Production of butyric acid by batch fermentation of cheese whey withClostridium beijerinckii

Summary The effect of pH on the fermentation of butyric acid byClostridium beijerinckii using cheese whey as a substrate was studied. Maximum concentrations of the acid were produced when the pH was controlled at 5.5. Raising or lowering of pH was found to reduce the total acid formation. This particular strain ofC. beijerinckii produced insignificant amounts of butanol in all the pure culture cases investigated. A comparative study of the fermentation in a synthetic glucose medium and in cheese whey showed the whey to produce more butyric acid.     

Continuous ethanol fermentation of cheese whey powder solution: effects of hydraulic residence time

Continuous ethanol fermentation of cheese whey powder solution was realized using pure culture of Kluyveromyces marxianus (DSMZ 7239) at hydraulic residence times (HRT) between 12.5 and 60 h. Sugar utilization, ethanol and biomass formation were investigated as functions of HRT. Effluent sugar concentration decreased, but percent sugar utilization, ethanol and biomass concentrations increased with HRT. Ethanol productivity was maximum (0.745 gE l⁻¹h⁻¹) at an HRT of 43.2 h where the biomass productivity was almost minimum (0.18 gX l⁻¹ h⁻¹). The ethanol yield coefficient was almost constant at 0.4 gE g⁻¹S up to HRT of 43.2 h and the growth yield coefficient was minimum at HRT of 43.2 h. Kinetic models were developed and the constants were determined by using the experimental data.     

Hydration of oleic acid by a Selenomonas strain from the ovine rumen

J.A. HUDSON, C.A.M. MACKENZIE AND K.N. JOBLIN. 1996. A Selenomonas sp., isolated from the ovine rumen, was characterized with regard to its ability to hydrate oleic acid to 10-hydroxystearic acid. Hydration occurred only in stationary phase in a medium containing 0.1%, 0.5% (w/v) galactose or 0.5% (w/v) glucose, but not in a medium containing 1% galactose. Growth under a hydrogen headspace did not result in the production of stearic acid, the biohydrogenated product of oleic acid. Linoleic and linolenic acids (0.1% v/v) were not hydrated. It is concluded that the growing bacterium is unlikely to contribute to oleic acid hydration in the rumen.     

Bacterial fermentation of cheese whey for production of a ruminant feed supplement rich in curde protein.

A simple and efficient process for the production of a ruminant feed supplement, rich in crude protein (defined as total N X 6.25), by bacterial fermentation of cheese whey has been developed. The lactose in unpasteurized whey is fermented to lactate acid by Lactobacillus bulgaricus at a temperature of 43 degrees C and pH 5.5. The lactic acid produced is continually neutralized with ammonia to form ammonium lactate. The fermented product is concentrated by evaporation to a solids content of about 70% and adjusted to pH 6.8 with additional ammonia. The concentrated product contains about 55% crude protein. Approximately 6 to 8% of the crude protein is derived from bacterial cells. 17% from whey proteins, and 75 to 77% from ammonium lactate. The efficiency of conversion of lactose to lactic acid usually exceeds 95%. The fermentation time is greatly reduced upon the addition of 0.2% yeast extract or 0.1% corn steep liquor as a source of growth factors. Whey containing lactose at concentrations up to 7% can be fermented efficiently, but at higher concentrations lactose is fermented incompletely. The process has been scaled up to a pilot plant level, and 40 tons of concentrated product were produced fro animal feeding trials, without ever encountering putrefactive spoilage.     

Bacterial fermentation of cheese whey for production of a ruminant feed supplement rich in curde protein.

A simple and efficient process for the production of a ruminant feed supplement, rich in crude protein (defined as total N X 6.25), by bacterial fermentation of cheese whey has been developed. The lactose in unpasteurized whey is fermented to lactate acid by Lactobacillus bulgaricus at a temperature of 43 degrees C and pH 5.5. The lactic acid produced is continually neutralized with ammonia to form ammonium lactate. The fermented product is concentrated by evaporation to a solids content of about 70% and adjusted to pH 6.8 with additional ammonia. The concentrated product contains about 55% crude protein. Approximately 6 to 8% of the crude protein is derived from bacterial cells. 17% from whey proteins, and 75 to 77% from ammonium lactate. The efficiency of conversion of lactose to lactic acid usually exceeds 95%. The fermentation time is greatly reduced upon the addition of 0.2% yeast extract or 0.1% corn steep liquor as a source of growth factors. Whey containing lactose at concentrations up to 7% can be fermented efficiently, but at higher concentrations lactose is fermented incompletely. The process has been scaled up to a pilot plant level, and 40 tons of concentrated product were produced fro animal feeding trials, without ever encountering putrefactive spoilage.     

Glutamine metabolism by rumen microorganisms: effect of monensin]

Transformation of glutamine of mixed population of microorganisms-symbionts is demonstrated. Protection of glutamine and its intermediates (glutamate and pyroglutamate) under the influence of ionophore (monensin) is found. It is accompanied by the reduced (by 30-70 per cent and more) levels of ammonia formation, total VFA, acetate, butyrate, pH, alpha-ketoglutarate dehydrogenase and glutamine synthetase at parallel increase of L-aspartate and L-alanine: 2-oxoglutarate, aminotransferase activity, redox potential of stability of protein content. It is suggested that the rapid change of Eh level on the 24th hour of incubation reflects the main stage of pyroglutamate formation being one of the final products of glutamine degradation when monensin is used. Ionophore affects first of all the inhibition of metabolic processes in gram-positive rumen microorganisms.     

Effect of initial bacteria concentration on hydrogen gas production from cheese whey powder solution by thermophilic dark fermentation

Dark fermentative hydrogen gas production from cheese whey powder solution was realized at 55°C. Experiments were performed at different initial biomass concentrations varying between 0.48 and 2.86 g L^?1 with a constant initial substrate concentration of 26 ± 2 g total sugar (TS) per liter. The highest cumulative hydrogen evolution (633 mL, 30°C), hydrogen yield (1.56 mol H₂ mol^?1 glucose), and H₂ formation rate (3.45 mL h^?1) were obtained with 1.92 g L^?1 biomass concentration. The specific H₂ production rate decreased with increasing biomasss concentration from the highest value (47.7 mL g^?1 h^?1) at 0.48 g L^?1 biomass concentration. Total volatile fatty acid concentration varied beetween 10 and 14 g L^?1 with the highest level of 14.2 g L^?1 at biomass concentration of 0.48 g L^?1 and initial TS content of 28.4 g L^?1. The experimental data were correlated with the Gompertz equation and the constants were determined. The most suitable initial biomass to substrate ratio yielding the highest H₂ yield and formation rate was 0.082 g biomass per gram of TS. © 2012 American Institute of Chemical Engineers Biotechnol. Prog., 28: 931–936, 2012     

Instability caused by high strength of cheese whey in a UASB reactor

The anaerobic digestion of cheese whey was studied in a UASB reactor. The profiles of the reactor, i.e., the distributions of the substrate concentration and pH under different operating conditions were developed. From the concentrations of substrates measured at various levels above the bottom of the reactor, two reaction stages, namely acidogenesis and methanogenesis, were distinguished. The instability caused by high influent concentration was interpreted as the accumulation of VFAs in the acidogenic stage beyond the assimilative capacity of the methanogenic stage. A range of stable operating conditions was predicted from the results of the profile measurements. The optimal influent concentration was found to be between 25 and 30 g COD/L at an HRT of 5 days for system stability. Other options fro stability control were discussed. (c) 1993 John Wiley & Sons, Inc.     

Fermentation of cheese whey by a mixed culture ofClostridium beijerinckii andBacillus cereus

Summary Fermentation of cheese whey to produce butanol and butyric acid was carried out using a mixed culture ofClostridium beijerinkii andBacillus cereus. Fermentation selectivities were studied by controlling the pH of the system. Controlled pH values higher than 6.5 as well as those below 5.0 were not conducive to butanol production. Maximum product formation was obtained by controlling the pH at 5.5. When compared with the results obtained using the pure culture ofC. beijerinckii, a higher butanol concentration was obtained in the mixed culture without sacrificing the level of butyric acid formed.     

Biohydrogenation of unsaturated fatty acids by a mixed culture of rumen microorganisms

The biohydrogenation of C-18 unsaturated fatty acids was examined in a mixed culture of microorganisms prepared by inoculating a proper growth medium with a sample of rumen fluid. Some major factors influencing the hydrogenation capacity have been investigated. The age of the mixed culture, the type of inoculum used, the concentration of substrates as well as the presence of sterile rumen fluid in the growth medium were found to be important factors determining biohydrogenation behavior. It could be shown that the mixed microbial culture, which had been grown for about 24 h on a medium similar to that of Bryant and Robinson, contained sterile rumen fluid (10% v/v), and had been inoculated with a sample of the whole untreated rumen content, had the best biohydrogenation capacity. The culture was able to carry out the complete conversion of linoleic and linolenic acid to stearic acid.     

Interactions between substrate,fermentation end-products,buffering systems and gas production upon fermentation of different carbohydrates by mixed rumen microorganisms in vitro

Summary In animal nutrition, incubation of feed samples with CO₂/HCO₃-buffered rumen fluid is used to predict the nutritional values of the feed. During fermentation, volatile fatty acids (VFAs) are produced, which release CO₂ from the buffer through their H⁺ ions. This indirect gas production amounted to 20.8 ml gas per mmol VFA. By incubating glucose, rice starch and cellulose, the relationship between direct and indirect gas production in relation to fermentation kinetics was studied. The total amount of gas formed was found to be dependent on the composition of the fermentation end-products formed. This could be described by: ml gas = M_v·mmol HAc + 2M_v·mmol HB + 0.87M_v·mmol Tot. VFA where HAc = acetic acid; HB = butyric acid; and M_v = molar gas volume. No clear relationship was found between the rate of fermentation and total gas production. From rice starch more total gas was produced than from glucose and cellulose, which were fermented faster and slower, respectively. Correspondence to: S. F. Spoelstra     

Scaling-up of a batch whey fermentation by Kluyveromyces fragilis

Summary A whey fermentation by Kluyveromyces fragilis was scaled-up to a 1000-dm³ stirred fermentor, by varying the stirrer speed, the air-flow rate and the initial concentration of lactose. Its evolution was simulated by applying the same unstructured model (consisting of a microbial specific growth rate of pseudo-first order with respect to the COD concentration and constant biomass yield per unit COD removed) set up in previous experiments using 8- to 80-dm³ fermentors. Despite the great scale-up ratios, very different operating conditions, and geometric dissimilarity, a series of empirical regressions previously developed allowed approximate, but acceptable prediction of the stoichiometric and kinetic coefficients of the above mathematical model, thus confirming the capability of this model to provide a reliable basis for further scale-up of this fermentation process to a production scale.     

Modulation of the intestinal Ca2+ uptake by a cheese whey protein digest

We have previously constructed a system which enables the search for factors that could modulate the intestinal calcium transporter, CaT1 (TRPV6; Takano et al., Cytotechnology, 43, 113 (2003)). This system evaluates the CaT1-mediated calcium uptake by using CHO cells stably expressing human CaT1 (CHO-hCaT1 cells). We found that a cheese whey protein digest (CWP-D) increased the calcium uptake by the CHO-hCaT1 cells. CWP-D also enhanced the calcium uptake in human intestinal Caco-2 cells. The in vivo effects of CWP-D were then measured by using rats with enteral feeding. Although enteral feeding decreased the portal calcium concentration, CWP-D partially suppressed the decrease, suggesting that CWP-D could be used for food to enhance calcium absorption.     

Effect of carbon monoxide on fermentation of fiber, starch, and amino acids by mixed rumen microorganisms in vitro

When 1 atm (101.3 kPa) of carbon monoxide was added to mixed rumen bacterial incubations containing timothy hay, methane production was inhibited by 88% without an increase in hydrogen. The molar ratio of propionate to acetate increased from 0.83 to 1.53, extracellular ammonia declined from 5.2 to 2.4 mM, and hemicellulose and cellulose digestions were inhibited by 40 and 27%, respectively. Even low levels of carbon monoxide (less than 0.1 atm [10.13 kPa]) significantly changed the products of fermentation. With starch, methane production was once again inhibited, but the magnitude of starch fermentation was unaffected. Decrease in acetate was accompanied by an equal molar increase in lactate. Ammonia production from the amino acid source, Trypticase, declined 20% as carbon monoxide was increased to 1.0 atm, and 93% of this decrease was explained by a selective inhibition of branched-chain amino acid fermentation.     

Production of solvents (ABE fermentation) from whey permeate by continuous fermentation in a membrane bioreactor

A continuous bioreactor where cells were recycled using a cross-flow microfiltration (CFM) membrane plant was investigated for the production of solvents (ABE fermentation) from whey permeate using Clostridium acetobutylicum P262. A tubular CFM membrane plant capable of being backflushed was used.The continuous fermentations were characterized by cyclic solventogenic and acidogenic behaviour, and ultimately degenerated to an acidogenic state. Steady-state solvent production was obtained for only short periods. This degeneration is attributed to the complex morphological behaviour of this strain of organism on this substrate.It is postulated that to achieve steady-state solvent production over extended periods of time, it is necessary to maintain a balance among the various morphological cell forms, i.e. acid-producing vegetative cells, solvent-producing clostridial cells, and inert forms, e.g. spores.     

Effect of carbon monoxide on fermentation of fiber, starch, and amino acids by mixed rumen microorganisms in vitro.

When 1 atm (101.3 kPa) of carbon monoxide was added to mixed rumen bacterial incubations containing timothy hay, methane production was inhibited by 88% without an increase in hydrogen. The molar ratio of propionate to acetate increased from 0.83 to 1.53, extracellular ammonia declined from 5.2 to 2.4 mM, and hemicellulose and cellulose digestions were inhibited by 40 and 27%, respectively. Even low levels of carbon monoxide (less than 0.1 atm [10.13 kPa]) significantly changed the products of fermentation. With starch, methane production was once again inhibited, but the magnitude of starch fermentation was unaffected. Decrease in acetate was accompanied by an equal molar increase in lactate. Ammonia production from the amino acid source, Trypticase, declined 20% as carbon monoxide was increased to 1.0 atm, and 93% of this decrease was explained by a selective inhibition of branched-chain amino acid fermentation.     

Production of exopolysaccharide by a new mutant strain ofAchromobacter delicatulus using whey fermentation

A novel mutant strain ofAchromobacter delicatulus was cultivated in a 75-L fermentor, using whey as carbon source and production of exocellular glucan was measured. The fermentation had a biphasic character: growth was followed by the phase of polysaccharide production, the maximum of which was 17 g/L.     

Lactic acid production by batch fermentation of whey permeate: A mathematical model

Summary The batch fermentation of whey permeate to lactic acid was improved by supplementing the broth with enzyme-hydrolyzed whey protein. A mathematical model based on laboratory results predicts to a 99% confidence limit the kinetics of this fermentation. Cell growth, acid production and protein and sugar use rates are defined in quantifiable terms related to the state of cell metabolism. The model shows that the constants of the Leudeking-Piret model are not true constants, but must vary with the medium composition, and especially the peptide average molecular weight. The kinetic mechanism on which the model is based also is presented.Nomenclature K _i lactic acid inhibition constant (g/l) - K _pr protein saturation constant during cell growth (g/l) - K _pr protein saturation constant during maintenance (g/l) - K _s lactose saturation constant (g/l) - [LA] lactic acid concentration (g/l) - [PR] protein concentration (g/l) - [S] lactose concentration (g/l) - t time (h) - [X] cell mass concentration (g/l) - , fermentation constants of Leudeking and Piret - specific growth rate (l/h) - Y _{g, LA/S} acid yield during cell growth (g acid/g sugar) - Y _{m, LA/S} acid yield during maintenance (g acid/g sugar) - Y _x/pr yield (g cells/g protein) - specific sugar use rate during cell growth (g sugar/h·g cell) - specific sugar use rate during maintenance (g sugar/h·cell)