[Properties of the phospholipases C from Bacillus cereus]. / Nekotorye svoistva fosfolipaz C iz Bacillus cereus.

Three different phospholipases C--the so-called phospholipase C which hydrolyses phosphatidylcholine (Pch-PLC), sphingomyelinase (SM-PLC) and phosphatidylinositol hydrolysing phospholipase C (PI-PLC)--were separated from the culture filtrate of Bacillus cereus using column chromatography on DEAE-sephadex A-50. The pI values were estimated to be 5.0 +/- 0.3 for PI-PLC and 5.3 +/- 0.2 for SM-PLC. The effect of some bivalent cations was studied. Metal ions had no effect on the activity of PI-PLC, whereas Mg2+ and Co2+ in concentrations from 1 to 5 mM highly activated SM-PLC. Mg2+ failed to activate PCh-PLC, and Co2+ even inhibited it. EDTA of o-phenantroline had a rather inhibitory effect on Pch-PLC, but they almost did not affect SM-PLC.

[Biosynthesis of extracellular phospholipase C (lecithinase) from Bacillus cereus depending on the nutrient medium composition and pH]. / Binosintez vnekletochnoi fosfolipazy S (letsitinazy) Bacillus cereus v zavisimosti ot sostava pitatel'noi spedy i pH.

The nutrient medium to provide rapid growth of microbial cells of Bacillus cereus str. 504, and biosynthesis of extracellular phospholipase C(EC 3.1.4.3) was selected. The nutrient medium contained acidic casein hydrolyzate, yeast extract or enzymatic hydrolyzate of fodder yeast, glucose, NaCl, NaHCO3, and Na2HPO4. The activity of secreted phospholipase C reached maximum at pH 6.3--6.6.

[Purification of phospholipase C from Bacillus cereus by chromatography on aminoalkylpolysaccharide adsorbents]. / Khromatograficheskaia ochistka fosfolipazy s iz Bacillus cereus na aminoalkilpolisakharidnykh sorbentakh.

Purification of phospholipase C from Bac. cereus by chromatography on aminoalkylpolysaccharide adsorbents is described. The dependence of the degree of enzyme purification on the amount of ligant and effect of pH and buffer systems on the adsorption-desorption of phospholipase have been studied. At a pH below 9.0 phospholipase C is not retained by the adsorbents and is purified 4-5-fold and up to 23-fold, when aminoalkyl-Sepharose and hexamethylenediamine Sephadex are used respectively. With an increase in the pH value up to 10.0, the enzyme is bound by the adsorbent and is eluted with a 40-90% yield of activity and 7-10-fold purification. The resulting phospholipase C is highly purified and electrophoretically homogeneous. A mechanism of the enzyme-adsorbent interaction is discussed.

[Phospholipase of Bacillus cereus]. / Fosfolipaza Bacillus cereus

Phospholipase activity of 10 strains of Bacillus cereus was studied. The most active strain of Bac. cereus--phospholipase producer was selected. A cultivation mixture of Bac. cereus optimal for the phospholipase synthesis was found to include peptone, yeast extract, glucose, NaCl and Na2HPO4. Proper conditions for the synthesis of phospholipase in flasks, 20 l and 250 l fermenters were tested. The maximum increase of the phospholipase activity occurred by the 5-9th hour of microbial growth at pH 6.0-8.0. Further cultivation, foaming, strong aeration, pH increase (over 8.0) reduced the accumulated activity. By fractionation with (NH4)2SO4, ethanol precipitation, protamine sulphate treatment with subsequent Sephadex G-100 gel filtration phospholipase (EC 3.1.4.3) was purified 300-fold from the culture liquid of Bac. cereus str. 504. The preparation was examined electrophoretically in 7% polyacrylamide gel at alkaline pH. The effect of metal salts and EDTA on phospholipase activity was studied. Thermostability, substrate specificity and pH optimum of purified phospholipase were investigated.