharide (LPS) of cell membrane is an attaching structure for them. It has been established that enzymic treatment of LPS preparation with its further deproteinization by phenol is necessary for isolation of biologically active lipopolysaccharide. The process of absorption by LPS has been studied quantitatively and it has been shown that it is a low-efficient receptor as compared with LPS included in the native cell membranes. An approach has been proposed for the first time to the estimation of monosaccharide composition of LPS-receptor based on relations between bacteriocin sensitivity and content of monosaccharides. Study of six strains of E. carotovora subsp. carotovora from different sources has shown that the structure of LPS-receptors includes mannose, fucose, xylose, ramnose and two lipophylic monosaccharides of unknown nature. A conclusion has been made that S-LPS (0-chain) is that part which contains the sites of attachment of macromolecular carotovoricins.