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The plant-beneficial bacterium Azospirillum brasilense can swim in liquids and swarm or migrate with the formation of microcolonies in soft media. To get closer to understanding the influence of natural environments on A. brasilense motility, we studied the individual and social movement of the bacterium in the presence of various plant lectins. The lectins with specificity for N-acetyl-beta-d-glucosamine oligomers (wheat germ, Solanum tuberosum and Ulex europeus agglutinins) decreased A. brasilense swimming speed and induced the formation of branched-granular colonies instead of the swarming rings. These effects seemed to be a consequence of specific interactions between the agglutinins and the lectin-binding polymers present in the A. brasilense cell envelope. Concanavalin A (with an affinity for terminal alpha-d-mannosyl and alpha-d-glucosyl residues) and Phaseolus vulgaris phytohemagglutinin P (with unknown specificity) almost did not affect the motility of A. brasilense.

In semiliquid laboratory media, the bacterium Azospirillum brasilense migrates with the formation of swarming rings. It is demonstrated that adsorption of the sulfonated azodye Congo Red confers on A. brasilense the ability to consistently spread in a semiliquid agar and form microcolonies. Spontaneous variants of A. brasilense with rapid swarming are described, as well as variants that swarm in the presence of Congo Red. It is assumed that at least two types of compounds are formed, which are (a) necessary for swarming and/or spreading with the formation of microcolonies and (b) capable of interacting with Congo Red.

Formation of extracellular structures in pure culture and in interaction with wheat root surface was studied by scanning and transmission electron microscopy. The effect of various factors (growth temperature as well as pretreatment of agrobacteria with kalanchoe extract, acetosyringone, and centrifugation) on formation of extracellular structures was tested. The data on Agrobacterium tumefaciens (wild strain C58 and mutants LBA2525 (virB2::lacZ) and LBA288 (without Ti plasmid)) adhesion to wheat root surface and root hairs after pretreatment of agrobacteria with inducer of virulence genes (vir) acetosyringone were obtained. Formation of agrobacterial cell aggregates on wheat root hair tips was demonstrated. The proportion of root hairs with agrobacterial aggregates on the root hair tip insignificantly changed after pretreatment with acetosyringone but considerably increased after treatment of A. tumefaciens C58 and LBA2525 with kalanchoe leaf extract. The most active colonization of root hairs and formation of agrobacterial aggregates on hair root tips was observed at 22 degrees C. The capacity of agrobacteria for adhesion on monocotyledon surface could be changed by pretreatment of bacteria with various surface-active substances. Bacterial cells subjected to centrifugation had a decreased capacity for attachment to both wheat root surface and root hairs. The relationship between the capacity for adhesion and pile production in agrobacteria was considered.

Three mutants of Azospirillum brasilense Sp245 incapable of both formation of the polar flagellum (Fla-phenotype) and swarming in semisolid media (Swa-phenotype) were characterized. These mutants were shown to have lost the 85-MDa plasmid and to carry the Tn5-Mob transposon and pSUP5011 vector in different regions of their genomes. With the use of A. brasilense Sp245 gene bank, the capacity for both polar flagellum formation and swarming was restored in the above mutants and in the previously generated transposon mutants A. brasilense Sp245 and S27. The transconjugants obtained were only slightly motile in the liquid culture. In the gene bank of Sp245, the recombinant plasmids carrying wild-type fla/swa loci were identified.

Azospirillum brasilense Sp245 has a mixed type of flagellation: a single polar flagellum (Fla) is synthesized constitutively, and abundant lateral flagella (Laf) are produced only in solid and semisolid media. In the present study, Omegon-Km Fla-Laf-, Fla-Laf+, Fla-/Mot-Laf-. Fla-/Mot-Laf+, Mot-Laf-, and Che- mutants of Sp245 were constructed in vivo. In some of the mutants, a number of cells possessed from 1 to 5 subpolar long flagella (Sfl). These Sfl provided the host cells with unusual motility patterns. Mutants producing shortened Fla and Laf were also detected. In the mutants still producing Laf, their expression retained the wild-type inducibility. However, all the mutants described were unable to form swarm rings in semisolid media. The results suggest the existence of common control or structural elements in assembly and rotation apparatus of both Fla and Laf systems. Single Omegon-Km insertions were localized in 85 MD (in two mutants) and in 120 MD (in one mutant) indigenous plasmids, as well as to least in two different regions of chromosomal DNA (in other mutants).

Correlation between the loss of the 120 and/or 130 kb plasmids by the spontaneous Azospirillum brasilense mutant and appearance of the Che(-)-phenotype towards 9-mono- and disaccharides has been established. The plasmid rearrangement is concomitant with the appearance of a new 44 Kda protein among the membrane proteins of azospirilli. Chemotaxis to alanine, glutamic acid, and to organic acids is not impaired.

A new high-viscous polysaccharide polymyxan from Bacillus polymyxa 88A is described. Polymyxan consists of an acid high-viscous polysaccharide (Mw 1-10 MD) and a neutral low-viscous polysaccharide (Mw 100-300 kD), which is a glucomannan containing equal amounts of monosaccharides and traces of uronic acids. The acid high-viscous polysaccharide consists of 36% glucose, 36% mannose, 7% galactose and 21% glucuronic acid. Data are presented on the application of polymyxan in baking industry and for preparation of drilling muds.

The mutants of Azospirillum brasilense Sp245 altered in the production of anthranilic (Ant) and indolyl-3-acetic (IAA) acids were selected after the chemical or transposon facilitated mutagenesis and divided into the following three classes: Ant+IAA+, Ant+IAA- and Ant-IAA-. A hypothesis on the existence of a pattern for tryptophan conversion to anthranilate that is different from the classic pattern, and on the connection of the indolyl-3-acetic synthesis with this process is suggested.

Indole acetic acid (IAA) production in Azospirillum brasilense strain Sp245 is controlled by a 85 MDa plasmid naturally present in this bacterium. In the presence of L-tryptophan, anthranilic acid production and almost no IAA production occurs in a derivative strain harbouring a Tn5-Mob insertion in the 85 MDa plasmid. Agrobacterium tumefaciens strain GM19023, upon transfer of Tn5-Mob labelled 85 MDa plasmid of A. brasilense Sp245, gains the ability to produce anthranilic acid.

In the period between 1967 and 1985 the authors operated on 5 patients with chemodectoma; their ages ranged from 29 to 39. The duration of the disease ranged from 2 to 4 years. The tumor was on the right side in 3 and on the left side in 2 patients. Carotid angiography, which was conducted in all cases, revealed a richly vascularized tumor in the region of the carotid artery bifurcation with characteristic "angulation" and "cuff" signs. Damage to the carotid arteries was avoided during the operation in 3 patients and the chemodectoma was removed subadventitionally. In 2 patients the arteries were injured. There were neither neurological complications nor fatal outcomes.

The expressed difference in the plasmid profile of A. brasilense Sp245 is registered as a result of Tn5-Mob-mutability. Integration of the vector pSUP5011 into one of the A. brasilense Sp245 plasmid and using of the Tn5-Mob transposon to mobilize the 85Md cryptic plasmid are reported. The properties of A. brasilense Sp245 with the mutant plasmids composition (surface structure, acetylene and nitrate reduction, ability to a number of carbohydrates utilization, formation of melanin, antibiotics resistance specter) have been analyzed. The transposon Tn5-Mob insertion into the 85Md plasmid resulted in isolation of a mutant excreting a melanin-like pigment into the medium. The results suppose 85Md plasmid participation in melaninogenesis.

The effect of pH and MgCl2 concentration on the fluorescence of 1-anilinonaphthalene-8-sulfonate (ANS), an anion probe, was studied in suspensions of Staphylococcus aureus. The maximum of ANS fluorescence shifted towards the short wavelength region of the spectrum and its intensity increased when the cells were incubated in the medium with low pH and high ionic strength. The results are discussed in terms of electrostatic interactions between the anions of the probe and the negative space charge of the cell wall.

It was shown that mutants can occur in various microorganisms after a short-term exposure to electromagnetic field of 40 to 100 W/cm3 at 2375 MHz. Induction of mutants usually increases as the temperature rises and cell death rate grows to reach a maximum at a minimum survival rate. Colonial-morphological and biochemical phenotype changes are noted. Both specific and individual radiosensitivity are observed (from a 100 per cent loss of the studied character to the complete absence of the effect). Changes occur more frequently in the parameters determined by plasmids. There is a possibility to select thermoresistant variants without changing the genotype.

One hundred and forty one strains of Lactobacillus were isolated from intestinal contents of persons being in long-term contact with antibiotics. Their sensitivity to 10 chemotherapeutic agents was studied with the method of serial dilutions in solid media under aerobic and anaerobic conditions. A single administration of antibiotics in the therapeutic doses led to selection of Lactobacillus polyresistant strains in the intestine of rats. The antibiotic resistance spectrum of the Lactobacillus cultures was unstable and changed under nonselective conditions of their storage and after their lyophilization or short-term exposure to heat. The changes in the resistance spectrum were accompanied by changes in the plasmid profile. An electrophoretogram of plasmid DNA from the intestinal isolate L plantarum MT205 is presented. Relation between the marker of lincomycin resistance and the presence of plasmid DNA weighing 130 kb was shown in the isolate.

Peculiarities of dissociation in the cultures of nitrogen-fixating soil microorganism Azospirillum brasilense have been studied. The possible transfer among colony-morphology variants is established. The relations between variants are described by the following scheme: R in equilibrium with SR----S Electrophoretic analysis of plasmid contents in different variants of Azospirillum brasilense supposes the possible participation of plasmid DNA in the dissociation process in this microorganism.

Inheritance of the plasmid vector pAS8-1213 in Azospirillum brasilense Sp245 cells has been studied. The plasmid pAS8-1213 is shown to be uncapable of autonomous replication in the new host but able to integrate into the genetic structures of Azospirillum with high frequency. 90-95% of KmR-transconjugants of A. brasilense harbor pAS8-1213 cointegrated with the smaller host plasmid pAbSP245c(85Md). The formed cointegrate can be transferred into Azospirillum spp. 75 and RecA- strains of E. coli (HB101 and DH1) and stably maintained in these cells. The IS21 element inherent of the plasmid pAS8-1213 is supposed to participate in pAS8-1213::pAbSP245c cointegrate formation.