Characterization of antibiotic producing rare actinomycete Nonomuraea sp. JAJ18 derived from an Indian coastal solar saltern

Abstract

Rare actinomycete genera are accepted as a promising source of novel metabolites having pharmaceutical importance. One such genus of rare actinomycete is Nonomuraea. The present study was aimed at characterizing the antibiotic producing Nonomuraea strain JAJ18 which was previously isolated from coastal solar saltern. Strain JAJ18 was recognized as a member of genus Nonomuraea based on its almost complete 16S rRNA gene sequence and phenotypic characteristics. The strain JAJ18 was found to be closely related to Nonomuraea maheshkhaliensis 16-5-14(T) (98.90%), Nonomuraea candida HMC10(T) (98.58%), and Nonomuraea jabiensis A4036(T) (98.43%). From cell-free culture broth of strain JAJ18, an antibiotic was extracted and purified by silica column chromatography. The obtained antibiotic was found to be active against a range of Gram-positive and Gram-negative bacteria including drug-resistant Staphylococcus, with minimal inhibitory concentration (MIC) ranging from 0.5 to 16.0 µg mL(-1). The structural characteristics of antibiotic were determined by FTIR and NMR spectroscopy. The antibiotic was identified to be an aliphatic rich compound with significant dissimilarity to known antibiotics reported from members of the genus, Nonomuraea. As the trends to discover novel metabolites from Nonomuraea are vibrant, further studies are needed to understand the structural and biotechnological significance of antibiotic compound produced by Nonomuraea sp. JAJ18.

Figure 1

Neighbour-joining tree based on almost complete 16S rRNA gene sequences of JAJ18. The phylogenetic tree shows the relationships between Nonomuraea sp. JAJ18 and members of the genus Nonomuraea. Actinoallomurus acacia GMKU 931^T was used as out-group. Numbers at nodes indicate the levels of bootstrap support (%) based on a neighbour-joining analysis of 1000 resampled datasets. Score bar represents 1 nucleotide substitution per 100 nucleotides.