Abstract
Previous study of the influence of plant tissue upon bacterial growth showed that sterile unheated plant tissue can replace blood in the cultivation of the so called hemophilic organism B. influenzæ. It was also found that plant tissue exerts a marked accelerating action upon the growth of pneumococcus. More recently it has been shown that the addition of unheated vegetable (potato) to plain bouillon makes possible the continued, ærobic growth of certain anærobic bacilli such as B. histolyticus, B. ærofetidis, B. oedematiens, and B. chauvei.
This growth promoting action upon three distinct groups of bacteria so widely different in their cultural requirements, indicates that plant tissue meets certain physiological needs of the bacterial cell not wholly provided for by the ordinary culture media. These studies suggest that this action may be dependent not only on the presence of some growth accessory substances in plant tissue but also upon the functioning of certain systems which are concerned in the cellular processes of oxidation and reduction.
McLeod and his associates have found that certain ærobic bacteria which are devoid of catalase form hydrogen peroxide when grown in the presence of air. In the case of pneumococcus, which possesses no catalase, hydrogen peroxide is known to accumulate in the fluid of ærobic cultures in concentrations which are bacteriostatic and even bacteriocidal. As far as is known anzrobic bacilli are also devoid of catalase, and hence these cells cannot destroy peroxides. From these relations it seems not unlikely that anærobic bacteria fail to grow in the presence of air, not because atmospheric oxygen as such is a direct poison to the cell, but because of the toxic action of peroxides which may be formed as the result of the union of molecular oxygen with some autoxidizable substance in the bacterial cell.
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