New antiepileptic drugs

Survival of Escherichia coli O157:H7 strains QA 326, and ATCC 43889, 43894, and 43895 after freezing (-20 degrees C, 24 h) and thawing (4 degrees C for 12 h, 23 degrees C for 3 h, or microwave heating of 700 W for 120 s) in ground beef patties was determined by reference most probable number (MPN), hydrophobic grid membrane filter SD-39 agar, and sorbitol MacConkey agar (SMA) spread-plating methods. Populations decreased from 0.62 to 2.52 log10 CFU/g, with the extent varying significantly by strain. Strain QA 326 populations almost always decreased the most, up to 1.87 log10 CFU/g more than the least sensitive strain. Microwave heating was the most lethal thawing treatment for strain QA 326, and 4 degrees C thawing was the most lethal treatment for strain ATCC 43894. Thawing treatments varied in relative lethality for the other two strains. For strain QA 326 (4 degrees C and microwave thaw treatments) and strain ATCC 43889 (4 and 23 degrees C thawing), the enumeration method significantly affected a population decrease. The SD-39 agar method best recovered strain QA 326 while the SD-39 agar method and the reference MPN method best recovered strain ATCC 43889 after 4 and 23 degrees C thawing, respectively. The greatest difference in population decrease measured by any two methods was 0.58 log10 CFU/g. Results showed (i) a wide range in freeze-thaw sensitivity among E. coli O157:H7 strains, (ii) no thawing method had consistently and significantly greater lethality, and (iii) the reference MPN, SD-39 agar, and SMA methods differed little in ability to enumerate E. coli O157:H7.     

Molecular lipophilicity potential by CLIP, a reliable tool for the description of the 3D distribution of lipophilicity: application to 3-phenyloxazolidin-2-one, a prototype series of reversible MAOA inhibitors

Six methods were compared for detection of three strains of Escherichia coli O157:H7 in enrichments of inoculated apple juice. Juice was inoculated at levels varying from 0.1 to 100 CFU/ml and centrifuged after overnight storage at 4 degrees C, and pellets were incubated at 37 degrees C in nonselective enrichment broth. At hourly intervals between 5 and 10 h and at 24 h, the enrichments were tested for E. coli O157:H7 by direct fluorescent antibody (DFA), antibody-direct epifluorescent filter technique (Ab-DEFT), direct selective plating on sorbitol MacConkey agar (SMA), immunomagnetic separation coupled to either selective plating (IMS-SMA) or the polymerase chain reaction (IMS-PCR), and flow cytometry (FC). The most consistent detection of 0.1 CFU/ml of the slowest growing strain of the pathogen was provided by the IMS-SMA and IMS-PCR after 8 h of enrichment. The time required for detection at the level of 0.1 CFU/ml for each assay was Ab-DEFT, 11 h; IMS-PCR, 16 h; FC, 24 h; IMS-SMA, 32 h; and SMA, 48 h. Absolute detection limits (without enrichment) were: IMS-PCR, 10(3) CFU/ml; Ab-DEFT and IMS-SMA, 10(4) CFU/ml; SMA, 10(5) CFU/ml; and DFA, 10(6) CFU/ml. Recovery of the pathogen (10 CFU/ml) in apple juice after 28 days of 4 degrees C storage was possible by means of an 8-h enrichment and Ab-DEFT, IMS-PCR, or IMS-SMA.     

Culture of dialysis fluids on nutrient-rich media for short periods at elevated temperatures underestimate microbial contamination

Recommended culture methods for monitoring bacterial contamination of H2O, dialysate and bicarbonate concentrate in dialysis centers in the USA involves culturing these fluids for 48 h at 37 degrees C. A variety of media and commercial culture methods are accepted for monitoring these fluids. Over a 3-month a comparison was made between an acceptable culture method, tryptic soy agar (TSA) employing the pour plate (PP) technique at 37 degrees C for 48 h, and PP cultures on standard methods agar (SMA) and R2A agar, incubated at ambient temperature (23 degrees C) for 48, 72, 168 h. Increases in the colony counts over time occurred for all three fluids. However, counts wee greater on SMA and R2A than on TSA. The increases over the standard 48-hour TSA cultures ranged as high as 10(4) times for 23 degrees C cultures at 7 days of incubation. Endotoxin levels even in the most contaminated samples were found to be below the acceptable 5 EU/ml recommended for reprocessor water. Bacterial colonies that appeared at 48, 72 and 168 h were isolated and identified. Pseudomonas, Moraxella, Acinetobacter and CDC group VI C-2 were among some of the common bacteria isolated. This study indicates that the media utilized, the time and temperature of incubation may result in a significant underestimation of the bacterial population of water and dialysis fluids, thus potentially placing the patient at a higher risk.     

Recovery of thermally-stressed Escherichia coli O157:H7 by media supplemented with pyruvate

Unheated and heat-stressed (57 degrees C, 50 min and 60 min) cells of Escherichia coli O157:H7, were enumerated using three media supplemented with 1% sodium pyruvate (NaPyr): plate count agar (PCA), tryptic soy agar (TSA) and phenol red sorbitol agar (PhRSA) using the spread plate method. The medium recovering the greatest numbers of severely heated E. coli O157:H7 was PCA with 1% NaPyr. Recovery of heat stressed E. coli O157:H7 on this medium was significantly higher (P < 0.05) than the two other media with pyruvate: 16.3% (50 min heating) and 0.55% (60 min heating) of the total population was recovered with TSA + 1% NaPyr when compared to those numbers found on PCA + 1% NaPyr. The ability of PhRSA + 1% NaPyr to recover heat-stressed E. coli O157:H7 was similar to that of TSA + 1% NaPyr. Using PhRSA + 1% NaPyr media. 12.9% (50 min heating) and 0.61% (60 min heating) of the total population were recovered when compared with the cells enumerated on PCA + 1% NaPyr. Recovery of the heat-stressed cells using the spread plate method was greater than using pour plate method. Recovery was significantly higher (P < 0.05) on the spread plates for highly stressed E. coli O157:H7(1.2 log) heated for 60 min than on the pour plates. Overall, the populations on the TSA spread and pour plates were low compared with the same heat-stressed cells recovered on media containing pyruvate. The     

Effect of chilling on the survival of Bacteroides fragilis

Factors affecting the susceptibility of Bacteroides fragilis subsp. fragilis to low temperature were examined. Predetermined numbers of cells were spread on agar media or suspended in enriched Trypticase soy broth and exposed to low temperature under both aerobic and anaerobic conditions. Exposure of 18-h growth of a freshly isolated B. fragilis strain to 4 degrees C aerobically or anaerobically resulted in a loss of at least 50% viability after 12 h. B. fragilis cells in early growth (6 h) were more tolerant to exposure at 4 degrees C than older cells (18 h). When the freshly isolated strain was repeatedly subcultured in the laboratory it was uniformly more cold tolerant than fresh clinical isolates. The incorporation of 1.0 M sucrose and 5 mM magnesium chloride into liquid media partially alleviated the lethal effects of cold temperature on B. fragilis subsp. fragilis.     

Thermal inactivation of Mycobacterium paratuberculosis in milk

Thermal inactivation of Mycobacterium paratuberculosis, a suspected human pathogen, was determined in ultrahigh-temperature whole milk. Three strains of M. paratuberculosis were examined for survival at temperatures from 55 to 75 degrees C using a submerged glass capillary tube method. Clumped and declumped suspensions of the cultures were used to determine the rate of heat inactivation and survival at pasteurization temperatures. Methods for declumping M. paratuberculosis included the use of glass beads, vortexing, and passing the cells through a 26-gauge needle. The latter procedure was found to be superior over other methods and did not affect the viability of cells. Capillary tubes filled with milk containing 4 x 10(6) to 3 x 10(7) CFU/ml were heated at temperatures ranging from 55 to 75 degrees C. At 55 degrees C, minimal thermal inactivation was observed for clumped and declumped cells. At 58 degrees C, thermal inactivation ranging from 0.3 to 0.7 log reduction was observed for both clumped and declumped suspensions. D values at 60 degrees C ranged from 8.6 to 11 min and 8.2 to 14.1 min for clumped and declumped cells, respectively. At 63 degrees C, the D values ranged from 2.7 to 2.9 and 1.6 to 2.5 min for clumped and declumped cells, respectively. Survival of M. paratuberculosis at initial levels ranging from 44 to 10(5) CFU/ml at pasteurization treatment (63 degrees C for 30 min and 72 degrees C for 15 s) was also determined. No survivors were observed after incubating plates for up to 4 months on Middlebrook 7H11 agar and up to 2 months on Herrold's egg yolk medium. The sensitivity of the plating method was 1 CFU/250 microliters. These results demonstrate that low levels of M. paratuberculosis, as might be found in raw milk, will not survive pasteurization treatments.     

Differential diagnosis of Staphylococcus aureus from Staphylococcus epidermidis and Staphylococcus saprophyticus by alphazurine A dye

Staphylococcal bacterial suspensions were streaked on Trypticase soy agar with 5% sheep blood culture plates. Paper discs containing alphazurine A, a triphenylmethane dye, were placed on the inoculated plates which were incubated at 37 degrees C for 24 hours. A wide zone of inhibition of growth of Staphylococcus aureus was present around the paper discs. Growth of Staphylococcus epidermidis and Staphylococcus saprophyticus was not inhibited.     

Measurement of mouth occlusion pressure as an index of respiratory centre output in man

Peptostreptococcus anaerobius strain VPI 4330-1 was used as the test organism in an evaluation of the bactericidal effect of anaerobic broth exposed to air. The test organism, grown under anaerobic conditions in Trypticase soy broth, was diluted in buffered salt solution, and about 2 x 10(4) cells were suspended in 10 ml of an aerated broth. Ninety percent of the cells were killed within 15 min in actinomyces broth and within 50 min in Trypticase soy broth. All cells survived for 2 h in fluid thioglycolate medium. Addition of DABCO [1,4-diazabicyclo (2.2.2) octane] or mannitol to Trypticase soy broth did not influence the death rate of the organism, whereas superoxide dismutase decreased the death rate. Addition of catalase or manganese dioxide to the broth kept all the cells viable for 2 h. Of the three broth media tested, actinomyces broth reduced oxygen at the highest rate and Trypticase soy broth reduced it at the slowest rate. Hydrogen peroxide could be demonstrated in actinomyces broth and in Trypticase soy broth but not in fluid thioglycolate medium. In addition to catalase, manganese dioxide also removed all hydrogen peroxide from Trypticase soy broth, and superoxide dismutase significantly decreased the concentration of hydrogen peroxide in the broth. The results suggest that hydrogen peroxide mediated the toxic effect of atmospheric oxygen in these broth media.     

The mechanism of increased renal clearance of amylase in acute pancreatitis

Penicillium urticae (NRRL 2159A) was grown in culture broth containing 1 muCi of [1-14C-A1acetate to produce [14C]patulin. [14C]patulin was purified from the broth and added to apple cider. After the patulin concentration of the cider was adjusted to 30 mug/ml with unlabeled patulin, the cider was subjected to various charcoal treatments. [14C]patulin was completely removed by shaking the cider with 20 mg of activated charcoal per ml and by eluting the cider through a 40- to 60-mesh charcoal column. Activated charcola at 5 mg/ml reduced patulin in naturally contaminated cider to nondetectable levels.     

Limited access to a dietary fat option affects ingestive behavior but not body composition in male rats

Survival, recoverability and sublethal injury of two strains of Listeria monocytogenes, Scott A and an environmental strain KM, on exposure to sea water at 12.8 or 20.8 degrees C was determined using in situ diffusion chambers. Plate counts were used to assess recoverability and injury while 5-cyano-2,3-ditolyl tetrazolium chloride (CTC) reduction was used to determine respiratory activity. T90 values (times for 10-fold decreases in numbers of recoverable cells) on non-selective medium (trypticase soya agar with 0.6% yeast extract) at 12.8 and 20.8 degrees C were 61.7 and 69.2 h for L. monocytogenes Scott A, and 103.0 and 67.0 h for L. monocytogenes KM, respectively. On selective medium (Oxford agar), T90 values at 12.8 and 20.8 degrees C were 60.6 and 56.9 h for L. monocytogenes Scott A, and 83.0 and 65.9 h for L. monocytogenes KM, respectively. With Scott A, the percentage of sublethally injured cells at 12.8 and 20.8 degrees C was 1.7 and 17.7%, respectively, while for KM the values were 19.0 and 1.6%, respectively. The fraction of cells reducing CTC but which were not recoverable on plating progressively increased on exposure to sea water. Listeria monocytogenes KM challenged at 58 degrees C showed an apparent increase in heat resistance after exposure to sea water at 20.8 degrees C for 7 d (D58 = 2.64 min) compared with before exposure (D58 = 1.24). This increase in thermal resistance was not apparent at temperatures greater than 63 degrees C, and analysis of the best-fit regression lines fitted to the thermal data obtained from the two cell populations indicated that their thermal resistance was not significantly different (P > 0.05) over the temperature range tested (58-62 degrees C).     

Identification of Bacillus cereus by Fourier transform infrared spectroscopy (FTIR)

The objective of this study was to evaluate the potential of Fourier transform infrared spectroscopy (FTIR) for rapid identification of Bacillus cereus isolates. Ten B. cereus group isolates (comprising B. cereus, Bacillus mycoides, and Bacillus thuringiensis strains), five other Bacillus spp., and five non-Bacillus spp. were used. Two types of media, brain heart infusion (BHI) and Trypticase soy agar (TSA), were tested. The results indicated that all B. cereus group isolates produced characteristic absorbance peaks at wave numbers between 1738 and 1740 cm-1. These peaks were not affected by the growth medium. None of the other bacteria tested showed a similar peak after growth on BHI or TSA. Absorbance peaks between 1800 and 1500 cm-1 of members of the B. cereus group had different shapes and sizes, suggesting that FTIR may be useful for rapid identification of species within the B. cereus group.     

Effect of growth temperature on the cryopreservation of prototheca

The temperature at which Prototheca spp. were grown determined their response to freezing to -196 degrees C and subsequent thawing. Cells cultured at 35 degrees C were the most sensitive to freezing injury; at lower growth temperatures, resistance to freezing damage was seen. At all culture temperatures examined, the freezing tolerance varied with the age of the culture.     

Effect of freezing method, thawing temperature and post-thaw dilution/washing on motility (CASA) and morphology characteristics of high-quality human sperm

Sixteen semen samples, 12 donor and four patient samples of high initial quality, were processed to compare the effect of two freezing methods, two thawing temperatures and the effect of dilution and washing on sperm motility and morphology characteristics. Sperm samples were divided in two equal parts and frozen either by fast vapour freezing or by slow computer-controlled freezing. For each freezing method, half of the straws were thawed at room temperature (22 degrees C), the other half were thawed at 37 degrees C. From each freeze-thawing treatment, one straw was evaluated immediately post-thawing; another straw was washed to remove the cryoprotectant solution. In this way, each semen sample was subjected to eight freeze-thawing treatments. No effect of the freezing method and thawing temperature was observed on motility characteristics evaluated by computer-assisted semen analysis, nor on light-microscopical morphology parameters. Post-thaw dilution and washing, however, exerted a deleterious effect on sperm motility, by reducing percentage motility by 50% compared to unwashed thawed specimens. Linearity and percentage of morphologically normal spermatozoa were obviously impaired, while percentage of abnormal tails and beat cross frequency increased significantly. In general, freeze-thawing was most successful when rapid vapour freezing was followed by 37 degrees C thawing, and when slower computer-controlled freezing was combined with 22 degrees C thawing, causing significant interactions between the freezing method and the thawing temperature. For semen samples of high initial quality, vapour and computer-controlled freezing were equally effective in terms of recovery of morphologically normal, motile spermatozoa.     

Inactivation of Escherichia coli O157:H7 in apple juice by irradiation

Three strains (932, Ent-C9490, and SEA13B88) of Escherichia coli O157:H7 were used to determine the effectiveness of low-dose gamma irradiation for eliminating E. coli O157:H7 from apple juice or cider and to characterize the effect of inducing pH-dependent, stationary-phase acid resistance on radiation resistance. The strains were grown in tryptic soy broth with or without 1% dextrose for 18 h to produce cells that were or were not induced to pH-dependent stationary-phase acid resistance. The bacteria were then transferred to clarified apple juice and irradiated at 2 degrees C with a cesium-137 irradiator. Non-acid-adapted cells had radiation D values (radiation doses needed to decrease a microbial population by 90%) ranging from 0.12 to 0.21 kGy. D values increased to 0.22 to 0.31 kGy for acid-adapted cells. When acid-adapted SEA13B88 cells were tested in five apple juice brands having different levels of suspended solids (absorbances ranging from 0.04 to 2.01 at 550 nm), radiation resistance increased with increasing levels of suspended solids, with D values ranging from 0.26 to 0.35 kGy. Based on these results, a dose of 1.8 kGy should be sufficient to achieve the 5D inactivation of E. coli recommended by the National Advisory Committee for Microbiological Criteria for Foods.     

Ascorbic acid and reducing agents regulate the fates and functions of S-nitrosothiols

The antibody-direct epifluorescent filter (Ab-DEFT) technique was evaluated as a rapid alternative to the most probable number (MPN) method for enumeration of artificially inoculated Listeria monocytogenes in ready-to-eat packaged salads and other fresh vegetables. Ab-DEFT was performed by homogenization of food in mesh-lined Stomacher bags, followed by prefiltration of homogenate through a 5 microns pore nylon filter, and passage of filtrate through a 0.4 micron pore black polycarbonate filter to collect and concentrate Listeria cells. After cells were stained with a fluorochrome-labeled polyclonal antibody to Listeria, the filter surface was examined by epifluorescence microscopy, and fluorescent cells were counted. A 3-tube MPN procedure was performed by successive enrichments of homogenized foods in Listeria enrichment and Fraser broths, followed by selective plating. Ab-DEFT provided quantitative determinations of Listeria cells that correlated with plate counts and MPN estimates in a linear response over a range of cell concentrations from 10 to 10(7) colony forming units (CFU)/mL. Microbial backgrounds as high as 10(8) CFU/mL did not affect performance of Ab-DEFT. In contrast to the MPN method, which required 5 days to perform, quantitation by Ab-DEFT could be completed in less than 1 h. Despite cross-reactivities demonstrated by the polyclonal fluorescent antibody, the potential of Ab-DEFT as a rapid alternative to MPN for microbial cell enumeration was evident.     

An improved direct plate method for the enumeration of stressed Escherichia coli O157:H7 from food

The use of sorbitol MacConkey agar (SMAC) performed poorly in supporting growth of stressed Escherichia coli O157:H7 cells. Up to a 3-log difference was observed between counts on SMAC and tryptone soy agar (TSA). It is critical in the risk assessment of certain foods to be able to enumerate stressed and healthy E. coli O157:H7 in a background of potentially healthy competing bacteria. Investigations carried out to overcome the inhibitory effect of SMAC included the reduction of the selective agent concentration, inclusion of a recovery stage in broth prior to plating out, addition of recovery agents, and delayed exposure to the selective agent. The only successful approach was delayed exposure to the selective agent. This was achieved by resuscitating the stressed cells on a membrane placed on the surface of a TSA plate and, after a defined time period sufficient for full resuscitation, transferring the membrane to the surface of a SMAC plate. The choice of membrane material was critical for maintaining the positive sorbitol color change used to identify wild-type E. coli. Track-etched polycarbonate membranes allowed the typical color reactions to be visualized, whereas cellulose acetate did not. The method was validated with E. coli O157:H7 cells stressed by low pH and high salt conditions, whereby all cells that would previously be undetectable on direct inoculation of SMAC were countable.     

The effect of temperature at which slow cooling is terminated and of thawing rate on the survival of one-cell mouse embryos frozen in dimethyl sulfoxide or 1,2-propanediol solutions

We investigated the slow freezing of one-cell mouse embryos with either dimethyl sulfoxide (Me2SO) or 1,2-propanediol (PROH) as the cryoprotectant. One-cell embryos, collected from superovulated C57BL/6J x CBA/Ca females were exposed to 1.5 M solutions of either Me2SO or PROH. The embryos were cooled at 0.3 degrees C/min to temperatures between -10 degrees and -80 degrees C before being plunged into LN2 and then warmed at either 20 degrees C/min or 450 degrees C/min. Survival was expressed as the percentage of hatching or hatched blastocysts per frozen-thawed embryo. When the slow cooling was in 1.5 M PROH, the temperature at which survival rates after slow thawing began to increase was -35 degrees C (52.6 +/- 5.2% survival). For slow cooling in 1.5 M Me2SO this temperature was -50 degrees C (45.0 +/- 2.9% survival). The addition of sucrose to the 1.5 M PROH solution raised the temperature at which survival rates after slow thawing began to increase to -30 degrees C (54.8 +/- 3.7% survival). If slow cooling was stopped at high subzero temperatures, embryos survived better after rapid thawing than slow thawing. If slow cooling was stopped at low subzero temperatures, the survival rate was not dependent on the thawing rate if freezing was done in 1.5 M PROH. When freezing was in Me2SO solutions and to subzero temperatures of -60 degrees and -80 degrees C, slow thawing gave better survival than rapid thawing. The addition of sucrose to the Me2SO freezing solution restored the survival rates at -60 degrees and -80 degrees C. These results indicate that high rates of survival may be obtained from one-cell mouse embryos by a rapid or a slow thawing procedure, as has been found for other developmental stages. The results also indicate that PROH provides superior protection compared to Me2SO against freezing-thawing damage and that the addition of sucrose to the freezing solutions prior to freezing improves the overall survival rates. Embryos that survived freezing and developed in culture implanted and formed normal fetuses at rates similar to those of nonfrozen control embryos (60% vs 68% and 53% vs 58%, respectively.     

The regeneration patterns of the canine hypogastric nerve when transplanted into the wall of the large intestine]

In an attempt to optimize a method of cryopreserving spermazoa from mice bearing mutations, we investigated the effect on motility of temperature for the collection of mouse sperm and the rate of thawing after freezing. Comparison among samples of sperm collected from both the caudae epididymides and vas deferens placed directly in a cryoprotectant of 3% skim milk and 18% raffinose equilibrated at 37, 23, and 3 degrees C showed no difference in the number of viable sperm harvested. Concentration and motility was highest after collection at 37 degrees C (22.3 x 10(6) sperm/ml with 80% motility) combined with rapid thawing at 37 degrees C (2.9 x 10(6) sperm/ml with 84% motility in the swim-up fraction). The fertilization capacity of sperm collected and thawed at 37 degrees C was analyzed in vitro and no difference was observed between the cryopreserved sperm and the control (91 and 89%, respectively). Transfer of in vitro fertilized embryos to pseudopregnant recipients resulted in 37% implantation at Day 10 of pregnancy and 38% live births at term.     

Cryopreservation and culture of human corneal keratocytes

PURPOSE: To assess the effects of two different concentrations of albumin in a cryoprotective solution and two freezing methods on human corneal keratocyte ctyopreservation. METHODS: Isolated keratocytes were used for cryopreservation. Solutions of 10% dimethylsulfoxide with either 2% or 10% human albumin were used as cryoprotective agents. Cells either were transferred directly into a -80 degrees C freezer (freezing rate, 2 degrees C/min) or were cooled in a programmed freezer (1 degrees C/min until -40 degrees C and then 10 degrees C/min), which resulted in four different cryopreservation protocols. Cells were stored at -80 degrees C, then were thawed at 37 degrees C, and subsequently were cultured. Keratocytes were studied by means of trypan blue staining, growth assay, apoptosis assays, transmission electron microscopy, and immunochemistry. RESULTS: The percentage of cells that were alive after thawing ranged from 80% to 99% by trypan blue staining and from 45% to 60% by flow cytometry. The ratio of the number of living cells at the end of primary culture after cryopreservation to that before cryopreservation was significantly (P=0.04) higher after direct transfer into the -80 degrees C freezer than after controlled-rate freezing, whereas the albumin concentration had no significant influence on this ratio (P=0.45). The percentage of apoptotic cells was significantly higher after cryopreservation than in the control group of noncryopreserved cells; more than 5% 24 hours after thawing. Cryopreservation did not modify the keratocyte ultrastructure. Fibroblast growth factor dramatically decreased the serum-induced cell expression of alpha smooth muscle actin, whereas cryopreservation had no influence on this cell expression. CONCLUSIONS: A freeze-thaw trauma, which was related to cryopreservation-induced cell apoptosis, was revealed during primary culture after thawing. Direct transfer into the -80 degrees C freezer resulted in better postcryopreservation growth in the culture than controlled-rate freezing. A change in albumin concentration from 2% to 10% did not affect the results.     

Pyrolysis gas-liquid chromatography of the genus Bacillus: effect of growth media on pyrochromatogram reproducibility

Pyrolysis gas-liquid chromatography was performed on dried Bacillus microorganisms to evaluate the effects of growth media. Six cultures of Bacillus and six lot numbers of Trypticase soy agar (BBL) were used to test the hypothesis that a microorganism grown on various lot numbers of the same chromatogram. Also tested was the effect of three different media on chromatogram reproduction using the same six cultures. Results show little or no differences observed between the chromatograms of the individual Bacillus spp. grown on the six lot numbers of Trypticase soy agar. When chromatograms of the three different media were compared, several differences were observed, particularly in the areas most characteristic of individual species. Pryolysis gas-liquid chromatography can be a useful tool for the characterization or identification of the genus Bacillus if the chromatographic and cultural conditions are maintained.