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PubMed1991

Comparative study of microorganisms and sensory attributes of condiments from the fermentation of different seeds.

Seeds of African locust bean, melon, castor oil bean and soybean were processed and fermented for 3 days to produce local condiments in the laboratory with a method that simulated the traditional production process. Microorganisms associated with their fermentation and the organoleptic properties of the products were compared. Altogether, seven species of bacteria were involved in the fermentation. These included five Bacillus spp. and one species each of Pseudomonas and Staphylococcus. Their occurrence vary between the seeds on the different days of fermentation. However, Bacillus spp. were present in all the seeds throughout the fermentation period. The sensory evaluation preference rating for the four products was highest for soybean condiment, followed by that made from locust bean. Melon condiment was the least preferred among the four products. Statistical analysis showed that there were significant differences (P less than or equal to 0.05) among the four products for each of the four organoleptic properties evaluated by the judges and also for titratable acidity. Glutamic acid level of soybean condiment was highest (0.31%) among the four products with that of melon being the lowest (0.04%). These results could serve as useful indices for the development of starter culture and optimization of production process in commercializing the production of these local condiments.

Bacillus↗
PubMed1998

A novel fermentation pathway in an Escherichia coli mutant producing succinic acid, acetic acid, and ethanol.

Escherichia coli strain NZN111, which is unable to grow fermentatively because of insertional inactivation of the genes encoding pyruvate: formate lyase and the fermentative lactate dehydrogenase, gave rise spontaneously to a chromosomal mutation that restored its ability to ferment glucose. The mutant strain, named AFP111, fermented glucose more slowly than did its wild-type ancestor, strain W1485, and generated a very different spectrum of products. AFP111 produced succinic acid, acetic acid, and ethanol in proportions of approx 2:1:1. Calculations of carbon and electron balances accounted fully for the observed products; 1 mol of glucose was converted to 1 mol of succinic acid and 0.5 mol each of acetic acid and ethanol. The data support the emergence in E. coli of a novel succinic acid:acetic acid:ethanol fermentation pathway.

Acetic Acid↗
PubMed2004

Protective effect of fermented red ginseng on a transient focal ischemic rats.

Red ginseng and fermented red ginseng were prepared, and their composition of ginsenosides and antiischemic effect were investigated. When ginseng was steamed at 98-100 degrees C for 4 h and dried for 5 h at 60 degrees C, and extracted with alcohol, its main components were ginsenoside Rg3> ginsenoside Rb1 > ginsenoside Rb2. When the ginseng was suspended in water and fermented for 5 days by previously cultured Bifidobacterium H-1 and freeze-dried (fermented red ginseng), its main components were compound K > ginsenoside Rg3 > or = ginsenoside Rh2. Orally administered red ginseng extract did not protect ischemia-reperfusion brain injury. However, fermented red ginseng significantly protected ischemica-reperfusion brain injury. These results suggest that ginsenoside Rh2 and compound K, which was found to be at a higher content in fermented red ginseng than red ginseng, may improve ischemic brain injury.

Animals↗
PubMed2003

Use of the mannitol pathway in fructose fermentation of Oenococcus oeni due to limiting redox regeneration capacity of the ethanol pathway.

The heterolactic bacterium Oenococcus oeni ferments fructose by a mixed heterolactic/mannitol fermentation. For heterolactic fermentation of fructose, the phosphoketolase pathway is used. The excess NAD(P)H from the phosphoketolase pathway is reoxidized by fructose (yielding mannitol). It is shown here that, under conditions of C-limitation or decreased growth rates, fructose can be fermented by heterolactic fermentation yielding nearly stoichiometric amounts of lactate, ethanol and CO(2). Quantitative evaluation of NAD(P)H-producing (phosphoketolase pathway) and -reoxidizing (ethanol, mannitol and erythritol pathways) reactions demonstrated that at high growth rates or in batch cultures the ethanol pathway does not have sufficient capacity for NAD(P)H reoxidation, requiring additional use of the mannitol pathway to maintain the growth rate. In addition, insufficient capacities to reoxidize NAD(P)H causes inhibition of growth, whereas increased NAD(P)H reoxidation by electron acceptors such as pyruvate increases the growth rate.

Aldehyde-Lyases↗
PubMed2003

Efficient 40 degrees C fermentation of L-lysine by a new Corynebacterium glutamicum mutant developed by genome breeding.

We have recently developed a new L-lysine-producing mutant of Corynebacterium glutamicum by "genome breeding" consisting of characterization and reconstitution of a mutation set essential for high-level production. The strain AHP-3 was examined for L-lysine fermentation on glucose at temperatures above 35 degrees C, at which no examples of efficient L-lysine production have been reported for this organism. We found that the strain had inherited the thermotolerance that the original coryneform bacteria was endowed with, and thereby grew and produced L-lysine efficiently up to 41 degrees C. A final titer of 85 g/l after only 28 h was achieved at temperatures around 40 degrees C, indicating the superior performance of the strain developed by genome breeding. When compared with the traditional 30 degrees C fermentation, the 40 degrees C fermentation allowed an increase in yield of about 20% with a concomitant decrease in final growth level, suggesting a significant transition of carbon flux distribution in glucose metabolism. DNA array analysis of metabolic changes between the 30 degrees C and 40 degrees C fermentations identified several differentially expressed genes in central carbon metabolism although we could not find stringent control-like global induction of amino-acid-biosynthetic genes in the 40 degrees C fermentation. Among these changes, two candidates were picked out as the potential causes of the increased production at 40 degrees C; decreased expression of the citrate synthase gene gltA and increased expression of malE, the product of which involves regeneration of pyruvate and NADPH.

Corynebacterium↗
PubMed2003

Evaluation of different organic phases for water-in-oil xanthan fermentation.

Water-in-oil (W/O) fermentation technology has the potential for overcoming the problems related with high broth viscosity in xanthan fermentations. By dispersing the aqueous broth in a continuous organic phase, the broth-thickening mechanisms are confined within the aqueous droplets without significantly increasing the overall viscosity. In this study, xanthan fermentations were made with perfluorocarbon (PFC) or vegetable oil as the organic phase. The results were compared with those obtained previously using n-hexadecane as the organic phase, to evaluate the effects of various properties. PFC provided easy phase separation at the end of fermentation but required higher power input for agitation, a direct result of its high density. The aqueous droplets formed were large (400-450 microm), limiting the cell concentration employable due to the occurrence of oxygen starvation in the inner core. One main advantage of using vegetable oil was its low cost. In addition, vegetable oil provided much finer droplets (<120 microm) and produced high xanthan concentrations (>100 g l(-1)). However, complete phase separation for product recovery was difficult to achieve. Fermentations in both organic phases were terminated by the occurrence of phase inversion to highly viscous O/W dispersions at aqueous-phase volume fractions of 0.53-0.56. The initial fraction was 0.3 but changed due to base addition for pH adjustment and nutrient addition for prolonged production.

Alkanes↗
PubMed2004

Evaluation of succinic acid continuous and repeat-batch biofilm fermentation by Actinobacillus succinogenes using plastic composite support bioreactors.

Continuous and repeat-batch biofilm fermentations using Actinobacillus succinogenes were performed with immobilized and suspended-cell systems. For the immobilized continuous system, plastic composite supports (PCS) containing 50% (w/w) polypropylene (PP), 35% (w/w) ground soybean hulls, 5% (w/w) dried bovine albumin, 2.5% (w/w) soybean flour, 2.5% (w/w) yeast extract, 2.5% (w/w) dried red blood cells, and 2.5% (w/w) peptone, or PP tubes (8.5 cm in length) were arranged around the agitator shaft in a grid formation. Agitation was controlled at 125 rpm and 150 rpm. Samples were taken at dilution rates of 0.2, 0.4, 0.6, 0.8, 1.0, and 1.2 h(-1) and analyzed for succinic acid production and glucose consumption (g l(-1)). For PCS bioreactors, the highest final succinic acid concentrations (10.1 g (-1), 10.4 g l(-1)) and percentage yields (62.6%, 71.6%) occurred at the dilution rate of 0.2 h(-1). PCS disks were evaluated in a repeat-batch biofilm reactor. Suspended-cell batch fermentations were performed in flasks and a repeat-batch bioreactor. The maximum concentration of succinic acid produced was 40 g l(-1). Peak succinic acid percentage yields in continuous and repeat-batch fermentations of A. succinogenes were observed in suspended-cell continuous fermentations at a dilution rate of 1.0 h(-1) (76.2%) and in PCS repeat-batch fermentations with an initial glucose concentration of 40 g l(-1) (86.7%).

Actinobacillus↗
PubMed2005

Optimization and scale up of industrial fermentation processes.

To increase product yields and to ensure consistent product quality, key issues of industrial fermentations, process optimization and scale up are aimed at maintaining optimum and homogenous reaction conditions minimizing microbial stress exposure and enhancing metabolic accuracy. For each individual product, process and facility, suitable strategies have to be elaborated by a comprehensive and detailed process characterization, identification of the most relevant process parameters influencing product yield and quality and their establishment as scale-up parameters to be kept constant as far as possible. Physical variables, which can only be restrictedly kept constant as single parameters, may be combined with other pertinent parameters to appropriate mathematical groups or dimensionless terms. Process characterization is preferably based on real-time or near real-time data collected by in situ and on-line measurements and may be facilitated by supportive approaches and tools like neural network based chemometric data analysis and modelling, clarification of the mixing and stream conditions through computational fluid dynamics and scale-down simulations. However, as fermentation facilities usually are not strictly designed according to scale-up criteria and the process conditions in the culture vessels thus may differ significantly and since any strategy and model can only insufficiently consider and reflect the highly complex interdependence and mutual interaction of fermentation parameters, successful scale up in most cases is not the result of a conclusive and straight-lined experimental strategy, but rather will be the outcome of a separate process development and optimization on each scale. This article gives an overview on the problems typically coming along with fermentation process optimization and scale up, and presents currently applied scale-up strategies while considering future technologies, with emphasis on Escherichia coli as one of the most commonly fermented organisms.

Bioreactors↗
PubMed2005

Ethanol fermentation from biomass resources: current state and prospects.

In recent years, growing attention has been devoted to the conversion of biomass into fuel ethanol, considered the cleanest liquid fuel alternative to fossil fuels. Significant advances have been made towards the technology of ethanol fermentation. This review provides practical examples and gives a broad overview of the current status of ethanol fermentation including biomass resources, microorganisms, and technology. Also, the promising prospects of ethanol fermentation are especially introduced. The prospects included are fermentation technology converting xylose to ethanol, cellulase enzyme utilized in the hydrolysis of lignocellulosic materials, immobilization of the microorganism in large systems, simultaneous saccharification and fermentation, and sugar conversion into ethanol.

Bacteria↗
PubMed2006

Enhanced ethanol fermentation of brewery wastewater using the genetically modified strain E. coli KO11.

We have used liquid waste obtained from a beer brewery process to produce ethanol. To increase the productivity, genetically modified organism, Escherichia coli KO11, was used for ethanol fermentation. Yeast was also used to produce ethanol from the same feed stock, and the ethanol production rates and resulting concentrations of sugars and ethanol were compared with those of KO11. In the experiments, first the raw wastewater was directly fermented using two strains with no saccharification enzymes added. Then, commercial enzymes, alpha-amylase, pectinase, or a combination of both, were used for simultaneous saccharification and fermentation, and the results were compared with those of the no-enzyme experiments for KO11 and yeast. Under the given conditions with or without the enzymes, yeast produced ethanol more rapidly than E. coli KO11, but the final ethanol concentrations were almost the same. For both yeast and KO11, the enzymes were observed to enhance the ethanol yields by 61-84% as compared to the fermentation without enzymes. The combination of the two enzymes increased ethanol production the most for the both strains. The advantages of using KO11 were not demonstrated clearly as compared to the yeast fermentation results.

Beer↗
PubMed1999

Benzene/toluene/p-xylene degradation. Part II. Effect of substrate interactions and feeding strategies in toluene/benzene and toluene/p-xylene fermentations in a partitioning bioreactor.

A two-phase aqueous/organic partitioning bioreactor scheme was used to degrade mixtures of toluene and benzene, and toluene and p-xylene, using simultaneous and sequential feeding strategies. The aqueous phase of the partitioning bioreactor contained Pseudomonas sp. ATCC 55595, an organism able to degrade benzene, toluene and p-xylene simultaneously. An industrial grade of oleyl alcohol served as the organic phase. In each experiment, the organic phase of the bioreactor was loaded with 10.15 g toluene, and either 2.0 g benzene or 2.1 g p-xylene. The resulting aqueous phase concentrations were 50 mg/l, 25 mg/l and 8 mg/l toluene, benzene and p-xylene respectively. The simultaneous fermentation of benzene and toluene consumed these compounds at volumetric rates of 0.024 g l-1 h-1 and 0.067 g l-1 h-1, respectively. The simultaneous fermentation of toluene and p-xylene consumed these xenobiotics at volumetric rates of 0.066 g l-1 h-1 and 0.018 g l-1 h-1, respectively. A sequential feeding strategy was employed in which toluene was added initially, but the benzene or p-xylene aliquot was added only after the cells had consumed half of the initial toluene concentration. This strategy was shown to improve overall degradation rates, and to reduce the stress on the microorganisms. In the sequential fermentation of benzene and toluene, the volumetric degradation rates were 0.056 g l-1 h-1 and 0.079 g l-1 h-1, respectively. In the toluene/p-xylene sequential fermentation, the initial toluene load was consumed before the p-xylene aliquot was consumed. After 12 h in which no p-xylene degradation was observed, a 4.0-g toluene aliquot was added, and p-xylene degradation resumed. Excluding that 12-h period, the microbes consumed toluene and p-xylene at volumetric rates of 0.074 g l-1 h-1 and 0.025 g l-1 h-1, respectively. Oxygen limitation occurred in all fermentations during the rapid growth phase.

Benzene↗
PubMed2004

In vitro fermentation characteristics of a mixture of Raftilose and guar gum by human faecal bacteria.

BACKGROUND: The therapeutic effects of indigestible carbohydrates in the human colon are well known. Most fermentation studies have examined only single carbohydrates. Considering the idiosyncratic actions of individual carbohydrates and the dose required, it is unlikely that any one carbohydrate will provide ideal physiological actions without having some undesirable effects. Little is known of how mixing non-digestible carbohydrates affects their fermentation. This necessitates fermentation studies using different carbohydrates in mixtures. AIM OF THE STUDY: The aim of this study was to test the effect of mixing Raftilose (R) and guar gum (G) on short chain fatty acid (SCFA) production in in vitro cultures of human faecal bacteria. METHOD: The fermentation of the individual carbohydrates (10 mg/ml) was compared with that of a 50:50 mixture in anaerobic in vitro cultures of human faeces. RESULTS: Cultures of R/G mixtures produced significantly more n-butyrate than 100 mg G alone at 8 and 24 hours (p < 0.02). There was no significant difference in the production of n-butyrate between cultures of 100 mg R and the R/G mixture at 8 and 24 hours. R (100 mg) produced a propionic/butyric (p/b) acid ratio of 1.18 compared with 3.88 for 100 mg G, whereas R/G mixture produced a p/b ratio of 2.01. CONCLUSION: The fermentation of R/G mixture was different compared with 100 mg of R or G alone. There was no loss of n-butyrate in the culture containing R/G (50 mg of each) mixture compared with the 100 mg R culture.

Adult↗
PubMed2005

Rheology and hydrodynamic properties of Tolypocladium inflatum fermentation broth and its simulation.

A physico-chemical, two phase simulated pseudoplastic fermentation (SPF) broth was investigated in which Solka Floc cellulose fibre was used to simulate the filamentous biomass, and a mixture of 0.1% (w/v) carboxymethyl cellulose (CMC) and 0.15 M aqueous sodium chloride was used to simulate the liquid fraction of the fermentation broth. An investigation of the rheological behaviour and hydrodynamic properties of the SPF broth was carried out, and compared to both a fungal Tolypocladium inflatum fermentation broth and a CMC solution in a 50 L stirred tank bioreactor equipped with conventional Rushton turbines. The experimental data confirmed the ability of the two phase SPF broth to mimic both the T. inflatum broth bulk rheology as well as the mixing and mass transfer behaviour. In contrast, using a homogeneous CMC solution with a similar bulk rheology to simulate the fermentation resulted in a significant underestimation of the mass transfer and mixing times. The presence of the solid phase and its microstructure in the SPF broth appear to play a significant role in gas holdup and bubble size, thus leading to the different behaviours. The SPF broth seems to be a more accurate simulation fluid that can be used to predict the bioreactor mixing and mass transfer performance in filamentous fermentations, in comparison with CMC solutions used in some previous studies.

Ascomycota↗
PubMed2004

Fermentation of a milk-soymilk and Lycium chinense Miller mixture using a new isolate of Lactobacillus paracasei subsp. paracasei NTU101 and Bifidobacterium longum.

A milk-soymilk mixture was fermented using Lactobacillus paracasei subsp. paracasei NTU101 and Bifidobacterium longum BCRC11847 at different inoculum ratios (1:1, 1:2, 1:5, 2:1, and 5:1). When the inoculum ratio was 1:2, the cell numbers of both strains were balanced after 12 h of cultivation. The pH and titratable acidity were very similar at the various inoculum ratios of cultivation. The milk-soymilk mixture was supplemented with 5, 10, 15, and 20% Lycium chinense Miller juice and fermented with Lactobacillus paracasei subsp. paracasei NTU101 and B. longum BCRC11847. Sensory evaluation results showed that supplementation with 5% Lycium chinense Miller juice improved the acceptability of the fermented milk-soymilk. The fermented beverage was stored at 4 degrees C for 14 days; variations in pH and titratable acidity were slight. The cell numbers of L. paracasei subsp. paracasei NTU101 and B. longum BCRC11847 in the fermented beverage were maintained at 1.2x10(9) CFU/ml and 6.3x10(8) CFU/ml, respectively, after 14 days of storage.

Animals↗
PubMed2006

Effect of n-dodecane on Crypthecodinium cohnii fermentations and DHA production.

The potential use of n-dodecane as an oxygen vector for enhancement of Crypthecodinium cohnii growth and docosahexaenoic acid (DHA) production was studied. The volumetric fraction of oxygen vector influenced the gas-liquid volumetric mass transfer coefficient k (L) a positively. The k (L) a increased almost linearly with the increase of volumetric fraction of n-dodecane up to 1%. The stirring rate showed a higher influence on the k (L) a than the aeration rate. The effects of this hydrocarbon on C. cohnii growth and DHA production were then investigated. A control batch fermentation without n-dodecane addition (CF) and a batch fermentation where n-dodecane 1% (v/v) was added (DF) were carried out simultaneously under the same experimental conditions. It was found that, before 86.7 h of fermentation, the biomass concentration, the specific growth rate, the DHA, and total fatty acids (TFA) production were higher in the CF. After this fermentation time, the biomass concentration, the DHA and TFA production were higher in the DF. The highest DHA content of biomass (6.14%), DHA percentage of TFA (51%), and DHA production volumetric rate r (DHA) (9.75 mg l(-1 )h(-1)) were obtained at the end of the fermentation with n-dodecane (135.2 h). The dissolved oxygen tension (DOT) was always higher in the DF, indicating a better oxygen transfer due to the oxygen vector presence. However, since the other C. cohnii unsaturated fatty acids percentages did not increase with the oxygen availability increase due to the n-dodecane presence, a desaturase oxygen-dependent mechanism involved in the C. cohnii DHA biosynthesis was not considered to explain the DHA production increase. A selective extraction through the n-dodecane was suggested.

Alkanes↗
PubMed2005

Do interventions which reduce colonic bacterial fermentation improve symptoms of irritable bowel syndrome?

Abnormal fermentation may be an important factor in irritable bowel syndrome (IBS). Gastroenteritis or antibiotic therapy may damage the colonic microflora, leading to increased fermentation and the accumulation of gas. Gas excretion may be measured by whole-body calorimetry but there has only been one such study on IBS to date. We aimed to assess the relationship between IBS symptoms and fermentation rates in IBS. A purpose-built, 1.4-m3, whole-body calorimeter was used to assess excretion of H2 and CH4 in IBS subjects while consuming a standard diet and, again, after open randomization on either the standard diet together with the antibiotic metronidazole or a fiber-free diet to reduce fermentation. Metronidazole significantly reduced the 24-hr excretion of hydrogen (median value compared to the control group, 397 vs 230 ml/24 hr) and total gas (H2 + CH4; 671 vs 422 ml/min) and the maximum rate of gas excretion (1.6 vs 0.8 ml/min), as did a no-fiber polymeric diet (hydrogen, 418 vs 176 ml/min; total gas, 564 vs 205 ml/min; maximum rate of gas excretion, 1.35 vs 0.45 ml/min), with a significant improvement in abdominal symptoms. IBS may be associated with rapid excretion of gaseous products of fermentation, whose reduction may improve symptoms.

Adult↗
PubMed1993

Carbohydrate fermentation decreases hepatic glucose output in healthy subjects.

Fermentation of undigested carbohydrate produces short-chain fatty acids (SCFA), some of which have been shown to reduce hepatic glucose production (HGP) in animals. The aim of this study was to examine whether carbohydrate fermentation decreases HGP in man. Ten healthy subjects consumed 90-g carbohydrate portions of either brown rice or barley for dinner in random order 1 week apart. The following morning, glucose kinetics were measured basally and during an oral glucose tolerance test (OGTT). HGP was calculated as the difference between the total rate of glucose appearance (calculated from % enrichment of 6,6 dideuterated glucose [6,6 D2 glucose]) and the rate of appearance of gut-derived glucose (calculated from 6-3H glucose in the glucose drink). To detect fermentation, breath H2 content was measured by end-expiratory sampling of alveolar air. Significantly more breath H2 was produced after barley consumption (24 +/- 4 v 4 +/- 1 ppm, P < .001), indicating that barley contains more fermentable carbohydrate than rice. Glucose tolerance improved after the barley meal, with the peak OGTT plasma glucose concentration being 0.7 mmol/L lower than that after the rice meal (7.7 +/- 0.4 v 8.4 +/- 0.3 mmol/L, P < .05). This was primarily due to a 30% reduction in HGP (area under the curve, 909 +/- 116 v 1,295 +/- 157 mumol/kg; P < .01). No difference in the rates of glucose disappearance or gut glucose absorption was observed. However, serum free fatty acid (FFA) concentrations were significantly reduced the morning after the barley meal. In summary, carbohydrate fermentation enhances the suppression of HGP and FFA levels by oral glucose in man.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Effect of fermentation of Ghanaian maize dough on the survival and proliferation of 4 strains of Shigella flexneri.

Fermented and non-fermented Ghanaian maize dough was seeded with approximately 10(7) colony forming units of 4 strains of Shigella flexneri which had been isolated from patients with dysentery. In the non-fermented maize dough (pH 6.2) the shigellae were detectable in large numbers for up to 24 h after exposure. In the maize dough that had been fermented for 3 d (pH 3.2) 3 strains were detectable in small numbers for up to 6 h after inoculation. Thereafter none was isolated. The fourth strain, though detectable for up to 24 h after inoculation, had its numbers reduced considerably. This suggests that traditional methods of food preparation using fermentation have important anti-diarrhoeal functions and the current decline in popularity of such food technologies in certain developing countries may increase the risk of childhood diarrhoea.

Colony Count, Microbial↗