Dharam Singh

Complete genome sequence of Arthrobacter sp. ERGS1:01, a putative novel bacterium with prospective cold active industrial enzymes, isolated from East Rathong glacier in India

We report the complete genome sequence of Arthrobacter sp. ERGS1:01, a novel bacterium which produces industrial enzymes at low temperature. East Rathong glacier in Sikkim Himalayas is untouched and unexplored for microbial diversity though it has a rich source of glaciers, alpine and meadows. Genome sequence has provided the basis for understanding its adaptation under harsh condition of Himalayan glacier, its ability to produce cold active industrial enzymes and has unlocked opportunities for microbial bioprospection from East Rathong glacier.

Genome Assembly of Chryseobacterium polytrichastri ERMR1:04, a Psychrotolerant Bacterium with Cold Active Proteases, Isolated from East Rathong Glacier in India

ABSTRACT We report here the genome assembly of a psychrotolerant bacterium, Chryseobacterium polytrichastri ERMR1:04, which secretes cold-active proteases. The bacterium was isolated from a pristine location, the East Rathong Glacier in the Sikkim Himalaya. The 5.53-Mb genome provides insight into the cold-active industrial enzyme and adaptation in the cold environment.

Biotechnological interventions for harnessing podophyllotoxin from plant and fungal species: current status, challenges, and opportunities for its commercialization

Abstract Podophyllotoxin is an aryltetralin lignan synthesized in several plant species, which is used in chemotherapies for cancers and tumor treatment. More potent semisynthetic derivatives of podophyllotoxin such as etoposide and teniposide are being developed and evaluated for their efficacy. To meet the ever increasing pharmaceutical needs, species having podophyllotoxin are uprooted extensively leading to the endangered status of selective species mainly Sinopodophyllum hexandrum. This has necessitated bioprospection of podophyllotoxin from different plant species to escalate the strain on this endangered species. The conventional and non-conventional mode of propagation and bioprospection with the integration of biotechnological interventions could contribute to sustainable supply of podophyllotoxin from the available plant resources. This review article is focused on the understanding of different means of propagation, development of genomic information, and its implications for elucidating podophyllotoxin biosynthesis and metabolic engineering of pathways. In addition, various strategies for sustainable production of this valuable metabolite are also discussed, besides a critical evaluation of future challenges and opportunities for the commercialization of podophyllotoxin.

Complete genome sequence of Arthrobacter alpinus ERGS4:06, a yellow pigmented bacterium tolerant to cold and radiations isolated from Sikkim Himalaya.

Arthrobacter alpinus ERGS4:06, a yellow pigmented bacterium which exhibited tolerance to cold and UV radiations was isolated from the glacial stream of East Rathong glacier in Sikkim Himalaya. Here we report the 4.3Mb complete genome assembly that has provided the basis for potential role of pigments as a survival strategy to combat stressed environment of cold and high UV-radiation and additionally the ability to produce cold active industrial enzymes.

First complete genome sequence of a species in the genus Microterricola, an extremophilic cold active enzyme producing bacterial strain ERGS5:02 isolated from Sikkim Himalaya.

Here, we report the first ever complete genome sequence of any species in the genus Microterricola. The bacterium Microterricola viridarii ERGS5:02 isolated from the glacial stream of Sikkim Himalaya survived at low temperature and exhibited enhanced growth upon UV treatment, in addition, it also produced cold active enzymes. The complete genome assembly of 3.7 Mb suggested for the presence of genetic elements favoring the survival of bacterium under extreme conditions of UV and low temperature besides producing amylase, lipase and protease of industrial relevance.

Complete genome sequence of Pseudomonas frederiksbergensis ERDD5:01 revealed genetic bases for survivability at high altitude ecosystem and bioprospection potential

Pseudomonas frederiksbergensis ERDD5:01 is a psychrotrophic bacteria isolated from the glacial stream flowing from East Rathong glacier in Sikkim Himalaya. The strain showed survivability at high altitude stress conditions like freezing, frequent freeze-thaw cycles, and UV-C radiations. The complete genome of 5,746,824 bp circular chromosome and a plasmid of 371,027 bp was sequenced to understand the genetic basis of its survival strategy. Multiple copies of cold-associated genes encoding cold active chaperons, general stress response, osmotic stress, oxidative stress, membrane/cell wall alteration, carbon storage/starvation and, DNA repair mechanisms supported its survivability at extreme cold and radiations corroborating with the bacterial physiological findings. The molecular cold adaptation analysis in comparison with the genome of 15 mesophilic Pseudomonas species revealed functional insight into the strategies of cold adaptation. The genomic data also revealed the presence of industrially important enzymes.

Bioplastic reservoir of diverse bacterial communities revealed along altitude gradient of Pangi-Chamba trans-Himalayan region

Himalaya hosts a unique environment for microbial ecology. The present study aimed to explore the bioplastic producing bacterial communities along altitude gradient of Pangi-Chamba trans-Himalayan region. A total of 411 bacteria were isolated and 70 characterized at the molecular level for potential polyhydroxyalkanoates (PHA) producers. The most abundant phylum for PHA synthesis was Proteobacteria (73%), followed by Actinobacteria (11%), Firmicutes (10%) and Bacteroidetes (6%). However, at the genus level, Pseudomonas and Janthinobacterium were dominantly reported. Also, the ability to synthesize PHA was reported for the first time for few genera such as Collimonas, Pseudarthrobacter and Paenarthrobacter. Phylogenetic analysis of partial 16S rDNA and phaC genes revealed conservation in phaC and possibility of horizontal gene transfer among distant taxa. Furthermore, GC-MS also confirmed the ability of potential bacterial isolates to synthesize PHA. In fact, we found that PHA-positive bacteria are dominant in the high altitude of Himalaya, suggesting the vital role of PHA in bacterial adaptation and survival. Together, these findings had revealed the rich bacterial diversity and genetic machinery for PHA synthesis which does have potential for further utilization in the commercial applications.

Antimicrobial homoisoflavonoids from the rhizomes of Polygonatum verticillatum

Three homoisoflavonoids, including a new compound, 5,7‐dihydroxy‐3‐(4‐methoxybenzyl)‐8‐methyl chroman‐4‐one (1), together with two known compounds, 5,7‐dihydroxy‐3‐(2‐hydroxy‐4‐methoxybenzyl)‐8‐methylchroman‐4‐one (2) and 5,7‐dihydroxy‐3‐(2‐hydroxy‐4‐methoxybenzyl)‐chroman‐4‐one (3), were isolated from the rhizomes of Polygonatum verticillatum (L.) All. (P. verticillatum). Isolated compounds were characterized on the basis of UV, FT‐IR, ESI‐MS, and 1D‐, 2D‐NMR data. Further, different extract fractions and pure compounds from Polygonatum verticillatum were screened for their antimicrobial potential. Among three pure compounds, compound 2 was found most potent with good zone of microbial growth inhibition as compared to the standards.

Diverse culturable bacterial communities with cellulolytic potential revealed from pristine habitat in Indian trans-Himalaya

The Pangi-Chamba Himalaya (PCH) region is very pristine, unique, and virgin niche for bioresource exploration. In the current study, for the first time, the bacterial diversity of this region was investigated for potential cellulose degraders. A total of 454 pure bacterial isolates were obtained from diverse sites in the PCH region, and 111 isolates were further selected for 16S rDNA characterization based on ARDRA grouping. The identified bacteria belonged to 28 genera representing four phyla: Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. Pseudomonas was most abundant genus, followed by Bacillus, Geobacillus, Arthrobacter, Paenibacillus, and Flavobacterium. In addition, six putative novel bacteria (based on 16S rDNA sequence similarity) and thermophiles from non-thermogenic sites were also reported for the first time. Screening for cellulose degradation ability on carboxymethyl cellulose plates revealed that 70.92% of bacteria were cellulolytic. The current study reports diverse bacterial genera (Arthrobacter, Paenibacillus, Chryseobacterium, Pedobacter, Streptomyces, Agromyces, Flavobacterium, and Pseudomonas) with high capacity for cellulose hydrolysis and cellulolytic functionality at wide pH and temperature not previously reported in the literature. Diverse bacterial genera with high cellulolytic activity in broad pH and temperature range provide opportunity to develop a bioprocess for efficient pretreatment of lignocellulosic biomass, which is currently being investigated.

Movement protein of Apple chlorotic leaf spot virus is genetically unstable and negatively regulated by Ribonuclease E in E. coli

Movement protein (MP) of Apple chlorotic leaf spot virus (ACLSV) belongs to “30 K” superfamily of proteins and members of this family are known to show a wide array of functions. In the present study this gene was found to be genetically unstable in E. coli when transformed DH5α cells were grown at 28 °C and 37 °C. However, genetic instability was not encountered at 20 °C. Heterologous over expression failed despite the use of different transcriptional promoters and translational fusion constructs. Total cell lysate when subjected to western blotting using anti-ACLSV MP antibodies, showed degradation/cleavage of the expressed full-length protein. This degradation pointed at severe proteolysis or instability of the corresponding mRNA. Predicted secondary structure analysis of the transcript revealed a potential cleavage site for an endoribonuclease (RNase E) of E. coli. The negating effect of RNase E on transcript stability and expression was confirmed by northern blotting and quantitative RT-PCR of the RNA extracted from RNase E temperature sensitive mutant (strain N3431). The five fold accumulation of transcripts at non-permissive temperature (43 °C) suggests the direct role of RNase E in regulating the expression of ACLSV MP in E. coli.