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At least 19 recordsLinked to original sources
PubMed1979

Bacterial growth inhibition by amniotic fluid. VIII. Evaluation of a radiometric bioassay for rapid, in vitro demonstration of phosphate-sensitive bacterial growth inhibitor in amniotic fluid.

A radiometric bioassay based on the continuous monitoring of 14CO2 released from labeled glucose in the presence of amniotic fluid or amniotic fluid with added phosphate has been employed to detect the presence of a phosphate-sensitive bacterial inhibitor in amniotic fluid near term. The time required for detection of the inhibitory activity is approximately 12 hours, in contrast to approximately 36 hours required for a previously reported technique. Application of this radiometric bioassay to demonstrate bacterial growth inhibition by amniotic fluid and physicochemical properties of the inhibitory activity yielded results comparable to those obtained with the older method of plate counts of viable bacteria. By the new technique it was possible to demonstrate that the inhibitory activity was phosephate sensitive, heat stable, inactivated by metal chelation, removed by bentonite, and present in a low-molecular-weight fraction of amniotic fluid.

Amniotic Fluid↗
PubMed2026

Pilea: profiling bacterial growth dynamics from metagenomes with sketching.

BACKGROUND: Quantifying bacteria's growth rates is essential for understanding their ecological roles and for building predictive models in environmental and clinical settings. Peak-to-trough ratios (PTRs) derived from shotgun metagenomes offer a culture-independent proxy for in situ growth rates of bacterial species, yet their reliable computation remains challenging. RESULTS: We introduce Pilea ( https://github.com/xinehc/pilea ), an alignment-free, sketching-based method that incorporates statistical models for robust PTR estimation. Pilea achieves speed improvements over existing methods while also enhancing accuracy, as demonstrated on both simulated and real datasets. CONCLUSIONS: By scaling efficiently to comprehensive reference collections such as the Genome Taxonomy Database (GTDB), Pilea enables large-scale analyses of bacterial growth dynamics across biomes, unlocking new insights for ecological research. Video Abstract.

Bacteria↗
PubMed1976

Bacterial growth inhibition by amniotic fluid. V. Phosphate-to-zinc ratio as a predictor of bacterial growth-inhibitory activity.

Human amniotic fluid has been shown to contain an inorganic bacterial growth-inhibitory component, zinc. The average zinc concentration in amniotic fluid was 0.44 mug per milliliter. The phosphate concentration of amniotic fluid appears to determine the expression of zinc inhibitory activity. The average phosphate concentration was 92 mug per milliliter. For 22 fluid samples tested, a phosphate-to-zinc ratio of 100 or less predicted a bactericidal fluid. A ratio between 100 and 200 predicted a bacteriostatic fluid. A ratio of greater than 200 predicted a noninhibitory fluid. The possible clinical significance of the ratio is discussed.

Amniocentesis↗
PubMed1977

Bacterial growth inhibition by amniotic fluid. VII. The effect of zinc supplementation on bacterial inhibitory activity of amniotic fluids from gestation of 20 weeks.

Twenty human amniotic fluids obtained from gestations of 20 weeks' duration supported bacterial growth. Nine of the 20 fluids could be made inhibitory by adjusting the phosphate to zinc ratios of the fluids to less than 200 mug per milliliter. These fluids contained the phosphate-sensitive bacterial inhibitor previously, but the fluids contained sufficient phosphate to inactivate the antibacterial system. The remaining 11 amniotic fluids did not contain the peptide component of the phosphate-sensitive bacterial inhibitor and could not be made inhibitory by adjusting the phosphate to zinc ratio to less than 200 mug per milliliter. The data obtained suggested synthesis of the peptide component may occur at a gestational age of approximately 20 weeks. The peptide may indirectly be detected in fluids by determining whether antibacterial activity is obtained when the phosphate to zinc ratio of the fluids is adjusted to less than 200 mug per milliliter.

Amniotic Fluid↗
PubMed1977

Rapid detection of bacterial growth in blood samples by a continuous-monitoring electrical impedance apparatus.

A growth detection method utilizing an automated apparatus capable of rapidly detecting bacterial growth by measuring changes of electrical impedance in bacteriological medium was utilized with "mock" blood cultures containing various gram-negative and gram-positive bacteria. Measurement of changes of electrical impedance was found to ba as accurate and comparable for time of growth detection as the radiometric method for detection of the same bacteria using mock blood cultures. In a limited clinical trial the use of the electrical impedance apparatus detected in 1 positive specimen from 40 clinical blood specimens as rapidly as by radiometric measurement. Both methods were considerably faster for detecting bacterial growth as compared with conventional culture methods. The selected species of gram-positive and -negative organisms tested were all detected by the electrical impedance method, including aerobes and anerobes. However, addition of 5% CO2 to the incubation atmosphere enhanced detection of gram-positive organisms.

Aerobiosis↗
PubMed1978

The effect of temperature on sperm motility. II. Is bacterial growth a factor?

The previous demonstration that sperm kept at body temperature (37 degrees C) had a marked deterioration in motility accompanied by an overgrowth of bacteria in the semen and a concomitant decrease in pH led to this study to test the hypothesis that the decrease in motility was caused by the bacteria or by bacterial alteration of seminal pH. Semen specimens from fertile prevasectomy patients with and without added antibiotics were maintained at 20 degrees C and 37 degrees C and evaluated at 3, 12, and 18 hours after collection. There was still a significant deterioration in spermatozoal motility in the samples kept at 37 degrees C even when bacterial growth and change in pH were prevented by buffered antibiotics. Although the decrease in spermatozoal motility at body temperature may in part be attributed to bacterial growth or the products of bacterial metabolism, clearly another factor is present related to time and temperature and independent of the presence of bacteria.

Humans↗
PubMed1979

Mechanism of action of monoketo-organomycin, cystaurimycin and their performic acid-oxidized modifications. I. Effects on bacterial growth and ribosomal peptidyl transferase activity.

The response of 15 bacterial cultures to the inhibitory effects of the above mentioned compounds was investigated. These varied considerably. Escherichia coli cultures resistant to the compounds tested showed that monoketo-organomycin and cystaurimycin inhibit bacterial growth by what appears to be the one and same mechanism which is not the same as that exhibited by their performic acid-oxidized modifications. This was confirmed by using cell free extracts of E. coli. In light of the puromycin reaction, using chloramphenicol and chlorotetracycline as control inhibitors, monoketo-organomycin and cystaurimycin were found to inhibit protein synthesis in vitro by inhibiting peptidyl transferase of ribosomes. In marked contrast, this enzyme was activated, as also was protein synthesis, by their performic acid-oxidized modifications. It was thus suggested that the growth inhibitory effects of the latter compounds might be due to their interference in other metabolic activities of the above test organism. The results obtained are discussed in light of the chemical similarities or differences existing between the compounds investigated.

Acyltransferases↗
PubMed1975

Bacterial growth in seafoood on restaurant premises.

Operational guidelines for a chain of the newer type of seafood restaurants and take-out stores were derived from plots of bacteriological and trimethylamine changes during the preparation and storage of cod fillets, shrimp, and clams. If fish is to be defrosted at room temperature it should be washed and portioned within 14 h. Subsequent storage at 5 degrees C should not exceed 72 h and once removed from the refrigerator it should be fried within 3 h. New stores should consider improved methods of defrosting. Trimethylamine content was a more sensitive measure of quality loss than bacterial growth. Shrimp quality can be improved by emphasizing the way shells are removed because most of the contamination was external. Shrimp shelled while still frozen had the best potential keeping quality. Clam meat is handled less and is always held at 5 degrees C; but bacterial growth indicated that it should not be held on the premises for more than 3 days including the time necessary for defrosting. Batter prepared fresh daily can be feft at room temperature. Frying can obliterate poor handling procedures, but adequate cooking is essential under any conditions. Clams are a gourmet item but the practice of cooking them lightly at customer request proved inadvisable.

Bacteria↗
PubMed1977

Removal of inhibitors of bacterial growth by dialysis culture.

Dialysis culture was used to investigate the extent to which growth inhibition in bacterial cultures may be caused by accumulation of metabolites. Escherichia coli B was grown in a glucose/salts medium. A concentrated nutrient solution was pumped at a constant rate into the growing culture to ensure that growth was not limited by exhaustion of nutrients. In this way the only difference between growth conditions in dialysis and non-dialysis cultures was the transfer of dialysable metabolites from the culture vessel to the reservoir in the dialysis culture system. By adjusting the glucose concentration in the feed and maintaining a constant rate of feeding, glucose-limited growth could be achieved. Under these conditions, with oxygen in excess, bacterial yields of 140 to 150 g dry wt l-1 were obtained in dialysis culture compared with 30 to 40 g l-1 in non-dialysis culture. The high yields in dialysis culture depended on the removal of end-products of glucose metabolism. Growth inhibition was demonstrated to be the result of the combined influence of acetate, lactate, pyruvate, succinate, propionate and isobutyrate in concentrations found at the end of growth in non-dialysis cultures of Escherichia coli B.

Antimetabolites↗
PubMed1975

The relationship between length of incubation, bacterial growth and tuberculin yield of a strain of Mycobacterium tuberculosis.

The relationship was studied between length of incubation in a liquid synthetic medium, amount of bacterial growth, pH of the culture filtrate and tuberculin yield of a single strain, DT, of Mycobacterium tuberculosis. No sinple relationship was found between the total crop of bacteria and the tuberculoprotein content of the culture filtrate. On the other hand, protein release and the pH of the culture filtrate were closely related. In each of two trials the bacterial crop increased rapidly during the early period of incubation, although maximum growth was not reached until 9 and 13 weeks respectively. The pH of the culture filtrate reached its maximum at a value of more than 9-0 after 5 weeks incubation and then fell until the 10th week; a second rise occurred until the 13th week when the pH dropped again and levelled off slightly on the alkaline side of neutrality. The rate of increase in tuberculin yield was most rapid during the first 7 weeks of incubation. After this, the rate of increase slowed down but the yield was still rising after 18 weeks. It is concluded that for the large-scale production of mammalian tuberculin by the method used in these trials, it is profitable to incubate production cultures for 14 weeks or longer.

Alanine↗
PubMed2026

dAMN: a genome-scale neural-mechanistic hybrid model to predict bacterial growth dynamics.

SUMMARY: This study presents dAMN, a genome-scale neural-mechanistic hybrid model that combines neural networks with dynamic flux balance analysis to predict bacterial growth dynamics across diverse nutrient environments. Using a residual network architecture, dAMN predicts reaction fluxes and lag-phase parameters from initial medium composition, then integrates these predictions under stoichiometric constraints derived from genome-scale metabolic models. Trained on Escherichia coli and Pseudomonas putida growth datasets across combinatorial media, dAMN accurately forecasts temporal growth dynamics and generalizes to unseen media conditions, with mean R² ≥ 0.9. The model also reproduces biologically relevant behaviors including substrate depletion, acetate overflow, and diauxic shifts, while explicitly modeling lag phases usually absent from standard dFBA. AVAILABILITY AND IMPLEMENTATION: The dAMN software, associated models, and datasets are available at https://github.com/brsynth/dAMN-main-release and via Zenodo DOI: 10.5281/zenodo.17908125.

Escherichia coli↗
PubMed1979

Influence of aminopenicillins on bacterial growth kinetics in vitro in comparison with the antibacterial effect in vivo.

To quantify the relative antibacterial efficacy of beta-lactam antibiotics in vitro, a mathematical description of bacterial growth was developed. Curves of growth in the presence of the antibiotic are expressed as quadratic functions of time, with initial growth rate (ko) and rate of change of growth (a) as concentration dependant variables. For these variables the concentration-effect slopes were not parallel; therefore the potency ratio varied between 1 (at about 2 mg/l) and 2 (at higher concentrations). The relative efficacy in vivo was expressed as a potency ratio with regard to the number of bacteria in an infected thigh muscle in mice. The potency ratio was 1.5, which is between the limits of the in vitro results.

Amoxicillin↗
PubMed1978

Interactions of helium, oxygen, and nitrous oxide affecting bacterial growth.

Helium at pressures of 20 to 70 atm in the presence of air found to stimulate growth of Streptococcus faecalis, Escherichia coli, and Staphylococcus aureus, mainly by increasing the rate of exponential growth. However, at these same pressures, helium potentiated the growth-inhibitory actions of oxygen and nitrous oxide (N2O). Oxygen was found to act essentially as an anesthetic gas in inhibiting growth of S. faecalis; its potency was approximately the same as that of N2O, and it acted additively in combination with N2O to inhibit the streptococcus. Oxygen proved to be more potent than N2O in inhibiting the growth of E. coli and S. aureus, and each gas potentiated the action of the other. Oxygen sensitivity was correlated with N2O sensitivity. Overall, our findings indicate that bacterial growth inhibition by anesthetic gases does not accurately reflect narcotic action.

Bacteria↗
PubMed1979

Role of bacterial growth rates in the epidemiology and pathogenesis of urinary infections in women.

The mean minimum generation time in shake culture in urine of 6 urinary isolates of Escherichia coli (21.7 +/- 0.6 min) was significantly shorter (P = 0.0003) than that of 14 isolates of less common urinary pathogens (46.0 +/- 18.6 min). Mixed populations of approximately equal numbers of E. coli cells paired with other urinary, fecal, and urethral organisms were introduced into a laboratory model of the lower human urinary tract. This model used urine as a medium and reproduced some features of the balance between bacterial growth and the flushing effect of urine. After 24 h E. coli formed greater than or equal to 99% of the bacterial population in the bladder model for 16 our of 18 pairs of isolates examined. Relatively high oxygen tensions in urine sample from 18 healthy women (10.9 +/- 22. kPA) and 18 infected patients (8.0 +/- 4.3 kPa) may explain why anaerobic urinary infections are uncommon. The rapid growth rate of E. coli may be one explanation why it is the commonest cause of urinary infection even though it is relatively uncommon at the urethral meatus.

Aerobiosis↗
PubMed1977

Failure of bacterial growth inhibition by amniotic fluid.

The bactericidal properties of amniotic fluid normally protect fetuses from late gestational infections by bacteria. Recently, such infections were found responsible for nearly a third of the perinatal deaths in Addis Ababa, Ethiopia. This prompted an analysis of the antimicrobial activity of amniotic fluid in patients in that city. The antimicrobial activity of fluid from 53 women, collected at term, was measured by a semiquantitative plate-count technique. Only one of the fluid samples was bactericidal, 12 were bacteriostatic, and 40 were noninhibitory to bacterial growth.

Amniotic Fluid↗
PubMed1976

[The importance of serum components, particularly complement factors, properdin and transferrin, in inhibition of bacterial growth by human serum (author's transl)].

In this study human serum was broken down of column chromatography into its protein components, which were than examined singly and in comnination for antibacterial activity. The bactericidal effect of serum was retained to an apperciable extent in only one of six fractions. Antibacterial inhibitory activity could be restored fully by combining the fractions however. There was no correlation with the specific antibody titers. Complement had an essential part in this unspecific defence. In the absence of C'9 all other combinations of the remanining complement components exhibited no appreciable inhibitory effect. Not all complement componets are required, however, for unspcific bacterial growth inhibition. In contrast to this all complement components are necessary in the antigen-antibody reaction. Futhermore, properdin displays bactericidal activity which is related to the presence of complements. A great deal of the antibacterial activity of human serum thus arises only from the combined action of several components. These do not include proteins with a molecular weight between 100,000 and 70,000, whereby transferrin plays a part.

Antibody Formation↗
PubMed1977

The relationship between rumen bacterial growth, intake of dry matter, digestible organic matter and volatile fatty acid production in buffalo (Bos bubalis) calves.

1. The production rates of bacteria in the rumen of buffalo (Bos bubalis) calves were estimated using an isotope-dilution technique. A series of fifteen experiments was done with animals given green maize and nine experiments with animals given cowpea (Vigna unguiculata). 2. The turnover time ranged from 205 to 567 min in the group given green maize and from 330 to 648 min in animals offered cowpea. The production rates of bacteria were (mean +/- SE; g/d) 145.77 +/- 7.240 and 237.09 +/- 11.847 in animals given green maize and cowpea respectively. 3. There was a significant correlation between bacterial production rates and dry matter intake, digestible organic matter and total volatile fatty acids formed in the rumen. 4. Regression equations obtained for the two foodstuffs were different suggesting that the bacterial growth rate may vary depending upon the quantity and quality of foodstuff digested and possibly the ratio nitrogen:energy of the foodstuff.

Animal Feed↗