scispace - formally typeset
Search or ask a question

Showing papers on "Bacteria published in 1973"



Journal ArticleDOI
TL;DR: Various species of Streptomyces possess aminoglycoside-modifying enzymes that catalyze reactions identical to those catalyzed by enzymes found in gram-negative bacteria containing R(antibiotic resistance)-factors, suggesting the possibility of an evolutionary relationship between these enzymes and the R-factors.
Abstract: Various species of Streptomyces possess aminoglycoside-modifying enzymes. Streptomyces kanamyceticus contains an enzyme that acetylates the 6′-amino group of kanamycin A and B, gentamicin C1a, and neomycin. Streptomyces spectabilis produces an enzyme that acetylates the 2′-amino group of the hexose ring of gentamicin C1a. These enzymes catalyze reactions identical to those catalyzed by enzymes found in gram-negative bacteria containing R(antibiotic resistance)-factors. The discovery of these enzymes suggests the possibility of an evolutionary relationship between the aminoglycosideinactivating enzymes (produced by resistance determinants) in bacteria containing R-factors and similar enzymes found in the actinomycetes.

493 citations



Journal ArticleDOI
TL;DR: It is suggested that a likely explanation for the survival of phagocytized bacteria in the presence of high concentrations of most antibiotics is the inability of the antibiotic to enter the phagocyte.
Abstract: Bacteria that survive inside polymorphonuclear neutrophils (PMN) following phagocytosis are protected from the bactericidal action of most antibiotics. Two possible explanations are altered metabolism by intraleukocytic bacteria or failure of antibiotics to enter the phagosome. The oxygen consumption of intraleukocytic and extraleukocytic bacteria was measured as an index of bacterial metabolism. PMN respiration and bactericidal activity were suppressed with large doses of hydrocortisone and extraleukocytic bacterial oxygen consumption was abolished by the addition of lysostaphin. Intraleukocytic bacterial continued to consume oxygen suggesting that surviving ingested micro-organisms are metabolically active. Neither penicillin (which cannot kill intraleukocytic bacteria) nor rifampin (which can kill intraleukocytic bacteria) was bactericidal for staphylococci at 5 degrees C. Thus, rifampin is not uniquely able to kill "resting" bacteria.Intraleukocytic or extraleukocytic Staphylococcus aurens were incubated with [benzyl-(14)C]penicillin for 2 h at 37 degrees C. Live intraleukocytic bacteria bound only 13% as much penicillin as live bacteria incubated with killed PMN. To measure the penetration of antibiotics into PMN, [(14)C]rifampin and [(14)C]penicillin were measured in leukocyte pellets and in the supernatant fluid. The total water space in the pellets was quantitated using tritium water and the extracellular water space was measured using Na(235)SO(4). All penicillin associated with the cell pellet could be accounted for in extracellular water. Thus penicillin was completely excluded from the leukocytes. Rifampin was concentrated in the cell pellet 2.2 times when compared with the supernatant concentration. These studies suggest that a likely explanation for the survival of phagocytized bacteria in the presence of high concentrations of most antibiotics is the inability of the antibiotic to enter the phagocyte. Rifampin, which is highly lipid soluble, can enter leukocytes and kill intracellular bacteria.

217 citations


Journal ArticleDOI
TL;DR: Results of a brining experiment indicated that oleuropein is degraded to antibacterial compounds when unheated olives are brined, a possible explanation for the previously reported observation that heating olives prior to brining renders them more fermentable by lactic acid bacteria.
Abstract: Oleuropein, the bitter glucoside in green olives, and products of its hydrolysis were tested for antibacterial action against certain species of lactic acid bacteria involved in the brine fermentation of olives. Oleuropein was not inhibitory, but two of its hydrolysis products, the aglycone and elenolic acid, inhibited growth of the four species of lactic acid bacteria tested. Another hydrolysis product, β-3,4-dihydroxyphenylethyl alcohol, was not inhibitory. The aglycone of oleuropein and elenolic acid were much more inhibitory when the broth medium contained 5% NaCl; 150 μg of either compound per ml prevented growth of Lactobacillus plantarum. A crude extract of oleuropein, tested by paper disk bioassay, was inhibitory to 3 of 17 species of bacteria screened, none of which were lactic acid bacteria. The acid hydrolysate of the extract was inhibitory to 11 of the bacteria, which included four species of lactic acid bacteria and other gram-positive and gram-negative species. Neither crude preparation was inhibitory to growth of the seven species of yeasts tested. A possible explanation is given for the previously reported observation that heating (3 min, 74 C) olives prior to brining renders them more fermentable by lactic acid bacteria. Results of a brining experiment indicated that oleuropein is degraded to antibacterial compounds when unheated olives are brined.

195 citations


Journal ArticleDOI
TL;DR: The intact lipopolysaccharide layer of gram-negative organisms apparently screens the cells against medium and long-chain fatty acids and prevents their accumulation on the inner cell membrane at inhibitory concentrations, which are relevant to the use of antimicrobial food additives.
Abstract: Growth, amino acid transport, and oxygen consumption of Escherichia coli and Salmonella typhimurium are inhibited by short-chain (C(2)-C(6)) but not by medium or long-chain fatty acids (C(10)-C(18)) at concentrations at which these processes are completely inhibited in Bacillus subtilis. The resistance of gram-negative organisms is not correlated with their ability to metabolize fatty acids, since an E. coli mutant unable to transport oleic acid is still resistant. However, mutants of both E. coli and S. typhimurium in which the lipopolysaccharide layer does not contain the residues beyond the 2-keto-3-deoxyoctonate core are inhibited by medium (C(10)) but not by long-chain (C(18)) fatty acids. Furthermore, removal of a portion of the lipopolysaccharide layer by ethylenediaminetetraacetate treatment renders the organisms sensitive to medium and partially sensitive to long-chain fatty acids. The intact lipopolysaccharide layer of gram-negative organisms apparently screens the cells against medium and long-chain fatty acids and prevents their accumulation on the inner cell membrane (site of amino acid transport) at inhibitory concentrations. These results are relevant to the use of antimicrobial food additives, and they allow the characterization of gram-positive versus gram-negative bacteria and their lipopolysaccharide mutants.

172 citations


Journal ArticleDOI
TL;DR: A modification of the broth-disk method of Schneierson allowed us to determine antibiotic susceptibility in a completely anaerobic environment and there was good correlation between results obtained by this broth- disk method and minimal inhibitory concentrations.
Abstract: The most commonly used method for testing the antibiotic susceptibility of aerobic and facultative bacteria is the disk diffusion method. However, some anaerobic bacteria do not grow well enough in anaerobic jars for performance of disk diffusion tests. A modification of the broth-disk method of Schneierson allowed us to determine antibiotic susceptibility in a completely anaerobic environment. Commercial antibiotic disks were added anaerobically to tubes of prereduced brain heart infusion broth to achieve a concentration of each antibiotic approximating that attainable in blood. The tubes were then inoculated and incubated for 18 h. Resistance or susceptibility to each antibiotic was determined according to the amount of growth in each tube as compared with a control culture without the antibiotic. There was good correlation between results obtained by this broth-disk method and minimal inhibitory concentrations.

166 citations



Journal ArticleDOI
TL;DR: A nitrite actidione polymyxin agar was developed for the enumeration of lactic acid bacteria and was effective in recovering organisms from pure cultures and from foods.
Abstract: A nitrite actidione polymyxin agar was developed for the enumeration of lactic acid bacteria. It was effective in recovering organisms from pure cultures and from foods.

130 citations


Journal ArticleDOI
01 Aug 1973
TL;DR: The effects of freezing on bacterial cells have been studied essentially for three purposes: to understand the underlying physical and chemical changes that occur during freezing of biological materials, to elucidate the possible changes brought about by freezing and thawing of bacterial cells, and to develop means for successful freezing of higher forms of cells.
Abstract: (1973). Freeze-Injury in Bacteria. CRC Critical Reviews in Clinical Laboratory Sciences: Vol. 4, No. 2, pp. 161-213.

129 citations


Journal ArticleDOI
TL;DR: Significant differences were observed among the fatty-acid patterns of the various bacterial genera included in the set of 20 strains examined, and rapid differentiation of most of the genera could thus be accomplished.
Abstract: Fatty-acid compositions were determined for 20 strains of marine and estuarine bacteria and two strains representative of terrestrial species. Results showed that the fatty acids of marine bacteria differed little from those of nonmarine organisms, and a primary role for hexadecenoic acid was indicated. Of the 20 strains examined, with the exception of one, the major fatty-acid species were C16, C16:1, and C18:1. Significant differences were observed among the fatty-acid patterns of the various bacterial genera included in the set of 20 strains examined, and rapid differentiation of most of the genera could thus be accomplished. A recently isolated marine species demonstrated a unique fatty-acid pattern wherein branched acids formed the major fatty-acid class. Effects of culture age, growth temperature, and salt concentration of the medium on the fatty-acid profiles were also investigated.

Journal ArticleDOI
TL;DR: From the morphological and physiological properties of the isolated bacteria, the genus of the bacteria was considered to be Pseudomonas or a close...
Abstract: The bacteria capable of degrading pentachlorophenol (PCP) were isolated from soil. In the soil perfused with 40 ppm PCP solution, PCP was decomposed and five chlorine atoms of PCP were liberated as chloride ion after about 3 weeks. Re-addition of PCP after its degradation, accelerated the rate of PCP degradation and de-chlorination. After the addition of PCP to the soil three times, bacteria which grew on PCP agar were counted to be about 2 × 107 per gram dry soil. In the liquid medium inoculated with the perfused soil, PCP degradation and complete de-chlorination were found. In this case, multiplication of bacteria capable of growing on PCP agar was found. The bacteria capable of growing on and degrading PCP in the medium with inorganic salts and 40 ppm PCP as a sole source of carbon were isolated from the agar plates for enumeration of the bacteria. From the morphological and physiological properties of the isolated bacteria, the genus of the bacteria was considered to be Pseudomonas or a close...

Journal ArticleDOI
TL;DR: Phospholipid compositions of 20 strains of marine and estuarine bacteria were determined and it was suggested that phylogenetic relationships among bacteria may be correlated with phospholipids.
Abstract: Phospholipid compositions of 20 strains of marine and estuarine bacteria were determined. Results showed that phospholipids of marine bacteria differed very little from those of nonmarine organisms with phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol being the predominant phospholipids in all strains examined. Lyso-phosphatidylethanolamine occurred in significant quantities among a number of the marine bacteria, and two of the isolates contained significant quantities of poly-β-hydroxybutyrate. Effects of age and growth temperature on the phospholipid composition were also investigated. It is suggested that phylogenetic relationships among bacteria may be correlated with phospholipid composition.

Journal ArticleDOI
TL;DR: Results suggest that undissociated short-chain fatty acids produced by the colon flora may be a mechanism of intestinal resistance to colonization by P. aeruginosa.
Abstract: Heat-stable antibacterial activity in the following suspensions was demonstrated against Pseudomonas aeruginosa at pH 6.5, 6.0, and 5.5: (i) pooled colon contents of normal mice; (ii) an anaerobic, 48-h culture of normal mouse feces; and (iii) anaerobic, 48-h cultures of different bacteria from human colon flora (Escherichia coli, Bacteroides fragilis, Klebsiella pneumoniae, and Proteus mirabilis). The lower the pH of the medium, the greater was the antibacterial activity of these suspensions. The antibacterial activity of five fatty acids (propionic, butyric, isobutyric, acetic, and formic acids) was greater against P. aeruginosa than against three Enterobacteriaceae (E. coli, K. pneumoniae, and P. mirabilis) at all fatty acid concentrations (0.16 M to 0.005 M) and at the 3 pH values studied (5.5, 6.0, and 6.5). As the pH value increased, the antibacterial activity decreased. Antibacterial activity was greater at higher fatty acid concentrations, and at each pH value it was greatest for the fatty acids having high pK(a) values. Lactic acid, with the lowest pK(a), exhibited little or no antibacterial activity. Acetic and butyric acids, two of the three predominant volatile fatty acids determined by gas chromatography in the mouse colon contents and in the anaerobic culture of mouse feces, occurred in vivo in concentrations which inhibited growth of P. aeruginosa in vitro at the pH of the mouse cecum. These results suggest that undissociated short-chain fatty acids produced by the colon flora may be a mechanism of intestinal resistance to colonization by P. aeruginosa.


Journal ArticleDOI
TL;DR: Microscopic examination of bulking activated sludge samples showed the presence of a variety of filamentous microorganisms, some of which have not yet been described in the literature, and a method was developed to obtain pure cultures of these threaded bacteria.
Abstract: Microscopic examination of bulking activated sludge samples showed the presence of a variety of filamentous microorganisms, some of which have not yet been described in the literature. A method was developed to obtain pure cultures of these threaded bacteria. To date, five clearly different groups of filamentous bacteria may be distinguished by the determination of a few morphological and physiological characteristics of the isolates.


Book ChapterDOI
TL;DR: The present chapter brings up to date all those publications on this group of bacteria, which had come to the author's attention by early 1972, and discusses the physiology of sulphate-reducing bacteria.
Abstract: Publisher Summary The chapter discusses the physiology of sulphate-reducing bacteria. The chapter presents an account of their ecology and economic activities as relevant to the subject as their multiplication can have considerable ecological and economic consequences, and since these are due to their special physiology, in particular, the production of hydrogen sulphide. The sulphate-reducing bacteria form a physiologically distinctive group of anaerobic bacteria, their oxidative metabolism being based, not on fermentation, but on the reduction of sulphate or certain other inorganic sulphur compounds. Their physiology has broad analogies with that of the nitrate-reducing bacteria (denitrifying bacteria), but they are all exacting anaerobes and no examples of facultative aerobes are known. Some representatives of the group are capable of growth by non-respiratory processes involving dismutation of substrates, such as pyruvate, fumarate, or choline. Even when reducing sulphate, these organisms are completely unable to oxidize their carbon compounds, such as fatty acids; usually acetic acid plus carbon dioxide are the normal end products of carbon metabolism. The present chapter brings up to date all those publications on this group of bacteria, which had come to the author's attention by early 1972. Reviews of related subjects that have been published during this period, and which makes reference to these bacteria reviewing the general metabolism of sulphur bacteria. The chapter also discusses the chemical and biochemical activities of these bacteria.

Journal ArticleDOI
TL;DR: Production of lactic acid appears to inhibit growth of S. aureus in the early but not the late stages of incubation, and competition for vital nutrients, especially niacin and biotin, and probably production of hydrogen peroxide contribute to inhibition.
Abstract: Representative strains of 15 species of lactic acid bacteria were examined for their ability to influence growth of Staphylococcus aureus and production of enterotoxin in associative culture. Among the organisms used as effectors the streptococci were most inhibitory, followed by Pediococcus cerevisiae. The lactobacilli and Leuconostoc citrovorum were not inhibitory to growth and only slightly inhibitory to production of enterotoxin. Enterotoxin was detected in all cultures in which the population of S. aureus reached 8 × 107 per ml. At lower S. aureus populations no enterotoxin was detected after incubation for 48 h. Mechanisms of inhibition of growth and enterotoxin production by S. aureus strain 243 grown in association with Streptococcus lactis A64 or P. cerevisiae 10791 in APT broth were investigated. Competition for vital nutrients, especially niacin and biotin, and probably production of hydrogen peroxide contribute to inhibition. Production of lactic acid appears to inhibit growth of S. aureus in the early but not the late stages of incubation.

Journal ArticleDOI
TL;DR: Quantitative cultures were performed in the present study which demonstrated that most pools contained relatively few microorganisms, although some harbored more than 500 bacteria/ml after ambient temperature storage.

Journal ArticleDOI
TL;DR: This article corrects the article on p. 453 in vol.
Abstract: [This corrects the article on p. 453 in vol. 37.].

Journal ArticleDOI
TL;DR: An enriched nutrient agar medium containing blue dextran has been utilized for the detection of dextanase-producing microorganisms in human dental plaque, and a cell-free preparation from one of the isolates has been shown to cause extensive endohydrolytic cleavage of high-molecular-weight dextrans.
Abstract: An enriched nutrient agar medium containing blue dextran has been utilized for the detection of dextranase-producing microorganisms in human dental plaque. When compared with the total viable anaerobic plaque flora, the proportion of these microbes in supragingival plaque from different individuals varied over a wide range. Preliminary characterization of some of the dextranase-producing microorganisms revealed a heterogeneous mixture of cell types with varying morphological and biochemical characteristics. Several bacterial isolates were tentatively identified as being members of the genus Actinomyces. An additional isolate appeared to belong to the genus Bacteroides. The dextran-degrading enzymes produced by these bacteria are extracellular, and a cell-free preparation from one of the isolates has been shown to cause extensive endohydrolytic cleavage of high-molecular-weight dextrans.

Journal ArticleDOI
01 Sep 1973-Virology
TL;DR: A partially purified cytoplasmic membrane fraction has been isolated from non-permissive Escherichia coli infected with various amber mutants of the bacteriophage f1 and two proteins associated with the membrane of the amber mutant infected bacteria were tentatively identified as the products of gene 2 and gene 4.

Journal ArticleDOI
TL;DR: Myxococcus xanthus produced an antibiotic during the end of its exponential growth phase which was capable of inhibiting growth of several gram-positive and gram-negative bacteria, and the role of the antibiotic in the predatory behavior of myxococci was studied.
Abstract: Myxococcus xanthus produced an antibiotic during the end of its exponential growth phase which was capable of inhibiting growth of several gram-positive and gram-negative bacteria. The antibiotic was bactericidal to growing cultures only; chloramphenicol inhibited the bactericidal action of the antibiotic. Upon addition of the antibiotic to Escherichia coli B, deoxyribonucleic acid and ribonucleic acid as well as turbidity of the culture continued to increase even after the viable count decreased; the culture lysed about 60 min after addition of sufficient concentrations of the antibiotic. Spheroplasts could be prepared if the antibiotic was added to a culture growing in the presence of high concentrations of sucrose and MgSO 4 . Mutants of M. xanthus FB which are incapable of fruiting body formation or glycerol-induced myxospore formation also produced the antibiotic. A mutant of E. coli resistant to the purified antibiotic was isolated in order to study the role of the antibiotic in the predatory behavior of myxococci.


Journal ArticleDOI
TL;DR: Megasphaera elsdenii, an anaerobic rumen bacterium, produced intracellular polysaccharide granules varying in size from 0.05 to 0.15 μm during growth in batch culture that were found to contain D-glucose as the only reducing sugar and resembled the glycogen granules produced by Arthrobacter globiformis and Escherichia coli.
Abstract: Megasphaera elsdenii, an anaerobic rumen bacterium, produced intracellular polysaccharide granules varying in size from 0.05 to 0.15 μm during growth in batch culture. This polysaccharide material was purified and was found to contain D-glucose as the only reducing sugar. The polyglucose polymer was highly opalescent in aqueous solution and formed a strong reddish-brown iodine complex with a maximum absorbance at 493 nm. Its infrared spectrum had characteristic absorption bands at 8.70, 9.25, and 9.75 μm and was identical with that of the glycogen of enteric bacteria and beef liver. When these polysaccharide granules were observed with an electron microscope, they resembled the glycogen granules produced by Arthrobacter globiformis and Escherichia coli. These properties indicate that the polysaccharide was a type of glycogen. The yield of crude glycogen was 16.82% of the dry weight of late log-phase cells (14-h).The lysis of cells of M. elsdenii and other rumen bacteria that store polysaccharide granules ...

Journal ArticleDOI
TL;DR: Evidence indicates that the E. coli envelope retains sufficient structural organization to preserve integrated biochemical function for at least 1 h after the bacteria have lost the ability to multiply.
Abstract: Phagocytosis and killing of gram-positive Bacillus megaterium and Micrococcus lysodeikticus by granulocytes in vitro is associated with almost immediate cessation of bacterial protein synthesis. By contrast, protein synthesis by Escherichia coli continues after ingestion and killing. After preincubation of E. coli with intact granulocytes for 15 min, when 95% or more of the bacteria can no longer multiply, induction of β-galactosidase proceeds at rates about half of control values. With disrupted granulocytes, which kill E. coli as rapidly as intact cells, the rate of induction of β-galactosidase does not fall until after 30 min of preincubation. We attribute the different effects of phagocytosis on the biochemical apparatus of these microorganisms to the different fates of their envelopes. Specifically labeled protein, ribonucleic acid, deoxyribonucleic acid, and lipid of all three species of bacteria and peptidoglycan of E. coli are apparently incompletely degraded during phagocytosis. However, the cell walls of M. lysodeikticus and B. megaterium undergo rapid and almost complete degradation. The resulting structural disintegration of these gram-positive microorganisms must cause extensive biochemical disorganization as well. Our evidence indicates that the E. coli envelope, on the other hand, retains sufficient structural organization to preserve integrated biochemical function for at least 1 h after the bacteria have lost the ability to multiply.

Journal ArticleDOI
TL;DR: It was concluded that the alkaline phosphatase of B. ruminicola is firmly bound to a structural component within the periplasmic area of the cell wall and that the enzyme is released in large amounts only when the cells break down.
Abstract: Of the three species (Bacteroides ruminicola, B succinogenes, and Megasphaera elsdenii) of anaerobic gram-negative rumen bacteria studied, only B ruminicola produced significant amounts of alkaline phosphatase This enzyme, which is constitutive, showed a greater affinity for p-nitrophenylphosphate than for sodium-beta-glycerophosphate and was shown to be located exclusively in the periplasmic space of log-phase cells Small amounts of this enzyme were released from these cells in stationary-phase cultures, but washing in 001 M MgCl(2) and the production of spheroplasts by using lysozyme in 001 M MgCl(2) did not release significant amounts of the enzyme Exposure to 02 M MgCl(2) did not release significant amounts of the periplasmic alkaline phosphatase of the cell, and when these cells were spheroplasted with lysozyme in 02 M MgCl(2) only 25% of the enzyme was released Spheroplasts were formed spontaneously in aging cultures of B ruminicola, but even these cells retained most of their periplasmic alkaline phosphatase It was concluded that the alkaline phosphatase of B ruminicola is firmly bound to a structural component within the periplasmic area of the cell wall and that the enzyme is released in large amounts only when the cells break down The behavior of alkaline phosphatase in this bacterium contrasts with that of conventional periplasmic enzymes of aerobic bacteria, which are released upon conversion into spheroplasts by lysozyme and ethylenediaminetetraacetic acid and by other types of cell wall damage All three species of bacteria studied here, as well as bacteria found in mixed populations in the rumen, have thick, complex layers external to the double-track layer of their cell walls In addition, B ruminicola produces a loose extracellular material

Journal ArticleDOI
TL;DR: Macrophages obtained from mouse peritoneal washings or the culture of human peripheral monocytes, were incubated in vitro with opsonized E. coli to demonstrate rifampin is able to penetrate macrophages and kill bacteria that have survived phagocytosis.
Abstract: SummaryMacrophages obtained from mouse peritoneal washings or the culture of human peripheral monocytes, were incubated in vitro with opsonized E. coli. Macrophages containing viable E. coli were then incubated with either rifampin, gentamicin or ampicillin. Only rifampin killed all intracellular and extracellular bacteria whereas gentamicin and ampicillin eradicated only extracellular bacteria. Rifampin is able to penetrate macrophages and kill bacteria that have survived phagocytosis.