The assimilation of amino-acids by bacteria; the effect of protein synthesis on glutamic acid accumulation and the action thereon of sulphathiazole.
TL;DR: The level of free glutamic acid accumulating within cells of certain Gram-positive cocci is lower in growing cells than in ‘resting’ cells, other conditions being equal.
Abstract: SUMMARY: The level of free glutamic acid accumulating within cells of certain Gram-positive cocci is lower in growing cells than in ‘resting’ cells, other conditions being equal. Part of the glutamic acid assimilated by growing Staphylococcus aureus is condensed into peptides or proteins, thus accounting for this apparent drop in glutamic acid accumulation. Sulphathiazole interferes with this condensation of glutamic acid into peptide form.
Citations
More filters
TL;DR: The essential feature of an enzymatically controlled transport is a combined action of two surface enzymes separated by the cell membrane, whereby the substrate is temporarily changed to a membrane-soluble transport form capable of penetrating the membrane.
Abstract: Publisher Summary The cell membrane is considered as a passive structure allowing solutes to penetrate according to the properties of their molecules, such as size, membrane solubility, and electric charge. Membrane is a part of the cell machinery, which contains special enzymes, participating both in the control of cell metabolism and in the transport of substances. The essential feature of an enzymatically controlled transport is a combined action of two surface enzymes separated by the cell membrane, whereby the substrate is temporarily changed to a membrane-soluble transport form capable of penetrating the membrane. The identification of a transport as enzymatically controlled meets with greater difficulties if it is not thermodynamically active. Indirect criteria then have to be used. They include (1) non-conformity with the laws of diffusion, particularly a constant penetration rate independent of the concentration difference, (2) competition of simultaneously penetrating substrates, (3) high structural specificity, particularly stereospecificity, and (4) action of enzyme effectors (inhibitors or activators) on the rate of transport.
100 citations
TL;DR: This chapter discusses the assimilation of amino acids by gram-positive bacteria, species of bacteria that are unable to synthesize amino acids, assimilates the preformed substances, to form suitable material for the study.
Abstract: Publisher Summary This chapter discusses the assimilation of amino acids by gram-positive bacteria. The growth of the bacterial cell involves, and is the result of, synthesis of all its components. Many bacteria can synthesize protein from ammonia and a carbon source, such as glucose. “Biochemical mutants” of molds and bacteria have indicated the probable biosynthetic pathways and individual steps in pathways that have been studied with cell-free extracts of microorganisms. Species of bacteria that are unable to synthesize amino acids, assimilates the preformed substances, to form suitable material for the study. Experimental correlations among the various processes are observed, and certain stages in the processes are found to be sensitive to antibiotics and growth inhibitors.
87 citations
72 citations
TL;DR: Comparison of the general properties of normal and penicillin-inactivated cells show that the respiration, glucose oxidation, glucose fermentation and lysine assimilation of the latter are normal.
Abstract: SUMMARY: The effect on glutamic acid assimilation of the addition of penicillin to growing cultures of Staphylococcus aureus is described. When Staph, aureus is grown in media containing glutamic acid this substance accumulates in steadily increasing concentration in the cells. The addition of penicillin to the medium is followed after an interval by rapidly decreasing concentration of glutamic acid within the cells. The assimilation of glutamic acid by normal washed cells is not affected by penicillin in high concentration. The assimilation of glutamic acid by cells which have grown in the presence of penicillin is impaired and may be completely inhibited. Complete inhibition of assimilation is brought about by bactericidal concentrations of penicillin, low concentrations requiring a longer time to become completely effective than high ones. The loss of assimilatory power can be correlated with loss of viability. Comparison of the general properties of normal and penicillin-inactivated cells show that the respiration, glucose oxidation, glucose fermentation and lysine assimilation of the latter are normal. The internal metabolism of glutamic acid is normal in penicillin-treated cells, but, since the passage of glutamic acid across the cell wall is blocked, is limited by the existing internal concentration.
57 citations
TL;DR: It is thought that the essential growth factor for PPLO furnished by serum or ascitic fluid is a protein of low molecular weight, possibly of the globin type, or a degradation product of protein.
Abstract: A characteristic of the parasitic pleuropneumonialike organisms (PPLO) is the requirement of serum or ascitic fluid for growth in vitro. Reference has been made by previous workers to some of the properties of the growth factor contained in serum. Tang, Wei, McWhirter, and Edgar (1935) reported that a hemoglobin solution had an enriching property for the bovine pleuropneumonia organisms. The apparent heat stability of this growth factor was alluded to by Nelson (1939). Tissue cultures employed for the cultivation of the fowl coryza bodies, considered to be PPLO, still supported their growth after being heated at 100 C for 1 hour or being stored in the refrigerator for 6 months. Chocolate agar, used for isolating the gonococcus, supported growth of PPLO according to Salaman (1946). Gilmore and Sprince (1949) reported that as little as 0.02 per cent bovine hemoglobin (Armour) permitted growth of PPLO in a liquid medium in the absence of serum. It was emphasized by Morton, Smith, and Leberman (1949) that native animal protein was unnecessary when these investigators observed symbiotic growth of PPLO with bacteria. Since the PPLO comprise a group of microorganisms with peculiar properties and the addition of serum or ascitic fluid to the medium is undesirable for many types of experiments, an attempt was made to isolate and characterize the growth factor present in serum and ascitic fluid. On the basis of work to be reported, it is thought that the essential growth factor for PPLO furnished by serum or ascitic fluid is a protein of low molecular weight, possibly of the globin type, or a degradation product of protein.
44 citations