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1.  Effect of initial pH on aflatoxin production. 
Applied Microbiology  1975;30(6):1050-1051.
The effect of initial pH on aflatoxin production by Aspergillus parasiticus NRRL 2999 was examined in a semisynthetic medium. Maximal growth, aflatoxin production, and aflatoxin production per unit of growth occurred at initial pH levels of 5.0, 6.0, and 7.0 respectively. Initial pH levels less than pH 6.0 favored production of the B toxins, whereas levels greater than pH 6.0 favored production of the G toxins.
PMCID: PMC376591  PMID: 2104
2.  Fate of ochratoxin A in brewing. 
Applied Microbiology  1975;30(6):1048-1049.
The fate of ochratoxin A in brewing was investigated by adding (3H)ochratoxin A to the raw materials at 1- and 10-mug/g levels during mashing in a conventional microbrewing process. The results indicated that large portions (28 to 39%) of the added toxin were recovered in spent grains, with less recovery in the yeast (8 to 20%) and beer (14 to 18%). About 38 and 12% of the added toxin at levels of 1 and 10 mug/g, respectively, were degraded during brewing.
PMCID: PMC376590  PMID: 1211934
3.  Improved method of selection for mutants of Pseudomonas putida. 
Applied Microbiology  1975;30(6):1046-1047.
Optimum conditions for enrichment of mutants of Pseudomonas putida in liquid culture were established using a procedure which combines N-methyl-N'-nitro-N-nitrosoguanidine mutagenesis with an improved D-cycloserine selection.
PMCID: PMC376589  PMID: 1108792
4.  Repulsion of bacteria from marine surfaces. 
Applied Microbiology  1975;30(6):1043-1045.
Organic compounds are capable of repelling motile bacteria from marine surfaces. The most effective compounds were acrylamide and benzoic and tannic acids. These were active at concentrations that were not toxic to the bacteria. Repellents were incorporated in nontoxic paints and applied to metal panels. Treated panels immersed in seawater developed a bacterial film of only 10(6) bacteria per cm6 after 12 days compared with untreated panels, which had 5 times 10(12) bacteria per cm2 after the same period. Field studies confirmed the effectiveness of these repellents. The use of biological repellents provides a new approach to the control of marine fouling.
PMCID: PMC376588  PMID: 1211933
5.  Evaluation of petroleum-degrading potential of bacteria from water and sediment. 
Applied Microbiology  1975;30(6):1036-1039.
Bacteria from water and sediment of an oil-polluted harbor were examined for ability to degrade petroleum. Water samples contained a greater variety of bacterial species capable of degrading petroleum than sediment. Cultures from both water and sediment contained Pseudomonas and Acinetobacter spp. Bacteria present in the water samples produced significantly greater degradation of 2-,3-,4-, and 5-ring cycloalkanes and mono-, di-, tri-, tetra-, and pentaaromatics compared with bacteria in sediment samples.
PMCID: PMC376586  PMID: 1211932
6.  New medium for isolating iron-oxidizing and heterotrophic acidophilic bacteria from acid mine drainage. 
Applied Microbiology  1975;30(6):1010-1016.
A new solid medium is described for growing iron and heterotrophic bacteria from acid mine drainage (AMD). Examination of AMD from five states revealed several kinds of colonies of iron-oxidizing bacteria: (i) smooth, (ii) smooth with secondary growth sectors or branching, (iii) star-shaped, (iv) radiating lobe, and (v) flat-rough. All AMD samples yielded whitish colonies that could not use ferrous iron, sulfur, or hydrogen, nor could they grow on nutrient agar, brain heart infusion agar, or Trypticase soy agar. Glucose and sucrose supported growth if the sugar-salts medium was at pH 3.0. The new iron medium has several advantages over others: (i) easy preparation, (ii) rapid growth, (iii) larger colonies, (iv) differentiation of colony morphology, and (v) detection of a new group of heterotrophic acidophilic bacteria.
PMCID: PMC376583  PMID: 2103
7.  Ultrastructure of Rhizobium-induced infection threads in clover root hairs. 
Applied Microbiology  1975;30(6):1003-1009.
Ultrastructural studies of Rhizobium-induced infection threads in clover root hairs show that the infection thread is initiated by an invagination process. Root hair wall growth is redirected at a localized point, resulting in the formation of an open pore. There is no direct penetration through the wall, and the bacteria remain extracellular within the root hair.
PMCID: PMC376582  PMID: 1211931
8.  Kinetics of a bacterial culture growth: validity of the affinity rule in biological systems. 
Applied Microbiology  1975;30(6):994-1002.
The kinetic study of a process is usually performed by measuring a convenient intensive property, P, as a function of time. The "affinity rule" states that, when a given process takes place under different external constraints (e.g., different temperatures, pressures, pH values, etc.), the various P versus time curves are related by an affinity transformation parallel to the time axis: in other words the P versus log time curves are parallel and can be superimposed by translation. The validity of the rule has been extensively tested in chemical and physiochemical processes, but there is no evidence as yet that it extends to biological systems. The present paper shows that the rule is indeed valid for the kinetics of growth of an Escherichia coli culture at various temperatures and pH values. More extended experiments are necessary to prove or disprove the general validity of the rule in biological systems, but its practical interest is evident: whenever it is valid it will be possible, from a very small number of measurements, to predict the complete behavior of the system in a number of various external conditions
PMCID: PMC376581  PMID: 2109
9.  Growth potential of Clostridium botulinum in fresh mushrooms packaged in semipermeable plastic film. 
Applied Microbiology  1975;30(6):964-969.
Fresh mushrooms (Agaricus bisporus) were inoculated in the stem, gill, or cap with Clostridium botulinum spores. They were placed with uninoculated mushrooms in paper board trays, which were then covered and sealed in a polyvinyl chloride stretch film to simulate prepackaged mushrooms available at retail stores. When incubated at 20 C, botulinum toxin could be detected as early as day 3, or 4, when the mushrooms still appear edible. Mushrooms inoculated in the stem with 1,000 type A spores frequently became botulinogenic; higher spore levels were needed if gills or caps were inoculation sites. Type B spores were less apt to produce toxic mushrooms. Respiration of the fresh mushrooms used up O2 more rapidly than could enter through the semipermeable wrapping film, so that the equilibrium O2 concentration became low enough for growth of C. botulinum. Inoculated mushrooms did not become botulinogenic when held at 4 C.
PMCID: PMC376576  PMID: 1108793
10.  Distribution and effects of 2,4,5-trichlorophenoxyacetic acid in cells of Bacillus megaterium. 
Applied Microbiology  1975;30(6):959-963.
Cell death in a resting population of an asporogenous Bacillus megaterium was accelerated by ambient concentrations of 2,4,5-trichlorophenoxyacetic acid (2,4,5-T) equal to or greater than 10 mug/ml or 5 mug/mg of cells (dry weight), but only after prolonged exposure. Conversely, populations of growing cells were not markedly influenced even at 100 mug/ml. Effects on cell respiration were not manifest until the ambient concentration reached 1,000 mug of 2,4,5-T/ml, or 500 mug/mg. Cells of B. megaterium did, however, accumulate 2,4,5-T passively to a level approximately twofold above the ambient concentration. Most of the accumulated compound was easily washed from the cells, but, of the firmly bound herbicide, about 0.5 mug/mg of cells (dry weight), nearly 60% by weight, was localized in the protoplast membrane. The foregoing results, obtained with a purified preparation of 2,4,5-T were also elicited by 2,4,5-T analytical standards. The extracted contaminants did not produce the results alone nor did they influence the results when present in combination with 2,4,5-T.
PMCID: PMC376575  PMID: 813578
11.  Incorporation of (2-14C)acetate into lipids of mink (Mustela vison) liver and intestine during in vitro and in vivo treatment with aflatoxin B1. 
Applied Microbiology  1975;30(6):946-950.
The in vitro and in vivo incorporation of (2-14C)acetate into lipids of mink (Mustela vison) liver and intestines was studied. In vitro, a dose of aflatoxin B1 as small as 7.5 mug/ml of medium reduced by 20% the amount of (2-14C)acetate incorporated into lipids of mink liver slices, whereas 180 mug caused 76% reduction in the synthesis of lipids from the radioactive precusor. Similar inhibition of lipid synthesis by aflatoxin also was observed with tissues from mink intestines and fatty liver. The degree of inhibition (19 to 84% for tissue from intestines and 19 to 64% for tissue from fatty livers) depended on the amount of aflatoxin B1 (7.5 TO 180 MUG) present in the medium. In vivo, a substantially increased amount of 14C-labeled lipids was found in the livers of mink injected with 600 mug of aflatoxin B1 per kg of body weight 20, 28, and 40 h earlier. However, no appreciable difference in incorporation of (2-14C)acetate into lipids was observed between toxin-treated and control animals when these animals were sacrificed and examined for 14C-labeled lipids at 4 and 10 h after toxin was administered.
PMCID: PMC376573  PMID: 1211938
12.  Heat resistance of ileal loop reactive Bacillus cereus strains isolated from commercially canned food. 
Applied Microbiology  1975;30(6):943-945.
Sporeformers isolated from a commercially canned food were identified as Bacillus cereus, lactose-positive variants. The thermal resistance of spore crops produced from each of two representative cultures was determined in 0.067 M phosphate buffer at pH 7.0. The D121.1 values for one isolate were approximately 0.03 min (z = 9.9C), whereas the D121.1 values for the other isolate were 2.35 min (z = 7.9 C). Thermal inactivation results for heat-stressed isolates from each strain showed no significant alteration in heat resistance from that of the two parent spore crops. Both isolates were reactive when injected into the ligated rabbit ileum.
PMCID: PMC376572  PMID: 2108
13.  Screening test for assessment of ultimate biodegradability: linear alkylbenzene sulfonates. 
Applied Microbiology  1975;30(6):922-929.
A relatively simple shake-flask system for determining CO2 evolution was developed to assess the ultimate biodegradability by soil and sewage micro-organisms of chemicals which enter the environment. Linear alkylbenzene sulfonates (LAS) were used as model compounds to evaluate the method and were found to undergo substantial biodegradation in this dilute system. At the 30 mg/liter test concentration, higher-molecular-weight LAS compounds were biodegraded at a slower rate and to a lesser extent than lower-molecular-weight LAS, an effect which was eliminated or greatly reduced upon incremental addition of the LAS to the test medium during the first week of incubation. LA35S was used to demonstrate rapid LAS desulfonation, and 14CO2 evolution studies with (14C) benzene ring-labeled LAS indicated concomitant biodegradation of the entire LAS molecule as well as the LAS aromatic component. The test can be employed to examine numerous compounds at the same time and is readily adapted to studies of the effect of variation in temperature and oxygen concentration on biodegradation.
PMCID: PMC376569  PMID: 1211937
14.  Studies on the biosynthesis of aspergillin by Aspergillus niger. 
Applied Microbiology  1975;30(6):909-915.
Two inhibitors of the biosynthesis of aspergillin, the black spore pigment of Aspergillus niger, have been investigated. 2,4-Dithiopyrimidine exerted its inhibitory effect by intracellularly chelating cupric ion required for normal pigmentation. Dimethylsulfoxide prevented the synthesis of certain phenolic precursors of the native pigment. Partial purification and characterization of pigments from mature cultures revealed the presence of at least three components: (i) a high-molecular-weight (approximately 20,000) native pigment fraction in untreated mold cultures, (ii) a lower-molecular-weight (approximately 5,000) melanin pigment found in both types of inhibited cultures, and (iii) a low-molecular-weight (368) green pigment found only in the 2,4-dithiopyrimidine-inhibited cultures and proposed to be a pentacyclic quinonoid derivative. A pathway for aspergillin biosynthesis is suggested based on these results.
PMCID: PMC376567  PMID: 1211936
15.  High-temperature production of protein-enriched feed from cassava by fungi. 
Applied Microbiology  1975;30(6):897-904.
A simple, nonaseptic, low-cast process for the conversion of cassava, a starchy tropical root crop, into microbial protein for use as animal feed was sought. Screening tests culminated in the isolation of a thermotolerant, amylase-producing mold, designated I-21, which was identified as Aspergillus fumigatus. The optimum pH for protein synthesis was 3-5, but the optimum temperature was less than the desired temperature (larger than or equal to 45 C) required for a nonaseptic fermentation. A. fumigatus I-21 and its asporogenous mutant I-21A grew equally well in a medium prepared from whole cassava roots with a mean protein doubling time at 45 C and pH 3.5 of 3.5 h. In batch culture, approximately 4% carbohydrate, supplied as whole cassava, could be feremented in 20 h, giving a final yield of 24 g of dry product, containing 36.9% crude protein, per liter. The conversion of carbohydrate used to crude protein was 22.1%. When determined as amino acids, the protein content of the product, which contained cassava bark and other unfermented residues, was 27.1%. With urea as the nitrogen source, no pH control was necessary. Preliminary data indicated that medium prepared from whole cassava roots was inhibitory to the mold unless the cassava pulp was heated to 70 C immediately after being ground. Heating to 70 C was required to gelatinize the starch and permit its complete utilization.
PMCID: PMC376565  PMID: 2105
16.  Effect of substrates on acetoin production by Torulopsis colliculosa and Enterobacter species. 
Applied Microbiology  1975;30(6):889-892.
Under optimal conditions, Torulopsis colliculosa NRRL 172 and Enterobacter B-87 (ATCC 27613) produced 50 to 500 mg of acetoin per g of substrate. Whereas cane molasses, gur, glucose, and sucrose were suitable substrates for acetoin production, lactose and mannitol supported very good growth but yielded little or no acetoin. Production of acetoin increased with increases in the concentration of glucose, yeast extract, and peptone. Combination of substrates and intermittent feeding of substrate failed to increase the yields.
PMCID: PMC376563  PMID: 1239980
17.  Tetramethyl-p-phenylenediamine oxidase reaction in Azotobacter vinelandii. 
Applied Microbiology  1975;30(6):951-958.
It was possible to quantitate the tetramethyl-p-phenylenediamine (TMPD) oxidase reaction in Azotobacter vinelandii strain O using turbidimetrically standarized resting cell suspensions. The Q(O2) value obtained for whole cell oxidation of ascorbate-TMPD appeared to reflect the full measure of the high respiratory oxidative capability usually exhibited by this genera of organisms. The Q(O2) value for the TMPD oxidase reaction ranged from 1,700 to 2,000 and this value was equivalent to that obtained for the oxidation of the growth substrate, e.g., acetate. The kinetic analyses for TMPD oxidation by whole cells was similar to that obtained for the "particulate" A. vinelandii electron transport particle, that fraction which TMPD oxidase activity is exclusively associated with. Under the conditions used, there appeared to be no permeability problems; TMPD (reduced by ascorbate) readily penetrated the cell and oxidized at a rate comparable to that of the growth substrate. This, however, was not true for the oxidation of another electron donor, 2,6-dichloroindophenol, whose whole cell Q(O2) values, under comparable conditions, were twofold lower. The TMPD oxidase activity in A. vinelandii whole cells was found to be affected by the physiological growth conditions, and resting cells obtained from cells grown on sucrose, either under nitrogen-fixing conditions or on nitrate as the combined nitrogen source, exhibited low TMPD oxidase rates. Such low TMPD oxidase rates were also noted for chemically induced pleomorphic A. vinelandii cells, which suggests that modified growth conditions can (i) alter the nature of the intracellular terminal oxidase formed (or induced), or (ii) alter surface permeability, depending upon the growth conditions used. Preliminary studies on the quantitative TMPD oxidation reaction in mutant whole cells of both Azotobacter and a well-known Mucor bacilliformis strain AY1, deficient in cytochrome oxidase activity, showed this assay can be very useful for detecting respiratory deficiencies in the metabolism of whole cells.
PMCID: PMC376574  PMID: 174491
18.  Factors influencing detection and enumeration of Pseudomonas aeruginosa by most-probable-number and membrane filtration techniques. 
Applied Microbiology  1975;30(6):935-942.
Most-probable-number (MPN) and membrane filtration (mF) techniques were evaluated with respect to selectivity, sensitivity, and efficiency in recovering Pseudomonas aeruginosa strains in hospital fluids and extramural water environments. Known numbers of cells of a naturally occurring strain of P. aeruginosa maintained in distilled water or cells subcultured on Standard Methods agar were added to test samples containing various types and levels of background microbial contamiants. Environmental samples containing unknown numbers of P. aeruginosa strains also were tested. Asparagine and acetamide broths were employed as presumptive media in MPN tests, and mPA and Pseudosel agars were used in mF assays. Statistical analyses of data showed the superiority and comparability of the asparagine-MPN and mPA-mF systems. Greater precision and accuracy were consistently obtained in either assay technique by the use of naturally occurring cells as test organisms. The type of filter and nature of diluents employed, as well as pH of assay media, were found to greatly influence both recovery and developemnt of characteristic colonial morphology in the mPA-mF system.
PMCID: PMC376571  PMID: 2107
19.  Relationship of lactate dehydrogenase specificity and growth rate to lactate metabolism by Selenomonas ruminantium. 
Applied Microbiology  1975;30(6):916-921.
A lactate-fermenting strain of Selenomonas ruminantium (HD4) and a lactatenonfermenting strain (GA192) were examined with respect to the stereoisomers of lactate formed during glucose fermentation, the stereoisomers of lactate fermented by HD4, and the characteristics of the lactate dehydrogenases of the strains. GA192 formed L-lactate and HD4 formed L-lactate and small amounts of D-lactate from glucose. HD4 fermended L- but not D-lactate. Both strains contain nicotinamide adenine dinucleotide (NAD)-specific lactate dehydrogenases, and no NAD-independent lactate oxidation was detected. Continuous cultures of both strains grown with limiting glucose produced mainly propionate and acetate and little lactate at dilution rates less than 0.4/h, with shifts to increasing amounts of lactate and less acetate and propionate as the dilution rate was increased from 0.4/h to approximately 1/h.
PMCID: PMC376568  PMID: 174490
20.  Separation of Spores and Parasporal Crystals of Bacillus thuringiensis in Gradients of Certain X-Ray Contrasting Agents 
Applied Microbiology  1975;30(6):1052-1053.
Spores and parasporal crystals of Bacillus thuringiensis can be separated at moderate centrifugation speeds (10,000 to 12,000 rpm) in gradients of Renografin or sodium diatrizoate.
PMCID: PMC376592  PMID: 1211935
21.  Detection of Aflatoxin B1 in Silkworm Larvae Attacked by an Aspergillus flavus Isolate from a Sericultural Farm 
Applied Microbiology  1975;30(6):1034-1035.
Aflatoxin B1 (0.05 μM per larvae) was detected in silkworm larvae artificially attacked by an Aspergillus flavus isolate from a sericultural farm in Japan.
PMCID: PMC376585  PMID: 813577
22.  Removal of algae from Florida lakes by magnetic filtration. 
Applied Microbiology  1975;30(6):905-908.
Magnetic filtration was used for the removal of algal populations present in five lakes located in the vicinity of Gainesville, Fla. It was found that the use of this technique enabled a good removal (94%) of algal cells from three lakes where the pH was around 7. The other two lakes, with a higher pH, displayed a lower removal. However, the treatment was greatly improved by lowering the pH from 9.5 to 6.5.
PMCID: PMC376566  PMID: 2106
23.  Cross-reactive antigens and lectin as determinants of symbiotic specificity in the Rhizobium-clover association. 
Applied Microbiology  1975;30(6):1017-1033.
Cross-reactive antigens of clover roots and Rhizobium trifolii were detected on their cell surfaces by tube agglutination, immunofluorescent, and radioimmunoassay techniques. Anti-clover root antiserum had a higher agglutinating titer with infective strains of R. trifolii than with noninfective strains. The root antiserum previously adsorbed with noninfective R. trifolii cells remained reactive only with infective cells, including infective revertants. When adsorbed with infective cells, the root antiserum was reactive with neither infective nor noninfective cells. Other Rhizobium species incapable of infecting clover did not demonstrate surface antigens cross-reactive with clover. Radioimmunoassay indicated twice as much antigenic cross-reactivity of clover roots and R. trifolii 403 (infective) than R. trifolii Bart A (noninfective). Immunofluorescence with anti-R. trifolii (infective) antiserum was detected on the exposed surface of the root epidermal cells and diminished at the root meristem. The immunofluorescent crossreaction on clover roots was totally removed by adsorption of anti-R. trifolii (infective) antiserum with encapsulated infective cells but not with noninfective cells. The cross-reactive capsular antigens from R. trifolii strains were extracted and purified. The ability of these antigens to induce clover root hair deformation was much greater when they were obtained from the infective than noninfective strains. The cross-reactive capsular antigen of R. trifolii 403 was characterized as a high-molecular-weight (greater than 4.6 times 10(6) daltons), beta-linked, acidic heteropolysaccharide containing 2-deoxyglucose, galactose, glucose, and glucuronic acid. A soluble, nondialyzable, substance (clover lectin) capable of binding to the cross-reactive antigen and agglutinating only infective cells of R. trifolii was extracted from white clover seeds. This lectin was sensitive to heat, Pronase, and trypsin. inhibition studies indicated that 2-deoxyglucose was the most probable haptenic determinant of the cross-reactive capsular antigen capable of binding to the root antiserum and the clover lectin. A model is proposed suggesting the preferential adsorption of infective versus noninfective cells of R. trifolii on the surface of clover roots by a cross-bridging of their common surface antigens with a multivalent clover lectin.
PMCID: PMC376584  PMID: 55100
24.  Chemical alteration of carotene biosynthesis in Phycomyces blakesleeanus and mutants. 
Applied Microbiology  1975;30(6):988-993.
The effects of diphenylamine, dimethyl sulfoxide, streptomycin, AMO-1618, and beta-ionone on the carotene composition of a wild-type and three mutant strains of Phycomyces blakesleeanus have been examined. Diphenylamine increased the phytoene and phytofluene concentrations of all strains while reducing the levels of the color carotenes. Dimethyl sulfoxide reduced the concentration of both cyclic and acyclic carotenes, whereas AMO-1618 increased the levels of all carotenes in all the strains. The wild type and mutants responded differently to the presence of streptomycin and beta-ionone. The possible mode of action of the above agents on carotenoid biosynthesis is discussed.
PMCID: PMC376580  PMID: 1211939
25.  Effects of three environmental variables on sulfate uptake by aerobic bacteria. 
Applied Microbiology  1975;30(6):975-981.
The effects of various concentrations of sulfate, organic sulfur, and organic carbon on sulfate uptake by aerobic bacteria were studied using pure cultures growing in a defined medium. Cultures of Pseudomonas fluorescens and Corynebacterium striatum took up sulfate faster when young, but sulfate uptake by Serratia marcescens was faster in older cultures. Organic sulfur was found to decrease sulfate uptake, but at concentrations somewhat higher than occurs in most natural freshwater ecosystems. Low levels of sulfate can theoretically directly limit bacterial biomass production but such limitation probably does not occur in natural systems. Evidence is presented which indirectly links the uptake of sulfate and organic carbon, adding credibility to the proposal that sulfate uptake can be used as an indicator of microbial biomass production in freshwater ecosystems.
PMCID: PMC376578  PMID: 813579

Results 1-25 (5509)