Production of the same antibiotics by members of different genera of microorganisms

Purification and structural elucidation of three bioactive compounds isolated from Streptomyces coelicoflavus BC 01 and their biological activity

The strain Streptomyces coelicoflavus BC 01 was isolated from mangrove soil and used as inoculum for submerged fermentation. The fermented broth was extracted with ethyl acetate, the crude extract was subjected to silica gel column chromatography and the homogeneity of the isolated fractions was determined by TLC and then subjected to RP-HPLC for their purity. The purification steps led to the isolation of three pure bioactive compounds named as BC 01_C1, BC 01_C2 and BC 01_C3. The chemical structure of these three compounds was established on the basis of their spectroscopic studies like UV, IR, ¹H and ¹³C NMR and GC–MS data by comparison with reference data from literature. The structure of the compound BC 01_C1 was established as 5-amino-2-(6-(2-hydroxyethyl)-3-oxononyl) cyclohex-2-enone. The compound BC 01_C2 was established as8-(aminomethyl)-7-hydroxy-1-(1-hydroxy-4-(hydroxylmethoxy)-2,3-dimethylbutyl)-2-methyl dodecahydro phenanthren-9(1H)-one and the compound BC 01_C3 was established as1-((E)-2-ethylhex-1-en-1-yl)2-((E)-2-ethylidenehexyl)cyclohexane-1,2-dicarboxylate. The MIC values of the three isolated compounds (BC 01_C1, BC 01_C2 and BC 01_C3) were found between 12.5–75 μg/ml for bacteria and 50–125 μg/ml for fungi used in this study. These compounds also possess in vitro antioxidant and anti-inflammatory activities.

Antibiotic pigment from desert soil actinomycetes; biological activity, purification and chemical screening

An actinomycete strain, Streptomyces hygroscopicus subsp. ossamyceticus (strain D10) was isolated from Thar Desert soil, Rajasthan during the year 2006 and found to produce a yellow color pigment with antibiotic activity. Crude pigment was produced from strain D10 by solid state fermentation using wheat bran medium followed by extraction with ethyl acetate. The antimicrobial activity of the crude pigment was evaluated against drug resistant pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Staphylococcus aureus, extended spectrum β-lactamase producing cultures of Escherichia coli, Pseudomonas aeruginosa and Klebsiella sp. About 420 mg of crude pigment was produced per 10 g of wheat bran medium. In the disc diffusion method the crude ethyl acetate extract showed a minimum of 10 mm inhibition against Klebsiella sp. and maximum of 19 mm of inhibition against Escherichia coli. The crude pigment was partially purified using thin layer chromatography with the solvent system chloroform:methanol (30:70) and the Rf value was calculated as 0.768. Antimicrobial activity of the partially purified compound from thin layer chromatography was determined using the bioautography method. The purified pigment showed minimum of 15 mm inhibition against Klebsiella sp. and a maximum of 23 mm of inhibition against vancomycin-resistant Staphylococcus aureus in the disc diffusion method. Based on the results of chemical screening, the pigment was tentatively identified as group of sugar containing molecules.

Amino acid control mechanism for bacitracin formation by Bacillus licheniformis

Several amino acids affected the amount of bacitracin produced by Bacillus licheniformis ATCC 10716 and the high-yielding mutant B. licheniformis AL. The possibility of an amino acid control mechanism for bacitracin biosynthesis is discussed. The two strains showed a different response to the addition of some amino acids. This indicate that they may have differences in their amino acid control mechanism.