Stepwise discriminant analysis was used to identify the most powerful selective substrates which could be used to formulate media capable of enriching for antibiotic-producing soil isolates. This was achieved by characterizing collection of 74 soil bacteria, including eubacteria and actinomycetes, according to their ability to produc antibacterial antibiotics and their growth responses to 43 physiological and nutritional tests. The characters which were selective for actinomycetes relative to eubacteria included growth on proline (1%, w/v) and humic acid (0.1%) as sole sources of both carbon and nitrogen, growth on nitrate as a nitrogen source, and growth at pH 7.7 8.0. Growth on proline (1 %) and humic acid (0.1%) as sole carbon/nitrogen sources, growth on asparagine as: nitrogen source, and growth in the presence of vitamins were among the characteristics which allowed antibiotic producing actinomycetes to be differentiated from non-antibiotic-producing strains. Several simple isolation media which incorporated the selective substrates identified by discriminant analysis succeeded in increasing the proportion of actinomycetes isolated from soil samples. Furthermore, the percentage of isolates capable of antibiotic production was considerably increased.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error