Submerged citric acid fermentation of sugar beet molasses: increase in scale

Factors affecting the production of citric acid in the submerged fermentation of ferrocyanide-treated beet molasses by Aspergillus niger were studied in 2.5 and 36 liter fermenters. The small fermenters were used to determine the effects of changes in sterilization technique, phosphate supplement, ferrocyanide treatment, inoculum level, initial pH, fermentation temperature, and aeration rate. The relation between ferrocyanide concentration and inoculum level was also studied. Four different samples of molasses were fermented successfully. An average yield of 8.2% citric acid (64% conversion) was obtained from 51 small-scale fermentations. Comparable yields were obtained in the large fermenters under comparable conditions. Most of the information obtained with the small fermenters was applicable to the larger-scale fermenters, but in the latter the fermentation was significantly more stable. Aeration was the main problem in the scale-up and aeration rates approximately double those calculated on a fermenter cross-sectional area basis were required for comparable results in the large fermenters.

Choline fermentation by Desulfovibrio desulfuricans

Baker, F. D. (Western Reserve University, Cleveland, Ohio), H. R. Papiska, and L. Leon Campbell. Choline fermentation by Desulfovibrio desulfuricans. J. Bacteriol. 84:973-978. 1962-Hayward and Stadtman pointed out that the organism they described as Vibrio cholinicus is closely related to Desulfovibrio desulfuricans. We have established that some strains of D. desulfuricans carry out the same fermentation of choline as does V. cholinicus. We have also shown that V. cholinicus carries out the sulfate-linked fermentation of lactate identical with that of D. desulfuricans. Both organisms have identical reduced cytochrome spectra, with peaks at 417 to 420, 525, and 553 mmu. V. cholinicus also contains the green pigment desulfoviridin, characteristic of D. desulfuricans, which in alkaline solution gives a red fluorescence at 365 mmu. Immunological data from cross-agglutination and absorption tests show that the two organisms have similar antigenic properties. Morphological, cultural, and biochemical studies have also demonstrated that V. cholinicus is indistinguishable from D. desulfuricans. Therefore, V. cholinicus should be regarded taxonomically as a strain of D. desulfuricans.

Enzymes of glucose and pyruvate catabolism in cells, spores, and germinated spores of Clostridium botulinum

Simmons, R. J. (Michigan State University, East Lansing), and R. N. Costilow. Enzymes of glucose and pyruvate catabolism in cells, spores, and germinated spores of Clostridium botulinum. J. Bacteriol. 84:1274-1281. 1962.-An investigation was made of the enzymes of vegetative cells, spores, and germinated spores of Clostridium botulinum 62-A to elucidate a pathway of glucose metabolism. Manometric studies were conducted with intact cells, and various enzymes and enzyme systems were assayed in cell-free and spore-free extracts by use of spectrophotometric and colorimetric procedures. Glucose fermentation was found to be inducible; glucokinase was the controlling enzyme. All other enzymes of the Embden-Meyerhof-Parnas (EMP) pathway were found in both induced and non-induced cells, but they were in relatively low concentrations in the latter. This, plus the fact that no glucose-6-phosphate dehydrogenase was detected, led to the conclusion that glucose is catabolized primarily by the EMP system. A number of glycolytic enzymes were also found in extracts of spores and germinated spores of this organism, but the activities were extremely low as compared with activities in cell extracts. A phosphoroclastic-type reaction was readily demonstrated in both glucose-adapted and non-adapted cells, but not in spores and germinated spores. However, both acetokinase and phosphotransacetylase, as well as coenzyme A transphorase, were detected in spores and germinated-spore extracts, although at very low activity levels as compared with cell extracts. The specific activity of diaphorase in spore extracts was about one-half that of corresponding cell extracts, and the activity of reduced diphosphopyridine nucleotide (DPNH) oxidase was actually higher in the spore extracts. In addition, the DPNH oxidase in spore extracts was considerably more heat-stable than that in extracts of cells or germinated spores.

Fermentative activities of control and radiation-"killed" spores of Clostridium botulinum

Costilow, Ralph N. (Michigan State University, East Lansing). Fermentative activities of control and radiation-"killed" spores of Clostridium botulinum. J. Bacteriol. 84:1268-1273. 1962.-Spores of Clostridium botulinum 62-A exposed to high levels of ionizing radiation will undergo the initial steps in germination as rapidly as control spores. Manometric experiments demonstrated that these irradiated nonviable spores would ferment a tryptic digest of casein (Trypticase) at an increasing rate during germination, with the production of CO(2) and H(2). There was, however, an increasing lag in the development of rapid rates of fermentation as the radiation level was increased. Such a lag could be simulated by the addition of chloramphenicol, and the two effects were additive. By using high spore concentrations (about 8 mg/ml), it was possible to detect the fermentation of a number of individual amino acids and of glucose. Irradiation of spores at 8.3 x 10(5) rads had no measurable effect on the fermentation of l-arginine or glucose, or on the endogenous rate, but it partially inhibited the Stickland reaction with l-alanine and l-proline as substrates. The endogenous activity and the l-alanine, l-proline fermentation were also inhibited by chloramphenicol to basic levels which were the same in both control and irradiated spores. Neither the l-arginine nor glucose fermentation was inhibited by this antibiotic. The data indicate that spores of C. botulinum 62-A contain basic levels of the enzymes required for their primary catabolic processes, and that, as expected, ionizing radiation levels sufficient to render the spores nonviable do not significantly affect these enzymes. Furthermore, it is indicated that spores exposed to radiation levels of up to 1.25 x 10(6) rads retain the ability to synthesize new protein, although it appears to be somewhat impaired.

Aerobic fermentation and the depletion of the amino acid pool in yeast cells

The amino acid pool of yeast cells, Saccharomyces cerevisiae, incubated with galactose remains at a constant level for 100 minutes. This is 30 minutes beyond the time at which the oxidative phase of the induced-enzyme formation begins. Washed yeast cells, the pools of which have been depleted 60 per cent by incubation with glucose, do not replenish their pools as do washed cells incubated without a substrate. These facts indicate that the induced enzymes are formed at least partially from pool-replenishing amino acids. The time of onset of pool depletion is the time at which the aerobic fermentation phase of induced-enzyme formation begins for cells incubated with galactose. With 0.1 per cent galactose the respiratory phase begins at 100 minutes but no aerobic fermentation nor pool depletion occurs. The rates of respiration and aerobic fermentation are constant for four glucose concentrations from 0.1 to 1.0 per cent. The amount of aerobicfermentation is proportional to the initial concentration of glucose. Amino acid pool depletion occurs for all concentrations but depletion ceases and is followed by pool replenishment after aerobic fermentation is complete. Ultraviolet radiations, which delay the appearance of the respiratory phase of induced-enzyme formation, completely eliminate both the appearance of aerobic fermentation and pool depletion. The results indicate an intimate association between aerobic fermentation and amino acid pool depletion.

AN IMPROVED FORMATE LACTOSE GLUTAMATE MEDIUM FOR THE DETECTION OF ESCHERICHIA COLI AND OTHER COLIFORM ORGANISMS IN WATER

A chemically defined fluid medium—improved formate lactose glutamate—is described of which the cost is less than a quarter that of standard MacConkey broth and which is at least equally suitable for routine bacteriological examination of water. It has actual advantages in that the medium after fermentation is clearer and that, therefore, acid and gas production is more easily seen; moreover more isolations of both coliform bacteria and ofEsch. coliare obtained with fewer false positive reactions. Trials with a solid version of the medium suggest that the relative freedom from false positive reactions arises from the failure of the medium to growCl. welchii—one of the commonest causes—and enterococci, another suspected participant. In fact, without any inhibitory agent the medium appears to be virtually specific for the coliform group and particularly favoursEsch. coli.It remains to be seen whether certain aerobic spore-bearers found from time to time in surface waters may, to some slight extent, interfere with the almost complete specificity so far discovered.

The medium is recommended in place of MacConkey broth and other peptonecontaining media, not only for the prospect of better results, in that suppression of the coliform group does not occur, but also for cheapness and for freedom from the inevitable variability associated with media incorporating peptone and, particularly, bile salt. It is hoped that this medium will shortly become available commercially in dehydrated form at a price still considerably less than that required to make up MacConkey broth from its constituents.

Some labour-saving curtailments in the routine of water examination are also suggested.

It is hoped not only that the fluid medium will supplant MacConkey broth for the dilution method of water analysis but that the solid medium, without material alteration, will also prove suitable for water examination by membrane filtration.

I am deeply grateful to my laboratory staff, particularly Mr J. H. Evans, F.I.M.L.T., and Mr G. H. Lowe, F.I.M.L.T., for undertaking so much of the work when routine work was particularly heavy, and for many valuable suggestions. My thanks in addition are due to Mrs Peggy Johnson and Mrs Marilyn Childs, who made up the medium, and also to the directors of the participating P.H.L.S. laboratories not only for having the work carried out but for helpful comments.

CHEMOSTATIC CONCENTRATED CULTURES OF HETEROPLOID MAMMALIAN CELL SUSPENSIONS IN DIALYZING FERMENTORS. I. EXPERIMENTAL EVIDENCE AND THEORETICAL CONSIDERATIONS

Concentrated chemostatic cultures of HeLa S3-1, KB, and HEp # 2 cells have been grown in a dialysis fermentor. Stationary cell concentrations of approximately 1.2 x 10(6) cells per ml have been produced at rates of 15 x 10(-3) to 20 x 10(-3) cells per hour for as long as 40 days. The dialysis fermentor appears to be useful in controlling the effects of nutrients on the growth rate of the cultures. Theoretical considerations are offered.

PHYSIOLOGY OF THE ENTEROCOCCI AS RELATED TO THEIR TAXONOMY

Deibel, R. H. (American Meat Institute Foundation, Chicago, Ill.), Donald E. Lake, and C. F. Niven, Jr. Physiology of the enterococci as related to their taxonomy. J. Bacteriol. 86:1275-1282. 1963-Studies on a collection of enterococci isolated from diverse sources have confirmed the existence of two distinct species, namely, Streptococcus faecalis and Streptococcus faecium. In contrast with S. faecium, S. faecalis characteristically ferments melezitose, sorbitol, glycerol (anaerobically), citrate, and gluconate; fails to ferment arabinose and melibiose; has strong reducing capacities as demonstrated by prompt reduction of litmus in milk or tetrazolium in an agar medium; initiates growth on an agar medium containing 0.04% potassium tellurite; does not require folic acid for growth; and does not produce strong greening in blood agar. S. liquefaciens and S. zymogenes differ from S. faecalis only in their proteolytic capacities and, therefore, deserve only varietal status. Some S. faecalis and S. faecium strains are proteolytic when tested on agar media. S. durans differs from S. faecium only in its inability to ferment arabinose and mannitol, and the failure of most strains to ferment sucrose. Therefore, it should be considered as a variety of S. faecium. It is recommended that the term "enterococcus" be used only when referring to S. faecalis and S. faecium, and their respective varieties.

AEROBIC DEGRADATION OF CHOLINE. I. FERMENTATION OF CHOLINE BY A MARINE BACTERIUM, ACHROMOBACTER CHOLINOPHAGUM N. SP

A marine bacterium, isolated by an enrichment technique, is able to utilize choline as the sole carbon and nitrogen source in a medium containing various salts. The morphological and biochemical characteristics of the organism indicate that it is a new species. Substrate feeding coupled with culture filtrate analyses indicate that choline is metabolized as follows: choline → betaine → dimethylglycine + formaldehyde → sarcosine + formaldehyde → serine → pyruvate + ammonia without transmethylation being involved. This pathway has not previously been reported for other bacteria or for animal tissues.

PREPARATION OF PREPHENIC ACID AND ITS CONVERSION TO PHENYLALANINE AND TYROSINE BY PLANT ENZYMES

Enzymes from mung bean (Phaseolus aureus Roxb.) convert prephenic acid to phenylalanine and tyrosine. In addition to glutamate NADP was required for the production of tyrosine but no cofactor appeared necessary for the formation of phenylalanine. Prephenic acid was produced by growing the auxotroph, Escherichia coli, 58-278, in 20 liters of medium in fermenters at 30 °C. From 275 to 325 mg of prephenic acid was obtained per liter. The culture nitrates were concentrated, and the prephenic acid adsorbed and eluted from Dowex 1 resin and charcoal before being recovered in 40–50% yield as the crystalline barium salt.

ISOLATION OF OBLIGATELY ANAEROBIC PSYCHROPHILIC BACTERIA

Sinclair, N. A. (Washington State University, Pullman), and J. L. Stokes. Isolation of obligately anaerobic psychrophilic bacteria. J. Bacteriol. 87:562-565. 1964.-A total of 11 strains of strictly anaerobic psychrophilic bacteria have been isolated from soil, mud, and sewage. The organisms grow well at 0 C in liquid and on solid media, and grow only in the complete absence of oxygen. On the basis of shape, sporulation, flagellation, and strictly anaerobic growth, all of the organisms were classified as strains of Clostridium. Some of the biochemical properties of the strains and the effect of temperature on growth are described.

CHARACTERIZATION OF STAPHYLOCOCCI ISOLATED FROM RAW MILK

To evaluate the pathogenicity of staphylococci from bovine raw milk, the general characteristics of 775 strains isolated from 798 samples of milk were studied. The coagulase test was performed by use of rabbit plasma. Chromogenesis, mannitol fermentation, and gelatin liquefaction were investigated on Chapman's Medium 110, after 48 hr of incubation. Production of beta-hemolysin, which has been considered indicative of pathogenic staphylococci of animal origin, was determined by streaking different strains on sheep blood-agar plates in the presence of a strain of Lancefield group B streptococci. Plates were incubated at 37 C for 24 hr, and strong hemolysis was produced in the zone of interaction of beta-hemolysin and some substance liberated by streptococcus (CAMP test). Of 404 strains found to be coagulase-positive, 95.8% exhibited a deep-orange pigment, 76.5% produced beta-hemolysin, 91.8% fermented mannitol, and 75% liquefield gelatin. Of 371 strains which gave a negative coagulase test, about 16% fermented mannitol and liquefied gelatin; none of these strains produced beta-hemolysin. When results are grouped according to pigmentation and coagulase production, beta-hemolysin seems to be developed by pathogenic strains of Staphylococcus aureus only. If suitability of these tests for investigation of pathogenicity is compared, production of beta-hemolysin appears to be the most useful one, since no "false positive" results were found. The use of the CAMP test as a simple and rapid technique to determine production of beta-hemolysin by pathogenic strains of animal staphylococci during routine bacteriological work is suggested.

TAXONOMY OF CLOSTRIDIUM BIFERMENTANS AND CLOSTRIDIUM SORDELLII. II. TOXIGENIC AND SPORULATING POTENCIES IN SUBSTRAINS OF A CLOSTRIDIUM SORDELLII STRAIN

Tamai, Kenzo (Kanazawa University, Kanazawa, Japan), and Shoki Nishida. Taxonomy of Clostridium bifermentans and Clostridium sordellii. II. Toxigenic and sporulating potencies in substrains of a Clostridium sordellii strain. J. Bacteriol. 88:1647-1651. 1964.-The existence of six biological criteria for distinction of Clostridium bifermentans and C. sordellii was confirmed. The difference in the six criteria gradually disappeared as the sporulating potency of the substrains of C. sordellii 4708 was strengthened. The substrains which could resist heating at 90 C for 10, 20, or 30 min were found to have lost all six criteria for distinction and were biologically in agreement with C. bifermentans. We further demonstrated that all newly isolated strains of C. bifermentans examined possessed extremely strong sporulating potency.

A FERMENTATION TUBE AND MEDIUM FOR FASTIDIOUS ANAEROBES

A modified fermentation tube was devised by introducing a glass rod in the small inverted Durham tube to keep its mouth away from the bottom of the outer main tube, thus providing the maximum opportunity for gas collection. A medium containing autoclavable growth factors was developed, which, when added to the main tubes with a few particles of cooked meat, allowed growth of fastidious anaerobes. Each ingredient was shown to be free of any fermentable substance that might lead to gas formation. The fermentation tubes were incubated in an anaerobic jar.

COTTON CLOSURE AS AN AERATION BARRIER IN SHAKEN FLASK FERMENTATIONS

Oxygen transfer through a cotton plug follows Fick's law of diffusion. The apparent diffusion constant decreases as the density of cotton packing is increased. Formulas are derived which relate oxygen transfer to cotton-plug dimensions. Calculations indicate that the dimensions of a cotton plug can affect both the maximal oxygen uptake rate and the gas composition inside a shaken flask. In some situations, as with large flasks, the cotton closure can become the limiting factor to aeration.

FUMARATE REDUCTION AND ITS ROLE IN THE DIVERSION OF GLUCOSE FERMENTATION BY STREPTOCOCCUS FAECALIS

Deibel, R. H. (American Meat Institute Foundation, Chicago, Ill.), and M. J. Kvetkas. Fumarate reduction and its role in the diversion of glucose fermentation by Streptococcus faecalis. J. Bacteriol. 88:858-864. 1964.-Fumarate diverts the normal fermentation of glucose by Streptococcus faecalis FB82, as shown by the production of increased amounts of CO(2), formate, acetate, and acetoin, and decreased formation of lactate and ethanol. Experiments with d-glucose-1-C(14), in which low levels of labeled CO(2) were recovered, indicated that C-1 cleavage of the glucose molecule was not involved. The presence of fumarate afforded consistently larger cell crops in growth studies with glucose and other energy sources. On a molar growth-yield basis, anaerobically grown, glucose-fumarate cultures were equivalent to aerobically grown, glucose cultures. The reduction of fumarate by cell suspensions indicated that glucose, gluconate, and, to a lesser extent, glycerol and mannitol could serve as hydrogen donors. Several common metabolic inhibitors had no effect upon the fumarate reductase system in cell suspensions, although some sensitivity to acidic pH was noted. Significant levels of succinate oxidation activity were not detected. Fumarate reductase activity was demonstrated in all five S. faecalis strains tested. Distribution of this ability in S. faecium strains was variable, ranging from activity comparable with that of S. faecalis to total inactivity. The observations support the conclusion that fumarate functions as an alternate hydrogen acceptor, thus allowing pyruvate to participate in the energy-yielding phosphoroclastic and dismutation pathways.

D-ARABITOL PRODUCTION BY ENDOMYCOPSIS CHODATI

Endomycopsis chodati in an aerated fermentation produced d-arabitol in yields of 35 to 40% of the sugar supplied. Glucose, mannose, and sucrose were suitable substrates. A synthetic medium was developed for the fermentation that showed that nitrogen in the medium must be limiting to obtain high yields of arabitol. Excess phosphate also tended to lower arabitol yields, although the effect was not so great as with nitrogen. Pilot plant-size fermentations were made in which all the nutrients were supplied by blackstrap molasses and urea. Arabitol yields in these fermentations were about 40% of the sugar supplied.

DEGRADATION AND UTILIZATION OF ISOLATED HEMICELLULOSE BY PURE CULTURES OF CELLULOLYTIC RUMEN BACTERIA

Dehority, B. A. (Ohio Agricultural Experiment Station, Wooster). Degradation and utilization of isolated hemicellulose by pure cultures of cellulolytic rumen bacteria. J. Bacteriol. 89:1515-1520. 1965.-Hemicelluloses isolated from flax, corn hulls, alfalfa, oat hulls, and fescue grass were used as sole energy sources to study the ability of pure cultures of cellulolytic rumen bacteria to degrade and utilize these materials. From a total of eight bacterial strains tested (three strains of Bacteroides succinogenes, four strains of Ruminococcus flavefaciens, and one strain of Ruminococcus albus), only three strains of ruminococci were able to utilize the hemicelluloses for growth. Hemicellulose fermentation mixtures were analyzed for total pentose, residual hemicellulose (pentose precipitated in 80% ethyl alcohol), and ethyl alcohol-soluble pentose. The three strains of ruminococci were able to partially utilize the different hemicelluloses as energy sources, as determined by total pentose loss, and they were capable of almost complete degradation of the original hemicellulose from an ethyl alcohol-insoluble to ethyl alcohol-soluble form. The extent of both degradation and utilization varied markedly between the three strains and different substrates. Tests on the other strains indicated that no growth, production of organic acid end products, or appreciable loss of total pentose had occurred. However, analysis of the culture medium for residual hemicellulose indicated that these strains were able to extensively degrade the original hemicelluloses to an ethyl alcohol-soluble form. Marked differences were observed among strains and hemicelluloses in the amount of hemicellulose degraded. Of the different hemicelluloses, corn-hull hemicellulose was the most resistant to degradation and utilization by the cellulolytic rumen bacteria.

PHYSIOLOGY OF THE SPORULATION PROCESS IN CLOSTRIDIUM BOTULINUM. I. CORRELATION OF MORPHOLOGICAL CHANGES WITH CATABOLIC ACTIVITIES, SYNTHESIS OF DIPICOLINIC ACID, AND DEVELOPMENT OF HEAT RESISTANCE

Day, Lawrence E. (Michigan State University, East Lansing), and Ralph N. Costilow. Physiology of the sporulation process in Clostridium botulinum. I. Correlation of morphological changes with catabolic activities, synthesis of dipicolinic acid, and development of heat resistance. J. Bacteriol. 88:690-694. 1964.-A reasonable degree of synchrony in the sporulation of Clostridium botulinum 62-A was attained by using a large inoculum of a young culture into a medium containing 4% Trypticase and 1 ppm of thiamine. Sporulation was complete within 24 to 36 hr. Cells harvested at various intervals were studied for their fermentative activity with l-alanine and l-proline as substrates. The Q values (microliters of gas per hour per milligram of dry cells) were maximal at the time a large percentage of the cells had initiated sporulation as indicated by swelling. They declined to a plateau at about the same level as found in vegetative cells by the time 10% of the cells had completed sporulation, and finally to a much lower level when sporulation was completed. The rates of accumulation of volatile acids (acetic, valeric, and propionic acids) corresponded closely with the catabolic potential observed. However, in the case of acetic acid, there was a significant decrease in the total acid present as the number of mature spores increased to over 50% of the final number. The total acetic acid then increased at a slow rate. The production of basic compounds during growth and sporulation more than balanced the rate of acid production, because the hydrogen ion concentration decreased exponentially throughout the period as indicated by the steady increase in pH. The synthesis of dipicolinic acid coincided closely with the development of heat resistance. Refractility developed 3 to 5 hr in advance of heat resistance.

OBLIGATELY PSYCHROPHILIC YEASTS FROM THE POLAR REGIONS

Sixty-seven pure cultures of psychrophilic bacteria and yeasts were isolated from polar ice, snow, soil, and other materials. Low temperatures were maintained during all phases of the isolation procedure to avoid possible destruction of obligate psychrophiles. Four of the cultures, all yeasts, proved to be obligate psychrophiles. Three are species of Candida and one of Torulopsis. They grew in the range of 0 °C to 20 °C and the optimum growth temperature was 15 °C. They died rapidly when exposed to temperatures of 30 °C or 40 °C.The rate of fermentation of glucose by psychrophilic Candida sp. P16 was higher than that of mesophilic Saccharomyces cerevisiae at temperatures below 25 °C. At and above 25 °C, this rate relationship was reversed and at 35 °C all fermentative activity of the psychrophilic yeast was destroyed while that of the mesophile was maximal. Oxidative activity of Candida sp. P16 was much less sensitive to 35 °C, which suggests that fermentation and oxidation proceed by different pathways.The extent of occurrence of obligately psychrophilic microorganisms in nature is discussed.