Steep Medium Research Articles

Optimization of a corn steep medium for production of ethanol from synthesis gas fermentation by Clostridium ragsdalei

Fermentation of biomass derived synthesis gas to ethanol is a sustainable approach that can provide more usable energy and environmental benefits than food-based biofuels. The effects of various medium components on ethanol production by Clostridium ragsdalei utilizing syngas components (CO:CO(2)) were investigated, and corn steep liquor (CSL) was used as an inexpensive nutrient source for ethanol production by C. ragsdalei. Elimination of Mg(2+), NH(4) (+) and PO(4) (3-) decreased ethanol production from 38 to 3.7, 23 and 5.93 mM, respectively. Eliminating Na(+), Ca(2+), and K(+) or increasing Ca(2+), Mg(2+), K(+), NH(4) (+) and PO(4) (3-) concentrations had no effect on ethanol production. However, increased Na(+) concentration (171 mM) inhibited growth and ethanol production. Yeast extract (0.5 g l(-1)) and trace metals were necessary for growth of C. ragsdalei. CSL alone did not support growth and ethanol production. Nutrients limiting in CSL were trace metals, NH(4) (+) and reducing agent (Cys: cysteine sulfide). Supplementation of trace metals, NH(4) (+) and CyS to CSL (20 g l(-1), wet weight basis) yielded better growth and similar ethanol production as compared to control medium. Using 10 g l(-1), the nutritional limitation led to reduced ethanol production. Higher concentrations of CSL (50 and 100 g l(-1)) were inhibitory for cell growth and ethanol production. The CSL could replace yeast extract, vitamins and minerals (excluding NH(4) (+)). The optimized CSL medium produced 120 and 50 mM of ethanol and acetate, respectively. The CSL could provide as an inexpensive source of most of the nutrients required for the syngas fermentation, and thus could improve the economics of ethanol production from biomass derived synthesis gas by C. ragsdalei.

Development of a cost-effective glucose-corn steep medium for production of butanol by Clostridium beijerinckii

Corn steep water (CSW) medium (1.6% solids plus 6% glucose) was evaluated for growth and butanol production by Clostridium beijerinckii NCIMB 8052 wild-type and hyper-amylolytic, hyper-butanol-producing mutant strain BA101. CSW alone was not a suitable substrate, whereas addition of glucose supported growth and butanol production by both strains. In a batch-scale fermentation using an optimized 6% glucose-1.6% solids CSW medium, C. beijerinckii NCIMB 8052 and strain BA101 produced 10.7 g L−1 and 14.5 g L−1 of butanol, respectively. The total solvents (acetone, butanol, and ethanol) produced by C. beijerinckii NCIMB 8052 and strain BA101 were 14 g L−1 and 20 g L−1, respectively. Initial fermentation in small-scale flasks containing 6% maltodextrin-1.6% solids concentration CSW medium resulted in 6 g L−1 and 12.6 g L−1 of butanol production by C. beijerinckii NCIMB 8052 and strain BA101, respectively. CSW can serve as an economic source of nitrogen, vitamins, amino acids, minerals, and other nutrients. Thus, it is feasible to use 6% glucose-1.6% solids CSW medium in place of semi-defined P2 medium.

Effect of mercury on the growth of wood-rotting basidiomycetes Pleurotus ostreatus, Pycnoporus cinnabarinus and Serpula lacrymans

Mercury inhibits the growth of six wood-rotting basidiomycetes in different ways. Growth rates on glucose-corn steep medium (0.1 mmol/L Hg) decreased to 6% of the control in Pleurotus ostreatus, 16% in Serpula lacrymans, 22% in Ganodema applanatum, 36% in Pycnoporus cinnabarinus, 67% in Daedalea quercina and 76% in Stereum hirsutum. The inhibition was higher in mineral than in complex medium. In Pycnoporus cinnabarinus, Hg caused changes in mycelial morphology and induced fruit body formation.

Role of Antibiotics Produced byChaetomium globosumin Biocontrol ofPythium ultimum,a Causal Agent of Damping-Off

Production of antifungal compounds by Chaetomium globosum and the role in suppression of Pythium damping-off of sugarbeet were evaluated. Two metabolites with antifungal activity against Pythium ultimum, 2-(buta-1,3-dienyl)-3-hydroxy-4-(penta-1,3-dienyl)-tetrahydrofuran (BHT) and the epidithiadiketopiperazine, chaetomin, were isolated from liquid cultures of C. globosum. BHT was produced in 1% malt extract medium by six of eight tested C. globosum strains, whereas chaetomin was produced in 1% corn steep medium by five of nine tested strains (...)

Inhibitory activities of some marine algae on aflatoxin accumulation

A study was conducted to determine the ability of five marine algae of the phaeophyta class, namely, Sargassum despiense, Turbinaria decurrense, Dilophus ligulatus, Cystoseira myrica and Padina pavonia, to act against mycelial growth and/or aflatoxin accumulation by a toxigenic strain of Aspergillus flavus, at different levels, in rice corn steep medium. Aflatoxins were quantitated both intra- and extracellularly. At the level of 20 gm/100 ml, the first three algal species were the most effective, reducing mould growth to about 22% and aflatoxin accumulation to 8.5–12% of control. The other two algae also reduced aflatoxin production by about 84%. The volatile oils of the three algae showed antifungal properties. Fortification of the medium with either fatty acids or unsaponifiable matter resulted in reducting aflatoxin formation to 11% and 25% respectively with milder effect on mould growth.

Aflatoxins: Production of the Toxins on Rice-Corn Steep Medium According to Some Cultural Conditions

Rice powder-corn steep (RC) medium proved to be the most suitable among 6 nutrient liquid media for both aflatoxin formation and mycelial growth by the Aspergillus flavus strain No. 182, isolated locally. The production of aflatoxins by the mould was studied in relation to some cultural conditions on RC medium. Highest aflatoxin yields (2527 microgram/50 ml) by A. flavus were attained using rice (5%, w/v) + corn steep (4%, w/v), at initial pH level of 4,25 degree C and 6 days incubation. The initial pH levels at either extreme of the range used (3 and 11), and temperatures of incubation below 20 degree C or above 40 degree C were inhibitory to mould growth and aflatoxin formation. The ratio of aflatoxin B1 to G1 varied with different cultural conditions. The aflatoxin content of the mycelia highly exceeded that of the culture filtrates.

Inhibition of aflatoxin formation by some spices.

The effects of black pepper, cinnamon, peppermint, cumin, ginger and clove on growth and aflatoxin formation of Aspergillus flavus were studied in rice powdercorn steep (RC) medium. The effects of the first five spices were judged to be inhibition of aflatoxin formation rather than of mycelial growth. Clove completely inhibited both mycelial growth and aflatoxin formation at a concentration above 0.1%. No aflatoxin was produced when cumin and mint levels of 5% and 10% were used. Black pepper and ginger levels of 10% decreased aflatoxin formation by 100%. Higher concentrations of cinnamon, mint, cumin and ginger stimulated mycelial growth.

Aflatoxins: production of the toxins on rice-corn steep medium according to different cultural conditions: Souhair S. Mabrouk and Nefisa M.A. El-Shayeb Laboratory of Natural Products, National Research Centre, Dokki, Cairo, Egypt

Aflatoxins: production of the toxins on rice-corn steep medium according to different cultural conditions: Souhair S. Mabrouk and Nefisa M.A. El-Shayeb Laboratory of Natural Products, National Research Centre, Dokki, Cairo, Egypt

STUDIES ON FUNGAL NEPHROTOXICITY

Nephrotoxic compounds were isolated from a strain of Penicillium viridicatum Westling. This strain was isolated from a batch of barley which by feeding caused a chronic kidney degeneration in pigs and rats. Liquid corn steep medium was inoculated and incubated as stationary culture. After fractionation of the liquid medium fractions and isolated compounds were perorally administered to rats during a period of 2–3 weeks. Two compounds were found nephrotoxic: Citrinin and oxalic acid. Oxalates cause in rats during a long‐term experiment a chronic kidney damage, characterized by dilated tubules, formation of cysts and connective tissue and crystals of calcium oxalate in the tubules. No nuclear alterations were observed. Citrinin‐induced kidney damage is characterized by enlarged kidneys. Degeneration of the proximal tubules in the form of hydropic degeneration, loss of brush border, and pyknotic nuclei are observed. These lesions are accompanied by thickening of the tubular basement membranes, activation of interstitial cells and formation of collagen. Some tubules are dilated into cysts. This kidney degeneration is comparable to the kidney damage in rats and pigs caused by feeding barley inoculated with P. viridicatum as well as by feeding the batch of barley from which the fungus was isolated. The kidney damage in pigs is comparable to the chronic kidney degeneration observed among Danish pigs fed mouldy feed. Thus it is assumed that the kidney degeneration naturally occurring among Danish pigs is a mycotoxicosis caused by citrinin, although a synergistic effect with other compounds may exist.

New procedures for purification of L-asparaginase with high yield from Escherichia coli.

l-Asparaginase is now known to be a potent antineoplastic agent in animals and has given complete remission in some human leukemias. Extensive clinical trials of this enzyme, however, were not possible in the past because of inadequate production of this substance. We have developed practical procedures for producing l-asparaginase in yields of sufficient quantity and purity for more extensive clinical evaluation. The nutritional requirements for optimal production of biologically active l-asparaginase by a strain of Escherichia coli have been ascertained. The highest yields of enzyme were obtained when cells were grown aerobically in a corn steep medium. Good enzyme production was associated with media containing l-glutamic acid, l-methionine, and lactic acid. The addition of glucose to the medium, however, resulted in depressed production of l-asparaginase. Sodium ion appeared to suppress l-asparaginase production. With the procedure described for isolation of biologically active l-asparaginase from E. coli, stable l-asparaginase preparations with a specific activity of 620 IU per mg of protein (1,240-fold purification with 40% total recovery) were obtained.

The influence of phosphorus on the development of Streptomyces aureofaciens and on its ability to produce chlortetracycline.

SUMMARY: Parallel physiological and cytological investigations of a chlortetra-cycline-producing culture—Streptomyces aureofaciens, strain 536—indicate some intracellular causes of the dependence of chlortetracycline biosynthesis upon the inorganic phosphorus content of the nutrient medium. Increase of inorganic phosphorus in the fermentation medium led to a formation of large nuclear elements containing much DNA (in corn steep medium) or ribonucleo-proteid complexes in the shape of large volutin granules (corn steep liquor ash medium). As compared with the control, the nuclear substance/cytoplasm ratio in the hyphae is increased. The ability of mycelium overloaded with nuclear elements or volutin granules for chlortetracycline biosynthesis is markedly decreased. The iufluence of phosphorus on the microscopical structure of mycelium and biosynthesis of antibiotic depends on the composition of medium. The poor quality of certain batches of corn steep liquor used for the production of chlortetracycline is largely due to their high content of inorganic phosphorus.

Production of Hydrocyanic Acid by Cultures of a Basidiomycete

(1950). Production of Hydrocyanic Acid by Cultures of a Basidiomycete. Mycologia: Vol. 42, No. 1, pp. 161-166.

A CASEIN DIGEST MEDIUM FOR TOXIN PRODUCTION BY CLOSTRIDIUM

A simplified casein digest–corn steep medium is described that lends itself to large scale use. The advantages stressed are: use of fresh or frozen pancreas as a source of trypsin, a digest that is readily clarified, the clarification of corn steep by steaming in alkaline solution. The product is a medium that supports good growth of many species of bacteria and in which Clostridium botulinum produces large and consistent yields of toxin.

YIELD OF BOTULINUM TOXIN IN CONCENTRATED MEDIA

In the preceding paper in this series it was shown that Type A Clostridium parabotulinum when grown under accurately controlled conditions on a casein digest – glucose – corn steep medium produced large and consistent yields of toxin. In this paper a modified procedure is described. Cultures were inoculated in the usual manner and incubated for 10 hr., or until growth reached the upper third of logarithmic increase. Concentrate of the same medium was then added by a continuous drip method for 18 to 60 hr., or until the concentration of the medium was doubled to quadrupled.Under these circumstances the organisms continued to increase for some 40 hr. while in the controls in unconcentrated media growth ceased at 18 to 20 hr. The yield of toxin was increased two to three times over the controls in unconcentrated media.