Cocultures of three Listeria species, L. monocytogenes, L, seeligeri, and L. innocua with Acanthamoeba castellanii, and Tetrahymena pyriformis, respectively, were investigated. The Listeria were ingested intracellularly by the protozoans. However, they were not killed, on the contrary, they survived. The two hemolytic Listeria species, i.e. L. monocytogenes and L. seeligeri ruptured their host cells completely after a few days and became free. Subsequently, they died. On the other hand, the apathogenic L. innocua partially lysed the protozoans and coexisted intracellularly as well as extracellularly for some weeks. Additionally, cocultures of L. monocytogenes, Escherichia coli, Salmonella typhimurium, and A. castellanii, T. pyriformis, respectively, were studied. The results showed that both protozoans possess similar distinct preferences for the Salmonella and Listeria, but E. coli was not desirable ‘prey.’ Ingested S. typhimurium were killed but L. monocytogenes survived. The observed phenomena provide a special insight regarding L. monocytogenes infection in man and animals in respect to the different behaviour patterns of the three Listeria species investigated.
The cytochrome absorption spectra of whole cell pastes and the co-enzyme Q system were analyzed in eighteen species in the yeast genera Candida and Pichia. C. silvanorum, C. entomophila and C. homilentoma had Co-Q 8 as the major component and Co-Q 6, 7 and 9 as minor components. The other yeasts had Co-Q 9 as the major component with Co-Q 8 as the first minor component associated with an additional Co-Q 7 in five species (C. shehatae, C. naeodendra, C. butyri, C. tenuis and C. fluviotilis) or Co-Q 10 in three others (C. diddensii, C. polymorpha and C. atmosphaerica). Pichia stipitis may no longer be considered as the perfect form of C. shehatae. These results confirmed that Co-Q system composition is a valuable tool for the chemotaxonomy of yeasts when used in conjunction with spectrophotometric analysis of cytochromes and other techniques such as GC content, DNA/DNA hybridization or serology.
An Escherichia coli mutant was isolated which overproduces component γ of penicillin-binding protein (PBP)-1Bs. The mutant formed normal amounts of components α and its proteolytic product β. The mutation was located in mrcB, the structural gene coding for PBP-1Bα and γ. The overproduction of the mutant-type PBP-1Bγ was caused by an alteration of one nucleotide which changed the GGC coding for glycine at residue 8 from the N-terminal of PBP-1Bγ to GAC coding for aspartate.
The composition of free amino acids in nitrogen-fixing cells of Anabaenacylindrica was changed by varying the ratio of N2 to CO2 in the gas phase of the medium. Glutamate, aspartate and alanine were the major components in the free amino acid pool of cells incubated in the light and with air supplemented with 0.5% CO2. When the cells were bubbled with pure N2, cellular glutamine, citrulline and arginine increased while glutamate decreased. Adding NH+4 in the dark stimulated the increase of glutamine but not citrulline. Light was required for the rapid synthesis and accumulation of citrulline. Carbonylcyanide metachlorophenylhydrazone (CCCP), which inhibits ATP synthesis, suppressed the NH+4- timulated increase in citrulline in the light. It is concluded that the balance in nitrogen and carbon supply and cellular ATP level determined the metabolism of glutamine, which changed the composition of the cellular free amino acid.
Determination of nucleotide sequence of a 2.8kb DNA fragment involving the murG and murC genes has completed the sequencing of the total 12kb mra region at 2min on the Escherichia coli chromosome map, which functions in the growth and division of the cell. Product proteins of the genes in the mra region have also been identified, of which the MurC and MurG proteins are reported here. Considerable homologies were found in the deduced amino acid sequences of four ligases, products of the murC, murD, murE and murF genes in the mra region. These synthesize UDP-N-acetylmuramyl-pentapeptide from UDP-N-acetylmuramic acid in peptidoglycan synthesis. The MurG protein, also involved in the cell growth of E. coli, showed considerable homology of the deduced amino acid sequence with that of a peptide coded for by an open reading frame in the spoVE-ftsZ region of the B. subtilis chromosome.
Organic fractions in municipal sewage sludge were markedly digested by a mixture of 11 strains of thermophilic bacilli (9 strains of Bacillusstearothermophilus and 2 strains of Thermus sp.) isolated from sewage sludge compost. The organic fractions were also digested by the culture extract of the mixture of the bacilli grown on a medium containing the sewage sludge. The culture extract contained some lytic enzymes, with digestive activities on freeze-dried sewage sludge and on scleroproteins, so it was concluded that the proteolytic activity may be useful as a specific easure for composting activity and that these thermophilic bacilli can partially digest or mineralize municipal sewage sludge.