Degradation of Humic Acids, Extracted from Manure and Soil by Some Streptomycetes and Fungi

Abstract

Humate-decomposing microorganisms were isolated from alluvial soil, farmyard manure and peat by direct plating and enrichment techniques. Peat was found to harbour more of these organisms than soil and manure. Out of 21 actinomycetes and 6 fungi 9 and 3 isolates, respectively, were found to utilize manure-humate as a sole source of carbon and to a less extent as a source of both carbon and nitrogen in liquid medium. These efficient cultures were identified as Streptomyces spec. (A 11 and A 12). Str. candidus, Str. violaceoruber (A 41 and A 42), Str. rubescens, Str. garyphalus, Str. viridochromogenes, Fusarium solani, Aspergillus fumigatus, and Penicillium roseopurpureum. Additional sources of carbon and nitrogen stimulated microbial degradation of humate. Only five isolates formed a zone of decolourization on humate-containing solid medium. Soil humic acid was utilized by Str. candidus as a sole source of carbon and nitrogen, however, F. solani utilized it only in the presence of additional carbon and nitrogen sources. Extent of soil-humate degradation was less than manure-humate.