Showing papers in "Journal of Applied Microbiology in 1974"
TL;DR: Treating seedling roots of several plant species with cultures of Azotobacter paspali changed plant growth and development and significantly increased weight of leaves and roots; effects were probably caused by plant growth regulators.
Abstract: Summary. Treating seedling roots of several plant species with cultures of Azotobacter paspali changed plant growth and development and significantly increased weight of leaves and roots; effects were probably caused by plant growth regulators. Culture supernatant fluids contained indolyl-3-acetic acid, at least 3 gibberellins and 2 cytokinins. The added inoculum of A. paspali survived in plant rhizospheres for only a few weeks and no nitrogen was fixed in the root zone of young Paspalum notatum, the grass with which A. paspali is associated.
167 citations
TL;DR: The heat resistance at 65° of 3 strains of salmonellae in solutions of sugars or polyols was enhanced as the concentration of the solutes increased, and for all solutes except glycerol there was a linear relationship between log D65 and concentration (% w/w) of solute.
Abstract: Summary. The heat resistance at 65° of 3 strains of salmonellae in solutions of sugars or polyols was enhanced as the concentration of the solutes increased. There was no linear relationship between heat resistance and water activity (aw), but for all solutes except glycerol there was a linear relationship between log D65 and concentration (% w/w) of solute. Comparison of D65 at a particular aw or percentage (w/w) solute concentration showed that the value decreased in the order: sucrose > glucose > sorbitol > fructose > glycerol. In glycerol, D65 values were always very much lower than in any other solute. With sucrose–glycerol or sucrose–glucose mixtures, heat resistance depended both on the total concentration (% w/w) of solutes present and also on the aw of the solution.
121 citations
114 citations
TL;DR: Anaerobic bacteria which decompose uric acid have been found in the caeca of chickens, turkeys, ducks, pheasants and guinea-fowl at levels between 5.4 × 108 and 1.8 × 1010/g of caecal material.
Abstract: Summary. Anaerobic bacteria which decompose uric acid have been found in the caeca of chickens, turkeys, ducks, pheasants and guinea-fowl at levels between 5.4 × 108 and 1.8 × 1010/g of caecal material (wet weight). A study has been made of the properties and identity of 35 strains which were present in high numbers in the chicken caecum. The isolates included strains of Bacteroides clostridiiformis var. clostridiiformis, Fusobacterium plauti, Clostridium malenominatum, Peptostreptococcus productus and a number of types which could not be identified with known species. Of these 3 were Bacteroides spp., 3 Eubacterium spp., 2 Peptostreptococcus spp. and 1 was an anaerobic Streptococcus. None of the strains had an absolute requirement for uric acid.
85 citations
82 citations
TL;DR: The decrease in amount of free fatty acid associated with the bacteria and the decrease in the amount of triglyceride in the supernatant liquid when food particles were present, was wholly accounted for by the increase in amounts of these substrates associatedwith the food particles.
Abstract: Summary. Suspensions of mixed rumen bacteria were incubated with long-chain fatty acids and their corresponding triglycerides in the presence and absence of the food particles present in the rumen. The uptake of free fatty acids and triglycerides by the bacteria was due largely to physical adsorption. With increasing unsaturation of the free fatty acids, less adsorption occurred and in all instances the presence of food particles reduced greatly the extent to which the fatty acids were adsorbed on the bacteria. The triglycerides were adsorbed to the bacteria to a much less extent than their corresponding free fatty acids, more of the substrate remaining in the supernatant fraction. The presence of food particles had little effect on the extent to which the triglycerides became adsorbed to the bacteria, but reduced greatly the amount of triglyceride present in the supernatant fraction. The decrease in amount of free fatty acid associated with the bacteria and the decrease in the amount of triglyceride in the supernatant liquid when food particles were present, was wholly accounted for by the increase in amount of these substrates associated with the food particles. The implications of these findings with respect to the metabolism of lipids in the rumen is discussed.
72 citations
TL;DR: The results suggest that toxicity of RNB may be due to impairment of body defence mechanisms by PHA leading to tissue invasion by normally innocuous components of the intestinal microflora.
Abstract: Summary. The lethal and growth depressing effects of feeding raw navy beans (RNB) to Japanese quail have been shown to be due neither to poor palatability nor to dialysable, lipid or carbohydrate constituents, but to a protein material soluble at pH 3 and precipitable by saturation with (NH4)2SO4. This material proved resistant to digestion by pepsin and proteolytic bacteria but was destroyed by autoclaving at 121° for 15 min. Germfree birds given a diet containing RNB which had been fermented by coliforms grew well, indicating that toxicity of RNB is not dependent on the release by intestinal bacteria of poisons from innocuous precursors in the beans. Examination of the effects of feeding diets containing other raw legume seeds to quail have shown that toxicity is associated with the presence of high concentrations of phytohaemagglutinins (PHAs). Quail given RNB diet showed a greater incidence of liver infection than birds fed an autoclaved bean diet but bacteriological examination of gut contents of such birds revealed no marked qualitative or quantitative differences. Chemical examination of gut contents likewise revealed no marked differences. Experiments with gnotobiotic quail showed that coliforms derived from a variety of sources were capable of causing the death of birds on RNB diet and that the numbers attained in different parts of the intestine by a single coliform strain were not affected by the diet fed. The results suggest that toxicity of RNB may be due to impairment of body defence mechanisms by PHA leading to tissue invasion by normally innocuous components of the intestinal microflora.
62 citations
Journal Article•
TL;DR: In this article, Radiorespirometry was used to compare the primary pathways of glucose catabolism in 18 strains of Bacillus thuringiensis representing the 12 established serotypes.
Abstract: Radiorespirometry was used to compare the primary pathways of glucose catabolism in 18 strains of Bacillus thuringiensis representing the 12 established serotypes. Every strain utilizes the Embden-Meyerhof-Parnas pathway almost exclusively; pentose-phosphate pathway participation is minor. The Embden-Meyerhof-Parnas pathway predominates regardless of whether the cells were grown in a minimal medium or one containing yeast extract. The results indicate that the absolute requirement for citrate and related compounds is not a result of defective citrate or glucose transport and metabolism.
57 citations
TL;DR: Enterotoxin A was found to occur most frequently and enterotoxin B least frequently and the distribution of enterotoxigenicity in strains isolated from meat products differed from that of strain isolated from dairy products.
Abstract: Summary. The production of staphylococcal enterotoxins A, B, C, D and E among 200 strains of Staphylococcus aureus was surveyed using a double diffusion immunoprecipitation technique. Enterotoxin A was found to occur most frequently and enterotoxin B least frequently. The distribution of enterotoxigenicity in strains isolated from meat products differed from that of strains isolated from dairy products. The correlations of porcine plasma coagulation and of bacteriophage pattern with enterotoxigenicity were determined.
57 citations
TL;DR: A method for sampling quantitatively bacteria present in the subsurface pilo-sebaceous units of human skin is described and counts of up to 106 organisms/cm2 obtained.
Abstract: Summary. A method for sampling quantitatively bacteria present in the subsurface pilo-sebaceous units of human skin is described. Less than 0.5% of a marker surface organism was isolated and counts of up to 106 organisms/cm2 obtained.
52 citations
TL;DR: The lipolytic activity in supernatant fractions of cultures of Saccharomycopsis lipolytica, Micrococcus caseolyticus, Bacillus licheniformis, and a Staphylococcus sp.
Abstract: Summary. The lipolytic activity in supernatant fractions of cultures of Saccharomycopsis lipolytica, Micrococcus caseolyticus, Bacillus licheniformis, and a Staphylococcus sp. was studied. Nutrient broth with and without emulsified olive oil was used as substrate. Optimal pH values and temperatures for the lipase produced by the 4 different micro-organisms were determined. The lipolytic activity generally reached a maximum after incubation for 2–6 days. The subsequent decrease in the lipolytic activity was associated with a high proteolytic activity only for Micrococcus caseolyticus. The lipolytic activity was decreased by the presence of olive oil in the medium. Determination of the lipolytic activity after a certain time of incubation, the maximal lipolytic activity and a time-integrated lipolytic activity are compared as estimators for the potential hydrolytic capacity of micro-organisms.
TL;DR: A uni-directional downflow (‘laminar’flow) ventilation system for a single-bed patient-room showed that strains of Staphylococcus aureus carried on the nurses’external clothing were often transferred to the patients’bedclothes, and this possible route of patient infection was almost eliminated when the nurses wore disposable plastic aprons over their dresses.
Abstract: Summary. A uni-directional downflow (‘laminar’flow) ventilation system for a single-bed patient-room is described. It produced clean air at velocities as low as 0.12 m/sec (25 ft/min). Bacteriological studies on bed-making done in the room showed that strains of Staphylococcus aureus carried on the nurses’external clothing were often transferred to the patients’bedclothes. This possible route of patient infection was almost eliminated when the nurses wore disposable plastic aprons over their dresses.
TL;DR: Growth rates of Erwinia amylovora in yeast extract–peptone broth were assessed, by colony counts and turbidity measurements, and an Arrhenius plot showed a linear relationship between doubling rate and temperatures between 9 and 18°.
Abstract: Summary. Growth rates of Erwinia amylovora in yeast extract–peptone broth were assessed, by colony counts and turbidity measurements, at c. 3° intervals over the range 6.5–36.0°. An Arrhenius plot showed a linear relationship between doubling rate and temperatures between 9 and 18°. The slope of this line was comparable to that obtained for Escherichia coli by Ingraham (1958) between c. 12 and 30°. At 18° there was a sharp change in growth rate; between 18 and 28° the doubling time decreased only from 2.1 to 1.3 h (Q10= 1.8) but between 8 and 18° it increased from 2.1 to 14.0 h (Q10= 6.7). This apparently critical temperature is of special interest because maximum air temperatures > 18° appear necessary for epidemic blossom blight in North America.
TL;DR: Recovery of Pseudomonas aeruginosa, Escherichia coli, and Streptococcus faecalis from aqueous suspending media has been studied with a rich plating medium (trypticase-soy agar) and selective media andTap water was highly toxic to all strains investigated.
Abstract: Summary. The recovery of Pseudomonas aeruginosa, Escherichia coli, and Streptococcus faecalis from aqueous suspending media has been studied with a rich plating medium (trypticase-soy agar) and selective media. Tap water was highly toxic to all strains investigated. Recovery of Ps. aeruginosa was most successful when phosphate buffer was the diluent. Phosphate buffer did not improve the recovery of E. coli. Streptococcus faecalis remained viable when suspended in double distilled water, deionized distilled water or phosphate buffer. Following a lag period all strains grew in 0.1% peptone water or stream water. Injury preventing recovery of viable cells on selective media occurred during suspension in all aqueous media tested, including those which supported growth. These observations suggest difficulties inherent in the interpretation of bacteriological results obtained during surveys of water sources and a need to reduce the selectivity of recovery media against injured cells.
TL;DR: A study of the egg yolk reaction produced by various species of bacteria has shown that it is caused by the hydrolysis of phosphatidylcholine, which results in the formation of a sub-surface, opaque homogeneous zone around colonies growing on egg yolks agar and a collar of lipid material floating on the surface of eggYolk broth.
Abstract: Summary. A study of the egg yolk reaction produced by various species of bacteria has shown that it is caused by the hydrolysis of phosphatidylcholine. Staphylococcus aureus and Serratia marcescens degrade phosphatidylcholine by a series of hydrolytic reactions which are initiated by phosphatidylcholine: cholesterol o-acyltransferase. The degradation of phosphatidylcholine results in the formation of a sub-surface, opaque homogeneous zone around colonies growing on egg yolk agar and a collar of lipid material floating on the surface of egg yolk broth. This reaction may not be shown by all species growing in egg yolk media but it can be demonstrated if enzyme extracts are used.
TL;DR: The development and use of a selective diagnostic medium for the detection and enumeration of Clostridium perfringens in foods is described, which gives higher counts of Cl. perfringen and fewer false positives than existing media.
Abstract: Summary. This paper describes the development and use of a selective diagnostic medium for the detection and enumeration of Clostridium perfringens in foods. The medium gives higher counts of Cl. perfringens and fewer false positives than existing media.
TL;DR: Both the percentage of infected sheep and the number of salmonellae/g of faeces subsequently increased rapidly andamination of fleece and carcasses increased with time and with the degree to which the pens were contaminated.
Abstract: Summary. When sheep were held in abattoir pens, the fleece became contaminated with salmonellae within 1 day even when there was less than 1 salmonella/g of soil. Salmonellae were first shed in the faeces after 2–3 days. Both the percentage of infected sheep and the number of salmonellae/g of faeces subsequently increased rapidly. Contamination of fleece and carcasses increased with time and with the degree to which the pens were contaminated. The fleece appeared to be a significant source of salmonella contamination of the carcass.
Journal Article•
TL;DR: In this paper, a defined medium is described in which 18 strains of Bacillus thuringiensis representing the 12 established serotypes grow, sporulate, and produce a parasporal crystal.
Abstract: A defined medium is described in which 18 strains of Bacillus thuringiensis representing the 12 established serotypes grow, sporulate, and produce a parasporal crystal. This minimal medium contains glucose and salts supplemented with either aspartate, glutamate, or citrate. These organic acids are required and cannot be replaced by vitamin mixtures or succinate even though succinate is taken up at a rate similar to that of aspartate, glutamate, and citrate.
TL;DR: Experiments on the control of crown gall by inoculating susceptible plants with a non-pathogenic strain of Agrobacterium radiobacter have continued, achieving highly significant disease control and a significant increase in plant growth resulted from combined seed and root inoculation.
Abstract: Summary. Experiments on the control of crown gall by inoculating susceptible plants with a non-pathogenic strain of Agrobacterium radiobacter have continued. In all experiments, highly significant disease control was achieved. In one experiment, 42% of untreated plants growing in soil heavily infested with A. radiobacter var. tumefaciens died; inoculation of seed with the non-pathogenic strain reduced this to nil. Combined seed and root inoculation was more efficient than seed inoculation alone. In naturally infested soil, combined seed and root inoculation at transplanting gave 99% control of gall formation (as dry weight). A significant increase in plant growth resulted from combined seed and root inoculation. At transplanting, roots should probably be inoculated within 2 h of lifting. This method of biological control is now widely practised by commercial growers in South Australia.
TL;DR: Using this primary screening method, mutants have been isolated which, when tested later in shake flask cultures, gave larger penicillin yields than the parent strains.
Abstract: Summary. After UV treatment conidia of a strain of Aspergillus nidulans were plated on an agar medium. The survivors gave rise to individual colonies which were inoculated separately on agar discs and incubated. The discs were then transferred to biological assay plates seeded with spores of a strain of Bacillus subtilis sensitive to penicillin. Using this primary screening method, mutants have been isolated which, when tested later in shake flask cultures, gave larger penicillin yields than the parent strains.
TL;DR: This medium (ABPA) was very inhibitory to several Rhizobium strains when supplemented with 1 i.u./ml of penicillin, while YMA containing pentachloronitrobenzene and sodium azide did not inhibit 15 of 18 strains of rhizobia but was more inhibitatory to the general microflora of 4 soils than was YMA.
Abstract: Summary. Fortyseven strains of rhizobia were tested for sensitivity to 6 antibiotics (chloramphenicol, erythromycin, penicillin, streptomycin, sulphafurazole and tetra-cycline) using Oxoid Multodisks on yeast extract-mannitol agar (YMA); penicillin was the least inhibitory. Growth of selected strains on YMA was also compared with that on YMA containing one or more antimicrobial substances. Penicillin (1 i.u./ml of YMA) only slightly inhibited growth of some strains that were sensitive to it by the Multodisk test but higher concentrations were too inhibitory to be used in a selective medium. YMA containing pentachloronitrobenzene (5 p/m, suspended in a 5 p/m solution of Triton X-100), brilliant green (0.5 p/m) and sodium azide (0.5 p/m) did not inhibit 15 of 18 strains of rhizobia but was more inhibitory to the general microflora of 4 soils than was YMA. This medium (ABPA) was very inhibitory to several Rhizobium strains when supplemented with 1 i.u./ml of penicillin.
TL;DR: The presence of starch was essential for iodide oxidation, and its influence was not attributable to its indicator properties, but the polysaccharides glycogen and cellulose, but not pectin, could substitute for starch in the reaction.
Abstract: Summary. Iodide oxidation was catalysed by a haemoprotein peroxidase system produced by the marine bacterium Pseudomonas iodooxidans. The presence of starch was essential for iodide oxidation, and its influence was not attributable to its indicator properties. The polysaccharides glycogen and cellulose, but not pectin, could substitute for starch in the reaction. Dextrin, maltose and glucose were not effective. No explanation can be given at this stage for the requirement of a high polysaccharide for bacterial iodide oxidation.
TL;DR: Low concentrations of glutaraldehyde inhibited or prevented colony formation by Escherichia coli, Bacillus subtilis and B. pumilis in agar, and inhibited germination of spores of the Bacillus spp.
Abstract: Summary. Low concentrations (0.025–0.125%) of glutaraldehyde inhibited or prevented colony formation by Escherichia coli, Bacillus subtilis and B. pumilis in agar, and inhibited germination of spores of the Bacillus spp. in L-alanine plus D-glucose. Higher concentrations (2%) of glutaraldehyde at pH 8.5 were sporicidal. Pre-treatment of spores with glutaraldehyde lessened release of dipicolinic acid when the spores were subsequently heated at 100°, but not at 121°. Spores treated with glutaraldehyde and then with 0.5 M thioglycollic acid in 6 M urea at 70° were less sensitive to lysis by hydrogen peroxide than spores which had not been exposed to glutaraldehyde. Glutaraldehyde was less effective in preventing peroxide induced lysis if added to spores which had been previously exposed to thioglycollic acid plus urea at 70°. The mechanism of the sporicidal activity of glutaraldehyde is discussed in relation to these findings.
TL;DR: Growth of many strains was markedly inhibited, in the absence of added faeces, at 37° and 43° and the addition of 5% (w/v) of human stools to this medium resulted in a heavy growth of the added salmonellae, especially at 43°.
Abstract: Summary. The behaviour of 70 strains of salmonellae belonging to 44 serotypes in Rappaport's broth and in Muller-Kauffmann's tetrathionate broth was examined. With an inoculum of 5–25 cells, 5 strains did not grow in Rappaport's medium, 2 multiplied slowly and 63 grew strongly in 24 h. With an inoculum of 100–500 organisms all but one strain grew readily in 24 h. In Muller–Kauffmann's tetrathionate broth inoculated with pure cultures of salmonellae, growth of many strains was markedly inhibited, in the absence of added faeces, at 37° and 43°. This inhibition was more severe with light inocula at 43°. The addition of 0.05% (w/v) of salmonella-free human faeces to Muller–Kauffmann's tetrathionate broth, did not stimulate growth of salmonellae. In contrast, the addition of 5% (w/v) of human stools to this medium resulted in a heavy growth of the added salmonellae, especially at 43°.
TL;DR: Activated sludge receiving ammonium thiocyanate was able to nitrify and the 2- and 4-methyl pyridine derivatives inhibited both ammonia and nitrite oxidation.
Abstract: Summary. Activated sludge receiving ammonium thiocyanate (500 mg/l) was able to nitrify. The rate of ammonia oxidation was decreased when >3 mg/l of phenol (or cresols) was added to the sludge, and at 10 mg/l was inhibited completely. Concentrations of up to 100 mg/l of phenols did not affect nitrite oxidation. The 2- and 4-methyl pyridine derivatives inhibited both ammonia and nitrite oxidation.
TL;DR: A rapid reduction, after manufacture, in numbers of Rhizobium trifolii in commercial legume inoculants was observed in 1971 and explained by the presence of high concentrations of sodium chloride in the peat used as carrier material.
Abstract: Summary. A rapid reduction, after manufacture, in numbers of Rhizobium trifolii in commercial legume inoculants was observed in 1971 and explained by the presence of high concentrations of sodium chloride in the peat used as carrier material. A strain of R. trifolii growing in broth proved to be more sensitive to sodium ions than did 2 strains of R. meliloti but was more tolerant of up to 0.3% of chloride. The effect of salt differed somewhat according to the source of peat used as carrier, but peat containing °0.2% of chloride (expressed as a % of dry peat) may cause considerable loss of viability of rhizobia.
TL;DR: Outgrowth of spores at different incubation temperatures was similar for germinated and ungerminated spores, suggesting that recovery of heat-treated spores is not limited by their ability to germinate, rather than germination which is sensitive to temperature.
Abstract: Summary. The recovery of Bacillus subtilis spores was studied after different heat treatments at 95° and incubation at different temperatures in roll tubes in a gradient temperature incubator. Plate count agar and brain–heart infusion agar were used in the roll tubes. Unheated spores showed similar recoveries at 16–48° whereas heated spores had an optimum recovery temperature of c. 30.9. The rate of germination of untreated spores was greatest at c. 41° and ceased at 50°. Heated spores germinated at 52°5°, suggesting that recovery of heat-treated spores is not limited by their ability to germinate. Outgrowth of spores at different incubation temperatures was similar for germinated and ungerminated spores. Accordingly it is outgrowth rather than germination which is sensitive to temperature.
TL;DR: The acetylene reduction technique was used for a 3-year period to monitor potential nitrogen fixation by aerobic heterotrophic bacteria in the sea 2 miles offshore in Cardigan Bay, suggesting the presence of a few aerobic or facultatively anaerobic nitrogen fixers among much more numerous and efficient ‘fixed-nitrogen-scavengers’.
Abstract: Summary. The acetylene reduction technique was used for a 3-year period to monitor potential nitrogen fixation by aerobic heterotrophic bacteria in the sea 2 miles offshore in Cardigan Bay. Samples from depths down to 15 m were membrane-filtered and the residues incubated aerobically or anaerobically in acetylene-containing gas mixtures in sealed Millipore Field Monitors. Pure cultures of aerobic heterotrophs isolated from spread-plates or monitor membranes supplied with ‘nitrogen-free’media, were tested for ability to reduce acetylene. Glucose was the best of 14 substrates tested to support both growth and acetylene reduction by marine bacteria. The results suggested the presence of a few aerobic or facultatively anaerobic nitrogen fixers among much more numerous and efficient ‘fixed-nitrogen-scavengers’. The acetylene-reducing capacity of pure cultures was inexplicably variable, even under closely-standardized conditions: this is discussed. The more consistent acetylene reducers included various-sized rods (Gram positive and negative), coccobacilli and yeasts, which latter may have had non-culturable bacteria associated with them. No recognizable Azotobacter sp. was isolated, despite the strongly-selective conditions imposed. Similar results were obtained for seawater samples from the Irish Sea and an Iceland fjord.
TL;DR: The main phenotypic characters of the strains were determined; however their assignment to known species of the genus Bifidobacterium was based primarily on their deoxyribonucleic acid homology relationships following DNA-DNA hybridization tests.
Abstract: Summary. Ninety-five strains of bifidobacteria isolated from 52 specimens of piglet faeces collected at 19 farms were studied. The main phenotypic characters of the strains were determined; however their assignment to known species of the genus Bifidobacterium was based primarily on their deoxyribonucleic acid homology relationships following DNA-DNA hybridization tests. The majority of the strains were recognized as Bifidobacterium suis Matteuzzi et al. Some strains could not be assigned to any known species of the genus so they were allotted provisionally to 2 unassigned bacterial groups.