Paul A. Hartman

Extracellular Maltase of Bacillus brevis.

Bacillus brevis NRRL B-4389 produced extracellular maltase (alpha-glucosidase; EC 3.2.1.20) only in the presence of short alpha-1,4-glucosidic polymers, such as maltose and maltotriose. An optimum medium was developed; it contained 2.5% maltose, 0.5% nonfat dry milk, 0.4% yeast extract, and 0.01% CaCl(2). The enzyme was produced extracellularly during the logarithmic phase of growth; no cell-bound activity was detected at any time. Partial purification of the maltase was accomplished by using diethylaminoethyl cellulose batch adsorption, ammonium sulfate precipitation, and Sephadex G-200 gel filtration. Maltase, isomaltase (oligo-1,6-glucosidase), and glucosyltransferase activities were purified 20.0-, 19.1-, and 11.5-fold, respectively. Some properties of the partially purified maltase were determined: optimum pH, 6.5; optimum temperature, 48 to 50 degrees C; pH stability range, 5.0 to 7.0; temperature stability range, 0 to 50 degrees C; isoelectric point, pH 5.2; and molecular weight, 52,000. The relative rates of hydrolysis of maltose (G(2)), maltotriose (G(3)), G(4), methyl-alpha-d-maltoside, G(40), dextrin, and isomaltose were 100, 22, 12, 10, 10, 8, and 5%, respectively; the K(m) on maltose was 5.8 mM; d-glucose, p-nitrophenyl-alpha-d-glucoside, and tris (hydroxymethyl) aminomethane were competitive inhibitors; transglucosylase activity of the enzyme on maltose resulted in the synthesis of isomaltose, isomaltotroise, and larger oligosaccharides.

Bacillus stearothermophilus. II. Certain factors affecting amylase production on some undefined media.

We report on the effects of RF/MW on plants. Green Mint plant exposed to different levels of radiation (from 0.5 to 10.5 μW/cm 2 ) for this purpose. A USB2000 spectrophotometer was used to record fluorescence signals from intact leaves. Spectroscopic data (P.I.R and A.R) together with vegetative data (leaf dimensions and weight), revealed stressing effects on plant due to RF/MW in all groups except the control which was free of exposure. .

Coliform Analyses at 30 C1

The literature directly pertinent to coliform analyses at 30 C was reviewed. Original data were presented on effects of time of incubation of violet red bile (VRB) agar plates at 30 C and the effects of autoclave-sterilization and storage of VRB agar. When boiled VRB agar was used, an incubation period of at least 24 h was required for dairy products; an incubation period of 48 h was required for water, frozen vegetables, and other materials that contained coliforms that were slow in growth initiation. Additional observations should be made after incubation of plates for another 24 h to discover if substantial increases in colony count occurred. If autoclave-sterilized VRB agar was used, the recommended incubation periods should be extended for an additional 12–24 h. The pH of prepared VRB agar should be 7.2. A pH of 6.9 or below was indicative of extensive flaws in the method of preparation and/or storage. although some deterioration occurred in the absence of marked pH changes.