Increase In Lactose Concentration Research Articles

Bioethanol production from whey powder by immobilized E. coli expressing Vitreoscilla hemoglobin: optimization of sugar concentration and inoculum size

A combined Vitreoscilla hemoglobin/immobilization system was evaluated for ethanol production using whey powder as a carbon source and ethanologenic E. coli strain FBR5 and its Vitreoscilla hemoglobin (VHb) expressing derivative strain, TS3. The effects of varying the inoculation concentration (5, 10, 20 or 30%) of alginate beads containing cells of either strain, and the lactose levels (8–15%) of whey powder media (WP8-WP15), were studied. Ethanol production was enhanced in strain TS3 compared to strain FBR5 for all combinations of inoculation size and medium lactose concentration. This enhancement increased from 41% to 83% with an 8–15% increase in lactose concentration. The maximum amount of ethanol, 4.64% (v/v) with 99% fermentation efficiency, was produced after growth for 72 h by immobilized strain TS3, using 10% bead inoculation and medium containing 8% lactose.

Biohydrogen production from lactose: influence of substrate and nitrogen concentration

Hydrogen produced from renewable sources may be considered the energy vector of the future. However, reducing process costs is imperative in order to achieve this goal. In the present research, the effect of nitrogen (N), initial pH and substrate content for starting up the dark fermentative process was studied using the response surface methodology. Anaerobic digested dried sludge (biosolid pellets) was used as the inoculum. Synthetic wastewater was used as the substrate in batch reactors. A decrease in H2 production was observed with the increase in N and lactose concentrations. This drop was considerably greater when the concentration of lactose was at its lower level. Although the increase in lactose concentration results in a lower H2 production, the effect of N on the response is attenuated at higher levels of lactose. On the other hand, the effect of initial pH on the fermentation system was not significant. The evaluation on the process under semi-continuous conditions was performed using anaerobic sequencing batch reactors (ASBRs). The process was evaluated at different C/N ratios using synthetic wastewater. Results showed higher hydrogen yields with the gradual decrease in nitrogen content. The addition of cheese whey to the ASBR resulted in a H2 production rate of 0.18 L H2 L−1 d−1.

Response surface methodology applied to the enzymatic synthesis of galacto-oligosaccharides from cheese whey

In this study, a strategy was proposed for making galacto-oligossaccharides (GOS), a high valueadded product, from a byproduct of the dairy industry, cheese whey, using a commercial β-galactosidase from Kluyveromyces lactis (Lactozym® 3000L). The effects of the substrate concentration, temperature, and enzyme dosage were statistically studied and their optimum combinations were determined using response surface methodology. The increase in lactose concentration, temperature, and enzyme concentration favored a transgalactosylation reaction. The maximum values for GOS concentration (119.8 mg/mL) and yield (29.9%) in a 4 h process were obtained in the reaction system, composed of 400 mg/mL of lactose and 10 U/mL of enzyme at 40°C. Under these conditions, the lactose conversion was 68.7%. The maximum value for lactose conversion (87.8%) was observed at the same temperature and enzyme concentration, although the lactose level was 20%.

The high fermentative metabolism of Kluyveromyces marxianus UFV-3 relies on the increased expression of key lactose metabolic enzymes

The aim of this work was to obtain insights about the factors that determine the lactose fermentative metabolism of Kluyveromyces marxianus UFV-3. K. marxianus UFV-3 and Kluyveromyces lactis JA6 were cultured in a minimal medium containing different lactose concentrations (ranging from 0.25 to 64mmoll(-1)) under aerobic and hypoxic conditions to evaluate their growth kinetics, gene expression and enzymatic activity. The increase in lactose concentration and the decrease in oxygen level favoured ethanol yield for both yeasts but in K. marxianus UFV-3 the effect was more pronounced. Under hypoxic conditions, the activities of β-galactosidase and pyruvate decarboxylase from K. marxianus UFV-3 were significantly higher than those in K. lactis JA6. The expression of the LAC4 (β-galactosidase), RAG6 (pyruvate decarboxylase), GAL7 (galactose-1-phosphate uridylyltransferase) and GAL10 (epimerase) genes in K. marxianus UFV-3 was higher under hypoxic conditions than under aerobic conditions. The high expression of genes of the Leloir pathway, LAC4 and RAG6, associated with the high activity of β-galactosidase and pyruvate decarboxylase contribute to the high fermentative flux in K. marxianus UFV-3. These data on the fermentative metabolism of K. marxianus UFV-3 will be useful for optimising the conversion of cheese whey lactose to ethanol.

Possible synergistic effect between high lactate and insufficient intake of peptides caused biomass reduction during high-cell starter culture production

Lactic starter culture production is normally subjected to the end-product inhibition on growth, which limits the biomass produced per production batch. Removal of lactate ions during the biomass production has improved the biomass production. It allows for the use of higher sugar concentration so that high biomass concentration can be obtained. Lactate removal by ion exchange resin during Lactococcus lactis NZ133 cultivation was applied as a strategy for enhancing the production of lactic starter culture biomass. At high lactose concentrations of 180 g/l, the unexpected reduction in the biomass was evident regardless of the remaining sugar in the fermentation broth. The amount of protein and proteins/polypeptides pattern profile during cultivation were investigated as protein availability was suspected to be the potential cause of biomass reduction during high cell cultivation applying the ion exchange technique. Reduction in biomass concentration, after its maximum of 26 g/l, was observed after the protein concentration was unchanged while the remaining lactose continued to be utilised. A sharp decrease in protein concentration following the addition of resin corresponded to the disappearance of the smear band of protein sized 6,512-26,625 Da when more resin was added to remove lactate. The smear band remained throughout the conventional batch cultivation period. Based on the results, insufficient supply of peptides caused by the loss through adsorption onto ion exchange resin which occurred at high lactate level was postulated as the most probable cause of the biomass reduction. The result also indicated an inefficient use of supplemented protein sources supplied in correspond to the increase in lactose concentration due to the presence of appreciable amounts of residual protein at the end of cultivation process.

Milk yield, milk composition, eating behavior, and lamb performance of ewes fed diets containing soybean hulls replacing coastcross (Cynodon species) hay1,2

The objective of this experiment was to evaluate the effects of replacing coastcross hay NDF by soybean hull (SH) NDF on the lactation performance and eating behavior of ewes and also on the performance of their lambs. Fifty-six Santa Inês lactating ewes (56.1 +/- 6.8 kg of initial BW; mean +/- SD) were penned individually and used in a randomized complete block design with 14 blocks and 4 treatments. Diets were formulated to provide similar concentrations of NDF (56%) and CP (16%). The SH NDF replaced 33 (SH33), 67 (SH67), or 100% (SH100) of the NDF contributed by coastcross hay in a 70% forage-based diet (SH0), resulting in SH inclusion rates of 0, 25, 54, and 85% of the dietary DM. Once a week, from the second to the eighth week of lactation (weaning time), ewes were separated from their lambs, stimulated by a 6-IU i.v. oxytocin injection, and hand milked to empty the udder. After 3 h, milk production was obtained after the same procedure. Quadratic effect for milk production (142.4, 179.8, 212.6, and 202.9 g/3 h) and cubic effect for DMI (2.27, 2.69, 3.25, and 3.00 kg/d) were observed as SH inclusion increased from 0 to 85% of the dietary DM. Milk fat (7.59, 7.86, 7.59, and 7.74%), protein (4.53, 4.43, 4.40, and 4.55%), and total solids (18.24, 18.54, 18.39, and 18.64%) did not differ among the 70% forage-based diet and diets with SH NDF replacing 33, 67, or 100% of the NDF. A linear increase in lactose concentration was observed with SH inclusion. Ewe BW gain during the trial showed a cubic response (0.37, 0.03, 4.80, and 2.80 kg) with SH inclusion. The preweaning ADG of lambs increased linearly, and ADG of lambs after weaning decreased linearly with SH inclusion. Final BW of lambs (2 wk after weaning) did not differ among treatments. Eating behavior observations were conducted with 44 ewes. The same facilities, experimental design, dietary treatments, and feeding management were used. Observations were visually recorded every 5 min for a 24-h period when ewes were 46 +/- 6.8 d in milk. Eating time (min/d, min/g of DMI, and min/g of NDF intake) and time expended in rumination and chewing activities (min/g of DMI and min/g of NDF intake) decreased linearly with the addition of SH in the diets. The inclusion of SH improved DMI and milk production, also reflecting on the BW of lambs at weaning. Milk performance was not affected when SH NDF replaced 100% of hay NDF.

Batch kinetics and modelling of ethanolic fermentation of whey

SummaryThe fermentation of whey by Kluyveromyces marxianus strain MTCC 1288 was studied using varying lactose concentrations at constant temperature and pH. The increase in substrate concentration up to a certain limit was accompanied by an increase in ethanol formation, for example, at a substrate concentration of 10 g L−1, the production of ethanol was 0.618 g L−1 whereas at 50 g L−1 it was 3.98 g L−1. However, an increase in lactose concentration to 100 g L−1 led to a drastic decrease in product formation and substrate utilization. The maximum ethanol yield was obtained with an initial lactose concentration of 50 g L−1. A method of batch kinetics was utilized to formulate a mathematical model using substrate and product inhibition constants. The model successfully simulated the batch kinetics observed at S0 = 10 and 50 g L−1 but failed in case of S0 = 100 g L−1 because of strong substrate inhibition.

Ethanol production from cheese whey permeate by Kluyveromyces marxianus UFV-3: A flux analysis of oxido-reductive metabolism as a function of lactose concentration and oxygen levels

In order to investigate the effect of lactose concentration and oxygen level on the growth and metabolism of Kluyveromyces marxianus UFV-3 in cheese whey permeate, batch cultures were conducted under aerobic, hypoxic, and anoxic conditions, with lactose at initial concentration ranging from 1 to 240 g L −1. The increase in lactose concentration increased ethanol yield and ethanol volumetric productivity, and has reduced cell yield. When lactose concentration was equal or above 50 g L −1 and the oxygen levels were low, the ethanol yield was close to its theoretical value. Maximum ethanol concentrations attained in this study were 76 and 80 g L −1 in hipoxia and anoxia, respectively. The lactose consumption rate in anoxia was greater than in aerobiosis and hipoxia. However, under anoxia, the lactose consumption rate of K. marxianus followed a saturation kinetics, which was not observed in hypoxia and aerobiosis. All oxygen levels investigated, showed a tendency for saturation of the ethanol production rate above 65 g L −1 lactose. Ethanol production rate was also higher on anoxia.

Influence of growth conditions on the production of a nisin-like bacteriocin by Lactococcus lactis subsp. lactis A164 isolated from kimchi

The influence of growth parameters on the fermentative production of a nisin-like bacteriocin by Lactococcus lactis subsp. lactis A164 isolated from kimchi was studied. The bacteriocin production was greatly affected by carbon and nitrogen sources. Strain A164 produced at least 4-fold greater bacteriocin in M17 broth supplemented with lactose than other carbon sources. The amount of 3% yeast extract was found to be the optimal organic nitrogen source. While the maximum biomass was obtained at 37 °C, the optimal temperature for the bacteriocin production was 30 °C. The bacteriocin production was also affected by pH of the culture broth. The optimal pH for growth and bacteriocin production was 6.0. Although the cell growth at pH 6.0 was nearly the same level at pH 5.5 and 6.5, the greater bacteriocin activity was observed at pH 6.0. Exponential growth took place only during an initial period of the cultivation, and then linear growth was observed. Linear growth rates increased from 0.160 g DCW l −1 h −1 to 0.245 g DCW l −1 h −1 with increases in lactose concentrations from 0.5 to 3.0%. Maximum biomass was also increased from 1.88 g DCW l −1 to 4.29 g DCW l −1. However, increase in lactose concentration did not prolong the active growth phase. After 20 h cultivation, cell growth stopped regardless of lactose concentration. Production of the bacteriocin showed primary metabolic kinetics. However, bacteriocin yield based on cell mass increased greatly during the late growth phase. A maximum activity of 131×10 3 AU ml −1 was obtained at early stationary growth phase (20 h) during the batch fermentation in M17L broth (3.0% lactose) at 30 °C and pH 6.0.

Production of endo-1,4-?-glucanase and xylanase by Trichoderma reesei immobilized on polyurethane foam

Endo-1,4-β-glucanase and xylanase were produced by Trichoderma reesei immobilized on polyurethane foam using lactose as the main carbon source. The most porous carrier was found to be the best of those tested. The nitrogen source and KH2PO4 concentration of the production medium had a marked effect on culture pH during the course of fermentation and, consequently, on xylanase activity. An increase in lactose concentration from 7 to 27 g/l resulted in an increase in endoglucanase activity (max. 730 U/ml), xylanase activity (max. 3350 U/ml) and filter paper activity (max. 3.0 FPU/ml).

Mammary Epithelial Cell Tight Junction Integrity and Mammary Blood Flow During an Extended Milking Interval in Goats

The timing and relation of changes in mammary epithelial cell tight junction integrity and mammary blood flow during a 36-h milking interval were studied in six lactating Saanen goats. An increase in lactose concentration in plasma, a decrease in transepithelial potential difference, and changes in ionic milk composition were used to indicate tight junction patency. After 36h of milk accumulation, mammary tight junctions had become disrupted. Further analyses indicated that this disruption began after 21h of milk accumulation and that mammary blood flow also started to decline after 21h. The time when both events occurred was not significantly different from the time when milk secretion began to decline (19h). Moreover, positive but nonsignificant correlations existed between these events. Mammary tight junctions became disrupted when milk secretion declined, suggesting that impairment of mammary tight junction integrity is associated with decreased milk secretion during an extended milking interval. The decline in mammary blood flow may be the result of a negative feedback response to a reduced demand for metabolites, which is due to a reduced rate of milk secretion.

Progesterone and corticosteroids in the initiation of lactation in the sow.

The concentration of lactose in the mammary secretion from individual glands of two sows increased significantly (P less than 0.01) between 0 and 24 h after parturition. In six sows studied during the perinatal period there was a negative correlation (r = -0.80; P less than 0.02) at parturition between the concentration of progesterone in the blood and the concentration of lactose in the mammary secretion. Furthermore, the increase in concentration of lactose in the mammary secretion after parturition was related to the timing of the decline of plasma progesterone to low levels. The results indicate that the initiation of lactation occurs within 24 h of parturition in most sows, and the results are consistent with the hypothesis that progesterone withdrawal acts as the 'trigger'. Neither the changes in corticosteroid binding globulin nor the changes in total corticosteroids were temporally related to the initiation of lactation. However, a circadian rhythm was observed for total corticosteroids in the blood of three out of nine lactating and pregnant sows, whereas no circadian rhythm was observed in progesterone of the four pregnant sows. The results are discussed in relation to the disease complex mastitis-metritis-agalactia.

Effects of restricting the water intake of dairy cows upon their milk yield, body weight and blood composition

SUMMARY1. Water intake was measured in eight lactating cows. Subsequently n i an experiment of a 4 × 4 Latin square design, each cow received 100, 87, 73 and 60% of its voluntary intake for 6 days followed by an 8-day recovery period.2. Measurements were made of the intake of feed, milk yield and quality, water, Na and K balances, metabolic profiles, and serum and urine osmolalities. The cows were weighed at the beginning and end ofthe experimental periods, and pulse, respiration and rumination rates and rectal temperatures were measured daily.3. Milk yield decreased significantly with increasing water deprivation. A 40% reduction in water intake was associated with a 16% decrease in intake of dry matter and a concomitant 16% decrease in milk yield. The only significant change in milk composition was a small increase in lactose concentration with increasing water deprivation.4. There was no significant reduction in urine output, but the output of water in faeces was reduced and there was evidence of a reduction i n total body water which approximated the reduction in body weight. 5. Concentrations of serum Na and urea-N and serum osmolality increased significantly with increasing water deprivation.