Biomedical subjects

F Crociani

Publications and source records attributed to F Crociani.

22 records · Page 2Linked to original sources

PubMedDate not supplied

Antimicrobial susceptibility of Bifidobacterium.

The susceptibility pattern of 459 strains of bifidobacteria, representing 15 species, to 16 antimicrobial agents was determined by the broth dilution method. The majority of the strains derived from human faeces. Penicillin G, erythromycin, clindamycin, vancomycin and bacitracin were the most active compounds; they inhibited 90% of the strains at less than 1.6 micrograms/ml. All strains were susceptible to chloramphenicol (MIC90 = 2.0-5.8 micrograms/ml) and also to lincomycin (MIC50 = 0.64-1.5 micrograms/ml). Neomycin, streptomycin and tetracycline presented a great variability in their activity. Most strains were resistant to polymyxin B, nalidixic acid, kanamycin, gentamicin and metronidazole. The only variation in susceptibility which was observed among the different species concerned Bifidobacterium suis, which generally appeared to be more resistant than other species.

Actinomycetaceae↗

PubMedDate not supplied

Urease activity in the genus Bifidobacterium.

The urease activity of 414 strains representing 21 species of the genus Bifidobacterium was surveyed. The strongest ureolytic strains belong mostly to the species B. suis and only a few to B. breve, B. magnum and "subtile" homology group. The study of some strongly ureolytic strains showed that urea and organic nitrogen concentration did not influence urease production. The high urease activity found also in the absence of urea suggested that this enzyme is not inducible. An ammonia concentration of 14 mM did not repress urease activity.

Actinomycetaceae↗

PubMedDate not supplied

Amino acids produced by bifidobacteria and some Clostridia.

A lot of 121 strains of bifidobacteria and 9 strains of clostridia were examined for their ability to release free amino acids in the culture broth. The bifidobacteria studied belong to 18 species or "homology group" and the clostridia to 8 species. The growth in a synthetic medium with ammonium salts as sole nitrogen source was also studied. All the clostridia and the majority of the bifidobacteria produce various amino acids. The possible ecological significance of these findings is suggested.

Amino Acids↗

PubMedDate not supplied

Regulation of dihydrodipicolinate synthase and diaminopimelate decarboxylase activity in Bacillus stearothermophilus.

The feedback inhibition of the enzymes dihydrodipicolinate (DHDPS) and diaminopimelate decarboxylase (DAPD) in the wild strain Zu 183 of Bacillus stearothermophilus and in its S-(2-aminoethyl)-cysteine resistant L-lysine overproducing strain AEC 12 was studied. The optimum temperature and pH of both enzymes were also evaluated. No inhibition of DHDPS by L-lysine, L-threonine, L-methionine and L-isoleucine was observed either in the wild strain or in the AEC 12 mutant. DAPD was completely inhibited by L-lysine and only partially by L-threonine and L-methionine in Zu 183 and AEC 12 strains, but the concentration required was found to be much higher in the AEC 12 strain. The regulation mechanism of L-lysine biosynthesis in Bacillus stearothermophilus Zu 183 was also discussed.

Bacterial Proteins↗