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PubMed2001

Inactivation of Escherichia coli O157: H7 and Listeria monocytogenes by PR-26, a synthetic antibacterial peptide.

This study reports the antibacterial effect of PR-26, a synthetic peptide derived from the first 26 amino acid sequence of PR-39, an antimicrobial peptide isolated from porcine neutrophils. A three-strain mixture of Escherichia coli O157:H7 or Listeria monocytogenes of approximately 10(8) CFU was inoculated to a final concentration of 10(7) CFU/ml in 1% peptone water (pH 7.0), containing 50 or 75 microg/ml of PR-26, and incubated at 37 degrees C for 0, 6, 12, and 24 h; at 24 degrees C for 0, 12, 24, and 36 h; or at 10 or 4 degrees C for 0, 24, 72, and 120 h. Control samples included 1% peptone water inoculated with each pathogen mixture but containing no PR-26. The surviving population of each pathogen at each sampling time was determined by plating on tryptic soy agar with incubation at 37 degrees C for 24 h. At 37 degrees C, PR-26 decreased E. coli O157:H7 and L. monocytogenes populations by >5.0 log CFU/ml at 12 h, with complete inactivation at 24 h. At 24 degrees C, PR-26 reduced E. coli O157:H7 and L. monocytogenes by approximately 3.5, 4.0, and 4.5 log CFU/ml at the end of 12-, 24-, and 36-h incubations, respectively. At 4 and 10 degrees C, the inhibitory effect of PR-26 on E. coli O157:H7 and L. monocytogenes was significantly lower (P < 0.05) than that at 37 and 24 degrees C: a 2- to 3-log CFU/ml reduction was observed at 120-h incubation. Results indicate that PR-26 could potentially be used as an antimicrobial agent, but applications in appropriate foods need to be validated.

Anti-Bacterial Agents↗
PubMed2001

Altering the thermal resistance of foodborne bacterial pathogens with an eggshell membrane waste by-product.

Eggshells from egg-breaking operations are a significant waste disposal problem. Thus, the development of value-added by-products from this waste would be welcomed by the industry. The ability of extracted eggshell membranes containing, several bacteriolytic enzymes (i.e., lysozyme and beta-N-acetylglucosaminidase) or other membrane components to alter the thermal resistance of gram-positive and gram-negative bacterial pathogens was evaluated. Mid-log phase cells of Salmonella Enteritidis (SE), Salmonella Typhimurium (ST), Escherichia coli O157:H7 (EC), Listeria monocytogenes Scott A (LM), and Staphylococcus aureus (SA) were suspended in 100 ml of 0.1% peptone water (pH 6.9, 10(7-8) CFU/ml) containing either 0 (control) or 10 g of an eggshell membrane extract and incubated at 37 degrees C for 45 min. Following exposure, membrane-free samples (1.5 ml) were heated in a 56 degrees C (LM, SA), 54 degrees C (SE, ST), or 52 degrees C (EC) water bath from 0 to 14 min in sealed glass reaction vials (12 by 32 mm), and the survivors were recovered on brain heart infusion agar. Population reductions ranging from 27.6% (SA) to 99.8% (LM) (ST, 43.8%; SE, 47.5%; EC, 71.8%) were observed for cells treated for 45 min with extracted membrane, as compared to controls. D-value reductions ranging from 0 (LM) to 87.2% (SE) (SA, 36.7%; EC, 83.3%; ST, 86.3%) were observed when membrane-treated cells were subsequently heat inactivated. The effects of exposure pH, time, temperature, and organic load on membrane activity were also evaluated with Salmonella Typhimurium. Exposure pH (5.0 versus 6.9), time (15 versus 45 min), and temperature (4 degrees C versus 37 degrees C) did not significantly reduce the impact of eggshell membranes on D-values. However, the presence of organic matter (0.1% peptone water versus skim milk) significantly reduced the thermal resistance-reducing capacity of the membranes. These preliminary findings provide information on the potential use of extracted eggshell membranes to alter bacterial heat resistance.

Acetylglucosaminidase↗
PubMed2001

Development of a proposed standard method for assessing the efficacy of fresh produce sanitizers.

A series of studies was done for the purpose of developing a proposed standard method to evaluate point-of-use home sanitizers for fresh produce. Preliminary experiments were done to determine the survival of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes after inoculation onto the surface of ripe tomatoes and drying for up to 24 h at 22 +/- 2 degrees C. Within 2 h, the initial population (6.88 log10 CFU/tomato) of E. coli O157:H7 was reduced by approximately 3 log10, while reductions in similar initial populations of Salmonella and L. monocytogenes were approximately 1 and 0.6 log10 CFU/tomato, respectively, after 40 min and 3 h. A pilot study evaluated treatment with 200 ppm free chlorine and a prototype Fit produce wash (Fit) for their efficacy in killing a five-serotype mixture of Salmonella or L. monocytogenes spot inoculated on tomatoes using the proposed inoculation and recovery procedures. Inoculated tomatoes were sprayed with chlorinated water, Fit, or sterile distilled water (control) and hand rubbed for 30 s. Each tomato was then placed in a plastic bag and rinsed with 200 ml of sterile water by vigorously agitating for 30 s to simulate a procedure consumers might use for sanitizing and rinsing produce in a home setting. Each tomato was transferred to a second bag, and 20 ml of sterile 0.1% peptone was added; tomatoes were rubbed by hand for 40 s. Populations of Salmonella or L. monocytogenes in the rinse water and the 0.1% peptone wash solution were determined. Treatment with 200 ppm chlorine and Fit resulted in > or = 3.07 and > 6.83 log10 reductions, respectively, in Salmonella. Treatment with 200 ppm chlorine and Fit reduced the number of L. monocytogenes by > or = 3.33 and > or = 4.96 log10 CFU/tomato, respectively. The proposed standard method for testing the efficacy of point-of-use produce sanitizers needs to be evaluated for reproducibility of results through a larger scale series of experiments.

Chlorine↗
PubMed2002

Recovery of Listeria monocytogenes from vacuum-sealed packages of frankfurters: comparison of the U.S. Department of Agriculture (USDA) food safety and inspection service product composite enrichment method, the USDA Agricultural Research Service (ARS) product composite rinse method, and the USDA-ARS package rinse method.

This study compared three methods for the recovery of Listeria monocytogenes from commercially prepared and vacuum-packaged frankfurters that were inoculated with a five-strain mixture of this pathogen at averages of 22 and 20,133 CFU per package over three trials. The presence and levels of the pathogen were determined by (i) the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) product composite enrichment method, involving the selective enrichment of a 25-g composite of product and the subsequent plating of this product onto selective agar plates; (ii) the USDA Agricultural Research Service (ARS) product composite rinse method, involving the rinsing of a 25-g composite of product with 0.1% peptone water and the subsequent plating of a portion of the rinse fluid directly onto selective agar plates; and (iii) the USDA-ARS package rinse method, involving the use of 25 ml of 0.1% peptone water to rinse the entire contents of a package and the subsequent plating of a portion of the rinse fluid directly onto selective agar plates. For packages inoculated with 20,133 CFU. L. monocytogenes was recovered at a frequency (percentage of packages positive) of 100% by each of the three methods. The pathogen was recovered at efficiencies (percentages of recovery of L. monocytogenes) of 43 and 94% with the USDA-ARS product rinse method and the USDA-ARS package rinse method, respectively. For packages inoculated with 22 CFU, L. monocytogenes was recovered at frequencies of 17, 10, and 100% by the USDA-FSIS product composite enrichment method, the USDA-ARS product composite rinse method, and the USDA-ARS package rinse method, respectively. The pathogen was recovered at efficiencies of 20 and 95% with the USDA-ARS product composite rinse method and the USDA-ARS package rinse method, respectively. In a related study, the USDA-ARS package rinse method was the only method that detected the pathogen in 60 packages from each of five brands of frankfurters purchased from local grocery stores. These data establish that the USDA-ARS package rinse method is markedly more sensitive, as well as demonstrably more rapid and facile, than either the approved USDA-FSIS product composite enrichment method or the USDA-ARS product composite rinse method in determining the presence or absence of L. monocytogenes and establishing the levels of the pathogen that may be on the surface of ready-to-eat foods such as frankfurters.

Animals↗
PubMed2003

Comparison of sampling methods for the detection of Salmonella on whole broiler carcasses purchased from retail outlets.

An experiment was conducted to compare the effectiveness levels of two methods in recovering Salmonella from the same carcass. One hundred fresh whole broiler chickens were purchased from retail outlets over a 5-week period (20 carcasses per week). After carcasses had been aseptically removed from the packages and giblets had been removed, the carcasses were placed in sterile bags containing 400 ml of 1% buffered peptone water, the bags were shaken for 60 s, and a 30-ml aliquot was removed and incubated for 24 h at 37 degrees C (aliquot sample). Then, an additional 130 ml of 1% buffered peptone water was immediately added to the bag with the carcass (bringing the volume to 500 ml), the bag was reshaken, and the carcass and rinse were incubated for 24 h at 37 degrees C (whole-carcass enrichment sample). Following incubation, 0.5-ml samples for the two methods were placed into 10 ml of Rappaport-Vassiliadis broth and into 10 ml of tetrathionate (Hajna) broth and incubated at 42 degrees C for 24 h. Each broth was then streaked onto BG Sulfa agar and modified lysine iron agar and incubated for 24 h at 35 degrees C. Suspected Salmonella colonies were inoculated onto triple sugar iron and lysine iron agar slants and incubated at 35 degrees C for 24 h. Presumptive positive results were confirmed by Poly O and Poly H agglutination tests. Over the 5-week period, 13% of the aliquot samples tested positive for Salmonella, compared with 38% of the whole-carcass enrichment samples from the same carcasses. Recovery rates ranged from 0 of 20 samples to 4 of 20 samples for aliquot method and from 4 of 20 samples to 10 of 20 samples for the whole-carcass enrichment method over the 5-week period. These results indicate that when small numbers of Salmonella are expected, the sampling method has a major influence on the identification of Salmonella-positive carcasses.

Animals↗
PubMed2003

A simple method to screen cilantro and parsley for fecal indicator viruses.

A protocol has been developed to process cilantro and parsley samples for male-specific coliphages. Coliphage recovery depended on the duration of peptone rinsing, and whether the products were intact or cut. After 60 min of rinsing with 0.1% peptone, 78% of spiked coliphages were recovered from intact cilantro samples, and 60% of the spiked coliphages were recovered from cut cilantro samples. The protocol was field tested on a limited scale using cilantro and parsley samples from six retail outlets using enrichment-based and quantitative coliphage assays. Of the 18 retail cilantro and parsley samples that were analyzed, 50% (9 of 18) of the cilantro samples were positive for male-specific coliphages using the enrichment-based assay compared to 39% (7 of 18) of the parsley samples. Using the quantitative coliphage assay, only 28% (5 of 18) of the cilantro samples were positive, and none of the parsley samples were positive. The number of male-specific coliphages ranged between 1 and 11 plaque-forming units per 10 g of cilantro samples. None of the samples was positive for Escherichia coli. The results suggest that simplified male-specific coliphage screening of herb samples is possible and that male-specific coliphages be used along with conventional bacteriological indicators to screen produce for presence of fecal contamination.

Coliphages↗
PubMed2004

Improved quantitative recovery of Listeria monocytogenes from stainless steel surfaces using a one-ply composite tissue.

Four sampling devices, a sterile environmental sponge (ES), a sterile cotton-tipped swab (CS), a sterile calcium alginate fiber-tipped swab (CAS), and a one-ply composite tissue (CT), were evaluated for quantitative recovery of Listeria monocytogenes from a food-grade stainless steel surface. Sterile 304-grade stainless steel plates (6 by 6 cm) were inoculated with approximately 106 CFU/cm2 L. monocytogenes strain Scott A and dried for 1 h. The ES and CT sampling devices were rehydrated in phosphate buffer solution. After plate swabbing, ES and CT were placed in 40 ml of phosphate buffer solution, stomached for 1 min and hand massaged for 30 s. Each CS and CAS device was rehydrated in 0.1% peptone before swabbing. After swabbing, CS and CAS were vortexed in 0.1% peptone for 1 min. Samples were spiral plated on modified Oxford agar with modified Oxford agar Rodac Contact plates used to recover any remaining cells from the stainless steel surface. Potential inhibition from CT was examined in both phosphate buffer solution and in a modified disc-diffusion assay. Recovery was 2.70, 1.34, and 0.62 log greater using CT compared with ES, CS, and CAS, respectively, with these differences statistically significant (P < 0.001) for ES and CT and for CAS, CS, and CT (P < 0.05). Rodac plates were typically overgrown following ES, positive after CS and CAS, and negative after CT sampling. CT was noninhibitory in both phosphate buffer solution and the modified disc-diffusion assay. Using scanning electron microscopy, Listeria cells were observed on stainless steel plates sampled with each sampling device except CT. The CT device, which is inexpensive and easy to use, represents a major improvement over other methods in quantifying L. monocytogenes on stainless steel surfaces and is likely applicable to enrichment of environmental samples.

Bacterial Adhesion↗
PubMed2006

Comparison of methods for recovering Vibrio cholerae O1 from ice.

Alkaline peptone water (1% peptone, 1% NaCl, pH 8.5) and Trypticase soy yeast extract broth (TSYB) supplemented with 2.5% NaCl (pH 8.5) or 1% NaCl (pH 7.5) were evaluated as enrichment broths for the isolation of Vibrio cholerae O1 from ice. Thirty samples of sterile and nonsterile mineral water were inoculated with cell suspensions of this bacterium, quickly frozen, and stored for 3 days at--18 degrees C. After thawing, samples were analyzed by a three-tube most-probable-number technique. Incubation in TSYB with 2.5% NaCl (pH 8.5) for 18 h at 37 degrees C yielded the highest recovery of V. cholerae O1 cells (P < 0.05), a result that might be attributable to the nutrients and to the NaCl concentration of the TSYB, both of which would promote V. cholerae O1 growth and prevent the growth of competitive microbiota.

Colony Count, Microbial↗
PubMed2006

Evaluation of Escherichia coli O157:H7 growth media for use in test-and-hold procedures for ground beef processing.

Since the mid-1990s, the beef industry has used a process called test and hold, wherein beef trim and ground beef are tested to keep products contaminated with Escherichia coli O157:H7 out of commerce. Current O157:H7 detection methods rely on a threshold level of bacterial growth for detection, which is dependent on the growth medium used. Twelve media were examined for growth and doubling time: buffered peptone water (BPW), SOC (which contains tryptone, yeast extract, KCl, MgCl2, and glucose), buffered peptone water plus SOC (BPW-SOC), Bacto-NZYM, RapidChek E. coli O157:H7 medium, BioControl EHEC8 culture medium, Neogen Reveal for E. coli O157:H7--Eight Hour medium (Neogen Reveal 8), BAX System medium for E. coli O157:H7 (BAX) BAX System medium for E. coli O157:H7 MP (BAX-MP), modified E. coli broth, nutrient medium, and tryptic soy broth (TSB). All media were tested at 37 or 42 degrees C under static or shaking conditions. The eight media with the highest total CFU per milliliter and most rapid doubling times were BPW-SOC, NZYM, RapidChek, EHEC8, Neogen Reveal 8, BAX, BAX-MP, and TSB. The ability of these eight media to enrich E. coli O157:H7 in ground beef was further evaluated through time-course experiments using immunomagnetic separation. Of these media, TSB was the easiest to prepare, had a wide application base, and was the least expensive. In the test-and-hold process, the normal ratio of medium to product is 1:10. In this study, a 1:3 ratio worked as well as a 1:10 ratio. Processors using test-and-hold procedures could use 1 liter of TSB to enrich for E. coli O157:H7 in a 375-g sample instead of the usual 3.375 liters, thus saving reagents, time, and labor while maintaining accuracy.

Animals↗
PubMed2006

Antimicrobial activity of potassium hydroxide and lauric acid against microorganisms associated with poultry processing.

The antimicrobial activity of solutions of potassium hydroxide (KOH) and mixtures of KOH and lauric acid against microorganisms associated with poultry processing was determined. In vitro tests were performed by enumerating viable microorganisms recovered from bacterial cultures suspended in peptone water (control) and in solutions of 0.1% KOH or mixtures of 0.1% KOH and 0.25 or 0.50% lauric acid. Additional studies were conducted to identify changes in the native microbial flora of poultry skin washed in distilled water, KOH, or KOH-lauric acid. Although results of in vitro studies indicated that significantly fewer bacteria (P < or = 0.05) were recovered from cultures suspended in KOH than from cultures suspended in peptone water, there were also significantly fewer bacteria recovered from cultures suspended in KOH-lauric acid than from cultures suspended in KOH. Results of experiments with broiler skin indicated that although rinsates of skin washed in 1.0% KOH solutions contained significantly fewer total aerobic bacteria and enterococci than did skin washed in water, significantly fewer of these microorganisms were generally recovered from rinsates of skin washed in mixtures of 1.0% KOH and 0.5, 1.0, 1.5, or 2.0% lauric acid than from skin washed in KOH alone. Washing of broiler skin in solutions of 0.25 to 1.00% KOH or mixtures containing these concentrations of KOH and two parts lauric acid (wt/vol) also significantly reduced the populations of bacteria and yeasts in the native flora of broiler skin. Enterococci, lactic acid bacteria, and staphylococci in the native flora of the skin had the highest level of resistance to the bactericidal activity of KOH-lauric acid. These findings indicate that the antimicrobial activity of KOH-lauric acid is significantly greater than that of KOH alone in vitro and on poultry skin. Thus, KOH-lauric acid may be useful for reducing the level of microbial contamination associated with poultry processing.

Animals↗
PubMed2006

Recovery methods for detection and quantification of Campylobacter depend on meat matrices and bacteriological or PCR tools.

Campylobacter is one of the main causes of human foodborne bacterial disease associated with meat consumption in developed countries. Therefore, the most effective approach for recovery and detection of Campylobacter from meat should be determined. Two hundred ninety pork skin and chine samples were inoculated with Campylobacter jejuni NCTC 11168 and two strains of Campylobacter coli. Campylobacter cells were then recovered from suspensions and enumerated by direct plating. Campylobacter recovery was evaluated by comparing results for two methods of sample collection (swabbing and mechanical pummeling) and three recovery fluids (peptone water, 5% glucose serum, and demineralized water). End-point multiplex PCR was performed to evaluate the compatibility of the recovery fluids with direct PCR detection techniques. Mean recovery ratios differed significantly between pork skin and chine samples. Ratios were higher for mechanical pummeling (0.53 for pork skin and 0.49 for chine) than for swabbing (0.31 and 0.13, respectively). For pork skin, ratios obtained with peptone water (0.50) and with glucose serum (0.55) were higher than those obtained with demineralized water (0.16). Significant differences were not observed for chine samples. Direct multiplex PCR detection of Campylobacter was possible with pork skin samples. The tools for Campylobacter recovery must be appropriate for the meat matrix to be evaluated. In this study, less than 66% of inoculated Campylobacter was recovered from meat. This underestimation must be taken into account for quantitative risk analysis of Campylobacter infection.

Animals↗
PubMed1999

Application of factorial designs for optimization of cyclodextrin glycosyltransferase production from Klebsiella pneumoniae pneumoniae AS-22.

Production of cyclodextrin glycosyltransferase (CGTase) from Klebsiella pneumoniae pneumoniae AS-22 was optimized in shake flasks using a statistical experimental design approach. Effect of various components in the basal medium, like carbon, nitrogen, phosphorus, and mineral sources as well as initial pH and temperature, were tested on enzyme production. The optimum concentrations of the selected media components were determined using statistical experimental designs. Two level fractional factorial designs in five variables, namely, dextrin, peptone, yeast extract, ammonium dihydrogen orthophosphate, and magnesium sulphate concentrations were constructed. The optimum medium composition thus found consisted of 49.3 g/L dextrin, 20.6 g/L peptone, 18.3 g/L yeast extract, 6.7 g/L ammonium dihydrogen orthophosphate, and 0.5 g/L magnesium sulphate. The maximum CGTase activity obtained was 21.4 U/mL in 28 h of incubation. The cell growth and CGTase production profiles were studied with the optimized medium in shake flasks and in 1-L fermenters. It was observed that the enzyme production was growth associated both in shake flask and in fermenter, although it was slower in shake flask. The maximum CGTase activity obtained in the fermenter was 32.5 U/mL in 16 h. The optimized medium resulted in about 9-fold increase in the enzyme activity as compared to that obtained in the basal medium in shake flask as well as in fermenter.

Carbon↗
PubMed1975

The effect of various immunosuppressive agents on mouse peritoneal macrophages and on the in vitro phagocytosis of Escherichia coli O4:K3:H5 and degradation of 125I-labelled HSA-antibody complexes by these cells.

Large doses of hydrocortisone, cyclophosphamide, and methotrexate injected subcutaneously, and whole-body irradiation (500 rads) caused a reduction in the number of peritoneal cells (PE cells) obtained after intraperitoneal injection of the treated mice with proteose-peptone. The same dose of cyclophosphamide and irradiation induced morphological changes in PE macrophages. There were more giant cells in the peritoneal exudates from treated mice as compared to control mice. 'Pharmacological' and larger doses of hydrocortisone, methotrexate and azathioprine or anti-lymphocyte globulin had no effect on the in vitro phagocytic capacity of proteose-peptone-stimulated mouse PE macrophages. This also applied to doses of up to 50 mg/kg of cyclophosphamide. In contrast, whole-body irradiation (500 rad) and 100 mg/kg of cyclophosphamide decreased the phagocytic capacity of mouse macrophages in vitro and reduced the ability of PE cells to degrade 125I-labelled HSA-antibody complexes in vitro. The greatest effect was noted 4-5 days after whole-body irradiation or four to five subcutaneous injections of cyclophosphamide.

Animals↗
PubMedDate not supplied

[Serotypes of Salmonella isolated from the Luján River, Argentina].

In this work, the serotypes of Salmonella genus polluting the waters of Lujan River, situated in the north east of the province of Buenos Aires, Argentina, were studied. A total of 690 samples of water were collected and analysed from February 1988 through December 1989, at three different sites. They were obtained according to the Moore technique and then preenriched in buffered peptone water and enriched in Rappaport-Vassiliadis Soya peptone broth was carried out. The isolations were realised in brilliant green-desoxycholate agar and bismuth sulphite agar and the presumptive colonies to be Salmonella were tested by the standard biochemical identification. Salmonella spp. was isolated in 434 samples (62.9%). The predominant serotype was S. Anatum, followed in a decreasing order by S. Montevideo, S. Newport and S. Bredeney. A large amount of serotypes that are isolated with very low frequency and very rarely in other hidric courses in the country were: S. Westhampton, S. Poona and S. Saintpaul were found.

Argentina↗
PubMed1975

[Utilization of LIN (lysine-indole-motility) medium for the preliminary identification of enteropathogenic bacteria].

A multiple-test medium for the routine laboratory identification of enteropathogenic bacteria is described. The medium has the following formula: Bacto-peptone (Difco) 5 g; yeast extract (Difco) 3 g; casein tryptic digest peptone (Merek) 15 g; glucose 1 g; L-lysine-monohydrochloride (Merck, No. 5700) 5 g; NaCl 5 g; bromcresol purple 0.016 g; agar 2 g; distilled water 1000 ml; final pH 6.6. The medium is dispensed in amounts of 5 ml into tubes of 14 X 85 mm and autoclaved at 120 degrees C for 10 min. The tubes are tightly closed with rubber stoppers. - The medium is inoculated by stabbing to the bottom of the tube. Readings are made after over-night incubation at 37 degrees C. A scheme for the preliminary identification of enteropathogenic bacteria is given, based on LIM medium in conjunction with Kligler's iron agar, and the oxidase reaction.

Aeromonas↗
PubMed2000

Rapid micropropagation of Geodorum densiflorum (Lam) Schltr. in liquid culture.

Technique for rapid mass propagation of Geodorum densiflorum (Lam)Schltr. has been developed by using thin sections of stems of in vitro regenerated plantlets as explant source. Thin sections of stems (1.0-1.5 mm) when cultured in modified liquid and semisolid Knudson C (KnC) medium produced 1.8 and 1.2 protocorm like bodies (PLBs) per explant respectively. Peptone (2 g l-1) was effective in promoting the survival percentage of the explants but had no effect on PLB production. BAP and NAA when used individually enhanced the rate of PLB production. But a significant and manifold increase in PLB production was noted when BAP (3 mg l-1) and NAA (0.5 mg l-1) in combination were added to peptone supplemented liquid and semisolid KnC medium. PLBs thus obtained were subcultured in semisolid KnC medium and obtained well developed plantlets within 10-12 weeks.

Culture Media↗
PubMedDate not supplied

[Role of lipids in the acid resistance of saprophytic mycobacteria].

The resistance of saprophyte mycobacteria to acids increases on a medium containing paraffin. The content of free lipids and mycolic acids in the cells of Mycobacterium convolutum assimilating the hydrocarbon increases cf. that in the cells grown on meat-peptone broth. The structure of mycolic acids was established after studying their methyl esters by mass spectrometry. The cells grown on the medium with hexadecane contain mycolic acids C32--C36, with C34- and C36-compounds prevailing and the aliphatic chain in alpha-position containing 10, 11, 12, and 14 C-atoms. The cells cultivated on meat-peptone broth contain another type of acids of high molecular weight (greater than 700).

Alkanes↗
PubMed1975

Adherent and non-adherent mouse peritoneal exudate cells.

Administration of proteose peptone to donors of peritoneal exudate cells resulted not only in quantitative increase in the mono-histiocytic cells but also in their activation as judged by their rapid adherence to surfaces, strong acid phosphatase reaction and increased numbers of lysosomes and phagocytic vacuoles. The three-hour adherent fraction of peritoneal exudate cells (from normal as well as peptone-stimulated mice) contains a large number of activated lymphocytes and fibroblastoid cells and is not enriched in macrophages. Moreover, the adherent cells, when collected by scraping, are unsuitable for immediate biological use since they lose the enzymatic equipment. For purification of histiocytes and macrophages by adherence, the 2-day cultivation of peritoneal cells was found to be optimal, as judged by the number of acid phosphatase positive cells. Their decrease after 4-day cultivation may indicate over-growth of the fibroblast and epithelial cell lineages. The non-adherent fraction was found to be enriched in lymphocytes as well as in mast cells; numerous macrophages were observed, too.

Animals↗