The properties of a biologically formed manganese oxide,its availability to oats and its solution by root washings

Summary Manganese oxide, produced byCorynebacterium sp. in liquid medium was found to be amorphous, probably hydrated and was readily reduced by neutral quinol. Preparations of the oxide had values of n in the formula MnO_n which ranged from 1.76 to 1.88. The oxide was completely available to oats grown in sand culture but only slightly available in a manganese deficient soil. Plants grown under sterile conditions on agar slopes were able to obtain manganese from manganese oxide, indicating that the roots and not associated micro-organisms, were responsible for the solution process. Root washings of oat plants contained substances which dissolved manganese oxides and the activity of these substances increased with increasing acidity. The possible importance of these substances in making soil manganese available to plants is discussed.