A Cellulose‐Dextrin Medium for Identifying Cellulose Organisms in Soil

IN SOIL W.. H. FULLER AND A. G. NORMAN "THE enumeration, identification, and purification A of the aerobic cellulose-decomposing organisms in soil have proved difficult, partly because cellulose does not lend itself well to the usual dilution plating technic, and partly because the organisms vary considerably in their ability to use pure cellulose. Existing methods give little more than a rough indication of the nature, numbers, and kinds of cellulose-decomposing organisms in soils. As substrates, both pure cellulose, usually in the form of filter paper, and regenerated cellulose in agar or silica gel have been employed. For the enumeration of aerobic cellulose organisms the former has proved to be preferable though not really satisfactory. Comparisons are made on the basis of the highest dilutions at which growth is obtained on filter paper strips partially immersed in a nutrient solution' (2). Isolation of organisms can be accomplished in a similar manner, but purification then is a matter of uncertainty. Cultural purity is more readily assured if regenerated cellulose incorporated in agar is used, but the nature of the regenerated products is such that the forms isolated on them do not seem to be fully representative. Reprecipitated cuprammonium' cellulose was employed by Kellerman and McBeth (3) in this manner, and hydrocellulose similarly by Scales (4). Cellulose dextrins, prepared by the cold acid hydrolysis of cellulose, lend themselves well to incorporation in ordinary media, and appear to offer considerable advantages over the forms described above, both for isolation and enumeration of the aerobic cellulose bacteria. This paper reports the conditions of preparation and use that have been found most satisfactory.