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Notes: Abstract Recent research has yielded a dramatic increase in the number of connections between oncogenesis and the proteins which regulate the cell cycle. Three classes of protein which inhibit the activity of cyclin-dependent kinases (CDKs) have emerged as potential targets for oncogenic inactivation. p16 and related proteins inhibit the cyclin/CDK complexes which regulate the transition from G1 to S phase; numerous studies have revealed that p16 is mutated in most tumor cell lines and in some types of primary tumor. p21/WAF1/Cip1 and the related p27Kip protein inhibit a broader range of cyclin/CDK complexes than p16. Although the absence of p21/WAF1/Cip1 from cyclin/CDK complexes is correlated with cellular transformation, no mutations in this gene have been found in tumors or tumor-derived cell lines. A third class of genes which are potential targets for oncogenic inactivation are the kinases and phosphatases which regulate the activity of cyclin/CDK complexes by phosphorylation and dephosphorylation of the CDK proteins. Disruption of any of these genes would result in loss of normal regulation of cell growth.

Notes: Abstract. Methanosarcina barkeri strain Fusaro was found to grow on pyruvate as sole carbon and energy source after an incubation period of 10 – 12 weeks in the presence of high pyruvate concentrations (100 mM). Growth studies, cell suspension experiments and enzymatic investigations were performed with pyruvate-utilizing M. barkeri. For comparison acetate-adapted cells of M. barkeri were analyzed. 1. Pyruvate-utilizing M. barkeri grew on pyruvate (100 mM) with an initial doubling time of about 25 h (37 °C, pH 6.5) up to cell densities of about 0.8 g cell dry weight/l. The specific growth rate was linearily dependent on the pyruvate concentration up to 100 mM indicating that pyruvate was taken up by passive diffusion. Only CO2 and CH4 were detected as fermentation products. As calculated from fermentation balances pyruvate was converted to CH4 and CO2 according to following equation: Pyruvate−+H++0.5 H2O→1.25 CH4+1.75 CO2. The molar growth yield (YCH4) was about 14 g dry weight cells/mol CH4. In contrast the growth yield (YCH4) of M. barkeri during growth on acetate (Acetate−+H+→CH4+CO2) was about 3 g/mol CH4. 2. Cell suspensions of pyruvate-grown M. barkeri catalyzed the conversion of pyruvate to CH4, CO2 and H2 (5 – 15 nmol pyruvate consumed/min×mg protein). At low cell concentrations (0.5 mg protein/ml) 1 mol pyruvate was converted to 1 mol CH4, 2 mol CO2 and 1 mol H2. At higher cell concentration less H2 and CO2 and more CH4 were formed due to CH4 formation from H2/CO2. The rate of pyruvate conversion was linearily dependent on the pyruvate concentration up to about 30 mM. Cell suspensions of acetate-grown M. barkeri also catalyzed the conversion of 1 mol pyruvate to 1 mol CH4, 2 mol CO2 and 1 mol H2 at similar rates and with similar affinity for pyruvate as pyruvate-grown cells. 3. Cell extracts of both pyruvate-grown and acetate-grown M. barkeri contained pyruvate: ferredoxin oxidoreductase. The specific activity in pyruvate-grown cells (0.8 U/mg) was 8-fold higher than in acetate-grown cells (0.1 U/mg). Coenzyme F420 was excluded as primary electron acceptor of pyruvate oxidoreductase. Cell extracts of pyruvate-grown M. barkeri contained carbon monoxide dehydrogenase activity and hydrogenase activity catalyzing the reduction by carbon monoxide and hydrogen of both methylviologen and ferredoxin (from Clostridium). This is the first report on growth of a methanogen on pyruvate as sole carbon and energy source, i.e. on a substrate more complex than acetate.

Notes: Survival and growth of inoculated Clostridium sporogenes PA 3679 and of natural aerobic and anaerobic bacterial flora were studied in cooked, vacuum packed bratwurst containing 0.5% phosphates during refrigerated (5°C) and subsequent temperature abuse storage (24°C). Sodium acid pyrophosphate (SAPP), sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP) and sodium polyphosphate glassy (SPG) were tested. No significant bacterial inhibition by any phosphate was observed during refrigerated storage, nor was there appreciable growth in the control bratwurst. However, SAPP significantly inhibited aerobic and anaerobic bacteria (including C. sporogenes) upon temperature abuse, followed in effect by TSPP and STPP. Cooking to 65.5°C helped retain antimicrobial properties of phosphates to some extent. Enzymatic hydrolysis of phosphates is postulated as a major factor in loss of antimicrobial properties of phosphates in processed meats.

Notes: Sausage was prepared using three levels of sodium chloride. These sausages were made with a commerical starter culture, and with an inoculum of Staphylococcus aureus, strain Z-88. The sausages containing lower amounts of salt showed faster fermentations at two temperatures, 24°C and 38°C. At both temperatures the sausages containing 1.65% salt showed the least amount of staphylococcal growth followed by the sausages containing 2.415% and 3.3% salt respectively.

Notes: Dry packed broilers were cut up or kept as whole carcasses and vacuum packaged in a high barrier or low barrier film or stretch wrapped in a tray package. In an additional study, chicken was treated with 20 ppm chlorine in a chilled water dip; control chicken had no chlorine added to the water. The poultry was then packaged as previously indicated. The chicken was stored in a display case at about 5°C and examined for various bacteria and odor development at intervals up to 10 days. Vacuum packaging dry packed broilers resulted in significantly lower bacterial counts and longer keeping time compared with stretch wrapped chicken. Longest shelf life was obtained with a high barrier film, and chlorine as a dip did not provide increased storage life compared with vacuum packaged broilers maintained in the dry state.

Notes: The surface plate method was compared with the more conventional pour plate method for the enumeration of mesophiles, psychrotrophs, lactobacilli, coliforms, and streptococci on poultry. Surface plates were prepared by drying freshly poured plates at 37°C for 3 days. These plates were stored at 5°C until 4 hr before use when they were re-dried at 37°C. Pour plates were made using standard methods. The two methods were highly correlated but there was a significant difference between the surface plate and pour plate methods for coliforms and psychrotrophic counts. Higher counts were obtained with the surface plate technique for these organisms.

Notes: Ground beef patties were formulated with 20% fat, formed on a pattie machine at 113g each (4/lb) and frozen either by liquid nitrogen or liquid carbon dioxide in a cryogenic tunnel at -74°C or by a walk-in mechanical freezer at -29°C. Composition, TBA numbers, shrinkage and taste panel scores evaluated at 0, 30, 60, 90 and 120 days after manufacture showed a significant reduction in quality for the mechanically frozen patties when compared with the cryogenic methods. There was no difference between liquid nitrogen and liquid carbon dioxide for quality retention by ground beef patties.

Notes: Studies were conducted with four cultures of Pseudomonas isolated from frozen chicken. The effect of temperature on some biochemical activities of the organisms was evaluated and the individual response of the cultures to temperature was determined. Growth, survival and production of the green fluorescent pigment, pyoverdine, and extra-cellular proteinase and lipase activities were used as indices of the ability of pseudomonads to produce spoilage. The four isolates differed in their ability to perform the metabolic functions mentioned. The cultures were incubated at 15°, 5°, −18°, and −29°C. Assays for proteolysis were made by means of a dye binding method; lipolysis was determined by titration of free fatty acids released from chicken fat, and a photo-fluorometer was used to measure fluorescent pigment. Growth was determined by colony count. At temperatures above 0°C, survival was better and growth and enzyme activity were more extensive at 5° than at 15°C. Proteinase activity increased continuously, even when viable cells were decreasing; lipase production was correlated with growth. Formation of pyoverdine declined faster than did cell numbers. Survival of the cultures was better at −18° than at −29°C, Impairment of pyoverdine secretion was observed after exposure of the organisms to freezing temperatures, but the activity of the extracellular enzymes was not affected at temperatures below 0°C. No marked differences were observed among cultures in rate of cell division, but maximum populations, survival of organisms and stability of the proteolytic, lipolytic and fluorescent activities of the isolates were inversely related to biochemical activity above 0°C.

Notes: The effects of 0.5% sodium acid pyrophosphate (SAPP), sodium tripolyphosphate (STPP), tetrasodium pyrophosphate (TSPP) and sodium polyphosphate glassy (SPC) on aerobic mesophilic and psychrotrophic bacterial growth and on survival of inoculated Stuphylococcus aureus Z 88 were investigated in uncooked bratwurst stored at 5°C for 7 days. No significant microbial inhibition by phosphates was found, although SAPP addition resulted in consistently lower total aerobic plate counts. Phosphate-induced pH differences in the sausages had no effect on bacterial numbers. The possible role of meat enzymes in the hydrolysis of condensed phosphates to microbiologically inactive species is discussed.

Notes: Cooked samples of pork tenderloin were equilibrated in glycerol solutions at both high (55°± 2°C) and low (5°± 1°C) temperatures and the preservative effect of intermediate moisture conditions in meat was studied. Meat stored at room temperature was compared to controls held at refrigeration temperature for microbial numbers. In natural flora studies, bacterial counts were reduced to 〈101 per gram at both equilibration temperatures and both storage temperatures. The process was successful in preservation of pork for up to 3 wk after equilibration at high or low temperature and storage at room temperature or under refrigeration.