Studies on the decomposition of amino acids in soils

Summary 1. The kinetics of decomposition of 17 common amino acids in a garden soil have been followed by percolation techniques that permitted the measurement of O₂-uptake and CO₂-output consequent upon decomposition.2. Most of the amino acids decomposed rapidly; methionine and threonine decomposed much more slowly.3. After decomposition of amino acids in soil, the material residual in the soil had a C : N ratio of about 3 : 1; this possibly represents microbial protein.4. The significance of the results, and the potentialities of the manometric techniques used, are discussed.     

GROWTH FACTOR REQUIREMENTS OF SIX FUNGI ASSOCIATED WITH FRUIT DECAY.

Esposito, R. G. (United Fruit Co., Norwood, Mass.), H. Greenwood, and A. M. Fletcher. Growth factor requirements of six fungi associated with fruit decay. J. Bacteriol. 83:-250-255. 1962.-A study of the growth factor requirements of representatives of six genera of fruit-rotting fungi has been made. Gloeosporium musarum, Nigrospora sphaerica, Thielaviopsis paradoxa, and Verticillium theobromae all required biotin for growth. Under certain conditions in nitrate medium, Fusarium roseum appeared to be partially dependent on biotin. T. paradoxa also required thiamine for growth. In addition to biotin, N. sphaerica required an unknown material contained in extracts of yeast. Twenty-one known growth factors were tested and found to be inactive. Thiamine inhibited the growth of F. roseum, apparently by stimulating the formation of ethanol. Biotin reversed the effect of thiamine on growth and ethanol formation.