Anukriti Sharma

Arsenic rich Himalayan hot spring metagenomics reveal genetically novel predator-prey genotypes.

Bdellovibrio bacteriovorus are small Deltaproteobacteria that invade, kill and assimilate their prey. Metagenomic assembly analysis of the microbial mats of an arsenic rich, hot spring was performed to describe the genotypes of the predator Bdellovibrio and the ecogenetically adapted taxa Enterobacter. The microbial mats were enriched with Bdellovibrio (1.3%) and several Gram-negative bacteria including Bordetella (16%), Enterobacter (6.8%), Burkholderia (4.8%), Acinetobacter (2.3%) and Yersinia (1%). A high-quality (47 contigs, 25X coverage; 3.5 Mbp) draft genome of Bdellovibrio (strain ArHS; Arsenic Hot Spring) was reassembled, which lacked the marker gene Bd0108 associated with the usual method of prey interaction and invasion for this genus, while maintaining genes coding for the hydrolytic enzymes necessary for prey assimilation. By filtering microbial mat samples (< 0.45 μm) to enrich for small predatory cell sizes, we observed Bdellovibrio-like cells attached side-on to E. coli through electron microscopy. Furthermore, a draft pan-genome of the dominant potential host taxon, Enterobacter cloacae ArHS (4.8 Mb), along with three of its viral genotypes (n = 3; 42 kb, 49 kb and 50 kb), was assembled. These data were further used to analyse the population level evolutionary dynamics (taxonomical and functional) of reconstructed genotypes.

Draft Genome Sequence of Cellulosimicrobium sp. Strain MM, Isolated from Arsenic-Rich Microbial Mats of a Himalayan Hot Spring

ABSTRACT Microbial mats situated at the Manikaran hot springs (>95°C) are characterized by their high arsenic content (140 ppb), qualifying as a stressed niche. Here, we report the annotated draft genome (3.85 Mb) of Cellulosimicrobium sp. strain MM, isolated from these microbial mats, consisting of 3,718 coding sequences, with an average % G+C of 74.4%.

Survey of (Meta)genomic Approaches for Understanding Microbial Community Dynamics

Advancement in the next generation sequencing technologies has led to evolution of the field of genomics and metagenomics in a slim duration with nominal cost at precipitous higher rate. While metagenomics and genomics can be separately used to reveal the culture-independent and culture-based microbial evolution, respectively, (meta)genomics together can be used to demonstrate results at population level revealing in-depth complex community interactions for specific ecotypes. The field of metagenomics which started with answering “who is out there?” based on 16S rRNA gene has evolved immensely with the precise organismal reconstruction at species/strain level from the deeply covered metagenome data outweighing the need to isolate bacteria of which 99% are de facto non-cultivable. In this review we have underlined the appeal of metagenomic-derived genomes in providing insights into the evolutionary patterns, growth dynamics, genome/gene-specific sweeps, and durability of environmental pressures. We have demonstrated the use of culture-based genomics and environmental shotgun metagenome data together to elucidate environment specific genome modulations via metagenomic recruitments in terms of gene loss/gain, accessory and core-genome extent. We further illustrated the benefit of (meta)genomics in the understanding of infectious diseases by deducing the relationship between human microbiota and clinical microbiology. This review summarizes the technological advances in the (meta)genomic strategies using the genome and metagenome datasets together to increase the resolution of microbial population studies.

Meta)genomic insights into the pathogenome of Cellulosimicrobium cellulans

Despite having serious clinical manifestations, Cellulosimicrobium cellulans remain under-reported with only three genome sequences available at the time of writing. Genome sequences of C. cellulans LMG16121, C. cellulans J36 and Cellulosimicrobium sp. strain MM were used to determine distribution of pathogenicity islands (PAIs) across C. cellulans, which revealed 49 potential marker genes with known association to human infections, e.g. Fic and VbhA toxin-antitoxin system. Oligonucleotide composition-based analysis of orthologous proteins (n = 791) across three genomes revealed significant negative correlation (P < 0.05) between frequency of optimal codons (Fopt) and gene G+C content, highlighting the G+C-biased gene conversion (gBGC) effect across Cellulosimicrobium strains. Bayesian molecular-clock analysis performed on three virulent PAI proteins (Fic; D-alanyl-D-alanine-carboxypeptidase; transposase) dated the divergence event at 300 million years ago from the most common recent ancestor. Synteny-based annotation of hypothetical proteins highlighted gene transfers from non-pathogenic bacteria as a key factor in the evolution of PAIs. Additonally, deciphering the metagenomic islands using strain MM’s genome with environmental data from the site of isolation (hot-spring biofilm) revealed (an)aerobic respiration as population segregation factor across the in situ cohorts. Using reference genomes and metagenomic data, our results highlight the emergence and evolution of PAIs in the genus Cellulosimicrobium.

Intrauterine intussusception--a cause for ileal atresia.

A case of ileal atresia consequent to intrauterine intussusception is reported. The baby presented with features of neonatal intestinal obstruction but signs of peritonitis were absent. The intussusception was discovered on gross examination of distal atretic ileal segment. The case was managed successfully by resection and end to back anastomosis. This case is reported to highlight intrauterine intussusception as one of the causes of ileal atresia.

Fictibacillus halophilus sp. nov., from a microbial mat of a hot spring atop the Himalayan Range.

A Gram-stain-positive staining, motile, endospore forming and moderately halophilic bacterium, designated as strain AS8T, was isolated from a microbial mat deposited at thermal discharges of Manikaran hot spring (with surface water temperature ~95 °C) located in Himachal Pradesh, India. 16S rRNA gene sequence based phylogenetic analysis revealed that strain AS8T belonged to the genus Fictibacillus with the highest sequence similarity to Fictibacillus nanhaiensis DSM 23009T (99.9 %) and Fictibacillus phosphorivorans Ca7T (99.9 %), followed by Fictibacillus barbaricus V2-BIII-A2T (99.1 %) and Fictibacillus arsenicus Con a/3T (97.4 %). The polar lipids fraction consisted of diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The cell-wall peptidoglycan was of the type A1γ based on directly cross-linked meso-diaminopimelic acid. The DNA G+C content of strain AS8T was found to be 46.9 mol%. The quinone system of strain AS8T consisted of MK-7 predominantly, and the polyamine pattern primarily contained spermidine and spermine. The major cellular fatty acids in strain AS8T were iso-C15:0, anteiso-C15:0 and iso-C16:0. The strain showed DNA-DNA relatedness of 52.7 % with F. nanhaiensis DSM 23009T, 50.7 % with F. phosphorivorans Ca7T, 34.8 % with F. barbaricus V2-BIII-A2T and 38.0 % with F. arsenicus Con a/3T. In spite of the high 16S rRNA gene sequence similarities, the DNA-DNA hybridization and gyr B gene sequencing results (≤87 %) supported by physiological and biochemical tests demonstrated that strain AS8T is a representative of a novel species, for which the name Fictibacillus halophilus sp. nov. is proposed. The type strain is AS8T (=MCC 2765T=DSM 100124T=KCTC 33758T).

Response and resilience of soil microbial communities inhabiting in edible oil stress/contamination from industrial estates

BackgroundGauging the microbial community structures and functions become imperative to understand the ecological processes. To understand the impact of long-term oil contamination on microbial community structure soil samples were taken from oil fields located in different industrial regions across Kadi, near Ahmedabad, India. Soil collected was hence used for metagenomic DNA extraction to study the capabilities of intrinsic microbial community in tolerating the oil perturbation.ResultsTaxonomic profiling was carried out by two different complementary approaches i.e. 16S rDNA and lowest common ancestor. The community profiling revealed the enrichment of phylum “Proteobacteria” and genus “Chromobacterium,” respectively for polluted soil sample. Our results indicated that soil microbial diversity (Shannon diversity index) decreased significantly with contamination. Further, assignment of obtained metagenome reads to Clusters of Orthologous Groups (COG) of protein and Kyoto Encyclopedia of Genes and Genomes (KEGG) hits revealed metabolic potential of indigenous microbial community. Enzymes were mapped on fatty acid biosynthesis pathway to elucidate their roles in possible catalytic reactions.ConclusionTo the best of our knowledge this is first study for influence of edible oil on soil microbial communities via shotgun sequencing. The results indicated that long-term oil contamination significantly affects soil microbial community structure by acting as an environmental filter to decrease the regional differences distinguishing soil microbial communities.

Algoriphagus roseus sp. nov., isolated from a hexachlorocyclohexane contaminated dumpsite.

A Gram-staining negative, reddish-pink, non-motile, rod-shaped bacterial strain designated W29T, was isolated from a hexachlorocyclohexane-contaminated dumpsite located in the northern part of India at Ummari Village, Lucknow. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain W29T formed a lineage within the genus Algoriphagusand exhibited highest sequence similarity to Algoriphagus trabzonensis MS7T (98.8 %), followed by Algoriphagusalkaliphilus AC-74T (97.1 %). The 16S rRNA gene sequence similarity between strain W29T and other species of the genus Algoriphagusranged from 93.3-98.8 %. The DNA-DNA relatedness between strain W29T and A. trabzonensisMS7T was 47 % and with other related strains was found to be less than 45 %, confirming strain W29T represents a novel species. The DNA G+C content of strain W29T was 46.2 mol%. Strain W29T was oxidase- and catalase-positive. The major fatty acids (>10 %) of strain W29T were iso-C15 : 0, summed feature 9 (comprising 10-methyl C16 : 0 and/or iso-C17 : 1ω9c) and summed feature 3 (comprising C16 : 1ω6c and/or C16 : 1ω7c). The respiratory quinone was MK-7. The polar lipid profile consisted of phosphatidylethanolamine, diphosphatidylglycerol, two unidentified aminolipids, an unidentified aminophospholipid, an unidentified phospholipid and unidentified lipids. On the basis of the results obtained from DNA-DNA hybridization, and biochemical and physiological tests in this study, strain W29T represents a novel species of the genus Algoriphagus for which the name Algoriphagus roseus sp. nov. is proposed. The type strain is W29T (=KCTC 42940T=MCC 2876T=DSM 100160T).

Microbial taxonomy in the era of OMICS: application of DNA sequences, computational tools and techniques

The current prokaryotic taxonomy classifies phenotypically and genotypically diverse microorganisms using a polyphasic approach. With advances in the next-generation sequencing technologies and computational tools for analysis of genomes, the traditional polyphasic method is complemented with genomic data to delineate and classify bacterial genera and species as an alternative to cumbersome and error-prone laboratory tests. This review discusses the applications of sequence-based tools and techniques for bacterial classification and provides a scheme for more robust and reproducible bacterial classification based on genomic data. The present review highlights promising tools and techniques such as ortho-Average Nucleotide Identity, Genome to Genome Distance Calculator and Multi Locus Sequence Analysis, which can be validly employed for characterizing novel microorganisms and assessing phylogenetic relationships. In addition, the review discusses the possibility of employing metagenomic data to assess the phylogenetic associations of uncultured microorganisms. Through this article, we present a review of genomic approaches that can be included in the scheme of taxonomy of bacteria and archaea based on computational and in silico advances to boost the credibility of taxonomic classification in this genomic era.

Pontibacter virosus sp. nov., isolated from a hexachlorocyclohexane-contaminated dumpsite.

A Gram-staining-negative, red-pigmented, motile, rod-shaped bacterial strain, designated as W14T, was isolated from a hexachlorocyclohexane-contaminated dumpsite located in the northern part of India at Ummari Village, Lucknow. Phylogenetic analysis based on 16S rRNA gene sequence showed that the strain belongs to the genus Pontibacter with highest sequence similarity to Pontibacter lucknowensis DM9T (98.1 %). The 16S rRNA gene sequence similarity between strain W14T and members of other species of the genus Pontibacter ranged from 98.1 to 94.2 %. The DNA-DNA relatedness between strain W14T and P. lucknowensis DM9T was 33.7 % and with other closely related strains was found to be less than 20 %, confirming it to represent a novel species. The DNA G+C content of strain W14T was 51.3 mol%. Strain W14T was oxidase- and catalase-positive. The predominant cellular fatty acids were summed feature 4 (C17 : 1 iso I/anteiso B and C17 : 1 anteiso B/iso I), iso-C15 : 0 and iso-C17 : 0 3-OH. The polar lipid profile of strain W14T consisted of phosphatidylethanolamine, diphosphatidylglycerol, aminolipid and glycolipid. On the basis of the results obtained from DNA-DNA hybridization, biochemical and physiological tests in this study, strain W14T represents a novel species of the genus Pontibacter, for which the name Pontibacter virosus sp. nov. is proposed. The type strain is W14T (=MCC 2932T=DSM 100231T=KCTC 42941T).