The antagonistic effects of the two groups of lipids upon microbes were investigated. As an example, we will mention here the characteristic changes in Bac. anthracis treated with polyunsaturated fatty acids and insaponifiable fraction preparations. (Fig. 70) We investigated the microbes for their morphological, tinctorial, cultural and virulence characteristics. With the fatty acids added to media, changes which can be considered to be mutational were induced, leading to tiny Gram negative microbes growing on agar as transparent small colonies. The changes, however, were reversible. Usually several passages in normal media were sufficient to produce reversal. First small and separate, then larger and more confluent Gram positive granules were seen to appear in the microbes which, themselves, also became progressively plumper. Ultimately, all the characteristics,—morphological, tinctorial and cultural—of the normal microbes reappeared. (Fig. 71)

Microbes showed opposite changes when treated with insaponifiable fractions, (Fig. 70) losing their bacillus form. Abnormally intensive Gram positive cocci appeared. They grew on agar as very thick creamy white colonies. These changes were seen to persist for a long time and seldom were spontaneously reversed. Treatment with fatty acids induced reversal although inconsistently. We attempted to correlate the differences in changes induced by different lipids to the different levels of the microbe at which they work. The change to cocci can be regarded as corresponding to an influence exerted upon the membrane and the change to Gram positive to an influence upon differentiated formations present in the body. (313)

Influence of lipids upon microbes

Fig. 70. Influence of lipids upon microbes. Schematic drawing of the changes induced in Bacillus Anthracis by the influence exerted by the two groups of lipids. Treated with sterols (a) as in the unsaponifiable fraction of placenta, the microbes change into cocci irregularly shaped and intensely retaining the gram stain. Treated with fatty acids (c) from cod liver oil, the bacilli change into very tiny gram negative microbes, (b) shows untreated microbes.

Lipids and microbes

Fig. 71. Lipids and microbes. Drawing of the progressive passage toward normal bacilli of the tiny gram negative microbes obtained through the treatment of Bac. Anthracis with fatty acids. The passage takes place usually in successive steps. The gram positive formations appear first as fine granules; they later become clumps and finally give the microbes their normal aspect.

Effects Of Lipids On Protozoa

The effects of lipids upon monocellular organisms, especially tetra hymena pyriformis, were studied and an effort made to relate the nature of the main changes induced in these protozoa to changes observed at the cellular level of complex organisms. An initial effect was noted on the polarity in protozoa which seemed to be oppositely influenced by long chain polyunsaturated fatty acids and sterols. Lipids with a positive character were seen to induce a change in the form of protozoa causing them to become almost round, a change considered to correspond to reduced polarity. Lipids with a negative character had an opposite effect; the tetra hymena became abnormally elongated.

The administration of higher amounts of polyunsaturated fatty acids was seen to induce immediate changes localized at the anterior pole of the organism, changes which ultimately lead to the breakdown of the membrane particularly at this point. This effect parallels in intensity the degree of desaturation of the fatty acids. Other changes were seen in growth rate and survival time and, thus, in the aging process. (Note 34) (Fig. 74)

At the same time, resistance to heat was seen to increase as the result of treatment with negative lipids, while it decreased after treatment with the positive sterols. (Note 35) The same influence upon the aging processes, as manifested in a prolongation of the life span, was noted for polyunsaturated fatty acids with a long chain and even for some members of the saturated series but with a shorter chain.

Control

Control.

Treated with fatty acids

Treated with fatty acids.

Fig. 74. In a direct action of fatty acids on tetrahymena, a passage of fluid occurs at the surface with a break of the membrane especially manifest at the anterior pole (a), control untreated (b), (1200x).