Production of gibberellin-like substances by bacteria and actinomycetes

The production of gibberellin-like substances by bacteria and actinomycetes was investigated. Most of the bacterial cultures tested produced a gibberellic acid-like substance (A3) in amounts varying from 1 to 14 μg/liter. The production of a gibberellin-A9-like compound was much more limited, 6 out of 15 cultures yielding small amounts. Six out of 11 actinomycetes showed evidence of A3 synthesis; two produced A9. Antigibberellin substances co-chromatographing with A3 were detected in culture filtrates of Bacillus polymyxa and two actionmycetes. Cultural conditions and concentration of the ingredients of the medium influenced gibberellin synthesis by Agrobacterium radiobacter. Production of these substances was not growth linked and none was detected in stationary cultures. Microbial synthesis of the gibberellins was demonstrated also by means of assays with the dwarf maize mutants d1, d2, and d5.As added to soil was rapidly inactivated and it was postulated that the plant could derive maximum benefit from microbial synthesis of gibberellins and related substances only at the root surface—the rhizoplane.

REACTIONS OF SPORES AND CELLS OF BACILLUS CEREUS WITH PYRIMIDINE RIBOSIDES

Lawrence , N. L. (University of Alabama, Birmingham) and Yun-Chuan Tsan . Reaction of spores and cells of Bacillus cereus with pyrimidine ribosides. J. Bacteriol. 83: 228–233. 1962.—Cytidine deaminase and uridine ribosidase were essentially inactive in heat-resistant spores of Bacillus cereus T, but the activity increased as the spores germinated and proceeded to the vegetative form. The activity of germinated spores on cytidine was evident only after several hours lag, but then was nearly equal to that of vegetative cells. Cytosine deaminase was absent from all these preparations, but deoxycytidine was deaminated at nearly the same rate as cytidine. In the absence of added phosphate, cytidine was converted to uracil by intact vegetative cells more completely than was uridine.

COMPARISON OF GROWTH AND PECTOLYTIC ENZYME PRODUCTION BY BACILLUS POLYMYXA

Nagel, Charles W. (University of California, Davis) and Reese H. Vaughn . Comparison of growth and pectolytic enzyme production by Bacillus polymyxa . J. Bacteriol. 83: 1–5. 1962.—Studies were made of pectolytic enzyme production by Bacillus polymyxa during growth. It was found that elaboration of enzyme occurred during logarithmic growth and ceased when the stationary phase was reached. The specific activity of the extra-cellular enzyme remained relatively constant until lysis occurred. The increased specific activity of the intracellular pectolytic enzyme may be explained if one assumes that the rate of secretion of the intracellular enzyme is dependent upon the concentration of the extracellular enzyme. The concentration of the intracellular pectolytic enzyme dropped markedly at the end of the logarithmic growth phase; the enzyme was released into the medium during the stationary growth phase and subsequent lysis of the cells. It was shown that the intra- and extracellular enzymes were similar or identical in that both were calcium-dependent pectic acid transeliminases.