Four kinds of electrophoresis were used to characterize enzymes in 11 isolates from six species in the genus Pleurotus (Fr.) Quel: Pleurotusostreatus, P. pulmonarius, P. spodoleucus, P. salmoneostramineus, P. cornucopiae, and P. cystidiosus. They were agarose isoelectric focusing (IEF), polyacrylamide IEF, 7.5% polyacrylamide gel electrophoresis (PAGE) and 4-15% gradient PAGE. Ultimately, the 4-15% polyacrylamide gel-slab electrophoresis was found to be most suitable for our study in numerically analyzing the patterns of seven enzymes. The enzymes were 6-phosphogluconate dehydrogenase (EC 184.108.40.206 6PGDH), malate dehydrogenase (EC 220.127.116.11 MDH), lactate dehydrogenase (EC 18.104.22.168 LDH), glutamate dehydrogenase (EC 22.214.171.124 GDH), glucose-6-phosphate dehydrogenase (EC 126.96.36.199 G6PDH), alcohol dehydrogenase (EC 188.8.131.52 ADH), and esterase (EC 184.108.40.206 Est). The isolates were compared by using an index of similarity (Sm) based on relative mobilities (Rm) of the enzyme bands. By this method, the isolates were reasonably grouped as species. Based on the Sm values, as well as intercompatibilities and morphological characters, the relationships between P. ostreatus, P. spodoleucus and P. pulmonarius were analyzed.
The potential of strains of Rhizobium and Bradyrhizobium to solubilize rock phosphate was evaluated in vitro. Almost all organisms tested effectively solubilized rock phosphate and lowered the medium pH. The presence or absence of (NH4)2SO4 made little difference in the solubilization of rock phosphate. Among the strains, Rhizobium leguminosarum biovar viceae BICC635 was the most effective solubilizer. Maximum solubilization of phosphate and acid production was achieved after 3 days of incubation. The strain produced 2-ketogluconic acid in the culture medium, the primary cause of rock phosphate solubilization. Increasing the phosphate status of the medium had little effect on the extent of dissolution of Purulia rock phosphate. Adding calcium as CaCl2, CaCO3 and Ca(OH)2 reduced the phosphate solubilization from phosphate rocks. The results indicated that pH, per se, is of less importance in phosphate solubilization. EDTA increased the extent of rock phosphate solubilization, possibly by chelation of the calcium ions that the solubilization produced.
Cells of the psychrotrophic Pseudomonas species grown and ‘aged’ at 20°C in the nonpermissive medium Boylen and Brock broth then inoculated into the permissive medium half-strength. Trypticase Soy broth produced no exopolymer at 10°C, a minimal amount at 15°C, a maximal amount at 25°C, and a reduced amount at 30°C. Cells grown and aged at 10°C, produced exopolymer at 20°C but not at 10°C. Cells grown and aged at 5°C, produced no exopolymer at 5°C, but produced exopolymer at 20°C when the aging period was increased from 48 to 72h. The accumulation of potential for exopolymer production during the aging period was affected by temperature; it occurred when buffer or saline were substituted for spent medium, and in the ‘packed’ cell condition; it was affected by pH; and it did not involve the selection of cells capable of exopolymer production. Exopolymer-producing cells assimilated considerably more 14C-glucose than nonexopolymer-producing cells even though growth rates and total cell yields were the same. All of the carbon sources tested promoted growth and exopolymer production by suitably aged cells.
The stimulative effect of tricarboxylic acid (TCA) cycle intermediates on the acetic acid production of Acetobacter aceti M23 was investigated in batch and continuous cultures. Cell growth was hardly affected by the supplement of the TCA cycle intermediates; however, the acetic acid production rate in a continuous culture at the dilution rate of 0.097h-1 increased 3.2 times in the medium supplemented with 2mM citric acid. The optimum concentration of citric acid as an additive in the medium was 10mM. Acetic acid production was enhanced by adding citric acid only when there was an insufficient supply of oxygen.
The rate of lactic acid production by Lactobacillus delbrueckii strain YPX was greatly improved by converting the acid to Na-lactate and continuously removing the salt from the fermentation broth with an electrodialyzer. The fermentation using glucose (85gl-1) as a raw material was completed in 9.9h and the lactic acid concentration in the permeate compartment reached 90gl-1. The average production rate was 8.7gl-1 h-1, which was 12 times higher than that of the fermentation with direct electrodialysis of the lactic acid produced. The phosphate ions in the culture broth were electrodialyzed simultaneously with the lactate ions which caused a decrease in the fermentation rate in some cases.
A restriction endonuclease, designated ApaORI, was purified from cellfree extracts of A. pasteurianus IFO 13752 by streptomycin treatment, ammonium sulfate fractionation, phosphocellulose treatment, hydroxylapatite and heparin-Sepharose CL-6B column chromatography, and gel filtration using a Superose 12 (HR10/30) column. The purified enzyme was homogeneous on polyacrylamide gel disc electrophoresis. The molecular weight of the purified enzyme was found by gel filtration to be 21, 000 daltons. The isoelectric point of the purified enzyme was neutral (6.9). The purified enzyme cleaved λ, φX174 RF I, M13mp7 RF I, and pBR322 DNAs at 18 or more, 2, 4 or more, and 4 or more sites, respectively. The purified enzyme worked best at 37°C and pH 7.5 in a reaction mixture (50μl) containing 1.0μg λDNA, 10mM Tris-HCl, 7mM 2-mercaptoethanol, 7mM MgCl2, and 50mM NaCl. However, the purified enzyme did not require NaCl for its reaction. The purified enzyme recognizes the palindromic pentanucleotides 5′-CC (AorT)GG-3′ and cuts between C and A (or T), producing 5′-cohesive mononucleotide extensions (isoschizomer of BstNI).
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