Showing papers in "Antonie Van Leeuwenhoek International Journal of General and Molecular Microbiology in 1982"
TL;DR: The two species are now considered to be two varieties of the species, F. neoformans and F. bacillispora, and the segregation of phenotypic markers among the tetrads isolated from this interspecific cross proved that meiosis had occurred.
Abstract: The taxonomy of Filobasidiella neoformans Kwon-Chung and F. bacillispora Kwon-Chung and their anamorphs were reinvestigated. Although the cross between the type cultures of the two species failed to produce viable basidio-spores, another pair of isolates did yield viable basidiospores. The segregation of phenotypic markers among the tetrads isolated from this interspecific cross proved that meiosis had occurred. On the basis of other previously known differences and the present genetic study, the two species are now considered to be two varieties of the species, F. neoformans. The anamorph of F. neoformans var. neoformans grew well at 37°C in vitro and produced fatal infection in mice while that of F. neoformans var. bacillispora grew poorly at 37°C and failed to produce fatal infection in mice. Cryptococcus bacillisporus Kwon-Chung et Bennett is regarded as a synonym of C. neoformans var. gattii Vanbreuseghem et Takashio.
181 citations
90 citations
TL;DR: It is concluded that a novel strain of Bacillus flavothermus is isolated from a hot spring on the northern island of New Zealand, which closely resembled B. coagulans, but two typical characteristics were contradictory to this conclusion, namely the intense yellow pigmentation of the colonies and the range of growth temperature.
Abstract: A sample from a hot spring on the northern island of New Zealand contained five different thermophilic bacterial strains. One strain with peculiar properties, i.e. the formation of dark yellow colonies at 30°C as well as at 70°C, was further characterized. It was found to be a gram-positive, facultatively aerobic, motile Bacillus species, with terminal endospores. According to the physiological properties the strain closely resembled B. coagulans. However, two typical characteristics were contradictory to this conclusion, namely the intense yellow pigmentation of the colonies and the range of growth temperature. The latter was found to reach from 30 to 70°C, with an optimum at 60°C under aerobic and at 65°C under anaerobic conditions. Growth at moderate temperatures was slower than at 60°C, but the final cell yields were almost equal. The strain can therefore be considered as facultatively thermophilic. The pigment, which was found to be located in the cytoplasmic membrane, was spectroscopically identified as a carotenoid. Because the characteristics of this strain did not correspond with any of the Bacillus species described thus far, we concluded, that we had isolated a novel strain, for which the name Bacillus flavothermus is proposed.
73 citations
TL;DR: Assessment of maximal colony counts of this organism by growth experiments in various types of tap water may give information about the concentrations of easily assimilable organic carbon.
Abstract: Two fluorescent pseudomonads, strains P17 and P500, belonging to different biotypes were tested for growth in tap water supplied with different concentrations of acetate and glutamate, low concentrations (10 and 20 μg of C per liter) of various other substrates and mixtures of related substrates, the latter being present in amounts of 1 μg of C per liter each. Amino acids appeared to be excellent substrates for both isolates, but many other substrates were utilized at very low concentrations as well. Saturation constants (Ks) of P17 with acetate, arginine, aspartate, glutamate, lactate, succinate, malonate, p-hydroxybenzoate and glucose were all below 1 μm. The Ks values of strain P500 were about 5 times larger than those of P17. Since especially P17 is able to use a large number of different substrates at low concentrations, assessment of maximal colony counts of this organism by growth experiments in various types of tap water may give information about the concentrations of easily assimilable organic carbon.
60 citations
TL;DR: It is shown that the cytotoxic effect is due to the butyrate concentrations present in the culture filtrates of these strains of B. gingivalis and B. asaccharolyticus.
Abstract: Culture filtrates of B. gingivalis and B. asaccharolyticus are cytotoxic for Vero cells. It is shown that the cytotoxic effect is due to the butyrate concentrations present in the culture filtrates of these strains. This cytotoxic effect proved to be reversible. Strains of the B. melaninogenicus subspecies intermedius and melaninogenicus did not produce butyrate and did not show cytotoxic activity towards Vero Cells. The significance of the production of toxic concentrations of butyrate for the etiology of especially periodontal diseases is discussed.
54 citations
TL;DR: It is concluded that T.A2 needs a continuous supply of an inorganic and an organic substrate to thrive whereas T. neapolitanus needs only a Continuous supply of a reduced inorganic sulfur source but also will persist in environments with interrupted addition of sulfide provided that the starvation period does not last too long.
Abstract: The results of ecophysiological studies on obligately and facultatively chemolithotrophic thiobacilli performed over the past years clearly show that the two types of organisms occupy different ecological niches. Chemostat experiments with cultures of the obligate chemolithotroph Thiobacillus neapolitanus and the facultative chemolithotroph Thiobacillus A2 have been carried out to explain the competitiveness of T. neapolitanus under conditions of strongly fluctuating substrate supply. Thiobacillus neapolitanus appeared to be very resistant to starvation periods whereafter it could oxidize sulfide (or thiosulfate) almost instantaneously at the original rate. Under alternate supply of 4 h sulfide and 4 h sulfate (or acetate which does not support growth of the organism either) to a chemostat culture of T. neapolitanus (D=0.05h-1) the sulfide concentration in the growth vessel never reached levels higher than 4 micrometers. This strategy is aimed at maximal reactivity. In contrast to T. neapolitanus the facultative chemolithotroph T.A2 appeared to be very flexible with respect to its energy generation. Under alternate supply of 4 h sulfide and 4 acetate (D=0.05h-1) T.A2 was able to grow continuously since it directed its metabolism to either heterotrophy or autotrophy by rapid induction-repression mechanisms. This flexible strategy seems to be incompatible with a reactive strategy within one organism, since the oxidation capacity for sulfide decreased during the acetate period resulting in accumulation of sulfide during the sulfide period. It is concluded that T.A2 needs a continuous supply of an inorganic and an organic substrate to thrive whereas T. neapolitanus needs only a continuous supply of a reduced inorganic sulfur source but also will persist in environments with interrupted addition of sulfide provided that the starvation period does not last too long.
32 citations
TL;DR: This bacterium is a mesophilic, motile, slightly curved rod that demonstrated a negative Gram reaction, formed spherical, (sub)terminal spores and performed a homoacetic fermentation with methanol, a CO2−2H2-gas mixture, glucose or fructose, respectively, as the substrate.
Abstract: Isolation and characterization of a new, obligatory, anaerobic, methylotrophic, homoacetogenic bacterium is described. This bacterium is a mesophilic, motile, slightly curved rod that demonstrated a negative Gram reaction, formed spherical, (sub)terminal spores and performed a homoacetic fermentation with methanol, a CO2−2H2-gas mixture, glucose or fructose, respectively, as the substrate. The methanol fermentation proceeded only when a suitable amount of NaHCO3 was available in the nutrient solution supplied.
28 citations
TL;DR: Brassicasterol is a rather unique sterol within the fungal kingdom and has hitherto not been found in the red yeasts, therefore, this sterol is of taxonomic significance in contrast with ergosterol, which is widespread among fungi.
Abstract: Species of the genera Taphrina Fr. and Protomyces Unger were screened for the presence of carotenoid pigments and the sterols ergosterol and brassicasterol. All strains produced carotenoids in variable amounts: Taphrina: 0.3–39 μg/g dry weight; Protomyces: 65–99 μg/g dry weight. It was concluded that the tow genera cannot be separated on the basis of presence or absence of carotenoids. Thirty strains (24 species) of Taphrina produced brassicasterol as the principal sterol; twenty-one strains (17 species) did not form ergosterol. Only four isolates (4 species) produced ergosterol without formation of brassicasterol. Brassicasterol was the major sterol in 3 species of Protomyces, whereas ergosterol was absent. Brassicasterol is a rather unique sterol within the fungal kingdom and has hitherto not been found in the red yeasts. Therefore, this sterol is of taxonomic significance in contrast with ergosterol, which is widespread among fungi.
27 citations
TL;DR: Antibodies to SEF prepared in a sheep did not react with other staphylococcal enterotoxins (A to E), and the LD50 for rabbits by subcutaneous and intravenous application of SEF was 6 μg and 180 μg, respectively.
Abstract: Staphyloccoccus aureus enterotoxin F (SEF), which is associated with S. aureus strains isolated from toxic-shock-syndrome patients, was purified by successive chromatography on CM sephadex C-25 and gelfiltration on sephadex G-75. When tested by disc-polyacrylamide gel-electrophoresis the toxin migrated as a homogeneous protein. In SDS-polyacrylamide gel-electrophoresis three protein bands were observed. The main component had a mol wt of 23000 and the two minor components had a mol wt<13 000. By iso-electric focussing a main protein band with an iso-electric point of 7.2 was obtained. The LD50 for rabbits (3–3.5 kg) by subcutaneous and intravenous application of SEF was 6 μg and 180 μg, respectively. Antibodies to SEF prepared in a sheep did not react with other staphylococcal enterotoxins (A to E).
24 citations
TL;DR: In this paper, the authors present a compilation of the common fungal flora from food and show that this flora is limited to about i00 species of moulds and yeasts whose identification is relatively simple.
Abstract: mented by fungal species. In the western world some of these food products are becoming popular (e.g. tempeh: soybeans fermented by Rhizopus oligosporus). To detect fungal contaminants as spoilage agents or producers of toxic metabolites many techniques have been described (Beuchat, 1978; Hartog, 1981). For direct quantification of spoilage by fungi, the Howard mould count can be applied, but with limitations (only for fruit or vegetable products, no species differentiation possible, etc.). For the detection of viable fungal contaminants cultural methods have to be applied. Here certain mycological media are recommended while others, such as Sabouraud agar, have to be avoided when cultivating the common species. Malt extract and oatmeal agars are suitable media for cultivation. The use of growth-inhibitors is useful, but rose bengal should be used with care, because of its toxic effect on certain yeasts and fungi. Identification of the fungal flora of the investigated food samples is often useful and necessary. Exact determination of the species not only provides information on the toxic properties of the organisms, but in many cases also gives a possible explanation of the contamination process (e.g. the presence of heat-resistant fungi in relation to sterilization of the food product). In the abcence of appropriate literature, the identification of food-borne species has often been omitted. A recent compilation (Samson et al., 1981) of the common fungal flora from food shows that this flora is limited to about i00 species of moulds and yeasts whose identification is relatively simple.
23 citations
TL;DR: Yeasts were found concentrated at the sediment surface and with the highest counts at the most polluted site, and species like Rhodotorula rubra related to basidiomycetous fungi were found in relatively low numbers.
Abstract: Yeasts were found concentrated at the sediment surface and with the highest counts at the most polluted site. Candida krusei, Pichia membranaefaciens and similar species typically forming rugose colonies with radiating ridges were the prevalent yeasts in these sediments, and species like Rhodotorula rubra related to basidiomycetous fungi were found in relatively low numbers.
TL;DR: Quantitatively, acetate and propionate were the only important intermediates in glucose degradation by glucose-adapted sludge, with acetate accounting for the largest part of intermediary fatty acid flux.
Abstract: A mineral salts medium containing 1% (w/v) glucose was subjected to anaerobic digestion in an upflow reactor. Performance with respect to utilization of glucose was monitored by collection of fermentation gases and calculation of carbon mass balances. Sub-samples of bacterial supennsions from the upflow reactor were incubated with (U-14C)-glucose, (U-14C)-acetate, (2-14C)-propionate, (1-14C)-butyrate or 14C-carbonate. Individual radioactive products in samples from incubation mixtures were analysed by radio gas chromatography.
TL;DR: Distribution of 14C into cell amino acids arising from 14C-labelled glucose, Na-pyruvate, and Na-acetate was investigated and carbon from glucose preferably entered into the amino acids of the pyruVate and glutamate family and from acetate mainly into leucine and the glutamate family.
Abstract: Incorporation of organic compounds into cell protein by the obligate chemolithotrophs Nitrosomonas spec., Nitrosococcus oceanus, Nitrosococcus mobilis, Nitrosovibrio tenuis, Nitrosolobus spec., and Nitrosospira spec. was studied. In the presence of ammonia as energy source organic substrates were supplied. Distribution of 14C into cell amino acids arising from 14C-labelled glucose, Na-pyruvate, and Na-acetate was investigated. While carbon from glucose was distributed unrestricted, carbon from pyruvate preferably entered into the amino acids of the pyruvate and glutamate family and from acetate mainly into leucine and the glutamate family. Among the strains examined, slight differences were observed, but all should be included under group A of the scheme of Smith and Hoare (1977).
TL;DR: It is concluded that particular treponemal proteins are involved in the human response to Tp and that specific sets of proteins react with antibodies in early, latent and late syphilitic sera.
Abstract: Despite the extensive knowledge about the human serological response to Treponema pallidum (Tp), the causative agent of syphilis, little information is available concerning treponemal antigens reacting with antibodies in human syphilitic serum. Identification of these antigens is certainly hampered by the failure to cultivate large numbers of the organism in vitro. Here, we report on a new apaproach for the detection of proteinaceous components of Tp as they relate to the serological response of human syphilitics. Tp Nichols strain organisms extracted from rabbit testes were purified by centrifugation on a urografin step gradient (Baseman et al., !974). Triton X-100-SDS-extracted Tp proteins were subjected to SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and electrophoretically transferred to nitrocellulose paper (Burnette, 1981). Blots were subsequently incubated with serum or serum fractions from human syphilitics, and thereafter with horse radish peroxidase-labelled antihuman immunoglobulin (HRP-conjugate) of desired specificity. Antigenic proteins were then visualized by soaking the blots in a buffer solution containing tetramethylbenzidine (TMB) and hydrogen peroxide. As indicated by a direct comparison of the protein profiles of SDS-polyacrylamide gels from Tp-infected and normal rabbit testes the Tp preparation was essentially free from rabbit host proteins. Moreover, small amounts of rabbit testicular tissue comparable to the amounts of Tp used in the experiments did not react with syphilitic serum. By comparing the profiles of blots incubated with syphilitic sera from different stages of the disease, a large number of antigenic Tp proteins with molecular weights (M) between 14 and 92 kilodaltons (kD) could be identified. Some of these proteins were only visualized in some stages, others in all stages of syphilis. Primary syphilitic sera contained IgM, IgG and IgA antibodies to a 46 kD protein, and only IgM antibodies to a 16 kD and IgG antibodies to a 14 kD protein. In secondary syphilitic sera IgM antibodies directed to a 46 kD, a 38 kD, and a 16kD protein were observed. IgG antibodies from secondary, latent and late syphilitic sera reacted with a common set of at least five treponemal proteins with M of 46 kD, 44 kD, 38 kD, 16 kD and 14 kD, respectively. Whereas in secondary syphilitic sera a set of three proteins with a M of about 32 kD was recognized by IgG antibodies, only one band migrating in this range was observed in sera from latent and late syphilitics. Sera from patients suffering from neurosyphilis contained IgG antibodies to a characteristic 36 kD Tp protein. For a synopsis of the results see Table 1. It is concluded that particular treponemal proteins are involved in the human response to Tp and that specific sets of proteins react with antibodies in early, latent and late syphilitic sera.
TL;DR: A clear distinction between the reference AME's AAC(3)-I, -li and -IV, AAC(6')-I and AAc(2') could be made now by comparing the sets of eight activity curves, and as expected these sets of activity curves offer better characteristics with regard to the substrates than the conventional substrate profiles do.
Abstract: None of the AME's tested was found to display an ideal enzymic behaviour over the whole concentration range of all substrates tested; all AME's suffered more or less from substrate inhibition. APH(3')-I and APH(3')-II could not be distinguished from each other since kanamycin and neomycin were phosphorylated very well, amikacin only very badly, and the other aminoglycosides not. According to the literature only butirosin should discriminate between these types. For clinical practice such a discrimination is thought irrelevant. Since APH(2\") modifies all the kanamycin and gentamicin derivatives tested, but not neomycin (which lacks an identical 2\"-hydroxy group), APH(3') will be recognized easily. Discrimination between ANT(2\") and ANT(4') should be easy since ANT(4') can not modify gentamicin derivatives in contrast to ANT(2\"). Until recently, subtyping of ANT(2\") seemed unnecessary, but recently Coombe and George (1981) claimed the existence of an ANT(2\")-II. Their conclusions are incomplete, since the reference ANT(2\")-I had not been included in their tests. A clear distinction between the reference AME's AAC(3)-I, -li and -IV, AAC(6')-I and AAc(2') could be made now by comparing the sets of eight activity curves. This was demonstrated by the fact, that an AAC present in a Proteus mirabilis strain and received as an AAC(2'), was unmistakably typed as an AAC(3)-I. Also the AAC(6')-I differed strongly from the staphylococcal AAC(6'). As expected these sets of activity curves offer better characteristics with regard to the substrates than the conventional substrate profiles do. Probably these sets will also be very helpful in the elucidation of the relation between enzymatic activity and MIC-inerease.
TL;DR: In this paper, Ueki et al. showed that the anaerobic bacterial count in balanced mesophilic piggery waste digesters is similar to the aerobic and non-methanogenic species.
Abstract: The complete degradation of complex organic matter to CO2 and CH4 is the result of the combined and coordinated metabolic activity of the digester population In this respect, metabolic interactions between methanogenic and non-methanogenic species are of extraordinary importance to the anaerobic digestion process In spite of several studies on the predominant non-methanogenic bacteria present in anaerobic digesters (Toerien et al, 1967; Mah and Susman, 1968; Kirsch, 1969; Hobson and Shaw, 1974; Ueki et al, 1980), detailed studies on generic and species identification of the hydrolytic and fermentative bacteria have not been reported Because at this stage it is still not clear whether the predominant organisms present in piggery waste digesters participate actively during anaerobic digestion, microbial studies have been performed with common laboratory fermentors fed with either a sterilized or a conventional input From the results of our experiments the following conclusions could be drawn: * In balanced mesophilic piggery waste digesters the anaerobic bacterial count is similar to the aerobic and facultative anaerobic count; generally, counts of around 106-10S/ml were obtained * In digesters fed with a sterilized input the bacterial count is always lower than in a conventional one; counts were of the order of 105-106/ml * In anaerobic digesters coliforms are only contaminating organisms, whereas some Bacillus species remain active during the digestion process Indeed, experiments with sterilized input revealed that several Bacillus spp were still active (104/ml) after more than 20 complete fermentor replacements (retention period = 15 days) The main species were: Bacillus subtilis, B pumilis, B cereus, B licheniformis and B circulans * Clostridium spp are among the most metabolically active bacteria The asaccbarolytic species C sporogenes, C subterminale and C hastiforme were most frequently isolated In peptone-containing media these proteolytic species do produce large amounts of iso-fatty acids Other important species were C cochlearium, C malenominatum, C butyricum and C tertium * The dominant anaerobic population of piggery waste digesters (with conventional or sterilized input) consists of species belonging to the genera: Bacteroides, Peptostreptococcus, Peptococcus, Ruminococcus, Coprococcus, Sarcina, Eubacterium, Clostridium, Propionibacterium, Actinomyces and Lactobacillus, the first two genera probably being the most important
TL;DR: The mean character distinguishing the new genus from the imperfect genus Sterigmatomyces is the development of a dikaryotic mycelium with clamp connections producing sexual spores in ramified whorls and lateral chlamydospores as well as blastospores.
Abstract: Sterigmatosporidium gen. n. is described as a new basidiomycetous yeast-like fungus with the single species Sterigmatosporidium polymorphum sp. n. for which a Latin diagnosis and a preliminary life cycle are presented. The mean character distinguishing the new genus from the imperfect genus Sterigmatomyces is the development of a dikaryotic mycelium with clamp connections producing sexual spores in ramified whorls and lateral chlamydospores as well as blastospores. The dikaryotic phase could be induced by crossing compatible haploid clones of the heterothallic fungus, which are similar to Sterigmatomyces but not identical with any known species.
TL;DR: Under heterotrophic conditions with fructose or gluconate as substrates neither colony formation on solid medium nor the growth rates in liquid media were drastically impaired by up to 100% oxygen, but autotrophic growth — with hydrogen, carbon dioxide and up to 80% oxygen in the gas atmosphere — was strongly depressed by high oxygen concentrations.
Abstract: Growth of various bacteria, especially aerobic hydrogen-oxidizing bacteria, in the presence of 2 to 100% (v/v) oxygen in the gas atmosphere was evaluated. The bacterial strains included Alcaligenes eutrophus, A. paradoxus, Aquaspirillum autotrophicum, Arthrobacter spec. strain 11X, Escherichia coli, Arthrobacter globiformis, Nocardia opaca, N. autotrophica, Paracoccus denitrificans, Pseudomonas facilis, P. putida, and Xanthobacter autotrophicus. Under heterotrophic conditions with fructose or gluconate as substrates neither colony formation on solid medium nor the growth rates in liquid media were drastically impaired by up to 100% oxygen. In contrast, autotrophic growth — with hydrogen, carbon dioxide and up to 80% oxygen in the gas atmosphere — was strongly depressed by high oxygen concentrations. However, only the growth rate, not the viability of the cells, was decreased. Growth retardation was accompanied by a decrease of hydrogenase activity.
TL;DR: It was shown that the transposon-specified site-specific recombination enzyme resolvase can replace the plasmid-encoded function of monomerizat ion of multimers and is essential in the phenomenon of incompatibility.
Abstract: tants it was shown that the transposon-specified site-specific recombination enzyme resolvase can replace the plasmid-encoded function of monomerizat ion of multimers. Using a series of Clo DF13 deletions as well as plasmids into which different parts of the Clo DF13 genome have been cloned, four regions, inc A, B, C and D could be identified that determine incompatibility (Hakkaar t et al., 1982b). The inc D region overlaps the replication control region of Clo DF13. The inc B region covers the Clo DF13 gene L. The gene L product, a protein with a molecular weight of 11 K D is also involved in plasmid stability and in the inhibition of multiplication of double-stranded phages like 2 and PI. In addition, two sites, inc A and ine C, are essential in the phenomenon of incompatibility. Site inc A is located in an AT-rich intercistronic region preceding the bacteriocine operon. The inc C site is situated in a region required for mobilisation of the plasmid, close to the origin o f transfer replication. The underlying mechanisms for stable maintenance of bacterial plasmids, e.g. for plasmid replication, replication control, stability and incompatibility are subject of current research in our laboratory.
TL;DR: From 1975–1980, about 130 000 Salmonella strains isolated from various sources were tested for resistance to ampicillin, chloramphenicol, kanamycin, tetracycline and trimethoprim, and recently, phage type 193 S. typhimurium strains have become predominant and they are invariably resistant to isoniax, and type 193 strains were hardly encountered in human patients, but the number of human isolates is slowly increasing.
Abstract: From 1975–1980, about 130 000 Salmonella strains isolated from various sources were tested for resistance to ampicillin, chloramphenicol, kanamycin, tetracycline and trimethoprim. Following the ban on incorporation of tetracycline in animal feeds for nutritive purposes, tetracycline resistance in S. typhimurium and S. panama strains of porcine origin dropped from about 90% in 1974 for both species, to about 34% and 1%, respectively, in 1980. The incidence of resistance in human strains concurrently decreased from about 80% in 1974 to 25% and 1%, respectively, in 1980.
TL;DR: The hands of personnel appeared to be the most important route of transmission: of 464 cultures of hands taken during the first weeks 83 were positive for one or more of the microorganisms mentioned above, and the question whether constitutional factors play a role needs further elucidation.
Abstract: was done with sera put at our disposal by Dr I. Smit, (Dept. of Medical Microbiology, Free University, Amsterdam). In case of doubt biotyping with API-50E was added. Enterobacter and Serratia strains were biotyped only. A selection of the Proteus spp. strains was typed by the production of and sensitivity to proticines (Bongaerts et al., 1981). From an analysis of the distribution patterns of the different types of Ps. aeruginosa in the first four weeks, we concluded that 5 out of 10 colonized patients had become colonized with a type already isolated from another patient or from the inanimate environment in the previous days of hospital stay. Two of these 5 patients had become colonized with two different types. In 13 cases the nebulizer of the respiratory equipment became contaminated with a previously isolated type of Ps aeruginosa. The hands of many personnel members were colonized with the same type of Ps. aeruginosa in the period before colonization of the patient or the nebulizer was detected. Cultures of drain pipes of wash stands yielded Ps. aeruginosa in several cases. We could not ascertain, whether they were a source in epidemiological sense or whether the isolates represented environmental contamination. After analyzing the epidemiological patterns of different types of various genera of Enterobacteriaceae, we concluded that out of 34 patients 6 became colonized with a type already isolated from another patient or from the inanimate environment in the previous days of admission. One patient became colonized with two different genera. In contrast to Ps. aeruginosa, for Enterobacteriaceae the nebulizer of the respiratory equipment could not be considered as an important route of transmission or source of contamination. Cultures of the hands of personnel were taken as often as possible at the start of treating or nursing a patient. The hands of personnel appeared to be the most important route of transmission: of 464 cultures of hands taken during the first weeks 83 (17.9~) were positive for one or more of the microorganisms mentioned above. In a later period we performed another 151 cultures of the same personnel, but now the cultures were taken directly after washing of hands with chlorhexidine (4~). Only 7 (4.6~) were positive (Fisher's test: p <0.001). Once again the importance of frequent washing of hands with a disinfectant is illustrated. Another interesting finding was that some persons showed a much higher percentage of positive cultures than others, the question whether constitutional factors play a role needs further elucidation.
TL;DR: Preliminary characterization revealed that Salmonella enterotoxin is a heatlabile protein of high molecular weight and it is suggested that enterotoxigenic and invasive propeties play a vital role in the pathogenesis ofSalmonella diarrhoea.
Abstract: A large number of enterotoxigenic strains was encountered in a group 56 Salmonella cultures belonging to 8 species viz., S. alachua, S. anatum, S. dublin, S. enteritidis, S. hindmarsh, S. newport, S. typhimurium, S. weltevreden, and 5 serotypes of S. arizona (16:z4:-; 48:1,v:z56; 53:z52:z53; 60:r:z; 61:i:z53). These cultures were isolated mainly from humans and animals suffering from gasteroenteritis. The enterotoxigenic (diarrhoeagenic) Salmonella cultures possess capacities for both skin permeation and epithelial penetration (invasiveness). Preliminary characterization revealed that Salmonella enterotoxin is a heatlabile protein of high molecular weight. It is suggested that enterotoxigenic and invasive propeties play a vital role in the pathogenesis of Salmonella diarrhoea.
TL;DR: From colony counts resulting from growth on the respective media, the proportion of fused complementary protoplasts (prototrophic colonies) to the total viable number of colony forming units was determined and it was not determined whether the prototrophic cultures were monokaryon, heterokaryons or a mixture of the two.
Abstract: Auxotrophic mutants of C. albicans obtained by the method described by Henson and McClary (1979) were conditioned in a tris buffered EDTA-dithiothreitol solution then converted to protoplasts by suspension in osmotically stabilized buffer containing β-glucuronidase. Complementary protoplasts were mixed in an osmotically stabilized polyethylene glycol solution and at appropriate times were plated respectively in osmotically stabilized minimal and complete agar media. From colony counts resulting from growth on the respective media, the proportion of fused complementary protoplasts (prototrophic colonies) to the total viable number of colony forming units was determined. Stability tests of selected colonies from the minimal and complete agar revealed multiple revertants, but the numbers declined to low frequencies upon repeated selective plating and isolation. Acridine orange staining of cultures thus stabilized revealed various sizes of cells with their numbers of nuclei (DNA-staining regions) varying from one to five, such that it was not determined whether the prototrophic cultures were monokaryons, heterokaryons or a mixture of the two.
TL;DR: From the absence of orchitis as well as seroconversion in rabbits, inoculated with blood-treponeme mixtures stored for 120 h or longer periods of time, it is concluded that after 120 h of storage infectivity is lost.
Abstract: The influence of storage at 4 degrees C on the survival of Treponema pallidum in donor blood, artificially infected with treponemes of the virulent Nichols strain was studied. Rabbits were inoculated in each testis with 0.5 ml of the blood-treponeme mixture, containing 5 X 10(5) microorganisms/ml, which was stored for up to 336 h. Under these circumstances, the blood-treponeme mixture appeared to be infectious for up to 96 h of storage, based on the demonstration of T. pallidum and serological findings, using FTA-ABS, TPHA and VDRL tests. The two former tests were found to be equally sensitive in detecting incubating syphilis in the rabbits, the VDRL test was significantly slower in this respect. From the absence of orchitis as well as seroconversion in rabbits, inoculated with blood-treponeme mixtures stored for 120 h or longer periods of time, it is concluded that after 120 h of storage infectivity is lost. The presently found survival time of treponemes in blood between 96 and 120 h of storage is discussed in relation with survival times found by other investigators.
TL;DR: The variations in surface ornamentation of conidia during the evolution of the genus Penicillium are considered and their possible relationship with certain habitats and ways of conidial dispersion are drawn attention.
Abstract: The morphology of conidia in 211 species and 12 varieties belonging to the genus Penicillium Link ex Gray have been studied and compared. According to surface ornamentation, conidia have been classified into six groups: A, smooth-walled (7% of the species); B, delicately roughened (13%); C, warty (28%); D, echinate 910%); E, striate with low irregular ridges (36%); and F, striate with scarce high ridges or bars (6%). Whereas the first two groups are closely related in both shape and average size, a gradual reduction was observed in size and in the length/width (l/w) ratio in the remaining groups. Echinate conidia were globose, having the largest average size. Only four species produced conidia not surpassing 2 micrometers in diameter. Maximum length observed was 8 micrometers, and most elongated conidia had a l/w ratio of 3.5. Forty per cent of the species studied had globose conidia. Conidia of the monoverticillate species were generally smaller, more globose and frequently with ridges. In the Asymmetrica, the conidia were generally larger, and showed ridges in comparatively few species. Conidia of the Symmetrica, which were frequently striate with ridges, presented the most elongated forms. The largest average size was found in the conidia of the Polyverticillata which were generally warty. Finally, we have considered the variations in surface ornamentation of conidia during the evolution of the genus Penicillium and drawn attention to their possible relationship with certain habitats and ways of conidial dispersion.
TL;DR: Observations suggest that between the execution points of cdc 3 and cdc 10, essential processes in the assembly of cell membrane occur, and this may help to explain why these strains stop growing after 3 hours of incubation at the non-permissive temperature.
Abstract: The four temperature-sensitive mutants of Saccharomyces cerevisiae in the cell division cycle defective in cytokinesis (cdc, 3, 10, 11 and 12), have been analyzed with respect to the biosynthesis of the cell wall polymers. After 3 hours of incubation at the non-permissive temperature (37°C) these strains stop growing. The synthesis of glucan, mannan and chitin (wall polymers) level off in a similar time, but glucan, mannan and chitin synthases remained active for at least 4 hours.
TL;DR: Selective isolation procedures were carried out on decaying leaves of Nymphoides peltata (Gmel.) O. Kuntze to study the pythiaceous fungi (Peronosporales) associated with the decomposition processes.
Abstract: Selective isolation procedures were carried out on decaying leaves of Nymphoides peltata (Gmel.) O. Kuntze in order to study the pythiaceous fungi (Peronosporales) associated with the decomposition processes. In addition to Pythium marsipium Drechsler and P. pleroticum T. Ito, a number of Pythium species were isolated with filamentous non-swollen sporangia. Under special culture conditions (in water under a day/night rhythm) sexual reproductive structures of P. diclinum Tokunaga and P. apleroticum Tokunaga were also obtained. However, several isolates designated as Pythium ‘F’, remained sterile. Within this group three types could be distinguished according to their temperature-growth relationships. As the species recorded have been found very rarely and only one was represented in the CBS collection, detailed descriptions with short discussions are presented.
TL;DR: A new Bacillus megaterium bacteriophage with regular polyhedral head belonging to Bradley's group B is characterized and is sensitive to 60°C and moderately sensitive to chloroform.
Abstract: A new Bacillus megaterium bacteriophage is characterized. It is a tailed phage with regular polyhedral head belonging to Bradley's group B. Head and tail dimensions are 56.4 and 300 nm, respectively. Lysis was restricted to strains of B. megaterium. No antigenic relationship with pumilus phage FP-1 or subtilis phage FS-1 was observed. The phage is sensitive to 60°C and moderately sensitive to chloroform. The nucleic acid is double-stranded linear DNA with a G-C mole % of 38.8 and a mol wt of (53±3)×106.
TL;DR: The effect of cerulenin on the production of β-lactamase and other periplasmic proteins was studied in Escherichia coli IA199 carrying plasmid pBR322 and cerulanin decreased incorporation of l-[35S]methionine into membranes during growth as well.
Abstract: The effect of cerulenin on the production of β-lactamase and other periplasmic proteins was studied in Escherichia coli IA199 carrying plasmid pBR322. Cerulenin (10 to 25 μg/ml) had almost no effect on the growth rate of E. coli but it decreased the amount of β-lactamase and other periplamic proteins in shock fluid. Higher amounts of the antibiotic (40 to 100 μg/ml)decreased turbidity and almost completely prevented synthesis of β-lactamase and other periplasmic proteins. Cerulenin decreased incorporation of l-[35S]methionine into membranes during growth as well. Spheroplasts secreted β-lactamase into the external medium, but during a 3-h incubation in the presence of cerulenin (25 μg/ml) this secretion was prevented by more than 90%. β-Lactamase was secreted into the isolated membrane vesicles from E. coli IA199. However, only 5% of the total amount of pre-β-lactamase was secreted and processed by the membranes in vitro. Cerulenin did not prevent processing in vitro but the membranes prepared from the cells grown in the presence of cerulenin (25 μg/ml) did not catalyze processing of pre-β-lactamase at all. Membrane preparations from Bacillus subtilis did not process pre-β-lactamase either in the absence or in the presence of cerulenin.