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M Surdeanu

Publications and source records attributed to M Surdeanu.

At least 19 recordsLinked to original sources
PubMed1976

Porphobilinogen-accumulating mutants of Salmonella typhimurium LT2.

Four independent porphobilinogen-accumulating mutants of Salmonella typhimurium LT2 were isolated by selecting for dwarf colony formation on neomycin agar media. Cell-free extracts of the parent strain, but not of the mutants, were able to convert 5-aminolaevulinic acid or porphobilinogen to porphyrins. The results indicated that the mutants were deficient in uroporphyrinogen I synthase (EC. 4.3.I. 8) activity: these are the first mutants of this type reported in S. typhimurium LT2. Mapping of the hemC locus (for uroporphyrinogen I synthase) by F-mediated conjugation and by P22-mediated transduction showed the gene sequence ilvEDAC-hemC-cya-metE.

Aminolevulinic Acid↗
PubMed1976

Two restriction and modification systems in Staphylococcus aureus NCTC8325.

The presence of two distinct host specificities in Staphylococcus aureus strain NCTC8325 was revealed by the isolation of restriction- and modification-deficient mutants. The two host specificity systems, designated S1 and S2, are both active on phage 80mualpha but are not additive in their restricting activity. Restriction-deficient, modification-proficient mutants were invariably affected in both restriction systems. The functional relationship between these two systems is discussed.

DNA, Bacterial↗
PubMed1970

Hemin-deficient mutants of Salmonella typhimurium.

Nine hemin-deficient mutants of Salmonella typhimurium LT2 were isolated as neomycin-resistant colonies. Five of these mutants could be stimulated by Delta-aminolevulinic acid (Delta-ALA), thus representing hemA mutants. Since S. typhimurium LT2 is not able to incorporate hemin, the identification of the mutants not stimulated by Delta-ALA was made on the basis of the simultaneous loss of catalase activity and cytochromes. The hemA gene was mapped by conjugation in the trp region, probably in the order purB-pyrD-hemA-trp; the episome FT(71)trp does not carry the hemA gene. Transductional intercrosses by phage P22 indicate that hemA 11, 12, 13, and 37 are at very closely linked sites, whereas hemA14 is at a more distant site in the same or an adjacent gene. No joint transduction was detected between hemA and trp or pyrF. The loci affected in the other hemin-deficient mutants were linked in conjugation to the pro(+) marker (frequency of linkage, 88 to 97%), but cotransduction of the two markers could not be obtained. The episome F lac hem purE, which originates from Escherichia coli K-12, could complement these hemin-deficient mutants of S. typhimurium LT2. As a result, the sequence of the markers on the chromosome of S. typhimurium LT2 is probably pro heme purE, analogous to the sequence found in E. coli K-12. Thus, the chromosome of S. typhimurium also possesses two hem regions, with a location similar to that described in E. coli K-12.

Amino Acids↗
PubMedDate not supplied

[Sensitivity to antibiotics and chemotherapeutic agents in some strains of Salmonella typhi isolated in Romania during the period 1974-1976].

Investigations were carried out on 781 S. typhi strains isolated from patients and carriers. Testing of the sensitivity to chemotherapeutical agents by diffusiometry and the incorporation technique led to the detection of four resistant strains: 1 strain isolated by coproculture from a carrier since 1958, resistant to A, K, N, Ca and Cf and 3 strains isolated by coproculture, biliculture and uroculture from a carrier since 1974, resistant to A and Ca. The R factors of these strains were transferred in their totality. The resistant strains did not manifest any particular pathogenicity for the laboratory animal, and their immunogenic potential was below that of the current typhoid vaccine. None of the 781S typhi were resistant to Cmx, C, G, T, Co and Po. Consequently, in Romania Chloramphenicol may be used in continuation in the treatment of typhoid fever, and Cotrimoxazol, Gentamycin, Tetracyclin and Ampicillin are and remain reserve substitutes. The possible unexpected appearance of resistant S. typhi strains demand, however, further control of the sensitivity to chemotherapeutics of all the isolated strains.

Anti-Bacterial Agents↗