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A novel cAMP-response element, CRE1, modulates expression of nor-1 in Aspergillus parasiticus.

The level of aflatoxin accumulation in the filamentous fungus Aspergillus parasiticus is modulated by a variety of environmental cues. The presence of glucose (a preferred carbon source) in liquid and solid glucose minimal salts (GMS) growth media strongly stimulated aflatoxin accumulation. Peptone (a non-preferred carbon source) in peptone minimal salts (PMS) media stimulated only low levels of aflatoxin accumulation. Glucose stimulated transcription of the aflatoxin structural genes ver-1 and nor-1 to similar intermediate levels in liquid GMS, while on solid media, ver-1 transcription was stimulated to 20-fold higher levels than nor-1. PMS liquid and solid media stimulated very low or non-detectable levels of transcription of both genes. Electrophoretic mobility shift analysis using a nor-1 promoter fragment (norR) and A. parasiticus cell protein extracts revealed specific DNA-protein complexes of different mobility on GMS and PMS solid and liquid media. An imperfect cAMP-response element, CRE1, was identified in norR that mediated formation of the specific DNA-protein complexes. Mutation in CRE1 or AflR1 (AflR cis-acting site) caused up to a 3-fold decrease in cAMP-mediated stimulation of nor-1 promoter activity on GMS agar. South-Western blot analysis identified a 32-kDa protein that specifically bound to norR. p32 could be co-immunoprecipitated by anti-AflR antibody and co-purified with an AflR-maltose-binding protein fusion demonstrating a physical interaction between AflR and p32 in vitro. We hypothesize that p32 assists AflR in binding to the nor-1 promoter, thereby modulating nor-1 gene expression in response to environmental cues.

Aflatoxins↗

Surveillance methodology for Vibrio cholerae in environmental samples.

The purpose of this study was to examine the prevalence of Vibrio cholerae in environmental water samples by using a series of biochemical tests. A total of 223 V. cholerae-like bacteria were isolated from TCBS agar after spreading the alkaline peptone water enriched sewer (n = 21) and water (n = 16) samples. All oxidase positive isolates were subjected to confirmation for V. cholerae by seven other biochemical tests and polymerase chain reaction. Only 74.2% isolates were found to be V. cholerae by PCR using primers against an outer membrane protein (ompW) gene, out of which only 2 isolates were positive for cholera toxin (ctxAB) gene. Among the various biochemical tests studied, arginine hydrolysis, arabinose fermentation and string test showed 92 - 100% sensitivity and 42 - 67% specificity. Eight isolates including the toxigenic ones, showed agglutination with V. cholerae O1 antiserum. The present study showed that no biochemical test is 100% specific for V. cholerae. However, a few tests, if performed in a sequence after growing the alkaline peptone water enriched samples onto TCBS media can be used for screening of V. cholerae from the environmental samples. This study also showed that most of the environmental isolates are non-O1/non-O139 and the chances of presence of toxigenic V. cholerae are very rare in the environment.

Animals↗

Phorbol myristate acetate stimulates pinocytosis and membrane spreading in mouse peritoneal macrophages.

Phorbol myristate acetate (PMA) at a concentration of 0.01 microgram/ml causes an approximately threefold increase in surface area of resident, proteose-peptone-elicited, and thioglycolate-broth-elicited mouse peritoneal macrophages. Resident and proteose-peptone-elicited macrophages, cultured for 24 h in the presence of PMA, increase their pinocytic rate twofold in response to addition of PMA (0.01 microgram/ml) to the medium. Thioglycolate-broth-elicited macrophages, cultured for 24 h in the absence of PMA, immediately increase their pinocytic rate 2- to 3.5-fold in response to a single challenge with PMA (0.01 microgram/ml). Cytochalasin B, colchicine, and podophyllotoxin have only modest inhibitory effects on the basal rate of pinocytosis and on PMA-induced cellular spreading, but completely block the stimulatory effects of PMA on pinocytosis in thioglycolate-broth-elicited macrophages. Cytochalasin D markedly inhibits both basal and PMA-stimulated pinocytosis in these cells. Thus, PMA is a useful tool for studying mechanisms of macrophage spreading and for enhancing the overall rate of pinosome formation.

Animals↗

Appearance of new phage types and new lysogenic strains after adaptation of lysogenic B. megatherium to ammonium sulfate culture medium.

1. Lysogenic B. megatherium 899a was adapted to growth in a minimal ammonium sulfate medium (ASCM). 2. Adaptation took place slowly and the following changes in the culture occurred: (a) The growth rate increased from 0.5 to 1.5-2.0/hr. (b) The culture changed from diffuse to mucoid. (c) The total phage titer, and the gelatinase concentration decreased to 1/100 or less. (d) The types of phage produced changed from >99 per cent T (wild type) to 30 to 60 per cent miscellaneous clear types. The original T phage was replaced by a different smaller t, never observed in the original 899a culture. (e) Several new colony types also appeared, but the colony morphology was not correlated with the phage types produced. None of the colony types was stable on repeated transfer either in peptone or ASCM, but continued to disassociate into different colony types (cf. Ivánovics, 1955). 3. Control experiments showed that these changes in phage production and colony types could not be brought about by growing sensitive B. megatherium in the presence of the various new phages, in ASCM. It is therefore unlikely that the changes observed in adapted culture were due to infection of a sensitive cell with phage. 4. Continued growth of the ASCM-adapted strain in peptone resulted in increasing the total phage titer, and also the gelatinase concentration. The growth rate returned to its original value and the ability to grow rapidly in ASCM was soon lost. The phage types, however, remained the same as in the ASCM. 5. An improved cell for steady state growth is described.

Ammonium Sulfate↗

Preparation of recombinant alpha-thrombin: high-level expression of recombinant human prethrombin-2 and its activation by recombinant ecarin.

We have established a large-scale manufacturing system to produce recombinant human alpha-thrombin. In this system, a high yield of alpha-thrombin is prepared from prethrombin-2 activated by recombinant ecarin. We produced human prethrombin-2 using mouse myeloma cells and an expression plasmid carrying the chicken beta-actin promoter and mutant dihydrofolate reductase gene for gene amplification. To increase prethrombin-2 expression further, we performed fed-batch cultivation with the addition of vegetable peptone in 50 liters of suspension culture. After five feedings of vegetable peptone, the expression level of the recombinant prethrombin-2 reached 200 micro g/ml. Subsequently, the recombinant prethrombin-2 could be activated to alpha-thrombin by recombinant ecarin expressed in a similar manner. Finally, recombinant alpha-thrombin was purified to homogeneity by affinity chromatography using a benzamidine-Sepharose gel. The yield from prethrombin-2 in culture medium was approximately 70%. The activity of the purified recombinant alpha-thrombin, including hydrolysis of a chromogenic substrate, release of fibrinopeptide A, and activation of protein C, was indistinguishable from that of plasma-derived alpha-thrombin. Our system is suitable for the large-scale production of recombinant alpha-thrombin, which can be used in place of clinically available alpha-thrombin derived from human or bovine plasma.

Actins↗

Effect of different growth media on the synthesis of carbohydrate-Binding protein from Dictyostelium discoideum NC-4.

The carbohydrate-binding protein, discoidin, was synthesized from Dictyostelium discoideum NC-4 grown on a Bacto peptone (Difco) containing medium together with bacteria. When the cells were transferred by serial passage to a Proteose peptone (Daigo)-containing medium, the productivity of discoidin was reduced to a negligible amount, but the cells formed aggregates, and another protein which binds with Sepharose 4B was detected by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. We conclude that discoidin synthesis is already regulated during growth, and even when the amount of this protein is nil or negligible, the cells still retain aggregate-forming ability.

Carrier Proteins↗

Clostridium peptidivorans sp. nov., a peptide-fermenting bacterium from an olive mill wastewater treatment digester.

A new peptide-degrading, strictly anaerobic bacterium, designated strain TMC4T, was isolated from an olive mill wastewater treatment digester. Cells of strain TMC4T were motile, rod-shaped (5-10 x 0.6-1.2 microm), stained Gram-positive and formed terminal to subterminal spores that distended the cells. Optimal growth occurred at 37 degrees C and pH 7 in an anaerobic basal medium containing 0.5% Casamino acids. Arginine, lysine, cysteine, methionine, histidine, serine, isoleucine, yeast extract, peptone, Biotrypcase, gelatin and crotonate also supported growth, but not carbohydrates, organic acids or alcohols. The end-products of degradation were: acetate and butyrate from lysine and crotonate; acetate, butyrate, H2 and CO2 from Biotrypcase, gelatin and peptone; acetate, alanine, H2 and CO2 from cysteine; acetate, H2 and CO2 from serine, cysteine and yeast extract; acetate and formate from histidine; propionate from methionine; methyl 2-butyrate, H2 and CO2 from isoleucine; acetate and ethanol from arginine; and acetate, propionate, butyrate, methyl 2-butyrate, H2 and CO2 from Casamino acids. The DNA G+C content of strain TMC4T was 31 mol%. Phylogeny based on 16S rRNA sequence analysis showed that strain TMC4T was a member of the low-G+C-content Gram-positive genus Clostridium, with the closest relative being Clostridium pascui (sequence similarity of 96 %). Due to considerable differences in genomic and phenotypic properties between strain TMC4T and those of its nearest relative, strain TMC4T is proposed as a new species of the genus Clostridium, Clostridium peptidivorans sp. nov. Strain TMC4T has been deposited in the DSMZ as strain DSM 12505T.

Amino Acids↗

Thermotoga petrophila sp. nov. and Thermotoga naphthophila sp. nov., two hyperthermophilic bacteria from the Kubiki oil reservoir in Niigata, Japan.

Two hyperthermophilic bacteria, strains RKU-1T and RKU-10T, which grew optimally at 80 degrees C, were isolated from the production fluid of the Kubiki oil reservoir in Niigata, Japan. They were strictly anaerobic, rod-shaped fermentative heterotrophs. Based on the presence of an outer sheath-like structure (toga) and 16S rDNA sequences, they were shown to belong to the genus Thermotoga. Cells of strain RKU-1T were 2-7 microm by 0.7-1.0 microm, with flagella. They grew at 47-88 degrees C on yeast extract, peptone, glucose, fructose, ribose, arabinose, sucrose, lactose, maltose, starch and cellulose as sole carbon sources. Cells of strain RKU-10T were 2-7 microm by 0.8-1.2 microm, with flagella. They grew at 48-86 degrees C on yeast extract, peptone, glucose, galactose, fructose, mannitol, ribose, arabinose, sucrose, lactose, maltose and starch as sole carbon sources. While strains RKU-1T and RKU-10T reduced elemental sulfur to hydrogen sulfide, their final cell yields and specific growth rates decreased in the presence of elemental sulfur. Thiosulfate also inhibited growth of strain RKU-1T but not strain RKU-10T. The G+C contents of the DNA from strains RKU-1T and RKU-10T were 46.8 and 46.1 mol%. Phenotypic characteristics and 165 rDNA sequences of the isolates were similar to those of Thermotoga maritima and Thermotoga neapolitana, both being hyperthermophilic bacteria isolated from hydrothermal fields. However, the isolates differed from these species in their minimum growth temperatures, utilization of some sugars, sensitivity to rifampicin and the effects of elemental sulfur and thiosulfate on growth. The low levels (less than 31%) of DNA reassociation between any two of these hyperthermophilic Thermotoga strains indicated that the isolates were novel species. Analysis of the gyrB gene sequences supported the view that the isolates were genotypically different from these reference species. The isolates were named Thermotoga petrophila sp. nov., with type strain RKU-1T (= DSM 13995T = JCM 10881T), and Thermotoga naphthophila sp. nov., with type strain RKU-10T (= DSM 13996T = JCM 10882T).

Anaerobiosis↗

Role of amino acids and endogenous protein in the germination of Mucor racemosus sporangiospores.

The role of amino acids as triggers of Mucor racemosus sporangiospore germination was investigated. No single amino acid was effective as glucose or peptone at triggering germination. Germination induced by glucose or peptone was pH-independent, whereas germination induced by glutamate was pH-dependent. The composition of the free amino acid pools of M-spores (those unable to germinate on glutamate) was qualitatively and quantitatively similar to that of C-spores (those capable of germinating on glutamate) with the exceptions of hydroxyproline and methionine and methionine whose concentrations were several-fold higher in C-spores. Glutamate and leucine were taken up by germinating and nongerminating spores; however, significant protein synthesis occurred only in germinating spores. Spores not triggered by 3-O-methyl-D-glucose (M-spores) contained about one-half the protein of those triggered by 3-O-methyl-D-glucose (C-spores). C-spores initiated to germinate by 3-O-methyl-D-glucose decreased in total organic carbon and protein over a 6 h period; removal of the 3-O-methyl-D-glucose resulted in an immediate halt of protein degradation and spore swelling. These results suggest that protein is a major endogenous reserve in M. racemosus sporangiospores and that its turnover is a necessary event for glucose-triggered germination.

3-O-Methylglucose↗

Sporulation of Streptomyces venezuelae in submerged cultures.

Shaken cultures of Streptomyces venezuelae ISP5230 in minimal medium with galactose and ammonium sulphate as carbon and nitrogen sources, respectively, showed extensive sporulation after 72 h incubation at 37 degrees C. The spores formed in these cultures resembled aerial spores in their characteristics. The ability of the spores to withstand lysozyme treatment was used to monitor the progress of sporulation in cultures and to determine the physiological requirements for sporulation. In media containing ammonium sulphate as the nitrogen source, galactose was the best of six carbon sources tested. With galactose S. venezuelae ISP5230 sporulated when supplied with any of several nitrogen sources; however, an excess of nitrogen source was inhibitory. In cultures containing galactose and ammonium sulphate, sporulation was suppressed by a peptone supplement. The onset of sporulation was accompanied by a drop in intracellular GTP content. When decoyinine, an inhibitor of GMP synthase, was added to a medium containing starch and ammonium sulphate, a slight increase in sporulation was seen after 2 d. The suppression of sporulation by peptone in liquid or agar cultures was not reversed by addition of decoyinine. A hypersporulating mutant of S. venezuelae ISP5230 was altered in its ability to assimilate sugars. In cultures containing glucose the mutant sporulated more profusely than did the wild-type and did not acidify the medium to the same extent. However, the suppressive effect of glucose on sporulation was not merely a secondary result of acid accumulation.

Adenosine↗

Effect of nitrogen source on the levels of nitrate reductase in the yeast Hansenula anomala.

Levels of nitrate reductase (NR) protein in Hansenula anomala and Hansenula wingei were determined using specific antiserum raised against the enzyme from H. anomala. Extracts from nitrate-grown cells contained NR protein, while in those from cells grown on ammonium, glutamine or peptone, no cross-reacting material could be observed. Enzyme activity correlated with the levels of cross-reacting material. When nitrate was used as nitrogen source, NR was always present, even in cultures with ammonium, glutamine or peptone, although in these cases both the levels of activity and protein were lower. NR activity was consistently two to four times higher in cells grown in glucose than in cells grown in ethanol. Nitrate was required for NR induction, and deprivation of nitrate from nitrate-grown cells resulted in a rapid loss of NR activity.

Cycloheximide↗

Continuous-culture studies of interactions among human skin-commensal bacteria.

Chemostat studies were made of an antibiotic-producing Staphylococcus epidermidis strain (S6+), a similar, but antibiotic non-producing S. epidermidis strain (S6-), and a sensitive indicator strain of Micrococcus sp. (M7). Pure and mixed continous cultures were investigated at low population levels (in 0-1% peptone water) and at higher levels (in 0-5% peptone water). Strain S6+ antagonised the growth of strain M7 when its colony count was maintained above 10(7-0) per ml, while strain S6- remained unaffected.

Anti-Bacterial Agents↗

Thermosipho atlanticus sp. nov., a novel member of the Thermotogales isolated from a Mid-Atlantic Ridge hydrothermal vent.

A novel anaerobic, thermophilic and heterotrophic bacterium, designated strain DV1140(T), was isolated from a deep-sea hydrothermal vent sample from the Mid-Atlantic Ridge. The cells were non-motile straight rods, 1.8 microm long and 0.4 microm wide, surrounded by an outer sheath-like structure (toga). They grew at 45-80 degrees C (optimum 65 degrees C), pH 5.0-9.0 (optimum pH 6.0) and at sea salt concentrations of 20-60 g l(-1) (optimum 30 g l(-1)). Strain DV1140(T) was able to ferment yeast extract, peptone, brain heart infusion, gelatin, starch, galactose, arabinose, glucose, trehalose and cellobiose. The fermentation products identified on glucose in the presence of yeast extract and peptone were acetate, isovalerate and hydrogen. The G+C content of the genomic DNA was 33 mol%. Phylogenetic analysis of the 16S rRNA gene sequence (GenBank accession number AJ577471) located the strain within the genus Thermosipho in the bacterial domain. On the basis of 16S rRNA gene sequence comparisons, and physiological and biochemical characteristics, the isolate represents a novel species, for which the name Thermosipho atlanticus sp. nov. is proposed. The type strain is DV1140(T) (=CIP 108053(T)=DSM 15807(T)).

Acetic Acid↗

Desulfurococcus fermentans sp. nov., a novel hyperthermophilic archaeon from a Kamchatka hot spring, and emended description of the genus Desulfurococcus.

An obligately anaerobic, hyperthermophilic, organoheterotrophic archaeon, strain Z-1312(T), was isolated from a freshwater hot spring of the Uzon caldera (Kamchatka Peninsula, Russia). The cells were regular cocci, 1-4 microm in diameter, with one long flagellum. The cell envelope was composed of a globular layer attached to the cytoplasmic membrane. The temperature range for growth was 63-89 degrees C, with an optimum between 80 and 82 degrees C. The pH range for growth at 80 degrees C was 4.8-6.8, with an optimum at pH 6.0. Strain Z-1312(T) grew by hydrolysis and/or fermentation of a wide range of polymeric and monomeric substrates, including agarose, amygdalin, arabinose, arbutin, casein hydrolysate, cellulose (filter paper, microcrystalline cellulose, carboxymethyl cellulose), dextran, dulcitol, fructose, lactose, laminarin, lichenan, maltose, pectin, peptone, ribose, starch and sucrose. No growth was detected on glucose, xylose, mannitol or sorbitol. Growth products when sucrose or starch were used as the substrate were acetate, H(2) and CO(2). Elemental sulfur, thiosulfate and nitrate added as potential electron acceptors for anaerobic respiration did not stimulate growth when tested with starch as the substrate. H(2) at 100 % in the gas phase did not inhibit growth on starch or peptone. The G+C content of the DNA was 42.5 mol%. 16S rRNA gene sequence analysis placed the isolated strain Z-1312(T) as a member of the genus Desulfurococcus, where it represented a novel species, for which the name Desulfurococcus fermentans sp. nov. (type strain Z-1312(T) = DSM 16532 (T) = VKM V-2316(T)) is proposed.

Acetic Acid↗

Tepidimicrobium ferriphilum gen. nov., sp. nov., a novel moderately thermophilic, Fe(III)-reducing bacterium of the order Clostridiales.

A moderately thermophilic, anaerobic bacterium (strain SB91T) was isolated from a freshwater hot spring at Barguzin Valley, Buryatiya, Russia. Cells of strain SB91T were straight to slightly curved rods, 0.5-0.6 microm in diameter and 3.0-7.0 mum in length. Formation of endospores was not observed. The temperature range for growth was 26-62 degrees C, with an optimum at 50 degrees C. The pH range for growth was 5.5-9.5, with an optimum at pH 7.5-8.0. The substrates utilized by strain SB91T in the presence of 9,10-anthraquinone 2,6-disulfonate included peptone, tryptone, Casamino acids, yeast extract, beef extract, casein hydrolysate, alanine plus glycine, alanine plus proline, L-valine and n-propanol. Carbohydrates were not utilized. Strain SB91T reduced amorphous Fe(III) oxide, Fe(III) citrate, Fe(III) EDTA or Fe(III) nitrilotriacetate with peptone, L-valine or n-propanol as an electron donor. Strain SB91T reduced 9,10-anthraquinone 2,6-disulfonate, thiosulfate, elemental sulfur, fumarate and selenite. Strain SB91T survived after exposure to gamma-radiation at a dose of 5.4 kGy. The G+C content of the DNA of strain SB91T was 33 mol%. Analysis of the 16S rRNA gene sequence revealed that the isolated organism belonged to cluster XII of the clostridia. On the basis of its physiological properties and the results of phylogenetic analyses, it is proposed that strain SB91T represents the sole species of a novel genus, Tepidimicrobium; the name Tepidimicrobium ferriphilum gen. nov., sp. nov. is proposed, with strain SB91T (=DSM 16624T=VKM B-2348T) as the type strain.

Bacteria, Anaerobic↗

Proteiniphilum acetatigenes gen. nov., sp. nov., from a UASB reactor treating brewery wastewater.

Two proteolytic, strictly anaerobic bacterial strains (TB107(T) and TB6-6) were isolated from the granule sludge of an upflow anaerobic sludge blanket reactor treating brewery wastewater. The strains were Gram-negative, non-spore-forming and motile. Cells were rod-shaped (0.6-0.9x1.9-2.2 microm). Growth of the strains was observed at 20-45 degrees C and pH 6.0-9.7. The strains were proteolytic. Yeast extract, peptone, pyruvate, glycine and l-arginine could be used as carbon and energy sources. Weak growth was also observed with tryptone, l-serine, l-threonine and l-alanine as carbon and energy sources. Both strains did not use any of the tested carbohydrates, alcohols and fatty acids except pyruvate. Acetic acid and NH3 were produced from yeast extract, peptone and l-arginine, and propionic acid was also produced from yeast extract. Pyruvate was converted to acetic acid and CO2. Gelatin was not hydrolysed. Indole and H2S were not produced. The two strains did not grow in medium containing 20 % bile. Addition of strain TB107T to a syntrophic propionate-degrading co-culture accelerated the propionate-degradation rate. The predominant cellular fatty acid was the branched-chain fatty acid anteiso-C(15 : 0) (46.21 %). The genomic DNA G+C contents of strains TB107T and TB6-6 were 46.6 and 48.9 mol%, respectively. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two strains represent a new phyletic sublineage within the Cytophaga-Flavobacterium-Bacteroides (CFB) group, with <91 % 16S rRNA gene sequence similarity to the closest species with validly published names. On the basis of polyphasic evidence from this study, a new genus and species, Proteiniphilum acetatigenes gen. nov., sp. nov., is proposed, with strain TB107T (=JCM 12891T=AS 1.5024T) as the type strain.

Anaerobiosis↗

Intestinal microflora and bile acids. In vitro cholic acid transformation by mixed fecal culture of rats.

In vitro cholic acid (CA) transformation by mixed fecal culture was investigated. Concentrations of glucose, peptone, and yeast extract in the medium and the initial pH of the medium markedly affected the CA transformation. Yeast extract enhanced the transformation, whereas high concentrations of glucose and peptone inhibited it. When the initial pH of the medium was below 6.5, CA was converted to 7-keto-deoxycholic acid (7KD), and formation of deoxycholic acid (DC) was not observed. In contrast, with an initial pH of 7.0, about 60% of the CA was converted to 7KD after 3 days of incubation, and then DC gradually formed after 4 days of incubation, following the disappearance of 7KD. The formation of DC in the cultured samples was paralleled in each case by disappearance of 7KD. In pure culture systems, Escherichia coli and some strains of Bacteroides formed 7KD from CA. No DC formation was observed in pure cultures of any of the strains examined.

Animals↗

Studies of latent cytomegalovirus infection: the macrophage as a virus-harboring cell.

During chronic infection of mice with mouse cytomegalovirus (MCMV), the virus was isolated from various tissues by cocultivation with allogeneic mouse embryonic fibroblasts (MEF). Infectious virus was recovered from over 15% of the pancreases, salivary glands, kidneys, lacrimal glands, and spleens. When activated macrophages were obtained by intraperitoneal injection of peptone into mice infected 3 months earlier, they harbored MCMV. Macrophages or lymphocytes were infected with MCMV in vitro and injected into normal mice intravenously. The peritoneal cavities of these mice were then stimulated by peptone injection 3 months after the transfer, and peritoneal or splenic macrophages and lymphocytes were cocultured with allogeneic MEF. MCMV was recovered from the peritoneal and splenic macrophages and not from the lymphocytes.

Animals↗