Ultrastructural changes in some pathogenic bacteria after treatment with ethylendiamintetraacetic acid.

The ultrastructure of Pseudomonas pseudomallei, Pseudomonas aeruginosa. Yersinia pseudotuberculosis, Salmonella typhimurium, Listeria monocytogenes was studied after treatment with EDTA. The study established that the most sensitive species were: Pseudomonas pseudomallei and Pseudomonas aeruginosa. In the case of Listeria monocytogenes changes were not observed. Typical ultrastructural changes in the cell wall and the cytoplasmic membrane were established by means of ultrathin sections, as well as with scanning electron microscopy of Pseudomonas pseudomallei and Pseudomonas aeruginosa.

Influence of D,L-ureidosuccinic acid dihydrazide on some biological properties of Pseudomonas pseudomallei and of Salmonella typhimurium.

The changes induced in strains of Pseudomonas pseudomallei and Salmonella typhimurium under the action of D.L-ureidosuccinic acid dihydrazide were characterized. A decrease of the speed of multiplication in vitro and of the oxygen consumption was established. The virulence of the strains was reduced and their susceptibility to phagocytosis in vitro was increased.

On the metabolic characteristics of hybrids Shigella flexneri x Escherichia coli, devoid of their ability for intracellular multiplication in the epithelial cells. IV. Growth characteristics in the presence of some tricarboxylic acid cycle intermediates.

The dynamics of avirulent xyl-str and xyl + hybrids Sh. flexneri was investigated in minimal medium in the presence of some tricarboxylic acid cycle intermediates (succinate, malate, fumarate) and pyruvate. It was established that the hybrids with a replaced xyl-str or xyl-region show a considerably lower rate of multiplication in artificial media than the virulent recipient strains.

On the metabolic characteristics of Shigella flexneri X Escherichia coli, devoid of ability for intracellular multiplication in epithelial cells. III. Oxygen uptake and dehydrogenase activity.

The oxygen uptake and dehydrogenase activity of avirulent xyl+ and xyl- str hybrids (KCP-), obtained from virulent strains Sh. flexneri (Sh. flexneri 222 5 a and Sh. flexneri M42-432a) and donor strain E. coli AB 313, devoid of ability for intracellular multiplication in epithelial cells are studied. Some tricarboxylic acid intermediates, hexoses and pentoses were used as substrates. A definite tendency has been established, indicating a decreased rate of oxygen consumption and dehydrogenase activity of the hybrids, compared to the respiratory activity of the virulent recipient strains tsh. flexneri in all substrates used.

Studies on the energetic metabolism of Shigella flexneri x Escherichia coli hybrids devoid of penetration ability. IV. Growth characteristics in the presence of some tricarboxylic acid cycle intermediates.

The dynamics of avirulant lac+KCP- hybrids Sh. flexneri multiplication was investigated in minimal medium in the presence of some tricarboxylic acid cycle intermediates (fumarate, succinate, malate) and pyruvate. It was established that in spite of the loss of virulence in the rate of the multiplication of the hybrid strains, in comparison with that of the virulent recipient strains of Sh. flexneri, considerable differences were not observed.

On the metabolic characteristic of hybrids Shigella flexneri x Escherichia coli devoid of their ability for intracellular multiplication in the epithelial cells. I. Glycolysis.

The glycolysis (aerobic and in the presence of KCN) of avirulent xyl+ and xyl-str hybrids Sh. flexneri x E. coli, devoid of their ability to multiply intracellularly in the epithelial cells, is studied. It is established that their glycolytic activity is considerably higher than the activity of the donor strain E. coli, and deviate significantly compared with shown activity of the virulent recipient strains Sh. flexneri. Xyl-str hybrids are showing high values of glycolysis in aerobic conditions and in the presence of KCN, while in xyl+ hybrids very active glycolysis is observed only in the presence of KCN - probably completely sufficient for the persistence of bacteria in the host-cell at anaerobic conditions.

On the metabolic characteristic of hybrids Shigella flexneri x Escherichia coli devoid of their ability for intracellular multiplication in the epithelial cells. II. Catalase and phosphatase activity.

The catalase and phosphatase activity of avirulent by keratoconjunctival test of guinea pigs xyl+ and xyl-str (KCP-) hybrids that have lost their ability for intracellular multiplication, received from virulent strains. Sh. flexneri (Sh. flexneri 222 5 a and Sh. flexneri M42-43) and donor strain E. coli AB 313 was investigated. It is established that there is a definite dependence between the changes in the catalase and the phosphatase activities of the hybrid strains and the newly received by the hybridization genetic information. The enzyme activity of the hybrid strains always correlated with the level of this activity in the donor strains E. coli.

Studies on the energetic metabolism of Shigella flexneri x Escherichia coli hybrids devoid of penetration ability. III. Catalase and phosphatase activity.

The catalase and phosphatase activity of avirulent by keratoconjunctival test of guinea pigs lac+, kcp- hybrids that have lost their ability of penetrating in the epithelium, received from virulent strains Shigella flexneri (Sh. flexneri 222 5a and Sh. flexneri M42-43) and donor strains Escherichia coli (E. coli K-12, P4x and E. coli H) was investigated. It was established that there is no any dependence between the lost of virulence of the hybrids and the level of the catalase activity. During the study of the phosphatase activity it was established, that in comparison with the recipient virulent shigella strains, the investigated avirulent lac+-hybrids revealed higher values of the enzyme activity.

Studies on the energetic metabolism of Shigella flexneri and Escherichia coli hybrids devoid of penetration ability. II. Oxygen uptake and dehydrogenase activity.

Oxygen uptake and dehydrogenase activity are studied with lac+ kcpminus hybrids of Shigella flexneri, being avirulent to the eyes of guinea pigs, because of having lost ability for penetration in epithelial cells. These strains were obtained by hybridization of the virulent strain Shigella flexneri 222 5 a with the Hfr strain Escherichia coli K-12 P4x. It is established that lac+ kcp minus hybrids are characterized by significant decrease of respiratory activity. This decrease is outlined as a tendency studying O2 uptake and is extremely well expressed studying the dehydrogenase activity. The tests being performed with these hybrids show that the loss of virulence and connected with it the loss of the ability for penetration is related to a decrease of the respiratory activity of these bacteria which supply a part of the energy needed for their viability.

Studies on the energetic metabolism of Shigella flexneri times Escherichia coli hybrids devoid of penetration ability I. Glycolysis.

The aerobic and anaerobic (in presence of KCN) glycolysis is studied of avirulent hybrids of Shigella flexneri according to the keratoconjunctivitis test of Sereny with genetic characteristics lac-+kcp-minus devoid of penetration ability. It is established that lac-+kcp-minus hybrids which have lost their ability to penetrate the cells due to replacement of KCP-gene of the chromosome of donor strain E. coli K-12 P4 times, are characterized with a steep decrease of their glycolitic activity in both aerobic and anaerobic conditions. The data shows that the loss of penetrate ability of the Shigella flexneri hybrids correlates with the decrease of their glycolitic ability.