Partial characterization of anEscherichia coll strain harboring a xylanase encoding plasmid

Summary The plasmid pRH271, harboring a xylanase gene cioned fromBacilius subtilis, has been transferred into a mutant ofE. coli SK2284 which allowed the release of part of the xylanase in the culture supernatant. Kinetic parameters of this recombinantE. coll strain were determined in microscale batch culture with and without the selective pressure of antibiotics. No significant difference in µ_max was observed for the nontransformedE. coli strain when compared to the recombinant strain. However, K₅ values for glucose were two times higher in the case of the recombinant strain. Preliminary study of xylanase production in a large batch farmenter was also described.     

Recovery of megakaryocyte thromboxane production in vitro after aspirin inhibition

Megakaryocytes isolated in high purity from guinea pigs produced thromboxane B₂ in response to exogenously provided arachidonic acid. This production was inhibited by in vitro treatment with acetylsalicylic acid with a concentration response relationship similar to that seen in platelets. During in vitro culture, the aspirin-treated megakaryocytes recovered thromboxane synthetic ability. Following a lag of 12 hours, recovery of megakaryocyte thromboxane production resumed at a rate of 16% of control per day. This recovery was inhibited by the addition of cycloheximide to the culture medium.     

The effect of the H2 partial pressure on the metabolite pattern ofLactobacillus casei,Escherichia coli andClostridium butyricum

Summary The metabolite pattern of batch cultures ofLactobacillus casei LMG 6400,Clostridium butyricum LMG 1213t1 andEscherichia coli LMG 2093 was effected only for the latter organism when the H₂ partial pressure was below 1 atmosphere: high hydrogen partial pressures increased the formate formation, low pressures gave rise to increased acetate production and higher cell yields.     

Influence of woodsmoke on aflatoxin production by Aspergillus flavus

Summary Woodsmoke delayed aflatoxius B₁ and G₁ release and significantly exerted inhibitory effects on the toxins production by a toxigenic Asperigillus flavus. The fungistatic efficiency of the woodsmoke increased with reduced moisture content in fish.     

Hypoxia enhances prostaglandin synthesis in renal mesangial cell cultures

In view of recent findings which suggest that renal prostaglandins mediate the effect of hypoxia on erythropoietin production, we have studied whether hypoxia is a stimulus for in vitro prostaglandin synthesis. Studies were carried out in rat renal mesangial cell cultures which produce erythropoietin in an oxygen-dependent manner. Production rates of PGE₂ and in specified samples also of 6-keto-PGF_1α, as a measure of PGI₂, and PGF_2α were determined by radioimmunoassay after incubation at either 20% O₂ (normoxic) or 2% O₂ (hypoxic) in gas permeable dishes for 24 hrs. Considerable variation in PGE₂ production was noted among independent cell lines. PGE₂ production appeared to be inversely correlated to the cellular density of the cultures. In addition, PGE₂ production was enhanced in hypoxic cell cultures. The mean increase was 50 to 60%. PGF_2α and 6-keto-PGF_1α increased by about the same rate. These results indicate that hypoxia is a stimulus for in vitro prostaglandin production.     

Production of cloned carboxypeptidase G2 by Escherichia coli: Genetic and environmental considerations

Summary The optimum production of cloned carboxypeptidase G₂ from plasmid pNM21 byEscherichia coli was found to be strongly strain- and temperature-dependent. The superior host was strain RV308 and the preferred growth temperature 28°C. Copy number, which decreased during exponential growth of all strains examined, did not relate in these studies to the level of enzyme production: the strain with the highest enzyme yield also having the lowest overall copy number.     

Exogenous hormone applications at pollination for in vitro and in vivo production of cotton interspecific hybrids

Interspecific hybridization of cotton (Gossypium) has been assisted by ovule and embryo culture. These culture methods were compared to exogenous hormone applications for efficient plant production from crosses between Upland cotton, G. hirsutum L., as the maternal parent, and various diploid and tetraploid wild species as the pollen donor. The best exogenous hormone treatment resulted in an average production of five seeds per boll and 4% boll abscission. Generally, exogenous hormones used with standard hybridization techniques were superior to in vitro methods, but for some crosses, embryo culture following hormone applications was warranted.Abbreviations GA gibberellic acid, >90% A₃ - NAA 1-naphthaleneacetic acid - NOA 2-naphthoxyacetic acid.     

CH4 production from H2 and CO2 byMethanobacterium thermoautotrophicum cells fixed on hollow fibers

Summary Methane was produced from H₂ and CO₂ byMethanobacterium thermoautotrophicum cells fixed on the surface of hollow fibers. The mineral solution permeated through the inside of fibers was consumed by the cells, while the gaseous substrate flowing outside the fibers was directly metabolized to methane. Methane production was proportional to hollow fiber length i.e., contact area between cell layer and gas phase. In repeated batch cultures, the production rates of methane and cell mass were 33.1 L/L reactor/day and 1.75 g cells/L reactor/day, respectively with 90% conversion rate.     

Ecological fish production in the inland delta of the Middle Danube, a floodplain river

Synopsis Ecological fish production in one parapotamal arm of the Middle Danube inland delta in Slovakia, based on 10 samplings during 5 consecutive years, ranged from 349 to 3272 (bar|x = 1066) kg ha^–1 in total production (P_T) and from 39 to 662 (bar|x = 204) kg ha^–1 in available production (P_A). Young-of-the-year fish made up an estimated 49–62% (bar|x = 54) of the P_T. According to the food production/food consumption budget calculated by three different methods, less than half of the P_T is of autochthonous origin, while most is from other sources. Floodplain fish production includes two components: fish originating within the floodplain and fish that are temporary immigrants. The latter component varies considerably in response to the hydrological regime. To assess the P_T in riverine ecosystems, different seasons and years are needed to give realistic values.This paper is dedicated to my friend and sometime co-worker, Eugene K. Balon, at the occasion of his 65th birthday and transition to University Professor Emeritus. He was one of the first ichthyologists to undertake quantitative studies in large rivers in the late 1950's, when most fish biologists thought that fishes inhabit only the sea, lakes, reservoirs and small streams.     

The effect of various atmospheric conditions on the 2,3-butanediol fermentation from glucose byBacillus polymyxa

The examination of the effect of N₂, air and O₂ on the glucose to 2,3-butanediol fermentation byBacillus polymyxa showed that N₂ sparging resulted in best 2,3-butanediol production at low yeast extract concentration (0.5%, w/v) whereas aeration produced best results with high yeast extract levels (1.2%, w/v). However, under all atmospheric conditions, improvements in rates and yields of 2,3-butanediol production and rates of glucose utilization were observed with high yeast extract. Regardless of the yeast extract levels, highest concentrations of ethanol and acetoin were obtained with N₂ sparging and aeration respectively. No acetoin accumulated under anaerobic (N₂) conditions and no ethanol accumulated with aeration. The rate of glucose utilization, in all fermentations, was highest under N₂ and lowest with O₂ sparging. In addition to the biochemical results, morphological observations with O₂, N₂ and air sparging are also reported.NRCC No. 23868     

Studies on themodulation of immunoglobulin production by prostaglandins

The present study investigated the effect of prostaglandins (PG) on the in vitro production of polyclonal IgG and IgM by pokeweed mitogen- stimulated normal human peripheral mononuclear cells. Concentrations of PGE₁ and PGA₁ in excess of 10⁻⁶M were suppressive. PGE₂ and PGs of the F series were less effective and significant suppression was seen in concentrations greater than 10⁻³M. Indomethacin added to cell cultures did not enhance Ig production. This discrepancy between physiologic PG concentrations and the very large pharmacologic concentration necessary to suppress Ig synthesis in vitro makes the physiologic role of PG in the modulation of Ig synthesis questionable.     

Production of L-DOPA from cell suspension culture of Mucuna pruriens f. pruriens

Summary Production of L-DOPA was studied in cell suspension culture of Mucuna pruriens f. pruriens. Suspension culture was established in MSI medium composed of half concentration of Murashige and Skoog's salts and 2% sucrose. A two-stage cell suspension culture was developed for enhanced accumulation of L-DOPA. In the first stage, the culture system was composed of MSI medium without CaCl, which was suitable for cell growth and in the second stage MSI medium containing 42.5 mg.l^–1 KH₂PO₄ and 4% sucrose favoured L-DOPA production. A discernible higher production of L-DOPA was obtained in this two-stage cell suspension culture in comparison to single stage culture.     

Prostaglandin-induced enhancement of the in vitro anamenstic response

The ability of various prostaglandins (PGs) to affect the in vitro anamnestic immune response of keyhole limpet hemocyanin (KLH)-primed rabbit popliteal lymph node cells was investigated. Of the four PGs studied (PGA₁, PGE₂ and PGF_2α), PGE₁ was found to have a stimulatory effect, whereas PGA₁, PGE₂ and PGF_2α were ineffective in stimulating or inhibiting the in vitro anamnestic response. Under the conditions studied, a 3.5-fold increase in antibody production was obtained in PGE₁-treated, KLH-stimulated cultures. Maximum enhancement was obtained when 0.2 μg of PGE₁ were added at the time of culture initiation and were allowed to remain in contact with the lymph node cells for 24 hours.     

Production of 2,3-butanediol from HF-hydrolyzed aspen wood

Hydrolyzates from hydrogen fluoride (HF) treated aspenwood were predominantly composed of oligosaccharides which are not readily utilized by Klebsiella pneumoniae. Attempts at further hydrolyzing these oligosaccharides using a variety of glycolytic and xylanolytic enzymes (i.e., amylases, cellulases, and xylanases) were only partially successful. When a post-hydrolysis step was carried out using 3% H₂SO₄, significant amounts of the component monosaccharides were detected. Sugars released by acid or enzymatic hydrolysis of the HF treated aspenwood were utilized by K. pneumoniae for the production of butanediol and ethanol.     

Effect of calcium chloride on the growth and ethanol production by free cells of Zymomonas mobilis

Summary The effect of calcium chloride concentration on the growth rate and ethanol production using free cells of Zymomonas mobilis was studied. There was no appreciable change in rates of cell mass production and ethanol formation in the medium containing upto 2g/L CaCl₂. On further increase in CaCl₂ concentration, the rates started decreasing. However, the ethanol yield decreased and biomass yield increased with increase in CaCl₂ concentration.     

Effect of calcium and sodium salts on ethanol production in high sugar fermentation by free cells ofZymomonas mobilis

Summary Addition of calcium carbonate enhanced ethanol production byZymomonas mobilis ZM4 and a mutant (ZMI₂), especially at higher concentrations (200–400 g/L) of glucose and sucrose, as well as at higher temperature (42°C) by the mutant. Calcium and sodium carbonates neutralized the acid produced in the medium and enhanced the ethanol production. The Na salts were less effective in the parent strain and were not favourable for the mutant. Ca²⁺ ions played a direct role in augmenting ethanol production as evidenced by the effect of calcium chloride at controlled pH (5.5).     

Morphology of Penicillium chrysogenum strains immobilized in calcium alginate beads and used in penicillin fermentation

Summary The morphology of two strains of Penicillium chrysogenum immobilized in calcium alginate and used in penicillin fermentation was examined. The degree and distribution of mycelial growth inside and on the surface of the beads depended on the strain, the cultivation media and the fermentation time. P. chrysogenum ATCC 12690 developed as a mycelial network inside the beads. The growth tendency of P. chrysogenum S₁ in micropellets was directed to the outer surface of the beads. At the end of the production phase only a trace of mycelia and no micropellets in the center of alginate beads were observed, while the outer surface and the subsurface were completely covered with mycelia.     

A new medium for growth and delta-endotoxin production by Bacillus thuringiensis var. kurstaki

Summary The influence of composition of media used for growth and delta-endotoxin production by B. thuringiensis var. kurstaki was studied with the idea of finding a cheap medium for attaining high yields of spore-crystal preparations. A new medium, based on malt sprouts is proposed. Data on growth and bioinsecticidal activity are given. A concentration of 2.1 × 10⁹ spores.ml^-1 was attained in a 48 h process. The spore-crystal preparations obtained present a LC₅₀ of 2.18 × 10⁸ spores.g^-1 against larvae of Galleria mellonella.     

Stereochemistry of naturally-occurring 25-hydroxyvitamin D3-26,23 lactone as determined by radioligand binding analysis and high-performance liquid chromatography

The four stereoisomers of 25-hydroxyvitamin D₃-26,23 lactone (25-OHD₃-26,23 lactone) were tested against in vivo 25-OHD₃-26,23 lactone to determine their relative competition in the radioligand binding assays for 25-OHD₃ and 1,25-(OH)₂D₃. The 25R-OHD₃-26,23S lactone and in vivo 25-OHD₃-26,23 lactone behaved identically in the radioligand binding assay for 25-OHD₃ and were ～5-fold more potent than 25-OHD₃ at displacing 25-OH[³H]D₃. The 25S-OHD₃-26,23S lactone was the poorest competitor in this assay, requiring a 10-fold excess relative to 25-OHD₃ to displace 50% of the 25-OH[³H]D₃. The order of competition in the 25-OHD₃ radioligand binding assay was 25R-OHD₃-26,23S lactone = in vivo 25-OHD₃-26,23 lactone ? 25S-OHD₃-26,23R lactone > 25-OHD₃ ? 25R-OHD₃-26,23R lactone > 25S-OHD₃-26,23S lactone. The order of competition in the 1,25-(OH)₂D₃ cytosol receptor assay was essentially reversed from the competition in the 25-OHD₃ assay and was 25S-OHD₃-26,23S lactone > 25-OHD₃ ? 25S-OHD₃-26,23R lactone > 25R-OHD₃-26,23S lactone = in vivo 25-OHD₃-26,23 lactone. When tested in a high-performance liquid chromatographic system which separates all four stereoisomers, the in vivo 25-OHD₃-26,23 lactone comigrated with synthetic 25R-OHD₃-26,23S lactone. These data firmly establish that the naturally-occurring 25-OHD₃-26,23 lactone has the 25R, 23S stereochemistry. In addition, these data are the first to demonstrate that the four stereoisomers of 25-OHD₃-26,23 lactone have different affinities for the plasma vitamin D binding protein and the 1,25-(OH)₂D cytosol receptor.