Effect of aeration and agitation on the biosynthetic activity of diffusely growing Aspergillus niger.

A considerable lowering of aeration demands occurs during diffuse growth of citric acid-producing Aspergillus niger in a submerged cultivation. However, the diffuse culture poses stricter demands on the type of aeration and agitation. The impeller frequency affects considerably the morphology of the producer fungus and the accumulation of citric acid.

Immunological changes after long-term feeding of germfree piglets with protein isolates and yeast cell walls from Candida utilis as food additives.

Germfree piglets were fed a diet supplemented with cell walls and a protein isolate from Candida utilis for 54 days. Besides morphological signs of activation of the lymphoid tissue which occurred primarily in the intestine of piglets which had been fed yeast cell walls, even an increased serum immunoglobulin level could be detected. In sera and intestinal content of piglets fed both with cell walls and isolated protein, specific antibodies capable of agglutinating yeasts were present.

Production of extracellular enzymes in continuous culture.

The production of bacterial enzymes in batch fermentations is compared with results obtained in continuous culture. When studying the production of alpha-amylase in Bacillus subtilis it was found that instability of the enzyme synthesis was due to nonhomogeneity of the population rather than to "the culture's history" (i.e.

Comparison of growth rates of two clones of Bacillus subtilis, producer of alpha-amylase.

In a population of the productive Bacillus subtilis strain the production of alpha-amylase differentiates at the cell level. Individual cells in the population were analyzed and the production of isolates was tested. The mean specific activity of alpha-amylase in the productive group after the isolation was 5.