The probability of most probable numbers

Man, J. C. de

doi:10.1007/bf01880621

Cited by 267 publications

(65 citation statements)

References 2 publications

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“…Nonculturable cells obtained in potassium-deficient Sauton medium were harvested, washed twice with fresh medium, resuspended in ADC-supplemented diluted Sauton medium, and left standing at 37°C. The number of resuscitated cells was estimated by most probable number (MPN) assay (17).…”

Section: Methodsmentioning

confidence: 99%

New 2-Thiopyridines as Potential Candidates for Killing both Actively Growing and Dormant Mycobacterium tuberculosis Cells

Salina

Ryabova

Kaprelyants

et al. 2014

Antimicrob Agents Chemother

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From in vivo observations, a majority of M. tuberculosis cells in latently infected individuals are in a dormant and probably nonculturable state, display little metabolic activity, and are phenotypically resistant to antibiotics. Despite many attempts, no specific antimicrobials effective against latent tuberculosis have yet been found, partly because of a lack of reliable and adequate in vitro models for screening of drug candidates. We propose here a novel in vitro model of M. tuberculosis dormancy that meets the important criteria of latency, namely, nonculturability of cells, considerable reduction of metabolic activity, and significant phenotypic resistance to the first-line antibiotics rifampin and isoniazid. Using this model, we found a new group of 2-thiopyridine derivatives that had potent antibacterial activity against both actively growing and dormant M. tuberculosis cells. By means of the model of M. tuberculosis nonculturability, several new 2-thiopyridine derivatives were found to have potent antitubercular activity. The compounds are effective against both active and dormant M. tuberculosis cells. The bactericidal effects of compounds against dormant M. tuberculosis was confirmed by using three different in vitro models of tuberculosis dormancy. The model of nonculturability could be used as a reliable tool for screening drug candidates, and 2-thiopyridine derivatives may be regarded as prominent compounds for further development of new drugs for curing latent M. tuberculosis infection.

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Section: Methodsmentioning

confidence: 99%

New 2-Thiopyridines as Potential Candidates for Killing both Actively Growing and Dormant Mycobacterium tuberculosis Cells

Salina

Ryabova

Kaprelyants

et al. 2014

Antimicrob Agents Chemother

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“…Cultures were harvested within the first 24 Enzyme assays. f8-D-Galactosidase, f8-N-acetylglucosaminidase, and a-L-fucosidase activities were measured by the rate of release of p-nitrophenol from their p-nitrophenyl glycosides.…”

Section: Methodsmentioning

confidence: 99%

“…The most probable numbers (MPN) (23) per gram feces of total bacteria, facultative anaerobes, bacteria producing extracellular glycosidases, and bacteria degrading mucin oligosaccharides were obtained from published tables (24,25). They were determined from the proportion of positive cultures among the replicates from each fecal dilution over the transition between those dilutions in which all replicates were positive and those in which none were positive.…”

Section: Methodsmentioning

confidence: 99%

Mucin Degradation in Human Colon Ecosystems

Hoskins¹,

Boulding²

1981

J. Clin. Invest.

182

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A B S T R A C T Recent work indicates that subpopulations of human fecal bacteria, averaging -1% of the total viable fecal flora, degrade the oligosaccharide side chains of hog gastric mucin, which structurally resembles human epithelial mucins. Here we report studies to determine whether degradation of mucin oligosaccharides is related to glycosidase production by bacteria growing in anaerobic fecal cultures. Triplicate cultures containing hog gastric mucin were inoculated with serially diluted feces from each of seven healthy subjects. When the stationary growth phase was attained, mucin oligosaccharide degradation and both cell-bound and extracellular activities of four glycosidases were measured in each culture. Cell-bound,j-D-galactosidase, ,B-N-acetylglucosaminidase, and sialidase were present in bacteria growing at all levels of fecal inocula, including 10-'1 g. In contrast, extracellular activities were present in every culture inoculated with 10-4-10-7 g feces, but were diminished or absent in cultures inoculated with 10-8_ 10-11 g feces.Bacterial autolysis was an unlikely cause of extracellular glycosidase activity, since p-nitrophenyl-a-Lfucosidase remained cell bound in cultures at every level of fecal inoculum. Degradation of mucin oligosaccharides was associated with extracellular, but not with cell-bound f3-D-galactosidase, 18-N-acetylglucosaminidase, and sialidase. Among the seven subjects, the estimated most probable numbers (MPN) of fecal bacteria producing extracellular 8-D-galactosidase, f8-N-acetylglucosaminidase, and sialidase ranged from 106_ 1010/g dry fecal wt, were comparable to the MPN of mucin-degrading bacteria, and were significantly smaller than the MPN of total fecal bacteria.Received for publication 30 June 1980 and in revised form 19 September 1980. We interpret these findings as evidence for the existence of bacterial subpopulations in the normal fecal flora that produce extracellular glycosidases, and that these subpopulations have a major role in degrading the complex oligosaccharides of mucin in the gut lumen.

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“…Finally, Griess reagent and diphenylamine were applied to examine whether nitrite or nitrate was formed. The abundance of nitrifiers was estimated based on classical MPN statistics (Man, 1975).…”

Section: Abundance Of Nitrifying Bacteriamentioning

confidence: 99%

Nitrification and inorganic nitrogen distribution in a large perturbed river/estuarine system: the Pearl River Estuary, China

Dai

Wang²,

Guo³

et al. 2008

Biogeosciences

222

176

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Abstract. We investigated the spatial distribution and seasonal variation of dissolved inorganic nitrogen in a large perturbed estuary, the Pearl River Estuary, based on three cruises conducted in winter (January 2005), summer (August 2005) and spring (March 2006). On-site incubation was also carried out for determining ammonium and nitrite oxidation rates (nitrification rates). We observed a year-round pattern of dramatic decrease in NH , accompanied by extremely high concentrations of ammonia (up to >800 µmol L −1 ) and nitrate (up to >300 µmol L −1 ). In summer, the upper estuary showed higher nitrification rates (ammonia oxidation rate ∼1.5-33.1 µmol N L −1 d −1 , nitrite oxidation rate ∼0.6-32.0 µmol N L −1 d −1 ) with lower concentrations of ammonia (<350 µmol L −1 ) and nitrate (<120 µmol L −1 ). The Most Probable Number test showed relatively lower nitrifier abundance in summer at most sampling stations, indicating a greater specific nitrification rate per cell in the warm season. Temperature appeared to control nitrification rates to a large degree in different seasons. Spatial variability of nitrification rates appeared to be controlled by a combination of many other factors such as nutrient concentrations, nitrifier abundance and dissolved oxygen (DO) concentrations. In addition to aerobic respiration, nitrification contributed significantly to the consumption of DO and production of free CO 2 at upper estuary. Nitrification-induced consumption accounted for up to approximately one third of the total waCorrespondence to: M. Dai (mdai@xmu.edu.cn) ter column community DO consumption in the upper estuary during the surveyed periods, boosting environmental stress on this large estuarine ecosystem.

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The probability of most probable numbers

Cited by 267 publications

References 2 publications

New 2-Thiopyridines as Potential Candidates for Killing both Actively Growing and Dormant Mycobacterium tuberculosis Cells

New 2-Thiopyridines as Potential Candidates for Killing both Actively Growing and Dormant Mycobacterium tuberculosis Cells

Mucin Degradation in Human Colon Ecosystems

Nitrification and inorganic nitrogen distribution in a large perturbed river/estuarine system: the Pearl River Estuary, China

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