Diversity of Magnetospirillum sp. from the southern coast of India

Abstract

Magnetotactic bacteria (MTB) are ubiquitous in the aquatic environment and have been identified from almost every continent; however, there are only a few reports of MTB from India. This article studies the diversity of cultivable MTB from the southern coast of India. Five strains of MTB have been identified in this study using gradient culturing; three of the five strains were isolated in pure culture. The strains iden-tified are vibrioid to helical in morphology and grow microaerophilically in oxygen-sulphide gradient me-dia. Phylogenetic analysis of isolates based on 16S rRNA gene sequences shows that they belong to the family Rhodospirillaceae, class Alphaproteobacteria, and genus Magnetospirillum. The three isolated strains were physiologically characterized and found to utilize a wide range of substrates as electron donors and electron acceptors for metabolism. The autotrophic growth of the strains was confirmed by the detection of type-II RuBisCO (cbbM) gene by PCR amplifi-cation. The presence of key magnetosome formation (mam) genes in the strains confirms the similar mechanism of magnetosome biomineralization among Magnetospirillum species. These reports of MTB from the Indian coast would contribute to the study of their evolution and biomineralization.