Normal Fermentation Research Articles

Data Preprocessing and Output Evaluation of an Autoassociative Neural Network Model for Online Fault Detection in Virginiamycin Production

In this study, an artificial autoassociative neural network (AANN) was used online to detect deviations from normal antibiotic production fermentation using conventional process variables. To improve the efficiency of extracting hidden information contained in multidimensional process variables, and to finally render the AANN adequate for fault detection, we explored the following methods: selection of process variables; preprocessing of data that involved normalizing the training data of the AANN; and evaluation of data that involved assessing the output of the AANN. A method for fault detection in virginiamycin M and S production by Streptomyces virginiae was successfully developed based on these techniques.

Characteristics and glycerol metabolism of fumarate-reducing Enterococcus faecalis RKY1.

Enterococcus faecalis RKY1, which converts fumarate to succinate with a high yield, was identified on the basis of a phylogenetic analysis of the 16S rDNA gene sequence. The strain was incubated at 38 degrees C for 18 h to examine the possible diversion of glucose or glycerol fermentation by fumarate. The products of glucose and glycerol fermentation with fumarate were quite different from those of normal fermentation, which ultimately produces lactate, in that mainly succinate is produced. Metabolic pathway stoichiometry was used to analyze the oxidation of glycerol to succinate by Enterococcus faecalis RKY1. The stoichiometric relationship between glycerol and fumarate was used as a guideline to accumulate succinate more efficiently.

Application of very high gravity technology to the cofermentation of sweet stem sorghum juice and sorghum grain

Ethanol production from mixtures of sweet stem sorghum juice and sorghum grain was investigated under normal and very high gravity (VHG) fermentation conditions. Fermentation was carried out using Saccharomyces cerevisiae yeast strain N96 at 30°C. For VHG fermentation, sucrose was added to the sweet sorghum juice to obtain a concentration of 34 g per 100 ml of dissolved solids. Fermentation was carried out for 96 h using malted and unmalted milled sorghum grain from sorghum cultivars DC-75 and SV-2. Under VHG conditions, maximum ethanol levels were about 16.8% (v/v) and 11% (v/v) for media containing malted and unmalted milled sorghum grain, respectively. Although fermentation did not occur to completion, levels of ethanol obtained under VHG conditions were three times higher than the levels obtained under normal fermentation conditions. Under VHG conditions, about 8 g/100 ml of dissolved solids remained in the fermentation media after ethanol production had ceased while under normal fermentation conditions, about 4 g/100 ml of dissolved solids remained unused in the fermentation media. There was an initial decline in free amino nitrogen (FAN) levels up to 34 h followed by an increase up to 96 h under VHG fermentation conditions. Levels of assayable proanthocyanidins (PAs) from sorghum cultivar DC-75 were reduced during fermentation.

Establishment of conditions for green table olive fermentation at low temperature

Four Lactobacillus plantarum strains were isolated from table olive cold fermentation brines. Their specific growth rate and acidification in MRS broth and in green table olive brines were studied by means of a mixed 2 pH (4.5 and 5.0)×3 salt (3, 4 and 5%, w/v, NaCl)×3 incubation temperature (9, 12 and 15°C) levels factorial design. In MRS broth, the greatest effect (linear) on acidification was due to temperature. In brine, the effects were considerably less, pH (linear) being the most important for specific growth rate, and temperature (linear) for acidification. In both media, an initial pH of 5.0 led to good acidification at 12–15°C. The effectiveness of the conditions found (initial pH of 5.0; 3%,w/v, NaCl; and incubation at 12°C) was confirmed in simulated green olive fermentations with three of the strains, which proved especially robust. Behaviour in terms of growth and acidification rates was similar for these strains, and comparable to that observed in traditional processes, although mannitol and sucrose were not metabolised and fructose was only partially used. This leads to the possibility of obtaining normal fermentation processes of table olives in cold regions when appropriate initial conditions and starter cultures are used.

Production of granulocyte-macrophage colony stimulating factor (GM-CSF) by high cell density fermentation of secretory recombination Escherichia Coli

High cell density fermentation production of recombinant human granulocyte-macrophage colony stimulating factor (GM-CSF) was studied in an Escherichia coli secretory expression system. By using glycerol instead of glucose as a carbon source and feeding in a specific fed-batch mode and by controlling the temperature at about 30°C and maintaining the dissolved oxygen level at 20∼25% saturation, cell density increased from 30 to 91.8 g l −1, the production of recombinant GM-CSF remained high and the fermentation time was reduced from 45 to 30 h. Recombination GM-CSF was purified by hydrophobic column-molecular sieve-ion exchange column chromatography. The expression of recombinant GM-CSF was not affected by fermentation methods, the production of GM-CSF reached 28.04% (about 1.68 g l −1) and 27.51% (about 1.64 g l −1) of total somatic proteins for high cell density and normal fermentation, respectively. The corresponding value for specific activity of GM-CSF was 2.6×10 7, and 2.4×10 7, respectively.

4-Hydroxycyclohexanecarboxylic Acid as a Substrate for Cyclohexanecarboxylic Acid Production during the “Zapatera” Spoilage of Spanish-Style Green Table Olives

Zapatera spoilage was reproduced in Spanish-style green olive brines adjusted to pH 5 and with a concentration of 5% (wt/vol) NaCl. A relationship between the formation of the compound responsible for the zapatera off odor, cyclohexanecarboxylic acid, and consumption of a new compound isolated from olive brines, 4-hydroxycyclohexanecarboxylic acid, was established. When the latter compound was added to a synthetic medium inoculated with a concentrated microbial suspension from a zapatera brine, cyclohexanecarboxylic acid was formed. 4-Hydroxy-cyclohexanecarboxylic acid was not detected in fresh olives, NaOH solutions, or water washes. In normal fermentation brines it was not detected after 30 days of brining, its concentration increasing in a progressive manner thereafter during typical lactic acid fermentation of Spanish-style green olives.

Dynamics of the anaerobic utilization of organic substrates in an anaerobic/aerobic sequencing batch reactor

The operation of an anaerobiclaerobic Sequencing Batch Reactor (SBR) with synthetic feed (glucose as the sole organic substrate) demonstrated periods of non-EBPR and EBPR operation to the absence of polyhydroxy alkanoate (PHA) storage. The glucose added as feed disappeared rapidly (within 10 minutes) and none of the normal fermentation products were detected in the supernatant in either mode of operation. Anaerobic/aerobic batch trials using the biomass from the SBR were conducted to examine the processes taking place and a rapid uptake of glucose was confirmed and was accompanied by a fall m pH. The biomass also demonstrated that anaerobic PHB storage occurred when acetate feed was used. The biomass was characterized by a large population of "G" bacteria, the absence of filamentous microorganisms, compact floc structure and high total carbohydrate (ca 40% w/w). The supernatant was characterized by low COD, TOC and the virtual absence of the glucose substrate. The observations indicate that EBPR was possible under circumstances which are not consistent with accepted mechanisms.

Dynamics of the anaerobic utilization of organic substrates in an anaerobic/aerobic sequencing batch reactor

The operation of an anaerobic/aerobic Sequencing Batch Reactor (SBR) with synthetic feed (glucose as the sole organic substrate) demonstrated periods of non-EBPR and EBPR operation in the absence of polyhydroxy alkanoate (PHA) storage. The glucose added as feed disappeared rapidly (within 10 minutes) and none of the normal fermentation products were detected in the supernatant in either mode of operation. Anaerobic/aerobic batch trials using the biomass from the SBR were conducted to examine the processes taking place and a rapid uptake of glucose was confirmed and was accompanied by a fall in pH. The biomass also demonstrated that anaerobic PHB storage occurred when acetate feed was used. The biomass was characterized by a large population of “G” bacteria, the absence of filamentous microorganisms, compact floc structure and high total carbohydrate (ca 40% w/w). The supernatant was characterized by low COD, TOC and the virtual absence of the glucose substrate. The observations indicate that EBPR was possible under circumstances which are not consistent with accepted mechanisms.

Influence of Higher Alcohol Availability on Ester Formation by Yeast

Esters, which are produced during fermentation, are an important contributor to the flavor of beer. Under normal fermentation conditions, beer ester levels are largely determined by the amounts of ...

Urinary Beta-Alanine Excretion Is a Marker of Abnormal as well as Normal Gut Fermentation

Normal gut fermentation is the process whereby non‐starch‐soluble polysaccharides are metabolized in the large bowel to provide nutrients. It is well represented in the literature. Abnormal fermentation however can also be present. A test for this demonstrates the production of trace amounts of ethanol, measurable in blood. Beta‐alanine production, measured by urinary excretion, is associated with normal fermentation, but this study demonstrates that beta‐alanine production may be a consequence of abnormal fermentation as well as normal. We consider that it may be an independent marker of the disease. process.

Enhancement of carotenoid synthesis by fungal metabolites

Carotenoids, mainly the all-trans-β-carotene, may be produced by the fungus Phycomyces blakesleeanus under normal fermentation conditions. A number of chemical compounds that stimulate or inhibit fungal carotenogenesis have been reported earlier. A procedure for the screening of organisms that enhance carotenogenesis on co-culturing with P. blakesleeanus is described. A water-soluble stimulator of carotenogenesis was obtained from the fermentation broth of an unidentified Aspergillus sp. isolated from soil. The crude preparation appears to be ten times more potent than dimethylphthalate.

Electrophoretic Examination of Alfalfa Silage Proteins

Effects of silage additives on proteolysis of ensiled alfalfa were studied using PAGE. First-cutting alfalfa was wilted (40% DM), chopped, and ensiled into 60 × 10-cm polyvinyl chloride silos. Treatments were control or treatment with glucose (50 g/kg DM), ammonium hydroxide (25 g/kg DM), or formic acid-formaldehyde (2:1 mixture of 90% HCOOH:37% HCOH applied at 1.83% of the DM). Samples were collected on d 0, 1, 2, 4, 7, 21, and 50 of fermentation. Samples were analyzed for N, NPN, ammonia N, pH, lactic acid, acetic acid, and soluble sugar. Also, buffer-soluble protein was characterized using PAGE. During fermentation of control silage, pH and concentrations of soluble sugar declined, and concentrations of lactic and acetic acids and NPN increased, indicating a normal fermentation. Similar shifts in concentrations of compounds occurred in treated silage but to a different extent. Proteins from alfalfa herbage and silage were characterized into molecular weight ranges based on relative mobility, and their disappearance with time of fermentation was estimated. Buffer-extractable proteins decreased rapidly with time of fermentation and essentially disappeared by d 7. Proteolysis was inhibited by formic acid-formaldehyde and ammonium hydroxide treatments but not by glucose. Formic acid-formaldehyde decreased the amount of extractable proteins by decreasing their solubility in the extraction buffer. Apparent degradation and extractability of proteins by buffer were affected by silage treatments; however, because buffer-extractable proteins represented only 36 to 40% of total plant proteins, results must be interpreted cautiously until better extraction procedures are developed.

Production of carotene stereoisomers by Phycomyces blakesleeanus

β-Carotene steroisomers, mainly all-trans and to a small extent 9-cis, may be produced by the fungus Phycomyces blakesleeanus under normal fermentation conditions. The amount of the 9-cis-β-carotene may comprise up to 15% of the total β-carotene. Similarly, cis-lycopene or-phytoene stereoisomers may be obtained when the fungus is fermented in the presence of specific β-carotene inhibitors such as nicotine or diphenylamine respectively. This is the first report on the occurrence of cis-stereoisomers of carotenes in mycelial fungi.

Mycological contamination of Ogiri (fermented sesame seeds) during production in Sierra Leone

'Ogiri' (fermented sesame seeds) was prepared in the laboratory and at home by selected participants. No fungal participation was observed during the normal fermentation process. However, fungal contamination was observed when improper handling techniques were employed. Out of the 49 samples examined, 41 fungal isolates were made. Aspergillus spp were the dominant group irrespective of the locality. Toxigenic Aspergillus included A. flavus Link ex Fries, A. tamarii Kita and A. ochraceus Wilhelm. P. citrinum Thom was the only toxigenicc Penicillium isolated. The role of the different types of wraps used for the fermentation, marketing and storage of the product was also determined.

UNMALTED CEREAL PRODUCTS FOR BEER BREWING. PART I. THE USE OF HIGH PERCENTAGES OF EXTRUDED OR REGULAR CORN STARCH AND SORGHUM

On the basis of results obtained in micro-brews four beers were produced on a 50 litre scale with 50% of the following adjunct materials: debranned sorghum, extruded debranned sorghum, corn starch and extruded corn starch. The extruded materials were processed in an infusion mash while the regular adjuncts were submitted to a preliminary boil, followed by a cooling step (to 45°C) and a subsequent infusion mash. The results indicate a normal fermentation in all cases, no impact of extrusion upon the colloidal stability and the colour of the resulting beers although the saccharification and filtration rates are seriously impaired during the production process inter alia due to the presence of intact starch granules in the extruded products. If these problems could be overcome, it seems perfectly possible to produce beers with high percentages of extruded adjuncts containing no nitrogeneous substances. Indeed, extrusion of debranned sorghum leads to the presence in beer of nitrogen containing compounds (e.g. alkylpyrazines) responsible for highly obnoxious flavours described by a professional taste panel as giving “artificial”, “coffee”, “burnt” or “caramel” odours. These negative flavour characteristics are absent in the beer produced with 50% of extruded corn starch.

SO 2-treated straw as a silage additive: The participation of soluble and cell wall monosaccharide residues in lucerne silage fermentation

The participation of neutral detergent (ND)-soluble and cell wall (CW) monosaccharide residues in the fermentation of silages made of lucerne + wheat straw was studied in 2-l laboratory glass silos. The treatments consisted of: (a) lucerne wilted to 30% dry matter (DM) prior to ensilage (WL); (b) fresh lucerne + untreated wheat straw at a ratio of 60 40 on a DM basis (L + WS); (c) fresh lucerne + SO 2-treated wheat straw at the same ratio (L + 40%TWS); (d) fresh lucerne + SO 2-treated wheat straw at a ratio of 50 50 on a DM basis (L + 50%TWS). Silos were opened after 90 days of fermentation and silages were analyzed. ND-soluble glucose was extensively or completely fermented in the four silages, whereas the ND-soluble uronic acid (pectin) was hardly affected after 90 days of fermentation. The highest recoveries of ND-soluble sugar residues were in the L + 50%TWS silage. CW glucose and xylose did not participate in silage fermentation, but the minor CW sugars (arabinose, galactose and mannose) were slightly degraded in the L + WS and L + 50%TWS silages. The results indicate that the level of inclusion of SO 2-treated wheat straw will determine whether the source material will be preserved as a result of direct acidification of the HSO 3 − residues present in the TWS, or as a consequence of normal fermentation of the CW-derived soluble sugars contributed by the TWS.

A new immobilized cell system with protection against toxic solvents

A new immobilized cell system providing protection against toxic solvents was investigated so that normal fermentations could be carried out in a medium containing toxic solvents. The system consists of immobilized growing cells in Ca-alginate gel beads to which vegetable oils, which are inexpensive absorbents of solvents, had been added. The ethanol fermentation of Saccharomyces cerevisiae ATCC 26603 was used as a model fermentation to study the protection afforded by the system against solvent toxicities. The fermentation was inhibited by solvents such as 2-octanol, benzene, toluene, and phenol. Ethanol production of one batch was not finished even after 35 h using immobilized growing yeast cells in conventional Ca-alginate gel beads in an ethanol production medium (5% glucose) containing 0.1% 2-octanol, which is used as a solvent for liquid-liquid extraction and is one of the most toxic solvents in our experiments. With the new immobilized growing cell system using vegetable oils, however, four repeated batch fermentations were completed in 35 h. Castor oil provided even more protection than soy bean, olive, and tung oils, and it was possible to complete six repeated batches in 35 h. The immobilized cell system with vegetable oils also provided protection against other toxic solvents such as benzene and toluene. A possible mechanism for the protective function of the new immobilized cell system is discussed.

Production of ethanol by Saccharomyces cerevisiae under high‐pressure conditions

A research project was initiated to examine the possibility of using supercritical carbon dioxide for in situ recovery of ethanol during its production by yeast Saccharomyces cerevisiae. As a preliminary step, it was necessary to study the behavior of ethanol production under high-pressure conditions, up to 7 MPa (1000 psi). The results show that pressure has a significant inhibiting effect on the production of ethanol. There is a significant decrease in the initial rate of production as well as in the final ethanol concentration as pressure is increased. This decrease is more significant when carbon dioxide is used to pressurize the fermentor. The pressure affects the ability of the cells to produce ethanol in a reversible way. When the fermentor is returned to atmospheric conditions, the reaction resumes its normal fermentation rate.

Effects of lead oxide and iron on glucose fermentation by Clostridium sp.

Lead oxide (PbO) was solubilized by a nitrogen-fixingClostridium sp. isolated from coal-cleaning waste. Dissolution of PbO was due to production of organic acids and lowering of the pH of growth medium. The solubilized lead affected the growth of the organism as well as the metabolic end products of glucose fermentation. In the normal fermentation of glucose, the bacterium produced acetic, butyric, and trace amounts of lactic acids (32∶63∶5), but in the presence of PbO, the ratio of organic acids changed (9∶38∶53), with lactic acid being the major end product. A similar shift in the fermentation pattern of glucose was also observed when the organism was grown in iron-poor medium. Lactic acid production was commensurate with an increase in concentration of soluble lead in the growth medium. Soluble lead in the culture medium interfered with the iron metabolism of the organism possibly by affecting the synthesis of iron-containing proteins involved in the electron transport system. The effect of lead, however, was reversed by the addition of excess iron to the growth medium.

Continuous ethanol production by zymomonas mobilis on an industrial scale

AbstractThe specific growth rate of the ethanol producing bacterium Zymomonas mobilis was lower in the presence of oxygen than under anaerobic conditions. Aerobically, considerable amounts of acetaldehyde and acetic acid were formed in addition to the normal fermentation products, ethanol and carbon dioxide. This bacterium contains considerable amounts of pentacyclic triterpenoids, mainly 1, 2, 3, 4‐tetrahydroxypentane‐29‐hopane. It seems that stability and permeability of the cytoplasmic membrane of this rather ethanol tolerant organism is achieved by the hopanoid content. A continuous culture of Zymomonas mobilis produced 60 g/l ethanol over a test period of 39 days. This strain was used for ethanol production from an enzymatically hydrolyzed wheat starch fraction on an industrial scale of 100 m3.