Summary1. A histochemical method has been applied to the detection of alkaline and acid phosphatase mutants in single colonies of Aspergillus nidulans.2. With the above method it has been possible to isolate mutants in which the alkaline and acid phosphatase activities are affected either separately or simultaneously.3. Crude extracts of wild-type A. nidulans contain four electrophoretically distinct phosphatase components, two with activity at alkaline pH and two with activity at acid pH. Genes affecting three of the four components have been identified.4. Two suppressor mutants of an alkaline phosphataseless mutant (palB7) have been isolated. In a strain carrying palB7 and one of these suppressors, the restoration of an alkaline phosphatase component is accompanied by loss of the faster acid phosphatase component. In a similar strain carrying the other suppressor, the partial restoration of the alkaline phosphatase component goes with an electrophoretic alteration of the slower acid phosphatase component.5. Genetic analysis of twenty-seven mutants has resulted in the identification of fifteen loci affecting the phosphatases. All these loci have been assigned to linkage groups, and twelve of them were also mapped meiotically in relation to other loci.6. One possible model (based on heteropolymeric proteins) has been proposed to account for the electrophoretic and genetic data on the various phosphatase and suppressor mutations.

Three mutants at three different phosphatase loci produce inactive enzymes at 35 degrees C but partially or fully active enzynmes at 25 degrees C. Furthermore, a suppressor mutant (su5palA1) which restores alkaline phosphatase activity in the palA1 mtutant is an allele of palcC4, a mzutant with a simultaneous reduction in alkaline and acid phosphatase activity. These data suggest that the phosphataseproteins may be made up of two or more different polypeptide chains, and that some of the polypeptide chains are common to two or more of these enzymes.

The nutritional requirements and culture conditions affecting biosynthesis of L-asparaginase in a mutant ofEscherichia coli HAP designated strain A-1 were studied. Asparaginase activity was increased by the addition of L-glutamic acid, L-glutamine, or commercial-grade monosodium glutamate. The rate of enzyme synthesis was dependent on the interaction between the pH of the culture and the amount of oxygen dissolved in the medium. A critical oxygen transfer rate essential for asparaginase formation was identified, and a fermentation procedure is described in which enzyme synthesis is controlled by aeration rate. Enhancement of L-asparaginase activity by monosodium glutamate was inhibited by the presence of glucose, culture pH, chloramphenicol, and oxygen dissolved in the fermentation medium.

SOC, a fungal growth medium composed of Solryth, oxgall, and caffeic acid, was evaluated as a medium to provide rapid, differential identification of Candida albicans and Cryptococcus neoformans. Using a variety of common isolation media to produce the yeast inocula, the germ tube methods tested ranked in the following order of decreasing sensitivity: SOC (97% +/- 1), serum (92% +/- 5), rabbit coagulase plasma with EDTA in combination with tryptic soy broth (89% +/- 5), TOC (89% +/- 6), and rabbit coagulase plasma with EDTA (83% +/- 4). In chlamydospore production, SOC also proved to be the most sensitive after 24 h incubation: SOC (96% +/- 2), TOC (80% +/- 2), and cornmeal-Tween 80 agar (14% +/- 3). Other medically important yeasts showed normal patterns of growth within 24 h on SOC, thus assisting in their identification. Eighty strains of Cryptococcus neoformans showed characteristic brown pigmentation on SOC and TOC within 18 h, while all other species of the genus Cryptococcus and 229 Candida isolates did not show a change in pigmentation.

In order to improve the isolation and identification of yeasts in a cancer research hospital, a protocol was developed utilizing an improved blood culture methodology and a four-test schema for rapid yeast identification. The blood culturing technique, based upon centrifugation, has shown a ten-fold increase in isolation of fungi from blood and has provided for: quantitation or organisms, unlimited selection of media and atmospheres for primary culturing, and a 1:200 dilution of microorganisms away from serum antimicrobial factors and antibiotics. The four-test schema, which may be adapted for the identification of any unknown yeast in pure culture, consists of a dye pour plate auxanogram (DPPA), Tween 80-Oxgall-Caffeic acid (TOC), a rapid nitrate-reductase test (swab test) and Urea 'R' Broth. Using this protocol, over 95% of the clinical isolates received were correctly identified within 24 hours and 100% by 48 hours. By using DPPA, a 14 sugar assimilation pattern for each isolate was determined within 12 to 16 hours; and in some cases, as little as 6 hours. Growth on TOC yielded one of the following results: (1) Candida albicans and Candida stellatoidea sequentially produced germ tubes and chlamydospores in 3 hours and 24 hours, respectively; (2) Cryptococcus neoformans produced a brown pigment specific for its identification in 12 hours or less. The swab test gave results on nitrate utilization in less than 15 minutes and urease was detected within 4 hours.