Growth of Pseudomonas aeruginosa PAO1 at 15 to 45°C in tryptic soy broth resulted in changes in the lipids, lipopolysaccharides (LPSs), and outer membrane proteins of the cells. Cells grown at 15TC contained, relative to those cultivated at 45°C, increased levels of the phospholipid fatty acids hexadecenoate and octadecenoate and reduced levels of the corresponding saturated fatty acids. Furthermore, the lipid A fatty acids also showed thermoadaptation with decreases in dodecanoic and hexadecanoic acids and increases in the level of 3-hydroxydecanoate and 2-hydroxdodecanoate as the growth temperature decreased. In addition, LPS extracted from cells cultivated at the lower temperatures contained a higher content of long-chain S-form molecules than that isolated from cells grown at higher temperatures. On the other hand, the percentage of LPS cores substituted with side-chain material decreased from 37.6 mol% at 45°C to 19.3 mol% at 15°C. The outer membrane protein profiles indicated that at low growth temperatures there was an increase in a polypeptide with an apparent molecular weight of 43,000 and decreases in the content of 21,000 (protein Hl)-and 27,500-molecular-weight proteins.Since Pseudomonas aeruginosa is ubiquitous in nature and is a demonstrated pathogen for plants and insects as well as mamnmals we are interested in the changes that temperature may have on the cellular chemistry, particularly as it affects membrane lipids, lipopolysaccharides (LPSs), and outer membrane proteins. P. aeruginosa strains contain both ester-and amidebonded fatty acids. 3-Hydroxydodecanoic acid (3-OH C12:0) is found amide linked to C-2 of glucosamine residues in the lipid A component of LPS (9, 10). The lipid A also contains ester-bound 3-hydroxydecanoate (3-OH C10:0), dodecanoate (C12:0), 2-hydroxydodecanoate (2-OH C12:0), and a small amount of hexadecanoate (C16:0 141]). The chloroformmethanol-extractable cellular lipids (neutral and phospholipids) contain predominantly hexadecanoic (C16:0), hexadecenoic (C16:1), octadecanoic (C18:0), and octadecenoic (C18i1) acids (14,32,33). In addition, variable amounts of other fatty acids have been observed, including 17-and 19-cyclopropane acids and tetradecanoate (14, 32, 33). While the effects of temperature on the fatty acid profiles of a number of microorganisms, including psychrophilic Pseudomonas species, have been studied in detail (3,4,12,13, 20,21,26,29,31,35), only one study has been done on thermal adaptation of P. aeruginosa. The experiments of Gill and Suisted (13) with P. aeruginosa grown in a chemostat under conditions of nitrogen limitation showed that the extractable lipids of these cells possessed an increased content of unsaturated fatty acids when cultivated at suboptimal temperatures.Studies on the effect of growth temperature on LPS chemistry have been largely restricted to members of the family Enterobacteriaceae. Modifications to the composition of the lipid A component of LPS isolated from Salmonella species (43) We have demonstrated, on the basis of incr...
A detailed study of the cultural characteristics and cellular fatty acid composition of 27 isolates of Corynebacterium acnes was performed to establish the properties by which this organism may be identified and characterized. The fatty acids were extracted directly from whole cells and examined as methyl esters by gas-liquid chromatography. Each strain possessed a similar fatty acid profile which was characterized by a large percentage of C15 branched-chain acid. Uniformity in certain biochemical reactions and cultural characteristics was also observed. All strains were catalase-positive, nonmotile, and urease-negative, reduced nitrate, liquefied gelatin, failed to hydrolyze esculin and starch, and gave a positive methyl red test. Glucose, fructose, and glycerol were fermented, but not lactose, salicin, sucrose, maltose, xylose, or arabinose. Production of hydrogen sulfide and indole, fermentation of mannitol, and hemolytic activity were variable characteristics. Two species of the genus Propionibacterium were also tested and found to be similar to C. acnes both in cultural characteristics and fatty acid composition. The results strengthen previous suggestions that C. Propionibacterium. acnes should be classified in the genus VOL.
The susceptibility of the Legionnaires disease bacterium to various antimicrobial agents was determined by inoculation of embryonated eggs via the yolk sac. When administered prophylactically, the minimal dose of drug preventing all deaths due to the infection was as follows: rifampin, 0.02 mg; gentamicin, 0.25 mg; streptomycin, 0.39 mg; erythromycin, 0.62 mg; sulfadiazine, 1.56 mg; chloramphenicol, 2.50 mg; and cephalothin, 20.0 mg. Smaller amounts delayed deaths, and larger or equal amounts rendered the embryos free of infection. Oxytetracycline in the largest tested amount, 5.0 mg, protected 80% of the embryos from death, and as little as 0.31 mg delayed death. Chlortetracycline (0.50 mg) and ampicillin (10.0 mg) were ineffective. The six most effective drugs were studied in an experiment in which they were administered at various times after infection in doses that were twice the minimal prophylactic dose preventing all deaths. In this therapeutic experiment, rifampin, and erythromycin allowed 100% survival when given even 72 h after infection; gentamicin, streptomycin, sulfadiazine, and chloramphenicol did so when given 48 h after infection. All six drugs increased mean survival time when administered 72 h after infection.
CHERRY. Technical considerations in the preparation of fluorescent-antibody conjugates. Appl. Microbiol. 12:343-348. 1964. A comparison was made of (NH4)2SO4, HCl, ethodin, and ethanol for fractionation of rabbit antiserum prior to conjugation with fluorescein isothiocyanate. Fractionation with the salt was found to be the method of choice from the standpoints of simplicity and recovery of antibody effective in conjugates prepared from the fractions. Effects of pH, temperature, dye-protein ratio, and molarity and type of buffer upon conjugation were studied. These technical factors were adjusted to produce conjugates for Corynebacterium diphtheriae which possessed higher specific titers than did reagents obtained by previously employed techniques.
Duplicate cultures of 53 strains representing 9 species of Neisseria were analyzed by gas-liquid chromatography for cellular fatty acids. N. sicca, N. mucosa, N. flava, N. flavescens, N. perflava, N. subflava, and the several serotypes of N. meningitidis
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