Showing papers in "Fems Microbiology Letters in 1983"

Regulation of ligninolytic activity by nutrient nitrogen in white-rot basidiomycetes

Abstract: Lignin-degrading basidiomycetes are of prime importance in the decay of wood and other lignocellulosic materials. The ligninolytic system of Phanerochaete chrysosporiurn Burds. is induced in the absence of exogenous lignin and is dependent on the cessation of vegetative growth and the onset of secondary metabolism [1,2]. Depletion of nutrients [2], including a utilizable nitrogen source [1], triggers development of the ligninolytic system. When added to nitrogen-starved cultures, many amino acids including L-glutamic acid stimulate vegetative growth while suppressing ligninolytic activity [3,4]. Preliminary experiments with Coriolus versicolor (L. ex Fr.) Qu61. indicated that its ligninolytic system was also stimulated by a decreased concentration of nutrient nitrogen [5]. However, little is known about the regulation of ligninolytic activity in other fungi. The purpose of this study was to determine whether nutrient nitrogen limitation stimulates the ligninolytic .activity of other commonly studied white-rot basidiomycetes. P. chrysosporium and C. versicolor were included for comparison.

The relation between growth rate and electrochemical proton gradient of Streptococcus cremoris

Abstract: It is now generally accepted that the electrochemical proton gradient (Ak~H+) or proton-motive force (pmf) plays an important role in the metabolism of microorganisms. It is the main driving force for energy-requiring processes, such as ATP synthesis and secondary solute transport across the cytoplasmic membrane [1,2]. Recently, it was shown that the A/~H+ is also involved in other metabolic processes, such as nitrogen fixation [3], ppGpp breakdown [4] and DNA-uptake by genetic transformation [5]. Although there exists a considerable knowledge about the role of the A/~H~ in several specific metabolic events, surprisingly little is known about the A/~H+ in relation to the overall process of microbial growth. Besides ATP, which acts as a molecular currency of metabolic energy the A~ H ÷ is in many cases an obligate intermediate between energy-consuming and energy-producing processes. A complete description of the energetics of microbial growth will only be possible if during growth the A~H+ of microorganisms can be recorded. In this report we present the results of a study on the magnitude and composition of the Ak~H~ of Streptococcus cremoris growing in continuous cultures at different rates and different pH values.

Research letterThe relation between growth rate and electrochemical proton gradient of Streptococcus cremoris

Abstract: It is now generally accepted that the electrochemical proton gradient (Ak~H+) or proton-motive force (pmf) plays an important role in the metabolism of microorganisms. It is the main driving force for energy-requiring processes, such as ATP synthesis and secondary solute transport across the cytoplasmic membrane [1,2]. Recently, it was shown that the A/~H+ is also involved in other metabolic processes, such as nitrogen fixation [3], ppGpp breakdown [4] and DNA-uptake by genetic transformation [5]. Although there exists a considerable knowledge about the role of the A/~H~ in several specific metabolic events, surprisingly little is known about the A/~H+ in relation to the overall process of microbial growth. Besides ATP, which acts as a molecular currency of metabolic energy the A~ H ÷ is in many cases an obligate intermediate between energy-consuming and energy-producing processes. A complete description of the energetics of microbial growth will only be possible if during growth the A~H+ of microorganisms can be recorded. In this report we present the results of a study on the magnitude and composition of the Ak~H~ of Streptococcus cremoris growing in continuous cultures at different rates and different pH values.

Encapsulation, slime production and surface hydrophobicity of coagulase-negative staphylococci

Abstract: Received 20 January 1983 Accepted 23 January 1983 1. INTRODUCTION 2. MATERIALS AND METHODS Infections associated with prosthetic implants or medical devices are most commonly caused by coagulase-negative staphylococci (CNS) [1]. The ability of CNS to produce slime has been sug- gested to play a critical role in the adhesion onto surfaces of implants and medical devices [2] and in the course of medical device-associated infections [3]. Staphylococcus aureus, the pathogenic counter- part of CNS, can be encapsulated [4]. Such strains possessed increased virulence in comparison with their non-encapsulated variant strains [5,6]. Char- acterization of CNS has been advocated [7,8], but no special attention has been given to the presence of a capsule, although encapsulated CNS have been reported [9]. Bacterial adhesion onto surfaces is also regarded to be an important virulence fac- tor [10]. Bacterial interaction with mammalian cells and artificial surfaces is promoted by the hydro- phobicity of the bacterial cell surface [11-13]. After characterization of twenty one CNS, the presence of a capsule and the ability to produce extracellular slime were studied. In addition, the surface hydrophobicity of the strains was mea- sured using a xylene-water system [14]. * Correspondence should be addressed to J. Dankert. 2.1. Bacterial strains and growth conditions 21 CNS strains isolated from open-heart surgery patients and laboratory staff members were classi- fied according to the scheme of Kloos and Schleifer [8] using the API Staph gallery (API Systems S.A., Montalieu Vercieu, France). 7 strains (NCTC) were a gift of Dr. R.R. Marples, Central Public Health Laboratory, Colindale Avenue, London, England. Strains stored at -20°C in skim milk were grown on sheep blood agar plates (Oxoid, Ltd., U.K.) and maintained on nutrient agar slants (Oxoid) at 4°C for 1 month. The strains were cultured in Trypticase soy broth (TSB, BBL Microbiology Systems, Cockeys- ville, MD) for 20 h at 37°C. Late exponential phase cells were obtained by culturing 2 ml of the overnight broth into 100 ml of fresh TSB for 5 h at 37°C in a rotary shaker incubator (New Bruns- wick Sci. Co., New Brunswick, N J) at 90 rev./min. The bacteria were harvested by centrifuging (20000 ×g, 4°C, 10 min; Beckman Instruments Inc., J2-21, Palo Alto, CA), washed three times with phosphate-buffered saline (PBS; 8.1 mM Na2HPO4, 1.5 mM KHzPO4, 140 mM NaC1, 3 mM KC1, pH 7.2) and resuspended in PBS. To determine the effect of glucose depletion, all strains were grown in glucose-free TSB (GF-TSB, BBL). 0378-1097/83/0000-0000/$03.00 © 1983 Federation of European Microbiological Societies

Research letterP-fimbriae of Escherichia coli are subject to phase variation

Abstract: Mise en evidence d'une rapide variation de phase chez la souche pyelonephoritogene KS71. Relations avec la virulence

P-fimbriae of Escherichia coli are subject to phase variation

Abstract: Mise en evidence d'une rapide variation de phase chez la souche pyelonephoritogene KS71. Relations avec la virulence

Distribution of cytochromes in methanogenic bacteria

Abstract: Various methanogenic bacteria belonging to the orders Methanobacteriales, Methanococcales, and Methanomicrobiales were examined for the presence of cytochromes. Those methanogens which are capable of growing only on H2 + CO2 or formate were found to lack cytochromes. However, membrane-bound cytochromes were detected in species able to utilize methanol, methylamines or acetate.

ATP synthesis driven by a potassium diffusion potential in Methanobacterium thermoautotrophicum is stimulated by sodium

Abstract: ATP synthesis driven by a potassium diffusion potential was studied in cell suspensions of Methanobacterium thermoautotrophicum (Marburg). This transient increase in the intracellular ATP content was stimulated five-fold by the addition of sodium ions, from about 2 nmol ATP/min × mg cells (dry weight) at 0.07 mM Na+ to about 10 nmol ATP/min × mg cells at 25 mM Na+.

Research letterDistribution and chemical characterization of regular arrays in the cell walls of strains of the genus Lactobacillus

Abstract: The presence of regular arrays (RAs) in the cell walls of strains of the genus Lactobacillus was examined by electron microscopy. The RAs were found in 6 species including L. bulgaricus, L. helveticus, L. acidophilus, L. fermentum, L. brevis and L. buchneri. The RAs were composed of a protein with an apparent Mr ranging from about 41000 to 55000, depending on the species upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The amino acid composition of the RA proteins was shown to be acidic and hydrophobic. The antigenicity of the RA protein from L. buchneri appeared to be specific but not common among the RA proteins from the other lactobacilli.

Distribution and chemical characterization of regular arrays in the cell walls of strains of the genus Lactobacillus

Abstract: The presence of regular arrays (RAs) in the cell walls of strains of the genus Lactobacillus was examined by electron microscopy. The RAs were found in 6 species including L. bulgaricus, L. helveticus, L. acidophilus, L. fermentum, L. brevis and L. buchneri. The RAs were composed of a protein with an apparent Mr ranging from about 41000 to 55000, depending on the species upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The amino acid composition of the RA proteins was shown to be acidic and hydrophobic. The antigenicity of the RA protein from L. buchneri appeared to be specific but not common among the RA proteins from the other lactobacilli.

Isolation and characterization of a cholera-related enterotoxin from Salmonella typhimurium

Abstract: Salmonella species cause gastroenteritis and enteric fever in human beings. The former syndrome frequently includes vomiting and diarrhea. While the pathogenesis of salmonellosis is believed to involve penetration of the intestinal epithelium by the bacteria and the production of an inflammatory reaction in the lamina propria [1-3], substantial evidence has accrued that Salmonella strains may also elaborate an enterotoxin-like factor. Peterson and his associates [4-8] reported that Salmonella produce a delayed permeability factor which, like cholera enterotoxin (chloleragen or CT) and the heat-labile enterotoxins (LTs) of Escherichica coli, causes distinctive morphological alterations and increases cyclic AMP in cultured Chinese hamster ovary (CHO) cells. The activity is neutralized by cholera antitoxin and by gangliosides. Immunization with procholeragenoid, an immunogenic high M r polymer formed by heating pure choleragen [9,10], protected rabbits against fluid accumulation in intestinal loops infected with live Salmonella [6]. According to Jiwa, similar activity is widely distributed among the Salmonellae [11]. However, despite considerable effort, the enterotoxin has not previously been isolated to

Mass spectrometric measurements of methane and oxygen utilization by methanotrophic bacteria

Abstract: A mass spectrometer with membrane inlet was used to measure methane and oxygen utilization rates at various methane concentrations in Methylosinus trichosporium and a locally isolated strain of a methane-oxidizing coccus (OU-4-1). The apparent Km for methane was found to be 2 μM for M. trichosporium and 0.8 μM for strain OU-4-1. These Km-values are 10–30 times lower than most previously reported values. The ratio of oxygen to methane utilization rates was 1.7 for M. trichosporium and 1.5 for strain OU-4-1 corresponding to a growth yield of 0.38 and 0.63 g dry weight/g methane, respectively.

Glucose metabolism by K+-limited Klebsiella aerogenes: Evidence for the involvement of a quinoprotein glucose dehydrogenase

Abstract: Like other members of the Enterobacteriaceae, Klebsiel la aerogenes transports glucose into the cell by means of a PEP-dependent phosphotransferase system (PTS; for review see [1]). This system has a high affinity for glucose and, not surprisingly, was found to be exceedingly active in cells of a slowly growing glucose-limited chemostat culture (apparent specific activity > 250 nmo l /min . (mg dry wt cells)-1 at D = 0 .1 /h [2]). Interestingly, the apparent activity of this system declined sharply as the growth rate was increased such that, at growth rates greater than 0.7/h, its activity was lower than that necessary to account for the actual rate of glucose uptake by the growing cells. More significantly, glucose-sufficient cultures (that were K +-, phosphateor ammonia-limited) consumed glucose at substantially higher rates than the corresponding glucose-limited culture, yet seemingly possessed uniformly low glucose-PTS activities. These discrepancies suggested that, at the higher growth rates a n d / o r with glucose-sufficient conditions, ancillary systems might contribute substantially to the overall rate of glucose flux, though such a supposition rested heavily on the assumption that the apparent glucose-PTS activity measured in vitro approximated closely to the actual activity of the undisturbed cells. However, the further observation that some glucose-sufficient cultures excreted gluconic and 2-ketoghiconic acid in substantial amounts [3] again pointed to the possibility of there being present in K. aerogenes processes of glucose catabolism that might not directly involve the glucose-PTS. Hence we undertook a search for this putative alternative glucosemetabolizing system which resulted in the finding of a quinoprotein glucose dehydrogenase (EC 1.1.99.17). To the best of our knowledge, this enzyme has not previously been reported to be present in K. aerogenes, or in related species.

Bacterial degradation of ochratoxin A

Abstract: Ochratoxins are formed as products of secondary metabolism in some species of Aspergillus [1] and Penicillium [2]. These fungi are widely distributed in nature and have been isolated from decaying vegetation, soils and foodstuffs. Ochratoxin A causes nephropathic effects in animals [3] and also gives rise to growth inhibition of Gram-posit ive bacteria [4]. In this paper we describe the degradation of ochratoxin A by a Gram-negative soil bacterium. This bacterium grows at the expense of phenylalanine and was therefore tested for its ability to utilize the phenylalanine moiety of ochratoxin A. Ochratoxin A was a gift from Prof. Dr. R. R~Sschenthaler (MOnster), Sephadex G I 0 and LH20 were from Pharmacia. All other chemicals were from Merck AG (Darmstadt).

Effect of papulacandin B on β-glucan synthesis in Schizosaccharomyces pombe

Abstract: The antifungal antibiotic papulacandin β inhibited B(1,3)glucan-synthase activity, in vitro, from Schizosaccharomyces pombe Levels of β(1,3)glucan-synthase from antibiotic-treated cultures were lower than the control cultures whereas mannan-synthase and β(1,3)glucanase activities were almost unaffected The presence of an osmotic stabilizer reduced the inhibition of growth caused by the antibiotic Addition of papulacandin β to a culture of S pombe specifically inhibited incorporation of glucose into the β-glucan cell wall fraction The fatty acids as well as the hydroxyl groups on the phenol residue of the papulacandin β molecule were essential for the inhibitory activity