Expression of the Aspergillus niger glucose oxidase gene in Saccharomyces cerevisiae and its potential applications in wine production.

There is a growing consumer demand for wines containing lower levels of alcohol and chemical preservatives. The objectives of this study were to express the Aspergillus niger gene encoding a glucose oxidase (GOX; beta- d-glucose:oxygen oxidoreductase, EC 1.1.3.4) in Saccharomyces cerevisiae and to evaluate the transformants for lower alcohol production and inhibition of wine spoilage organisms, such as acetic acid bacteria and lactic acid bacteria, during fermentation. The A. niger structural glucose oxidase (gox) gene was cloned into an integration vector (YIp5) containing the yeast mating pheromone alpha-factor secretion signal (MFalpha1(S)) and the phosphoglycerate-kinase-1 gene promoter (PGK1(P)) and terminator (PGK1(T)). The PGK1(P)- MFalpha1(S)- gox- PGK1(T) cassette (designated GOX1) was introduced into a laboratory strain (Sigma1278) of S. cerevisiae. Yeast transformants were analysed for the production of biologically active glucose oxidase on selective agar plates and in liquid assays. The results indicated that the recombinant glucose oxidase was active and was produced beginning early in the exponential growth phase, leading to a stable level in the stationary phase. The yeast transformants also displayed antimicrobial activity in a plate assay against lactic acid bacteria and acetic acid bacteria. This might be explained by the fact that a final product of the GOX enzymatic reaction is hydrogen peroxide, a known antimicrobial agent. Microvinification with the laboratory yeast transformants resulted in wines containing 1.8-2.0% less alcohol. This was probably due to the production of d-glucono-delta-lactone and gluconic acid from glucose by GOX. These results pave the way for the development of wine yeast starter culture strains for the production of wine with reduced levels of chemical preservatives and alcohol.

Clinical significance of aero-allergen identification in the western Cape.

Positive identification and documentation of the seasonal variation of aero-allergens and the immune responses to them has important implications for the timing of allergen avoidance measures and the selection of patients suitable for immunotherapy. The relative abundance of aero-allergens in the Cape Peninsula during 1984-1987 was measured by continuous volumetric air sampling, using a Burkard spore trap. Mould spore counts of greater than 3,000 spores/m3 were found throughout the year and were only exceeded by pollen grains in the months of September and October (range 4,800-7,400 spores/m3). Gramineae and Compositae spores were found perennially in significant numbers. Pollen from allergenic trees peaked at fixed times each year: oak in August; plane in September and pine between August and October. Grasses found on the Peninsula include sweet vernal, Bermuda grass, rye grass, common reed, Johnson grass, brome grass, canary grass, annual meadow and kikuyu. In vivo skin tests in 209 children with known allergic disease were positive to Dermatophygoides pteronyssimus (73%), South African grasses (38%), tree pollens (22.4%), flower and weed pollens (19.6%), cat (27%), dog (12%) and feathers (18.6%). One-third of the 1,372 children screened at Red Cross War Memorial Children's Hospital Allergy Service had positive specific IgE responses to environmental allergens. Investigation of 62 children possibly allergic to grass using the radio-allergosorbent test revealed positive results in 25 (41%). Of these, 92% were positive to Timothy grass, a grass not occurring in the Cape Peninsula. Knowledge of cross-reactivity profiles for local allergens minimises the number of tests required in allergy diagnosis.

Genetic and environmental influences on cord blood serum IgE and on atopic sensitisation in infancy.

It has recently been reported that cord blood serum IgE (CBsIgE) concentrations in a black Third-World cohort were significantly higher than those in a similar cohort of white and coloured newborns, and were not influenced by an atopic family history (aFH). This study reports on the 1-year follow-up of these newborns carried out to determine whether statistical differences in median CBsIgE values at birth could be found between infants in each ethnic group who subsequently developed clinical atopy in the first year of life and those who remained healthy. The infants were seen at 3, 7 and 12 months of age. At each visit a detailed history was taken from the mothers, the infants were examined clinically for the presence of atopic disease and blood was taken for immunological assay (total serum IgE by paper-disc radio-immunosorbent testing, and radio-allergosorbent testing for egg-white, cow's milk and Dermatophygoides pteronyssinus). A combination of clinical and immunological variables was assessed in order to categorise the infants into 'atopic' or 'not atopic' groups at the end of the 1-year follow-up period. The black infants who completed the study had the lowest incidence of aFH (16%), but 64% of them developed atopic disease during infancy. The median CBsIgE values for the black infants who became atopic were lower than, but not statistically different from, those for the group who remained non-atopic (P = 0.57). The white and coloured infants who completed the study had 81.6% and 30.4% incidences of aFH respectively, with 47.4% and 58.7% respectively developing atopic disease during infancy.(ABSTRACT TRUNCATED AT 250 WORDS)

A multi-allergen screening test for suspected allergic disease in coloured children.

The measurement of total serum IgE levels is widely used as a screening test for allergic disease but lacks specificity in South African subjects because of the presence of ethnic and environmental factors, e.g. parasite infestation, which also raise total serum IgE. The reliability of a new in vitro multi-allergen test, Phadiatop (Pharmacia), which is not influenced by parasitic infestation, was investigated as a screen for allergic disease in coloured children. Phadiatop assays and total serum IgE levels performed on 18 children with known allergic disease were compared with 21 non-allergic individuals. All the allergic, but only 2 of the non-allergic children had a positive Phadiatop result (P = less than 0.01; chi-square test) but there was no significant difference between the number of allergic or non-allergic children with elevated total serum IgE levels (P = greater than 0.1). The Phadiatop test demonstrated a specificity of 90% compared with 28% for total serum IgE. The predictive value of a negative Phadiatop result was 90% compared with 54% for total serum IgE levels. These data indicate that the Phadiatop test is a more specific screening test for allergic disease than total serum IgE levels in coloured children.

The influence of ethnicity, an atopic family history, and maternal ascariasis on cord blood serum IgE concentrations.

Raised concentrations of cord blood serum (CBs) IgE have previously been demonstrated to reflect a hereditary predisposition for atopy in First World, predominantly white populations. A cross-sectional study of 53 black, 52 white, and 58 mixed race newborn infants and maternal pairs was performed in a multiethnic, mixed First and Third World society. The CBs IgE concentrations were measured with a modification of the standard IgE PRIST, which could reliably determine IgE concentrations to an accuracy of 0.01 kU/L. The black group had the highest geometric mean and median CBs IgE concentrations (0.21; 0.16 kU/L), followed by the white group (0.12; 0.12 kU/L) and the mixed group (0.10; 0.08 kU/L). If those newborn infants with an atopic family history and maternal ascariasis were excluded, the remainder had geometric mean and median CBs IgE concentrations of 0.20; 0.16 kU/L in the black subgroup, followed by values of 0.06; 0.05 kU/L in the mixed subgroup, and 0.05; 0.07 kU/L in the white subgroup. Statistically significant ethnic differences in the median CBs IgE concentrations of these subgroups were demonstrated between the black-white (p less than 0.05) and the black-mixed (p less than 0.005) ethnic groups. A positive family history of atopy influenced the CBs IgE concentrations in the white and mixed groups but not in the black group. Of those newborn infants with a CBs IgE concentration greater than 0.5 kU/L, a family history of atopy was found in 100% of the white newborn infants, in 58.3% of the mixed newborn infants, and only in 14.3% of the black newborn infants. Many of the black newborn infants without a family history of atopy had extremely high CBs IgE concentrations. The influence of maternal ascariasis was equivocal in the mixed group but of no significance in the black group. The high CBs IgE concentrations in the black newborn infants, independent of an atopic family history and maternal ascariasis, suggest that this atopic marker may therefore be of limited use in identifying the "high allergic-risk" newborn infant in black Third World populations who appear to represent a pool of genetic high IgE-responder phenotypes.

Anti-Staphylococcus aureus-specific IgE in atopic dermatitis.

Serum samples from 60 adults and 64 children with atopic dermatitis were tested for antistaphylococcal IgE antibodies with RAST discs coupled to cellular proteins from Wood 46 strain S. aureus. Anti-S. aureus IgE antibodies were detected in 19 (29.6%) of the children and 14 (23.3%) of the adult patients. Anti-S. aureus IgE-positive adults had more severe and prolonged disease than those who were negative. Two groups of children comprising 10 who were anti-S. aureus IgE positive and 10 who were negative were compared. Children with anti-S. aureus IgE antibodies had more severe and more extensive disease (p less than 0.05), a greater prevalence of cutaneous S. aureus infections (p less than 0.05), higher mean total serum IgE level (p less than 0.05), a greater prevalence of specific IgE responses to food allergens (p less than 0.05), and a higher percentage of helper T cells (p less than 0.05) than children who were negative for these antibodies.