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PubMed2003

[Kinetic models for the effect of temperature on batch glutathione fermentation by Candida utilis].

Glutathione (L-gamma-glutamyl-L-cysteinylglycine), one of the major non-protein thiol compounds, is widely distributed in living cells and plays an important role in maintaining the normal redox environment of cells as an antioxidant. In the production of glutathione by fermentation, temperature is one of the most important environmental factors that affect the yield and the productivity of glutathione. Here the effect of temperature, varied from 24 degrees C to 32 degrees C, on the batch fermentation of glutathione in a 7 L stirred fermenter by Candida utilis WSH 02-08 was investigated. It was found that cell growth was hastened along with the increase of temperature. The maximum dry cell weight was achieved approximately 16 g/L under various temperatures, as soon as the glucose was exhausted. The effect of temperature on glutathione production was different from that on cell growth: the lower the temperature, the higher the glutathione production, i.e. the maximum glutathione concentration at 32 degrees C (235 mg/L) was only 75% and 64% of that at 30 degrees C and 26 degrees C, respectively. The maximum average specific growth rate (0.13 h(-1)) was achieved at 30 degrees C while the maximum glutathione concentration (366 mg x L(-1)) and the maximum intracellular glutathione content (2.3%) were obtained at 26 degrees C. Therefore, the optimum temperatures for cell growth and glutathione production are quite different in the batch fermentation. A modified Logistic equation was successfully applied to estimate the kinetics of cell growth. The maximum specific growth rate and the substrate inhibition constant, calculated from this equation, were both increased along with the temperature. In addition, the glutathione fermentation by C. utilis WSH 02-08 under various temperatures was proven to be a partial growth-associated process by estimating the process with the Luedeking-Piret equation. Based on the estimated parameon the estimated parameters, the effect of temperature on the kinetics of cell growth was further studied. An equation, dX / dt = [0.0224(T + 1.7)]2 X(1-X/Xmax) / 1 + S/ {8.26 x 10(6) x exp [-31477/R/(T+273)]}, was developed and applied to interlink the relationship between biomass concentration and temperature as well as substrate concentration in the batch glutathione fermentation. The experiment results showed that this model could predict the growth pattern very well.

Candida↗
PubMed2006

Effect of solids retention time on structure and characteristics of sludge flocs in sequencing batch reactors.

The effect of solids retention time (SRT) (4-20 d) on sludge floc structure, size distribution and morphology in laboratory-scale sequencing batch reactors receiving a glucose-based synthetic wastewater was studied using image analysis in a long-term experiment over one year. Floc size distribution (>10 microm) could be characterized by a log-normal model for no bulking situations, but a bi-modal distribution of floc size was observed for modest bulking situations. In each operating cycle of the SBRs, the variation in food /microorganisms ratio (0.03-1.0) had no significant influence on floc size distribution and morphology. The results from a long-term study over one year showed that no clear relationship existed between SRT and median floc size based on frequency. However, sludge flocs at the lower SRTs (4-9 d) were much more irregular and more variable in size with time than those at higher SRTs (16 and 20 d). The level of effluent-suspended solids at lower SRTs was higher than that at higher SRTs.

Bioreactors↗
PubMed1994

Insulin utilization and kinetic effect on hybridoma metabolism in batch and continuous cultures.

This paper discusses the insulin utilization kinetics and the effect of its concentration during batch and continuous mass cultures of the murine VO208 hybridoma cells, using a home-made serum-free medium. Our results show that insulin is utilized by the cells, with a specific rate of 1 relative units (RU) per 10(9) cells per h in batch culture. In continuous reactor running at different insulin levels, this consumption rate is observed to vary from 0.13 to 0.55 RU per 10(9) cells per h when the insulin activity increases from 0.3 to 35 RU l-1 and then to stabilize for higher insulin levels until 110 RU l-1. A low insulin amount in the medium around 0.01 RU l-1, which is near physiological levels, is found sufficient to promote the cell growth. Interestingly, we observe that too high insulin levels, above 25 RU l-1, induce a reduction of the cell density due to an inhibitory effect on the maximal specific cell growth rate. Furthermore, the specific rate of MAb production is found to be independent of the insulin amount in the medium.

Animals↗
PubMed2004

The effect of upflow air velocity on the structure of aerobic granules cultivated in a sequencing batch reactor.

The effect of upflow air velocity on the formation and structure of aerobic granules was studied in three column sequencing batch reactors. Upflow aeration would be the major cause of hydrodynamic shear force in the column reactor. Results showed that high upflow air velocity resulted in more compact, denser, rounder, stronger and smaller aerobic granules, while high biomass retention in the reactor was achieved. It was found that high upflow air velocity could induce granular sludge to secrete more cell polysaccharides which in turn contributed to the compact and strong structure. It appears from this study that the structure of aerobic granules could be controlled by manipulating the upflow air velocity.

Air Movements↗
PubMed2003

Effect of specific oxygen uptake rate on Enterobacter aerogenes energetics: carbon and reduction degree balances in batch cultivations.

The effect of oxygen availability on the metabolism of Enterobacter aerogenes NCIMB 10102 was studied through batch fermentations of glucose performed increasing the specific oxygen uptake rate up to 72.7 mmol(O2) C-mol(DW) (-1) x h(-1). The final concentrations of fermentation products of this biosystem (2,3-butanediol, hydrogen, acetoin, formate, acetate, carbon dioxide, ethanol, lactate, succinate, and biomass) were utilized to check the use of simple carbon mass and reduction degree balances for the study of microbial energetics even in batch cultivations.

Adenosine Triphosphate↗
PubMed2003

[Effects of dissolved oxygen and pH on Candida utilis batch fermentation of glutathione].

The effects of dissolved oxygen (DO) and pH on glutathione batch fermentation by Candida utilis WSH-02-08 in a 7 liters stirred fermentor were investigated. It was shown that DO concentration is an important factor in glutathione production. With the initial glucose concentration of 30 g/L and a 5 L/min air flow rate, and the agitation rate less than 250 r/min, the DO concentration was not sufficient to satisfy the oxygen requirement during the fermentation. With an agitation rate of more than 300 r/min, the cell growth and glutathione production were enhanced significantly, with the dry cell mass and glutathione production were 20% and 25% higher than that at 200 r/min. When C. utilis WSH 02-08 was cultivated in a batch process without pH control, cell growth and glutathione production were inhibited, likely due to a dramatic decrease in the pH. Intracellular glutathione leakages were observed when the pH was 1.5 or less. To assess the effect of pH on glutathione production, six batch processes controlled at pH 4.0, 4.5, 5.0, 5.5, 6.0 and 6.5 were conducted. The yield was highest at pH 5.5, when the dry cell mass and yield were 27% and 95% respectively higher than fermentation without pH control. The maximal intracellular glutathione content (2.15 %) was also achieved at the pH. To improve our understandings on the effect of pH on the batch glutathione production, a modified Logistic equation and Luedeking-Piret equation were used to simulate cell growth and glutathione production, respectively, under different pH. Based on the parameters obtained by the nonlinear estimation, kinetic analysis was performed to elucidate the effect of pH on the batch glutathione production. The process controlled at pH 5.5 was proven to be the best due to the higher value of K(I) (substrate inhibitory constant in the Logistic equation), lower value of a and higher value of beta (slope and intercept in the Luedeking-Piret equation, respectively).

Candida↗
PubMed1969

Control mechanisms operative in a natural microbial population selected for its ability to degrade L-lysine. I. Effect of glucose in batch systems.

A natural microbial population was selected in a medium containing L-lysine as the sole carbon source and ammonia as a nitrogen source. Cells were harvested from a batch-operated fermentor containing lysine and were grown through one transfer on lysine, glucose, or a mixture of lysine and glucose. By comparing the substrate removal rates and enzymatic capabilities of the cells, it was determined that the inducible enzyme system responsible for lysine degradation was subject to catabolic repression. Inhibition of the activity of preformed enzyme(s) played only a minor role. Preinduction by lysine offered only a small degree of protection against repression. The removal of ammonia nitrogen from the system did not overcome the effect of glucose.

Journal Article↗
PubMed2006

Effects of mechanical stress on Anammox granules in a sequencing batch reactor (SBR).

The effect of shear stress on Anammox process was studied in a sequencing batch reactor (SBR). The reactor was operated during 218 days under different stirring speeds (60-250 rpm) in order to expose the system to different shear conditions and to study the stability of the Anammox granules referred to their biological activity and size. The nitrogen loading rate (NLR) fed to the SBR was kept around 0.3g N(L day)(-1). The nitrite (limiting substrate) removal percentage was 98% during most of the operational period. The specific Anammox activity of the biomass was practically constant and around 0.4 g N(g VSSday)(-1) and the average feret diameter of the formed granules was 0.64 mm. Obtained results indicated that stirring speeds up to 180 rpm have no negative effect on the performance of the Anammox process, whereas Anammox activity decreased to 40% when a rotating speed of 250 rpm was tested and the average diameter decreased in 45%, the concentration of solids in the effluent increased to 0.2g TSSL(-1) and nitrite was accumulated in the reactor up to 60 mg NL(-1).

Anaerobiosis↗
PubMed2000

Effects of mixing on fed-batch fermentation of L-ornithine.

The effects of mixing on L-ornithine fermentation were studied using an L-arginine auxotrophic mutant of Brevibacterium ketoglutamicum ATCC 21092. Three different modes of fed-batch culture using two different impeller types were studied in a 7 l fermentor. The first two modes of fed-batch culture were carried out in a fermentor equipped with six-flat-blade disk-turbine impellers with top and bottom feeding. The third mode of fed batch culture was carried out using pitched-six-flat-blade disk-turbine impellers with top feeding. The titre of L-ornithine increased up to 1.8 fold with bottom-feeding or when the pitched-six-flat-blade disk-turbine impellers were used compared to when the six-flat-blade disk-turbine impellers with top-feeding were used. It was observed that the mixing time of the limiting nutrients varied significantly depending on both the direction of feeding and the impeller type. Since the profiles of the specific rates of CO2 evolution, oxygen and glucose uptakes were very similar for the three culture modes, it could be reasonably assumed that the microorganism exhibited similar growth rates for each mode used. However, different amino acid producing activities were observed in the three culture modes. From these results it is concluded that the productivity of L-ornithine fermentation is significantly improved by shortening the mixing time of the limiting nutrient in the fermentor.

Journal Article↗
PubMed2000

Inhibition effects of furfural on aerobic batch cultivation of Saccharomyces cerevisiae growing on ethanol and/or acetic acid.

Physiological effects of furfural on Saccharomyces cerevisiae growing on ethanol (15 g.l(-1)) or acetate (20 g.l(-1)) as the carbon and energy source were investigated. Furfural (4 g.l(-1)), which was added during the exponential growth phase in batch cultures, was found to strongly inhibit cell growth on both carbon sources. No biomass formation occurred in the presence of furfural. However, furfural was in both cases converted to furfuryl alcohol and furoic acid, and growth resumed after complete conversion of furfural. During growth on ethanol, a rapid initial conversion of furfural to furfuryl alcohol was observed during the first few minutes after the addition of furfural, after which the conversion rate decreased to approximately 0.15 g.g(-1).h(-1) for the remaining conversion time. Acetaldehyde accumulated in the medium during the first few hours of conversion. Interestingly, addition of acetate after furfural addition resulted in an increased conversion rate of furfural and a higher carbon dioxide evolution rate, but no growth was observed until after complete conversion of furfural. Furfural addition to cells growing on acetate as the sole carbon source induced no formation of acetaldehyde, and the furfural conversion rate was lower than that on ethanol. The relationship between inhibition effects of furfural and NADH consumption is discussed.

Journal Article↗
PubMed2005

Effect of sulfur sources on specific desulfurization activity of Rhodococcus erythropolis KA2-5-1 in exponential fed-batch culture.

The effects of sulfur sources on the desulfurization activity of Rhodococcus erythropolis KA2-5-1 were investigated by using an exponential fed-batch culture technique. The feed rate of a sulfur source was controlled independently of the feed rate of ethanol, which was used as a carbon and energy source. Among the sulfur sources examined were dibenzothiophene (DBT), ammonium sulfate, L-cysteine, L-methionine, and 2-amino-ethanesulfonic acid. When the fed-medium contained DBT as the sole sulfur source, KA2-5-1 cells showed a maximum desulfurization activity of approximately 130 mmol 2-HBP kg-cell(-1) h(-1). Similar levels of enzyme activity were also achieved with inexpensive ammonium sulfate by using the exponential fed-batch culture technique. In addition, higher levels of desulfurization activity were achieved by increasing the dosage of the DBT desulfurization (dsz) operon and dszD gene in R. erythropolis KA2-5-1. The recombinant strain showed a maximum desulfurization activity of approximately 250 mmol 2-HBP kg-cell(-1) h(-1) in the exponential fed-batch cultures.

Biodegradation, Environmental↗
PubMed1979

Effect of oxygen on batch and continuous cultures of a nitrogen-fixing Arthrobacter sp.

Growth, acetylene reduction, and respiration rate were studied in batch and continuous cultures of Arthrobacter fluorescents at different oxygen partial pressures. The optimum pO2 values for growth and acetylene reduction were 0.05 and 0.025 atm, respectively, but microorganisms can tolerate higher pO2 values. The growth of cultures provided with combined nitrogen was dependent on oxygen availability, and strict anaerobic conditions did not support growth. Acetylene reduction of a population grown in continuous culture and adapted to low pO2 (0.02 atm) was much more sensitive to oxygenation than that of a population adapted to high pO2 (0.4 atm). Their maximum nitrogenase activity, at their optimal pO2 values, were quite different. The respiratory activity of nitrogen-fixing cultures increased with increasing oxygen tensions until a pO2 of 0.2 atm. At higher pO2 values, the respiration rate began to decrease.

Acetylene↗
PubMed2002

Large batch freezing of bull semen: effect of time of freezing and fructose on fertility.

Large-scale batch freezing of bull semen should be done in a processing schedule that yields the highest fertility and when it can be fitted efficiently into the work schedule. Conflicting reports have appeared on survival and fertility of bull sperm frozen within a few hours of semen collection or on the next day. To study this problem, a factorially arranged experiment with semen from 10 bulls was conducted, comparing whole milk-glycerol semen extender with and without fructose, and semen frozen in 0.5-ml straws after 4 versus 18 h of equilibration at 5 degrees C. Both fructose and 18 h of equilibration resulted in a small but significant improvement in freeze-thaw survival of sperm. A field trial followed with replicated semen collections from nine bulls processed in a whole milk-glycerol control extender frozen after 4 h of equilibration versus the addition of 1.25% (wt/vol) fructose to whole milk glycerol divided to freeze sperm after 4 and 28 h of equilibration. Semen from these bulls was used to inseminate 14,775 first-service cows. The 56-d nonreturn rates obtained for these three treatments were 74.7, 74.3, and 73.9%, respectively. As there was no difference in fertility, it would appear that programs to freeze sperm in whole milk extenders the same day of collection or the day after semen collection should yield equivalent results.

Animals↗
PubMed2004

[Qualitative analysis of batch preparing cryopreserved fresh platelet rich plasma].

To evaluate the efficiency and effectiveness of batch preparing cryopreserved fresh platelet-rich plasma (cryo-FPRP) derived from the volunteer donors, platelet count (Plt), mean platelet volume (MPV), platelet distribution width (PDW), plasma pH, plasma lactic acid concentration, and lactic dehydrogenase (LDH) concentration, germiculture, CD62p positive rate, PAC-1 positive rate, and the fluorescence intensity of platelet GPIb-IX-V were detected in ACD whole blood, fresh platelet-rich plasma (FPRP), FPRP with 5% dimethyl sulphoxide DMSO (DMSO-FPRP), and thawed cryopreserved FPRP (cryo-FPRP); the procoagulant activity of FPRP and cryo-FPR was determinated. The results showed that (1) 70 percentage of platelet were separated from the whole blood into FPRP, and the counts of residual erythrocyte and leucocyte were below 1 x 10(9), and below 1 x 10(7) per unit respectively. (2) The plasma pH, lactic acid concentration and PAC-1 positive rate retained a stable level during the preparing, storing and thawing process. (3) Plasma LDH concentration, platelet CD62p positive rate and GPIb-IX-V concentration in platelet surface were enhanced significantly after being frozen and thawing. (4) The plasma clotting time induced by cryo-FPRP were significantly shorter than that induced by FPRP. It is concluded that: (1) The batch platelet preparing process can efficiently obtain platelet from whole blood donated by volunteer, and the process didn't activate the platelet. (2) Cryopreservation can prevent lactic acid accumulation, pH reduce and activation of GPIIb/IIIa. (3) The membrane of partial platelets are affected by freezing and thawing. (4) The density of GPIb-IX-V complexes in platelet surface and its procoagulant activity are enhanced significantly after the FPRP freezing and thawing process.

Blood Platelets↗
PubMed2003

Variable effects of American ginseng: a batch of American ginseng (Panax quinquefolius L.) with a depressed ginsenoside profile does not affect postprandial glycemia.

BACKGROUND: We have repeatedly reported that American ginseng (AG) with a specific ginsenoside profile significantly decreases postprandial glycemia. Whether this effect is reproducible using AG with a different profile is unknown. We therefore investigated the effect of a different batch of AG on glycemia following a 75 g oral glucose tolerance test (OGTT). METHODS: Using a randomized, single blind design, 12 normal subjects (six males and six females, aged 31+/-3 y, body mass index (BMI) 28+/-2 kg/m(2)) received 6 g AG or placebo 40 min before a 75 g OGTT. The protocol followed the guidelines for the OGTT, with venous blood samples drawn at -40, 0, 15, 30, 45, 60, 90 and 120 min. Ginsenosides in the AG were assessed by established methods for HPLC-UV. RESULTS: Repeated measures analysis of variance demonstrated that there was no significant effect of the AG on incremental plasma glucose (PG) or insulin (PI) or their areas under the curve Indices of insulin sensitivity (insulin sensitivity index (ISI)) and release (deltaPI(30-0)/deltaPG(30-0)) calculated from the OGTT were also unaffected. The AG contained 1.66% total ginsenosides, 0.90% (20S)-protopanaxadiol (PPD) ginsenosides, and 0.75% (20S)-protopanaxatriol (PPT) ginsenosides, with the following key ratios: PPD:PPT of 1.2, Rb(1):Rg(1) of 8.1, and Rb(2):Rc of 0.18. CONCLUSIONS: The present batch of AG was unable to reproduce the postprandial hypoglycemic effects we observed previously. Possible explanations for this discrepancy include marked decrements in total ginsenosides and the key ratios PPD:PPT, Rb(1):Rg(1), and Rb(2):Rc. These data suggest that the ginsenoside profile of AG might play a role in its hypoglycemic effects. The involvement of other components cannot, however, be precluded.

Adult↗
PubMed1980

Opposite effects of different strains or batches of same strain of BCG on in vitro generation of syngeneic and allogeneic antitumor cytotoxicity.

Pretreatment of mice with three batches of BCG Phipps strain 10 days before in vitro immunization of their spleen cells with syngeneic or allogeneic tumor cells augmented the levels of antitumor cytotoxicity (compared to the levels exhibited by in vitro immunized spleen cells from normal mice), whereas pretreatment with another batch of BCG Phipps strain or with a batch of BCG Tice strain suppressed antitumor cytotoxicity. The suppressive effects of these BCG vaccines could not be attributed to route of administration, dose of BCG, or percentage of colony-forming units in an inoculum. The effect of the interval between BCG pretreatment and in vitro immunization on the generation of antitumor cytotoxicity was evaluated; one BCG batch was of special interest, inasmuch as augmented cytotoxicity was obtained when the interval was short and suppressed cytotoxicity was obtained when the interval was long.

Animals↗
PubMed1992

Development of novel dental cements. II. Cement properties.

Following earlier work, three novel aluminoborate glasses have been studied as potential cement components. Factors studied include the effect of batch size on composition and manipulative characteristics, and the effect of tartaric acid and conditions of storage on mechanical properties. It was concluded that two materials have potential for application as dental luting agents.

Aluminum Silicates↗