Amino acid composition of humic acid-like polymers produced by streptomycetes and of humic acids from pasture and arable land

Abstract

Strains of streptomycetes, cultivated in a glycerol-nitrate medium, synthesized humic acid-like substances. With one strain 13.7 per cent of the NO 3 −-N in the medium was converted into humic acid-like substances after 59 days. Hydrolysis with 6 n HCl released 40 per cent of the ‘humic acid’ N as NH 4 +- and amino acid-N. With humic acids isolated from soils of arable land and 10-yr-old pasture about 60 per cent of the humic acid N was found to be present as NH 4 +- and amino acid-N in the hydrolysate. The amino acid patterns of the hydrolysates of pasture soil, arable soil and the humic acids of these soils were rather similar, resembling the amino acid composition of the hydrolysates of the ‘humic acids’ of two Streptomyces strains.