Efficacy of artificial humic acid as a selective nutrient in HV agar used for the isolation of soil actinomycetes

• Published in: Journal of fermentation technology (Osaka. 1977) Vol. 65; no. 6; pp. 609 - 616
• Main Authors: Hayakawa, Masayuki, Nonomura, Hideo
• Format: Journal Article
• Language: English
• Published: Osaka Elsevier B.V 1987; Society of Fermentation Technology
• Subjects: Agronomy. Soil science and plant productions; Bacteriological methods and techniques used in bacteriology; Bacteriology; Biological and medical sciences; Chemical, physicochemical, biochemical and biological properties; Fundamental and applied biological sciences. Psychology; Microbiology; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; Culture medium; Synthetic product; Nutrition; Selective media; Soil; Bacteria; Isolation; Actinomycetes; Humic acids; Natural compound; Method; Comparative study
• ISSN: 0385-6380
• DOI: 10.1016/0385-6380(87)90001-X

The efficacies of various kinds of humic acid, as the source of carbon and nitrogen in HV agar reported in the previous paper, were compared to the selective isolation of soil actinomycetes. The 4 types of natural humic acid, A, B, P and Rp were prepared from different soils, and 3 kinds of artificial humic acid were made from carbohydrates and urea in our laboratory. Among the natural humic acids, type Rp, which has been reported to be associated with an initial state of humification in natural conditions, showed the greatest efficacy. However, one of the artificial humic acids, which was prepared from glucose and urea, was considered to be superior to the Rp natural humic acid: 1) The HV agar containing this artificial humic acid (HV-glucose HA agar) produced the same large number of actinomycete colonies on the plate as that of the HV agar with type Rp soil humic acid (HV- Rp agar). 2) The HV-glucose HA agar restricted the number of bacterial colonies on the plates to one-half of that on HV- Rp agar plates. 3) The quality of natural himic acids varies, whereas artificial ones are more constant and can be made in any laboratory.