Discussion
A broad-spectrum antibiotic producing alkaliphilic actinomycetes
isolate A2D from phoomdi in Loktak Lake of Manipur,
India has been characterised and identified as
S. tanashiensis strain A2D. It was found that the antibiotic
production by S. tanashiensis A2D was positively affected by
the carbohydrates, nitrogen sources and NaCl.
The results showed that antibiotic production was higher
in medium having glucose (1%) as carbon source. The growth
as well as antibiotic production got reduced with the
increase or decrease of glucose concentration. This result
is quite comparable with S. sannanensis strain RJT-1, for
which glucose was found to be suitable carbon source for
the antibiotic production [31], while dextrose prove to be
the best carbon source for antibiotic production by
S. kanamyceticus M27 [21]. Similarly, Cruz et al. [3] reported
that the production of antibiotic by S. griseocarneus was
increased by glucose. High concentration of glucose is generally
regarded as repressor of secondary metabolisms [4] and
maximum cell growth rates can inhibit antimicrobial agent
production [8]. An example of catabolic repression of secondary
metabolism in actinomycetes is that of actinomycin
synthesis by S. antibioticus after more glucose is added to
the media [6].