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B K Ghosh

Publications and source records attributed to B K Ghosh.

At least 37 records · Page 2Linked to original sources
PubMed1977

Interrelationship of carbohydrate metabolism and alkaline phosphatase synthesis in Bacillus licheniformis 749/c.

Membrane-bound alkaline phosphatase of Bacillus licheniformis 749/c is derepressed by glucose in complex and chemically defined media. In the presence of lactate, pyruvate, or succinate the synthesis is repressed. The lactate repression neither affects total protein synthesis nor inhibits penicillinase synthesis. Thus, carbon sources specifically influence alkaline phosphatase synthesis. Although variations in the inorganic phosphate content of the growth media directly affect alkaline phosphatase synthesis, the intracellular inorganic and total phosphate pools appear to be unrelated to its repression or derepression. During lactate repression there is preferential incorporation of lactate molecules into glycogen, whereas no such incorporation could be detected from glucose. Net glycogen synthesis remains the same in glucose- or lactate-grown cells. It is postulated that, in phosphate-deficient growth medium, gluconeogenic metabolism regulates alkaline phosphatase synthesis.

Alkaline Phosphatase↗
PubMed1977

Process engineering studies on immobilized trypsin using molecular sieves as carriers.

In the present investigation molecular sieve has been found to be a suitable carrier for the immobilization of enzymes. From the present study it may be specifically found that trypsin and pappain can be immobilized by molecular sieve type 4a following a very simple techniqure. The immobilized enzyme can be used both in packed as well as in a continuous stirred tank reactor (CSTR).

Enzymes, Immobilized↗
PubMed1973

Abnormal cell envelope ultrastructure of a Saccharomyces mutant with invertase formation resistant to hexoses.

The most obvious morphological characteristic of Saccharomyces mutant FH4C cells is the tendency to form clumps (production of invertase and alpha-glucosidase by this mutant is highly resistant to repression by hexoses). This peculiar feature arises from the abnormal cell envelope ultrastructure of the mutant. Clumps are formed as a result of the failure of the cell wall of the bud to separate from that of the mother cell. The cell wall also shows irregular thickening. There are many cells with a doughnut shape and with small budlike protrusions. Abnormal septation and wall invagination into vacuoles give rise to cells of differing sizes and irregular profiles. Many vesicles, tubules, and coiled membranous bodies originate from invaginations of the plasmalemma. These structures are frequently observed in the cell wall or the periplasmic space. The cells of mutant FH4C growing in 0.2 M glucose, unlike parent strain 303-67, contain many mitochondria. Large numbers of glycogen deposits are also found in many cells of FH4C.

Cell Membrane↗
PubMed1971

Distribution of the sites of alkaline phosphatase(s) activity in vegetative cells of Bacillus subtilis.

Sites of alkaline phosphatase activity have been located by an electron microscopic histochemical (Gomori) technique in vegetative cells of a repressible strain SB15 of Bacillus subtilis, derepressed and repressed by inorganic phosphate, and in a mutant SB1004 which forms alkaline phosphatase in a medium high in phosphate. The sites of enzyme activity were revealed as discrete, dense, and largely spherical bodies of varying sizes (20 to 150 nm). Cells of both repressible and repression-resistant strains acted on a wide variety of phosphate esters (p-nitrophenylphosphate, beta-glycerophosphate, adenosine-5'-phosphate, glucose-6-phosphate, glucose-l-phosphate, adenosine triphosphate, and sodium pyrophosphate) to produce inorganic phosphorus under conditions of alkaline phosphatase assay [0.05 m tris(hydroxymethyl)aminomethane buffer (pH 8.4) containing 2 mm MgCl(2)]. The purified alkaline phosphatase also acted on all these esters, although much less effectively on adenosine triphosphate and sodium pyrophosphate than did the cells. Comparison of the relative utilization of the various substrates by repressed and derepressed cells and purified enzyme suggested the presence of multiple enzymes in the cells. Thus, the cytochemical method of trapping the newly generated inorganic phosphorus determines the location of an alkaline phosphatase of broad substrate profile, and in addition locates the sites of other enzymes generating inorganic phosphorus under identical conditions of assay. It is intriguing that all of these enzymes usually exist in a few clusters attached to the peripheral plasma membrane. In addition to this predominant location, there were a few sites of enzyme activity in the cytoplasm unattached to any discernible structure, and also in the cell wall of the repression-resistant and of the derepressed, repressible strains.

Alkaline Phosphatase↗
PubMed1969

Periplasmic structure of frozen-etched and negatively stained cells of Bacillus licheniformis as correlated with penicillinase formation.

Bacillus licheniformis strain 749/C (constitutive for penicillinase formation) and uninduced cells of strain 749 (penicillinase-inducible) were examined after freezeetching. In the early stationary phase, strain 749/C organisms had clusters of vesicles (30 to 40 nm in diameter) on the outer surface of the plasma membrane. These are randomly distributed on the membrane, including the region of septum formation. The vesicles are not intimately associated with the plasma membrane, and their inner and outer surfaces are devoid of particles. Periplasmic vesicles were not detected by freeze-etching in strain 749 (uninduced) or in young cells of 749/C; however, the membrane of mid-logarithmic phase 749/C cells had a corrugated appearance. Negatively stained 749/C cells (logarithmic phase) also showed many vesicular and tubular bodies in the periplasm as well as septal and cytoplasmic mesosomes of typical morphology. The periplasmic structures appear to be formed either by evagination of plasma membrane or by migration of vesicular bodies from the membranous pockets of the cytoplasm. Stationary phase cells of 749/C still have many periplasmic vesicular bodies; however, the mesosomes are greatly reduced both in number and size. In sharp contrast, strain 749 organisms have very few structures similar to the periplasmic bodies of strain 749/C. These findings support our previous view that penicillinase-producing cells of 749/C have periplasmic membranous structures that are rare in the uninduced strain 749, though there is some lack of correspondence between freeze-etching, negative staining, and thin section data. These structures may be important for the retention or storage of penicillinase in the cell.

Bacillus↗
PubMed1969

Fractionation and characterization of the plasma and mesosome membrane of Listeria monocytogenes.

Protoplasts of Listeria monocytogenes strain 42 were fractionated after control lysis on a Ficoll (a polysucrose) density gradient. Visually, five zones could be recognized in the gradient. The first one was composed of amorphous cytoplasmic solutes (fraction 1a) and a mixture of particles (fraction 1b). These were: (i) light particles that were lipase-sensitive and composed of six subunits and (ii) heavy particles, sensitive to ribonuclease and devoid of fine structure. The second zone consisted of tubules and vesicles still harboring cytoplasmic components (fraction 2), whereas the third zone contained only empty vesicles and protoplast ghosts (fraction 3). The material congregating into the fourth zone was morphologically identical to that of the third (fraction 3a). The fifth and heaviest zone contained a mixture of (i) particles without any substructure and (ii) partly lysed protoplasts (fraction 4). Fractions 1b and 4 were the richest in nucleic acids (ribonucleic acid, 11.4 and 9.4%, respectively; deoxyribonucleic acid, 5.1 and 4.8%, respectively), whereas fraction 1b had the highest protein contents (74.6%). Phospholipids were mainly found in fractions 2 and 3. Except for fraction 1, all materials contained significant amounts of protein-bound phosphorus. The main concentrations of four enzymes were: glucose-6-phosphate dehydrogenase (fraction 1a); adenosine triphosphatase and reduced nicotinamide adenine diphosphate oxidase (fraction 3); nitro blue tetrazolium chloride reductase (fraction 2). Fractionation of strain 42 after addition of (32)P during the mid-log phase of growth revealed that the radio-activity was mainly detected in fraction 1b, when growth in the presence of the marker was allowed for 10 min, and in fraction 2, when growth was allowed for 90 min. The vesicles of fraction 2, often tubular, are probably of mesosomal origin, whereas those of fraction 3, which are always spherical, represent, most likely, the bulk of the cell plasma membrane. Our data showed slight chemical differences between these two fractions, but the differences in enzymatic activities and lipid-phosphorus incorporation during long pulse experiments were most dramatic.

Adenosine Triphosphatases↗
PubMed1969

Characteristics of penicillinase secretion by growing cells and protoplasts of Bacillus licheniformis.

Cultures of the inducible penicillinase-producing strain 749 of Bacillus licheniformis, induced with small amounts of benzylpenicillin, synthesized penicillinase at a high rate for a short period, after which the rate of synthesis slowly declined. During the period of active synthesis, the rate of secretion, as a fraction of the level of cell-bound penicillinase (which is originally high), gradually decreased to a constant level. Chloramphenicol, at a concentration (40 mug/ml) which completely inhibited synthesis of penicillinase, partially inhibited secretion if added during the period of active synthesis. During the phase of reduced synthesis, chloramphenicol was without effect on secretion. Penicillinase secretion, by actively growing cultures of the constitutive penicillinase-producing mutant 749/C, was inhibited by 75% immediately after addition of chloramphenicol. The secretion of part of the penicillinase released during active growth is probably dependent on synthesis of penicillinase, but part of the secreted penicillinase can be released in the absence of synthesis. Protoplasts were obtained from which periplasmic penicillinase has been removed, and these protoplasts were capable of substantial growth and penicillinase synthesis without lysis. At pH 7.5, there was no net incorporation of penicillinase into the cell membrane; the enzyme released was almost entirely of the exo form and was roughly equivalent to the amount of new enzyme formed. At pH 6.0, there was some incorporation of penicillinase into the plasma membrane, and approximately half of the extracellular penicillinase was in the exo form; the remainder perhaps represented membrane fragments. In the presence of chloramphenicol, a small amount of penicillinase was released at pH 7.5 as the exo form; at pH 6.0, practically none was released. We suggest that, with the removal from protoplasts of the periplasmic penicillinase-containing particles, a restriction on secretion has been lifted.

Bacillus↗