THE BACTERIAL ENDOSPORE 



A BRIEF REVIEW OF BIOCHEMICAL ADVANCES AND 

 SOME NOTES ON SPOROGENESIS 



H. ORIN HALVORSON 



School of Life Sciences, University of Illinois, Urbana, III. (U.S.A.) 



Three crucial observations have, in my opinion, stimulated 

 many of the recent researches on spores. One, the observation 

 by Hills^ that spores will germinate rapidly in the presence 

 of a mixture of amino acids and nucleosides; two, the discovery 

 in our laboratory that spores contain active heat-resistant 

 enzymes-"^ and three, the observations made by Powell-^, that 

 dipicolinic acid is a major constituent of spores. I want to take 

 some time to discuss each of these observations. 



From early studies it was known that spores suspended in a 

 growth medium would lose their heat resistance in a relatively 

 short time. In looking into this further, Hills^ found that yeast 

 extract had the same effect. He then proceeded to fractionate 

 this to determine what nutrients were responsible for this effect, 

 and discovered that spores would germinate in a few minutes in 

 the presence of a few amino acids, with or without nucleosides 

 and glucose. L-Alanine and adenosine were found to be sufficient 

 for some species. This was studied in more detail by the late 

 Joan Powell^ et a/. They found that a large percentage of the 

 spores in a suspension (in the presence of the proper nutrilites) 

 would simultaneously lose their heat resistance and refractility, 

 and at the same time would become stainable. Many investiga- 

 tors have confirmed these findings since they were made early in 

 1950, In addition, the minimal germination requirements for 

 other species have been determined. In most cases germination 

 can be initiated by a few amino acids along with nucleosides, 

 although some species will germinate with glucose only. 



As a result of the studies on the germination requirements, we 

 have also gained a fairly good insight into the effect of environ- 



