Microbial populations of poultry pine-sawdust litter

Abstract

The average density of viable microorganisms in poultry pine-sawdust litter was 6·3 × 10⁷/g dry material (DP); 1·6% of the population were aerobic heterotrophic bacteria. Acidophile bacteria, aerobic spore-forming bacteria, actinomycetes and fungi were, respectively 4·8 × 10⁴, 8·1 × 10⁴, 5·2 × 10⁴ and 8·9 × 10⁴ CFU/g DP. However the latter did not have a measurable mycelium. Algae were in low densities (18/g DP) and cyanobacteria were not detected. Most of the population had proteolytic and ammonificant capacities, but there were very few ammonium oxidizers and nitrite oxidizers. Denitrifiers were in relatively high density and the anaerobic free-nitrogen fixers were more abundant than the aerobic ones. Aerobic cellulolytics were scarce, but anaerobic cellulolytics, amylolytics and pectolytics showed a similar, and relatively high average density. Sulphate reducers and anaerobic mineralizers of organic sulphur were more abundant than the elementary-sulphur oxidizers, and sulphide oxidizers were not detected. Except for algae, microbial populations generally tended to decrease with time of use of the litter. This decline affected mainly nitrifiers, anaerobic and aerobic cellulolytics and amylolytics while sulphate reducers and anaerobic free-nitrogen fixers increased.