The decomposition of uric acid in built up poultry litter appears to be brought about almost exclusively by the action of aerobic bacteria. Organisms decomposing uric acid usually comprised about one quarter of the bacterial population. They were strains of Corynebacterium and less frequently strains of Nocardia, Streptomyces, Psiudomonas, Alcaligencs and Achromobacter. Uric mid was converted to ammonia by some of the organisms but only to urea by the majority. Hydrolysis of urea to ammonia could be brought about by strains of Corynebacterium, Micrococcus, Alcaligenes, Achrornobacter and Cytophaga which had no aotion on uric acid. It is suggested that the ammoniacal smell and high alkalinity of built up poultry litter result largely from the decomposition of uric acid. The identity of the bacteria concerned is discussed.IN BIRDS nitrogen is excreted mainly in the form of uric acid and as this becomes the principal nitrogenous constituent in built up poultry litter it is reasonable to assume that its subsequent decomposition is responsible for the ammoniacal smell and high alkalinity characteristic of old litter. It was the object of this work to determine what role is played by micro-organisms in this decomposition process. Materials and MethodsNature of samples examined Samples were examined from 13 built up poultry litters. One sample of unused litter and one of poultry droppings were also investigated. Details of each sample are given in the previous paper (Schefferle, 1965). The aerobic decomposition of uric acid Bacterial culturesThese were picked nonselectively from high dilution plates of nutrient agar and of the crystal violet agar used earlier (Schefferle, 1965) for estimating total numbers of bacteria and counts of Gram negative organisms, respectively. The cultures were checked for purity and then approximately the same numbers of isolates from each plating were tested for their action on uric acid and on urea. Relatively more strains were examined from the one sample of unused litter. Recognition of organisms capable of decomposing uric acidThe medium was based on that used by Stapp (1920) and had the following composition: uric acid, 1 g; Na,HP0,.12H20, 6 g; yeast extract (Difco-Bacto), 2.6 g;

SUMWY. The numbers of viable bacteria in built up poultry litter were found t o be 101o-lO1l/g fresh weight and appeared to be little affected by factors such as age, temperature, moisture content and pH. Counta for unused litter and poultry droppings were lower. In built up litter of high alkalinity coryneform bacteria were predominant; micrococci occurred sporadically and smaIl numbers of nocardias, streptomycetes, aerobic spore formers and streptococci were encountered. A variety of Gram negative bacteria also occurred, the numbers of which appeared to be controlled by alkalinity; they were less abundant in litters where the pH and buffering capacity were high. Strongly alkaline conditions also tended to lower the fungal counts but had no effect on the count of enterococci.

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