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Polyphasic taxonomic analysis establishes Mycobacterium indicus pranii as a distinct species

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Title Polyphasic taxonomic analysis establishes Mycobacterium indicus pranii as a distinct species
 
Creator Saini, Vikram
Raghuvanshi, Saurabh
Talwar, Gursaran P.
Ahmed, Niyaz
Khurana, Jitendra P.
Hasnain, Seyed E.
Tyagi, Akhilesh K.
Tyagi, Anil K.
 
Subject Mycobacterium indicus pranii
Polyphasic Taxonomic Analysis
Mycobacterium
 
Description Background: Mycobacterium indicus pranii (MIP), popularly known as Mw, is a cultivable, non-pathogenic organism, which,
based on its growth and metabolic properties, is classified in Runyon Group IV along with M. fortuitum, M. smegmatis and M.
vaccae. The novelty of this bacterium was accredited to its immunological ability to undergo antigen driven blast
transformation of leukocytes and delayed hypersensitivity skin test in leprosy patients, a disease endemic in the Indian sub-
continent. Consequently, MIP has been extensively evaluated for its biochemical and immunological properties leading to
its usage as an immunomodulator in leprosy and tuberculosis patients. However, owing to advances in sequencing and
culture techniques, the citing of new strains with almost 100% similarity in the sequences of marker genes like 16S rRNA,
has compromised the identity of MIP as a novel species. Hence, to define its precise taxonomic position, we have carried out
polyphasic taxonomic studies on MIP that integrate its phenotypic, chemotaxonomic and molecular phylogenetic
attributes. Methodology/Principal Findings: The comparative analysis of 16S rRNA sequence of MIP by using BLAST algorithm at NCBI
(nr database) revealed a similarity of $99% with M. intracellulare, M. arosiense, M. chimaera, M. seoulense, M. avium subsp.
hominissuis, M. avium subsp. paratuberculosis and M. bohemicum. Further analysis with other widely used markers like rpoB
and hsp65 could resolve the phylogenetic relationship between MIP and other closely related mycobacteria apart from M.
intracellulare and M. chimaera, which shares $99% similarity with corresponding MIP orthologues. Molecular phylogenetic
analysis, based on the concatenation of candidate orthologues of 16S rRNA, hsp65 and rpoB, also substantiated its
distinctiveness from all the related organisms used in the analysis excluding M. intracellulare and M. chimaera with which it
exhibited a close proximity. This necessitated further analysis of MIP with more sensitive and segregating parameters to
ascertain its precise taxonomic position as a new species. The analysis of MIP and its comparison with other mycobacterial
reference strains based on cellular and biochemical features, growth characteristics and chemotaxonomic studies like FAME
profiling confirmed that MIP is uniquely endowed with diverse metabolic attributes that effectively distinguishes it from all
the closely related mycobacteria including M. intracellulare and M. chimaera.
Conclusion: The results presented in this study coupled with the non-pathogenic nature and different biochemical and
immunomodulatory properties of MIP affirm it as a distinct species belonging to M. avium complex (MAC). It is further
proposed to use an earlier suggested name Mycobacterium indicus pranii for this newly established mycobacterial species.
This study also exemplifies the growing need for a uniform, consensus based broader polyphasic frame work for the
purpose of taxonomy and speciation, particularly in the genus Mycobacterium.
This work was supported by a financial grant from the Department of Biotechnology, Govt. of India (http://dbtindia.nic.in/index.asp). Vikram Saini is
recipient of Senior Research Fellowship from the Council of Scientific and Industrial Research (CSIR), India(http://www.csir.res.in/). SEH is a J.C. Bose National
Fellow. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
 
Date 2014-02-13T09:26:26Z
2014-02-13T09:26:26Z
2009
9 June 2009
 
Type Article
 
Identifier PLoS One, 4: e6263
http://hdl.handle.net/123456789/127
 
Language en
 
Publisher PLOS