Shanmugam Mayilraj

Pseudomonas indica sp. nov., a novel butane-utilizing species.

The taxonomic position of two butane-utilizing bacteria was studied using a polyphasic approach. Biochemical and physiological characteristics indicated these to be members of the genus Pseudomonas, showing more similarity to Pseudomonas mendocina than to any other species. The major fatty acids found in these two strains also pointed to their similarity to P. mendocina. On the other hand, DNA-DNA hybridization studies with seven related Pseudomonas species belonging to the gamma-Proteobacteria and the deltaTm values of reassociated molecules clearly showed that these two strains do not belong to any of the seven species tested. The 16S rRNA gene was sequenced and compared with the sequences available in the GenBank database. Phylogenetic analysis using the region covering positions 31-1488 (Escherichia coli numbering) confirmed these observations and placed these two strains as members of the authentic Pseudomonas, but not in any existing species of the genus. On the basis of biochemical characteristics, fatty acid profiles, DNA-DNA reassociation and deltaTm values, as well as 16S rRNA gene sequence analyses, these two isolates were shown to belong to one species but to have characteristics distinct from those of validly described species of Pseudomonas (sensu stricto). These strains, therefore, should be recognized as a novel species, for which the name Pseudomonas indica sp. nov. is proposed. The type strain is strain IMT37T (= MTCC 3713T = DSM 14015T).

Biosynthesis of gold and silver nanoparticles using a novel marine strain of Stenotrophomonas

The present study aims at exploiting marine microbial diversity for biosynthesis of metal nanoparticles and also investigates role of microbial proteins in the process of bio-mineralization of gold and silver. This is the first report for concurrent production of gold and silver nanoparticles (AuNPs and AgNPs) by extracellular secretion of a novel strain of Stenotrophomonas, isolated from Indian marine origin. This novel strain has faster rate kinetics for AgNPs synthesis than any other organism reported earlier. The nanoparticles were further characterized using UV-vis spectrophotometer, TEM, DLS and EDAX confirming their size ranging from 10-50 nm and 40-60 nm in dimensions for AuNPs and AgNPs, respectively. TEM analysis indicated formation of multi-shaped nanoparticles with heterogeneous size distribution in both the cases. Finally, the SDS-PAGE analysis of extracellular media supernatant suggested a potential involvement of certain low molecular weight secretory proteins in AuNPs and AgNPs biosynthesis.

Production, purification and characterization of a novel thermotolerant endoglucanase (CMCase) from Bacillus strain isolated from cow dung

In an attempt to screen out cellulase producing bacteria from herbivorous animal fecal matter it was possible to isolate a potent bacterium from cow dung. The bacterium was identified as Bacillus sp. using 16S rDNA based molecular phylogenetic approach. The effect of different agricultural wastes, paper wastes and carboxymethyl cellulose on endoglucanase production was tested and was found to produce maximally at 8% carboxymethyl cellulose. The endoglucanase was precipitated by ammonium sulfate saturation and purified by DEAE- Sepharose column. The purification was achieved 8.5 fold from the crude extract with a yield of 68.1%. The molecular weight of the protein was determined to be 97 kDa by SDS-PAGE. The enzymatic activity was moderately reduced by detergents (SDS, Tween-80), metal ions (MnCl2, ZnCl2) and EDTA. The endoglucanase was stable between pH 5.0 – 9.0 and temperature between 20−70°C with optimal activity at pH 7.0 and temperature 50°C. The apparent Km value of the enzyme for the substrate carboxymethyl cellulose was recorded to be 0.25 mg/ml. The endoglucanase was stable in the presence of commercial detergents such as Ariel, Surf Excel and Tide, indicated might be of potential applications in detergent industry. The enzyme from this strain could also be applied in bioconversion of lignocellulosic biomass into fermentable sugars.

Bacillus horneckiae sp. nov., isolated from a spacecraft-assembly clean room

Five Gram-stain-positive, motile, aerobic strains were isolated from a clean room of the Kennedy Space Center where the Phoenix spacecraft was assembled. All strains are rod-shaped, spore-forming bacteria, whose spores were resistant to UV radiation up to 1000 J m(-2). The spores were subterminally positioned and produced an external layer. A polyphasic taxonomic study including traditional biochemical tests, fatty acid analysis, cell-wall typing, lipid analyses, 16S rRNA gene sequencing and DNA-DNA hybridization studies was performed to characterize these novel strains. 16S rRNA gene sequencing and lipid analyses convincingly grouped these novel strains within the genus Bacillus as a cluster separate from already described species. The similarity of 16S rRNA gene sequences among the novel strains was >99 %, but the similarity was only about 97 % with their nearest neighbours Bacillus pocheonensis, Bacillus firmus and Bacillus bataviensis. DNA-DNA hybridization dissociation values were <24 % to the closest related type strains. The novel strains had a G+C content 35.6+/-0.5 mol% and could liquefy gelatin but did not utilize or produce acids from any of the carbon substrates tested. The major fatty acids were iso-C(15 : 0) and anteiso-C(15 : 0) and the cell-wall diamino acid was meso-diaminopimelic acid. Based on phylogenetic and phenotypic results, it is concluded that these strains represent a novel species of the genus Bacillus, for which the name Bacillus horneckiae sp. nov. is proposed. The type strain is 1P01SC(T) (=NRRL B-59162(T) =MTCC 9535(T)).

Description of Paenisporosarcina quisquiliarum gen. nov., sp. nov., and reclassification of Sporosarcina macmurdoensis Reddy et al. 2003 as Paenisporosarcina macmurdoensis comb. nov.

In the course of a study of the prokaryotic diversity of a landfill site in Chandigarh, India, a strain designated SK 55(T) was isolated and characterized using a polyphasic approach. Its 16S rRNA gene sequence showed closest similarity (98.3 %) to that of Sporosarcina macmurdoensis CMS 21w(T). The sequence similarity to strains of other hitherto described species of Sporosarcina was less than 95.5 %. Strain SK 55(T) contains peptidoglycan of the A4alpha type (l-Lys-d-Asp), MK-8 and MK-7 as the major menaquinones and iso-C(15 : 0) as the major fatty acid. Strain SK 55(T), Sporosarcina macmurdoensis and Sporosarcina ureae, the type species of the genus, had some polar lipids in common (diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, a phospholipid and an unknown lipid). However, an aminolipid, an aminophospholipid and an unknown lipid found in the former two organisms are similar, though not identical, but quite different from the profile of S. ureae. The genomic DNA G+C contents of strain SK 55(T) (46.0 mol%) and S. macmurdoensis CMS 21w(T) (44.0 mol%) are higher than those reported for the majority of species of Sporosarcina (36-42 mol%). As revealed by 16S rRNA gene sequence analysis, strain SK 55(T) and S. macmurdoensis CMS 21w(T) form a clade which is distinct from the clade occupied by other species of Sporosarcina. On the basis of phenotypic characteristics including chemotaxonomic data and analysis of the 16S rRNA gene sequence, we conclude that strain SK 55(T) should be considered as a member of a novel genus and species, for which the name Paenisporosarcina quisquiliarum gen. nov., sp. nov. is proposed. The type strain of Paenisporosarcina quisquiliarum is SK 55(T) (=MTCC7604(T) =JCM 14041(T)). S. macmurdoensis CMS 21w(T) shows more similarity in its 16S rRNA gene sequence (98.3 %), DNA G+C content and polar lipid profile to strain SK 55(T) than to S. ureae DSM 2281(T). Phylogenetically, it forms a coherent cluster with strain SK 55(T) which is separate from the Sporosarcina cluster. Moreover, iso-C(15 : 0), anteiso-C(15 : 0) and C(16 : 1)omega7c alcohol are the three major fatty acids in both S. macmurdoensis CMS 21w(T) and SK 55(T). All these data suggest that S. macmurdoensis should be a member of the genus Paenisporosarcina. However, S. macmurdoensis can be differentiated from SK 55(T) in several physiological and biochemical characteristics, especially in the patterns of oxidation and acid production from carbohydrates. The genomic relatedness of S. macmurdoensis CMS 21w(T) and strain SK 55(T) was also very low (18.0 %). It is therefore logical to transfer Sporosarcina macmurdoensis to the newly created genus as Paenisporosarcina macmurdoensis comb. nov. The type strain is CMS 21w(T) (=MTCC4670(T) =DSM 15428(T)).

Complete genome sequence of Actinosynnema mirum type strain (101T)

Actinosynnema mirum Hasegawa et al. 1978 is the type species of the genus, and is of phylogenetic interest because of its central phylogenetic location in the Actinosynnemataceae, a rapidly growing family within the actinobacterial suborder Pseudonocardineae. A. mirum is characterized by its motile spores borne on synnemata and as a producer of nocardicin antibiotics. It is capable of growing aerobically and under a moderate CO2 atmosphere. The strain is a Gram-positive, aerial and substrate mycelium producing bacterium, originally isolated from a grass blade collected from the Raritan River, New Jersey. Here we describe the features of this organism, together with the complete genome sequence and annotation. This is the first complete genome sequence of a member of the family Actinosynnemataceae, and only the second sequence from the actinobacterial suborder Pseudonocardineae. The 8,248,144 bp long single replicon genome with its 7100 protein-coding and 77 RNA genes is part of the GenomicEncyclopedia ofBacteria andArchaea project.

Mycobacterium tuberculosis Keto-Mycolic Acid and Macrophage Nuclear Receptor TR4 Modulate Foamy Biogenesis in Granulomas: A Case of a Heterologous and Noncanonical Ligand-Receptor Pair

The cell wall of Mycobacterium tuberculosis is configured of bioactive lipid classes that are essential for virulence and potentially involved in the formation of foamy macrophages (FMs) and granulomas. Our recent work established crosstalk between M. tuberculosis cell wall lipids and the host lipid-sensing nuclear receptor TR4. In this study, we have characterized, identified, and adopted a heterologous ligand keto-mycolic acid from among M. tuberculosis lipid repertoire for the host orphan NR TR4. Crosstalk between cell wall lipids and TR4 was analyzed by transactivation and promoter reporter assays. Mycolic acid (MA) was found to transactivate TR4 significantly compared with other cell wall lipids. Among the MA, the oxygenated form, keto-MA, was responsible for transactivation, and the identity was validated by TR4 binding assays followed by TLC and nuclear magnetic resonance. Isothermal titration calorimetry revealed that keto-MA binding to TR4 is energetically favorable. This keto-MA–TR4 axis seems to be essential to this oxygenated MA induction of FMs and granuloma formation as evaluated by in vitro and in vivo model of granuloma formation. TR4 binding with keto-MA features a unique association of host nuclear receptor with a bacterial lipid and adds to the presently known ligand repertoire beyond dietary lipids. Pharmacologic modulation of this heterologous axis may hold promise as an adjunct therapy to frontline tuberculosis drugs.

Metabolic profiles and phylogenetic diversity of microbial communities from chlorinated pesticides contaminated sites of different geographical habitats of India.

Aims:  To study the microbial communities in three sites contaminated with chlorinated pesticides and evaluation of dehydrodechlorinase (linA) gene variants involved in gamma‐hexachlorocyclohexane (γ‐HCH, lindane) degradation.

Complete genome sequence of Nakamurella multipartita type strain (Y-104T)

Nakamurella multipartita (Yoshimi et al. 1996) Tao et al. 2004 is the type species of the monospecific genus Nakamurella in the actinobacterial suborder Frankineae. The nonmotile, coccus-shaped strain was isolated from activated sludge acclimated with sugar-containing synthetic wastewater, and is capable of accumulating large amounts of polysaccharides in its cells. Here we describe the features of the organism, together with the complete genome sequence and annotation. This is the first complete genome sequence of a member of the family Nakamurellaceae. The 6,060,298 bp long single replicon genome with its 5415 protein-coding and 56 RNA genes is part of the GenomicEncyclopedia ofBacteria andArchaea project.

Isolation and characterization of a Pseudomonas sp. strain IITR01 capable of degrading α‐endosulfan and endosulfan sulfate

Aim:  To isolate bacteria capable of degrading endosulfan (ES) and the more toxic ES sulfate and to characterize their metabolites.