Temperature - A critical abiotic paradigm that governs bacterial heterogeneity in natural ecological system

A baseline data has been presented here to prove that among the abiotic factors, temperature is the most critical factor that regulates and governs the bacterial diversity in a natural ecosystem. Present study in Yumesamdong hot springs riverine vicinity (Sikkim), parades a gamut of bacterial communities in it and hosts them from semi-frigid region (- 4-10 °C) to fervid region (50-60 °C) via an intermediate region (25-37 °C) within the same ecosystem. This is an extremely rare intriguing natural ecosystem that has no anthropogenic disturbances nor any artificial regulation of temperature. We scanned the bacterial flora through both the culture-dependent and culture-independent techniques in this naturally complex thermally graded habitat. High-throughput sequencing gave bacterial and archaeal phyla representatives of over 2000 species showcasing their biodiversity. Proteobacteria, Firmicutes, Bacteroidetes and Chloroflexi were the predominant phyla. A concave down-curve significance was found in temperature-abundance correlation as the number of microbial taxa decreased when the temperature increased from warm (35 °C) to hot (60 °C). Firmicutes showed significant linear increase from cold to hot environment whereas Proteobacteria followed the opposite trend. No significant correlation was observed for physicochemical parameters against the bacterial diversity. However, only temperature has shown significant positive correlation to the predominant phyla at their respective thermal gradients. The antibiotic resistance patterns correlated with temperature gradient where the prevalence of antibiotic resistance was higher in case of mesophiles than that of psychrophiles and there was no resistance in thermophiles. The antibiotic resistant genes obtained were solely from mesophiles as it conferred high resistance at mesophilic conditions enabling them to adapt and metabolically compete for survival. Our study concludes that the temperature is a major factor that plays a significant contribution in shaping the bacterial community structure in any thermal gradient edifice.

Baseline metagenome-assembled genome (MAG) data of Sikkim hot springs from Indian Himalayan geothermal belt (IHGB) showcasing its potential CAZymes, and sulfur-nitrogen metabolic activity

Here we present the construction and characterization of metagenome assembled genomes (MAGs) from two hot springs residing in the vicinity of Indian Himalayan Geothermal Belt (IHGB). A total of 78 and 7 taxonomic bins were obtained for Old Yume Samdong (OYS) and New Yume Samdong (NYS) hot springs respectively. After passing all the criteria only 21 and 4 MAGs were further studied based on the successful prediction of their 16 S rRNA. Various databases were used such as GTDB, Kaiju, EzTaxon, BLAST XY Plot and NCBI BLAST to get the taxonomic classification of various 16 S rRNA predicted MAGs. The bacterial genomes found were from both thermophilic and mesophilic bacteria among which Proteobacteria, Chloroflexi, Bacteroidetes and Firmicutes were the abundant phyla. However, in case of OYS, two genomes belonged to archaeal Methanobacterium and Methanocaldococcus. Functional characterization revealed the richness of CAZymes such as Glycosyl Transferase (GT) (56.7%), Glycoside Hydrolase (GH) (37.4%), Carbohydrate Esterase family (CE) (8.2%), and Polysaccharide Lyase (PL) (1.9%). There were negligible antibiotic resistance genes in the MAGs however, a significant heavy metal tolerance gene was found in the MAGs. Thus, it may be assumed that there is no coexistence of antibiotic and heavy metal resistance genes in these hot spring microbiomes. Since the selected hot springs possess good sulfur content thus, we also checked the presence of genes for sulfur and nitrogen metabolism. It was found that MAGs from both the hot springs possess significant number of genes related to sulfur and nitrogen metabolism.

Post-monsoon seasonal variation of prokaryotic diversity in solfataric soil from the North Sikkim hot spring

The solfataric soil sediments of the hot springs of Sikkim located at Yume Samdung and Lachen valley were studied for deciphering the bacterial diversity. The main aim here is to present a comparative study and generate a baseline data on the post-monsoon seasonal variation for the months of October and December, analyzed through 16S rRNA V3-V4 amplicon sequencing. The results have shown that there is not much variation at phylum level in the month of October in all the three hot springs such as New Yume Samdung (NYS), Old Yume Samdung (OYS), and Tarum (TAR) hot spring. The abundant phyla mainly present were Firmicutes, followed by Proteobacteria, Actinobacteria, and Bacteroidetes. Similarly, in the month of December, Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes were prevalent; however, the percent relative abundance of these phyla in the month of December is relatively less. Besides this decrease in percent abundance, it was interestingly seen that relatively more phyla were found contributing towards the bacterial diversity in the month of December. Similar to phylum level, at genus level, there was not much variation seen among various prevalent genera of the three studied hot springs in both months. The major genera prevalent in both months among all the three hot springs were followed by Bacillus, Desulfotomaculum, Lactobacillus, and Paenibacillus. A similar trend was also seen at gene level that relative abundance of various genera was higher in the month of October but more genera were found to be contributing towards bacterial diversity in the month of December. Few distinct genera were found to be more abundant in the month of December such as Rhodopirellula and Blastopirellula. The results may conclude that there is not much variation in the abundance and type of bacterial communities during the post-monsoon season in the month of October and December. However, this may be assumed that there is the accumulation or increase in the bacterial communities during the winter (relatively higher temperature among hot springs) and may favor few mesophilic and more thermophilic communities as well.

Coexistence of Heavy Metal Tolerance and Antibiotic Resistance in Thermophilic Bacteria Belonging to Genus Geobacillus

Hot springs are thought to be potential repositories for opportunistic infections, such as antibiotic-resistant strains. However, there is a scarcity of information on the mechanisms of antibiotic resistance gene (ARG) uptake, occurrence, and expression in thermophilic bacteria. Furthermore, because the genesis and proliferation of ARGs in environmental microorganisms are unknown, the research on antibiotic resistance profiles and probable mechanisms in thermophilic bacteria will become increasingly important. The goals of this study are to explore bacterial diversity, antibiotic and heavy metal resistance, and the prevalence and presence of ARG and metal resistance gene (MRG) in Geobacillus species. The 16S rRNA sequencing was used to determine the culturable bacterium diversity of 124 isolates. Standard Kirby Bauer Disc Diffusion and tube dilution procedures were used to determine antibiotic sensitivity and minimum inhibitory concentration (MIC). The tube dilution method was also used to check metal tolerance. To detect ARG and heavy MRG (HMRG), whole genome sequencing studies of the type species of the genus Geobacillus and five randomly selected Geobacillus species were performed. Graph Pad Prism and XLSTAT were used to perform statistical analyses such as ANOVA, EC50 analysis, and principal component analysis (PCA). The phylum Firmicutes and the genus Geobacillus dominated the culture-dependent bacterial diversity. Surprisingly, all thermophilic isolates, i.e., Geobacillus species, were sensitive to at least 10 different antibiotics, as evidenced by the lack of ARGs in whole genome sequencing analysis of numerous Geobacillus species. However, some of these isolates were resistant to at least five different heavy metals, and whole genome sequencing revealed the presence of MRGs in these thermophilic bacteria. The thermophilic genus Geobacillus is generally antibiotic sensitive, according to this study. In contrast, heavy metal is tolerated by them. As a result, it is possible that ARGs and MRGs do not coexist in these bacteria living in hot springs.

Bacterial diversity, physicochemical and geothermometry of South Asian hot springs

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Statistical analysis using physicochemical parameters reveals that the processes involved in the hot springs of HGB may include water mixing or exhibiting simple dissolution, ion exchange and reverse ion exchange.

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Study shows the water in the hot springs of HGB is mainly Na-Cl, Na-HCO₃, Ca⁺²-Na⁺-HCO₃⁻, Ca⁺²- HCO3⁻ and mixed type.

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Geothermometry reveals the temperature of these geothermal features ranges approximately between 100-250°C.

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Microbial study reveals that the Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria as predominant phyla showing significant positive correlation with physicochemical parameters like temperature, pH, Na, HCO₃, etc.

Extreme ecosystems with enormous arrays of physicochemical or biological physiognomies serve as an important indicator of various processes occurred and/or occurring in and on the Earth. Among extreme habitats, hot springs represent geothermal features which are complex systems with a well-defined plumbing system. Besides geological tectonic based hypsography and orology annotations, the hot springs have served as hot spots for ages where there is an amalgamation of nature, religion, faith, health, and science. Thus, there remains an escalating scope to study these hot springs all over the world. The Himalayan Geothermal Belt (HGB) banquets three densely demographic countries i.e. Pakistan, India and China, that hosts numerous hot springs. Studies on the hot springs distributed over these countries reveal Proteobacteria, Firmicutes, Bacteroidetes and Actinobacteria as the predominant bacterial phyla. The bacterial diversity shows a significant positive correlation with physicochemical parameters like temperature, pH, Na⁺, HCO₃⁻, etc. Physicochemical analyses of these hot springs indicate the water mainly as Na-Cl, Na-HCO₃, SO₄-Cl, and mixed type, with temperature ranging approximately between 100-250°C as predicted by various geothermometers. Numerous studies although done, not much of a comprehensive database of the analysis are provided on the hot springs harboured by the HGB. This review aims to give a cumulative illustration on comparative facets of various characteristic features of hot springs distributed over the HGB. These are found to be of great importance with respect to the exploitation of geothermal energy and microflora in various sectors of industries and biotechnology. They are also important sources in terms of socio-economic perspective, and routes to eco-medical tourism.

Draft genome sequence of Stenotrophomonas maltophilia strain P13 gives insight into its protease production and assessment of sulfur and nitrogen metabolism

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In this study draft genome sequence of Stenotrophomonas maltophilia strain P13 which was isolated from Kanchengayao glacier, North Sikkim, India.

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The genome of P13 strain possesses 2689,565 total reads, with an average G + C content of 69.9%.

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The major enzymes present are beta-galactosidase, thiol peroxidase, thiolredoxin reductase, glutamate synthase, and glutamate-ammonia-ligase adenyltransferase.

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FAME, morphological and biochemical characterization, and scanning electron microscopy (SEM) of Stenotrophomonas maltophilia strain P13 are provided.

Stenotrophomonas maltophilia strain P13 was isolated from the Kanchengayao glacier's accumulation zone. A comprehensive study was done on this strain as it produced protease enzyme and thus having industrial potential. The whole genome sequence, FAME, morphological and biochemical characteristics of the S. maltophilia strain P13 is being presented. The genome of P13 strain possesses 2,689,565 total reads, with an average G + C content of 69.9%. The whole-genome assembly is having 548 contigs (with PEGs). The genome contains 2,985 coding sequences with 55 rRNA predicted genes. More than 88% of the total pre-processed reads from samples were mapped. The identified coding proteins were classified into 27 functional categories based on COG classification. The genome was found to possess genes for ammonium assimilation, galactosylceramide and sulfatide metabolism. The major enzymes present are beta-galactosidase, thiol peroxidase, thiolredoxin reductase, glutamate synthase, and glutamate-ammonia-ligase adenyltransferase. The genome information of Stenotrophomonas maltophilia P13 provides the basis for understanding the functional properties and abilities to act as a potential cold-active enzyme producer and nitrogen-fixing bacteria.

Isolation and characterization of plant growth promoting rhizobacteria isolated from organically grown high yielding pole type native pea (Pisum sativum L.) variety Dentami of Sikkim, India

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The present research showcases the significant findings pertaining to the assessment and report of the first ever study on the isolation and identification of plant growth promoting rhizobacterial diversity of organic farming pea variety (Dentami) of Sikkim. Proteobacteria dominated the rhizospheric soil whereas the bulk soil was governed by Actinobacteria. Bacillus cereus P8 (66.5 µg ml⁻¹) and Bacillus mycoides PP1 (45.1 µg ml⁻¹) were the highest IAA producer and also showed other plant growth promoting and biocontrol traits, such as phosphorous and potassium solubilization, nitrogen-fixing activity and siderophore production. As, Sikkim is the first state in India to practice organic agriculture farming, hence, such study on the soil microbiology is of immense significance. In these rhizospheric soil, it was dominated by the Proteobacteria and similar bacterial isolates, suggesting that these soil flora might be playing significant roles to enhancing the crop production and soil fertility.

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Culture-dependent technique was used to assess plant growth promoting rhizobacterial diversity of pole type pea variety (Dentami) of Sikkim.

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The dominant phylum was Proteobacteria (56%) from rhizosphere soil and Actinobacteria (58%) from bulk soil.

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PCA analysis showed that Firmicutes (bulk soil) were positively correlated to SOC, and available K, whereas, Proteobacteria (rhizosphere soil) exhibited a high correlation to pH, and available P.

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Bacillus cereus P8, Arthrobacter woluwensis DP2, Paenarthrobacter nitroguajacolicus UP1, and Bacillus mycoides PP1 showed plant growth promotion and bio-control traits.

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Bacillus cereus P8 (66.5 µg mL⁻¹) and Bacillus mycoides PP1 (45.1 µg mL⁻¹) was thehighest IAA producer.

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Pot experiment confirmed that these isolates can be potential plant growth promoter under the agro-climatic conditions of Sikkim, India.

Organic farming is an eco-friendly and sustainable farming practice that enhances soil fertility and helps in improving soil quality. But with the commencement of more sophisticated advances in agricultural techniques, organic farming has gradually become limited in the world. Culture-dependent plant growth-promoting bacterial isolates were isolated from the bulk and rhizospheric soil, of the native high yielding pole type organic pea (Pisum sativum L.) cultivar Dentami of Dentam, West Sikkim, India. Based on the 16S rRNA gene sequencing identification of these isolates, it was found that from the bulk soil, Actinobacteria (58%) was the dominant phyla followed by Firmicutes (28%), and Proteobacteria (14%). In the rhizospheric soil it was dominated by Proteobacteria (56%), followed by Firmicutes (33%), and Bacteriodetes (11%). A total of 40 bacterial isolates were initially screened for the plant growth-promoting (PGP) activity and out of them only four bacterial isolates i.e., Bacillus cereus P8, Arthrobacter woluwensis DP2, Paenarthrobacter nitroguajacolicus PP3, and Bacillus mycoides PP10 with accession numbers MN589697, MN559516, MN519462 and MN589696 respectively were found to possess higher PGP activity (i.e. phosphorous, potassium solubilization and nitrogen-fixing activity) as compared to the other bacteria present in the soil. Based on the indole-3-acetic acid (IAA) quantitative assay and siderophore production assay, it was found that Bacillus cereus (MN589697) produced the highest IAA (65.5 µg mL⁻¹) and siderophore (71%) when compared with the other isolates. The statistical correlation suggests that pH and available phosphorus were the strongest influencing factors for the distribution of Proteobacteria in the rhizospheric soil. The results indicate that these isolates can be potential plant growth promoter under the agro-climatic conditions of Sikkim, India. To the best of our knowledge the present study is the first report of its kind and showcases significant findings pertaining to the assessment of diversity, isolation and identification of plant growth-promoting rhizobacteria of organic pea grown in Sikkim.

Isolation, Characterization, and Evaluation of Native Rhizobacterial Consortia Developed From the Rhizosphere of Rice Grown in Organic State Sikkim, India, and Their Effect on Plant Growth

Eight rhizospheric bacteria were isolated from the organic paddy fields of Sikkim, India, and identified as Pseudomonas kribbensis KSB, Burkholderia cenocepacia SRD, Kosakonia oryzendophytica YMA7, Pseudomonas rhodesiae SRB, Bacillus sp. ARA, Paenibacillus polymyxa COW3, Bacillus aryabhattai PSB2, and Bacillus megaterium PSB1. They showed plant growth-promoting attributes in rice and have bio-control potential against phytopathogen Colletotrichum gloeosporioides of large cardamom (Amomum subulatum). Burkholderia cenocepacia SRD showed production of indole acetic acid and ammonia and solubilization of phosphate and potassium and also possessed nitrogen fixation potential. It showed antagonistic activity against two other plant pathogens of large cardamom, viz., Curvularia eragrostidis and Pestalotiopsis sp., under in vitro conditions. The liquid bacterial consortium was prepared using the bacterial strains SRB, PSB1, and COW3 (Consortia-1); PSB2, SRD, and COW3 (Consortia-2); and COW3, KSB, and YMA7 (Consortia-3) to increase the growth and yield of rice plants under organic farming conditions. Greenhouse and field studies showed that the Consortia-3 had the highest plant growth-promoting activity. Consortia-3 demonstrated better agronomic performance in terms of root length (9.5 cm),number of leaflets per plant (5.3), grains per panicle (110.6), test grain weight (27.4 g), dry root weight per plant (0.73 g), and total dry biomass per plant (8.26 g).

Distribution of antibiotic and metal resistance genes in two glaciers of North Sikkim, India

Glacier studies as of late have ruffled many eyeballs, exploring this frigid ecology to understand the impact of climate change. Mapquesting the glaciers led to the discovery of concealed world of "psychrophiles" harboring in it. In the present study, the antibiotic resistance genes (ARGs) and heavy metal resistance genes (MRGs) were evaluated through both the culture-dependent and culture-independent methods. Samples were collected from two different glaciers, i.e., debris-covered glacier (Changme Khangpu) and debris-free glacier (Changme Khang). Functional metagenomics of both the glacier samples, provided evidence of presence of resistant genes against various antibiotic groups. Bacitracin resistant gene (bacA) was the predominant ARG in both the glaciers. MRGs in both the glacier samples were diversified as the genes detected were resistant against various heavy metals such as arsenic, tungsten, mercury, zinc, chromium, copper, cobalt, and iron. Unique MRGs identified from Changme Khangpu glacier were resistant to copper (cutA, cutE, cutC, cutF, cueR, copC, and copB) and chromium (yelf, ruvB, nfsA, chrR, and chrA) whereas, from Changme Khang glacier they showed resistance against cobalt (mgtA, dmef, corD, corC, corB, and cnrA), and iron (yefD, yefC, yefB, and yefA) heavy metals. ARGs aligned maximum identity with Gram-negative psychrotolerant bacteria. The cultured bacterial isolates showed tolerance to high concentrations of tested heavy metal solutions. Interestingly, some of the antibiotic resistant bacterial isolates also showed tolerance towards the higher concentrations of heavy metals. Thus, an introspection of the hypothesis of co-occurrence and/co-selection of ARGs and MRGs in such environments has been highlighted here.

Metavirome and its functional diversity analysis through microbiome study of the Sikkim Himalayan hot spring solfataric mud sediments

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This study is the first ever report on the virus diversity among the hot springs of Sikkim, India.

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The study revealed the dominance of Siphoviridae, Myoviridae and Phycodnaviridae in the two hot spring solfataric mud sediments.

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The metavirome ecology of the two hot springs have dsDNA viromes in abundance.

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Giant DNA viruses such as Pandoravirus and Pithovirus were found through metagenomic approach.

Viruses are the most prodigious repertory of the genetic material on the earth. They are elusive, breakneck, evolutionary life particles that constitute a riveting concealed world. Environmental viruses have been obscurely explored, and hence, such an intriguing world of viruses was studied in the Himalayan Geothermal Belt of Indian peninsula at Sikkim corridor through hot springs. The hot springs located at the North Sikkim district were selected for the current study. The solfataric mud sediment samples were pooled from both the hot springs. The virus community showed significant diversity among the two hot springs of Yume Samdung. Reads for viruses among the mud sediments at Old Yume Samdung hot springs (OYS) was observed to be 11% and in the case of New Yume Samdung hot springs (NYS) it was 6%. Both the hot springs were abundant in dsDNA viromes. The metavirome reads in both the OYS and NYS hot spring mud sediments showed the predominance of Caudovirales; Herpesvirales; Ortervirales among which viral reads from Siphoviridae, Myoviridae, Phycodnaviridae and Podoviridae were abundantly present. Other viral communities belonged to families like Baculoviridae, Mimiviridae, Parvoviridae, Marseilleviridae etc. Interestingly, in the case of NYS, the unassigned group reads belonged to some unclassified giant DNA viruses like genera Pandoravirus and Pithovirus. Other interesting findings were – reads for Badnavirus having ds (RT-DNA) was exclusively found in NYS whereas Rubulavirus having ss(-)RNA was exclusively found in OYS sample. This is the first ever report on viruses from any hot springs of Sikkim till date.

Diversity analysis and metagenomic insights into antibiotic and metal resistance among Himalayan hot spring bacteriobiome insinuating inherent environmental baseline levels of antibiotic and metal tolerance

OBJECTIVES

Mechanisms of occurrence and expression of antibiotic resistance genes (ARGs) in thermophilic bacteria are still unknown owing to limited research and data. In this research, comparative profiling of ARGs and metal tolerance genes among thermophilic bacteria has been done by functional metagenomic methods.

METHODS

Shotgun metagenomic sequence data were generated using Illumina HiSeq 4000. Putative ARGs from the PROKKA predicted genes were identified with the ardbAnno V.1.0 script available from the ARDB (Antibiotic Resistance Genes Database) consortium using the non-redundant resistance genes as a reference. Putative metal resistance genes (MRGs) were identified by using BacMetScan V.1.0. The whole-genome sequencing for bacterial isolates was performed using Illumina HiSeq 4000 sequencing technology with a paired-end sequencing module.

RESULTS

Metagenomic analysis showed the dominance of Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes in two hot springs of Sikkim. ARG analysis through shotgun gene sequencing was found to be negative in the case of thermophilic bacteria. However, few genes were detected but they showed maximum similarity with mesophilic bacteria. Concurrently, MRGs were also detected in the metagenome sequence of isolates from hot springs. Detection of MRGs and absence of ARGs investigated by whole-genome sequencing in the reference genome sequence of thermophilic Geobacillus also conveyed the same message.

CONCLUSION

The study of ARGs and MRGs (Heavy metal resistance gene) among culturable and non-culturable bacteria from the hot springs of Sikkim via metagenomics showed a preferential selection of MRGs over ARGs. The absence of ARGs also does not support the co-selection of ARGs and MRGs in these environments. This evolutionary selection of metal resistance over antibiotic genes may have been necessary to survive in the geological craters which have an abundance of different metals from earth sediments rather than antibiotics. Furthermore, the selection could be environment driven depending on the susceptibility of ARGs in a thermophilic environments as it reduces the chances of horizontal gene transfer.

Bacterial diversity and functional metagenomics expounding the diversity of xenobiotics, stress, defense and CRISPR gene ontology providing eco-efficiency to Himalayan Hot Springs

Sikkim is one of the bio-diverse states of India, which harbors diverse alkaline and sulfur rich hot springs in its vicinity. However, there is a dearth of data present in terms of microbial and its functional diversity as only a few hot springs have been studied in this area. Thus, in this regard, microbial and functional diversity of two hot springs by NGS, PLFA, and culture-independent approaches were carried out. PLFA and culture-dependent analysis was complementary as the Gram-positive bacteria were abundant in both the hot springs with the dominance of phylum Firmicutes with Geobacillus. Metagenomic analysis revealed the abundance of Proteobacteria, Actinobacteria, and Firmicutes in both hot springs. Functional metagenomics suggested that both Yumthang and Reshi hot spring possess a diverse set of genes analogous to stress such as genes allied to osmotic, heat shock, and acid stresses; defense analogies such as multidrug resistance efflux pump, multidrug transport system, and β-lactamase; and CRISPR analogues such as related to Cas1, Cas2, Cas3, cmr1-5 proteins, CT1972, and CT1133 gene families. The xenobiotic analogues were found against benzoate, nitrotolune, xylene, DDT, and chlorocyclohexane/chlorobenzene degradation. Thus, these defensive mechanisms against environmental and anthropogenic hiccups and hindrances provide the eco-efficiency to such thermal habitats. The higher enzymatic, degradation, defense, stress potential and the lower percentage identity (< 95%) of isolates encourage the further exploration and exploitation of these habitats for industrial and biotechnological purposes.

Microbial ecology of two hot springs of Sikkim: Predominate population and geochemistry

Northeastern regions of India are known for their floral and faunal biodiversity. Especially the state of Sikkim lies in the eastern Himalayan ecological hotspot region. The state harbors many sulfur rich hot springs which have therapeutic and spiritual values. However, these hot springs are yet to be explored for their microbial ecology. The development of neo generation techniques such as metagenomics has provided an opportunity for inclusive study of microbial community of different environment. The present study describes the microbial diversity in two hot springs of Sikkim that is Polok and Borong with the assist of culture dependent and culture independent approaches. The culture independent techniques used in this study were next generation sequencing (NGS) and Phospholipid Fatty Acid Analysis (PLFA). Having relatively distinct geochemistry both the hot springs are thermophilic environments with the temperature range of 50-77 °C and pH range of 5-8. Metagenomic data revealed the dominance of bacteria over archaea. The most abundant phyla were Proteobacteria and Bacteroidetes although other phyla were also present such as Acidobacteria, Nitrospirae, Firmicutes, Proteobacteria, Parcubacteria and Spirochaetes. The PLFA studies have shown the abundance of Gram Positive bacteria followed by Gram negative bacteria. The culture dependent technique was correlative with PLFA studies. Most abundant bacteria as isolated and identified were Gram-positive genus Geobacillus and Anoxybacillus. The genus Geobacillus has been reported for the first time in North-Eastern states of India. The Geobacillus species obtained from the concerned hot springs were Geobacillus toebii, Geobacillus lituanicus, Geobacillus Kaustophillus and the Anoxybacillus species includes Anoxybacillus gonensis and Anoxybacillus Caldiproteolyticus. The distribution of major genera and their statistical correlation analyses with the geochemistry of the springs predicted that the temperature, pH, alkalinity, Ca²⁺, Mg²⁺, Cl²⁺, and sulfur were main environmental variables influencing the microbial community composition and diversity. Also the piper diagram suggested that the water of both the hot springs are Ca-HCO^3- type and can be predicted as shallow fresh ground waters. This study has provided an insight into the ecological interaction of the diverse microbial communities and associated physicochemical parameters, which will help in determining the future studies on different biogeochemical pathways in these hot springs.

Geobacillus yumthangensis sp. nov., a thermophilic bacterium isolated from a north-east Indian hot spring

A thermophilic, spore-forming, rod-shaped bacterium isolated from the Yumthang hot spring in North Sikkim, India was subjected to taxonomic studies. The thermophilic bacterial isolate was designated as strain AYN2^T. Cells were Gram-stain-positive, aerobic, motile, rod-shaped, catalase-positive and methyl red-negative. Strain AYN2^T was able to grow in the pH range from 6 to 10 (optimum, pH 7.5-8.0), at 40-70 °C (60 °C) and in NaCl concentrations of 0-4 % (1 %). The major cellular fatty acids were iso-C15 : 0 (12.8 %), iso-C16 : 0 (13.9 %) and iso-C17 : 0 (13.8 %). No matches were found in the rtsba6 Sherlock libraries. The G+C content of the genomic DNA was 42.11 mol%. Based on phylogenetic analysis of the 16S rRNA gene sequences, strain AYN^T showed highest sequence similarity to the type strain of Geobacillus toebii (96 %). However, the phenotypic properties of strain AYN2^T were clearly distinct from those of G. toebii and related species. On the basis of polyphasic analysis, strain AYN2^T represents a novel species in the genus Geobacillus, for which the name Geobacillus yumthangensis sp. nov. is proposed. The type strain is AYN2^T(MTCC=12749=KCTC=33950= JCM 32596).

Bacterial Diversity in an Alpine Debris-Free and Debris-Cover Accumulation Zone Glacier Ice, North Sikkim, India

The Himalayas are water tower for billions of people; however in recent years due to climate change several glaciers of Himalaya are receding or getting extinct which can lead to water scarcity and political tensions. Thus, it requires immediate attention and necessary evaluation of all the environmental parameters which can lead to conservation of Himalayan glaciers. This study is the first attempt to investigate the bacterial diversity from debris-free Changme Khang (CKG) and debris-cover Changme Khangpu (CK) glacier, North Sikkim, India. The abundance of culturable bacteria in CKG glaciers was 1.5 × 10⁴ cells/mL and CK glacier 1.5 × 10⁵ cells/mL. A total of 50 isolates were isolated from both the glacier under aerobic growth condition. The majority of the isolates from both the glaciers were psychrotolerant according to their growth temperature. Optimum growth temperatures of the isolates were between 15 and 20 °C, pH 6-8 and NaCl 0-2%. The phylogenetic studies of 16S RNA gene sequence suggest that, these 21 isolates can be assigned within four phyla/class, i.e., Firmicutes, Beta-proteobacteria, Gamma-proteobacteria and Actinobacteria. The dominant phyla were Firmicutes 71.42% followed by Actinobacteria 14.28%, Alpha-proteobacteria 9.52% and Beta-proteobacteria 4.76%. The isolate Bacillus thuringiensis strain CKG2 showed the highest protease activity (2.24 unit/mL/min). Considering the fast rate at which Himalayan glaciers are melting and availability of limited number of research, there is urgent need to study the microbial communities confined in such environments.

A Case of Vulvar Myiasis

Myiasis occurs in humans and vertebrate animals mostly due to dipterous flies of the genera Chrysomyia and Cochliomyia. There have been reported cases of myiasis of skin, breast, intestine, eyes and ear but very few cases of vulvar myiasis have been reported in the medical literature. We report a case of a 20 years old female with vulvar myiasis. A 20-year old unmarried girl presented to our hospital with complains of vaginal discharge and vulvar irritation for 3 days with evidence of some worms around her vulvar region. Her menstrual history revealed the use of folded cloths instead of sanitary pads during her menstruation. Moreover, she washed those clothes with water and hanged them in the clothesline outside to let them dry before reuse. Examination of the external genitalia multiple ulcers measuring 1X1 cm on the inner surface of the labia minora, heavily infested with large number of maggots. The patient was admitted for 4 days during which she was given antibiotics, analgesics and anti-inflammatory medication. Daily local asepsis of the wound with antiseptic solution, betadine was done. We removed more than 30 larvae by the fourth day after which no more larvae were seen and she gradually recovered in the following days. It is our opinion that the cause of vulvar myiasis in our patient was her poor sanitary hygiene. Simple measures such as washing clothes thoroughly, drying and ironing of clothes are also necessary to reduce the risk of this human myiasis.

Multiple intestinal strictures with perforation in a patient under antitubercular treatment for abdominal tuberculosis

Abdominal tuberculosis (TB) constitutes about 12% of the extrapulmonaryTB. Abdominal TB can present with varying signs and symptoms likevague abdominal pain, abdominal mass, ascites and intestinal obstruction. Intestinal perforation is a relatively uncommon but a serious complication of abdominal TB. Antitubercular drugs are considered extremely effective but their role in the presence of a stenotic lesion of the bowel is controversial. Once symptoms of bowel obstruction or peritonitis appear, antitubercular drugs are of little use and surgery is inevitable. We report a case of abdominal TB in a patient under antitubercular treatment who later developed multiple intestinal strictures and a perforation.

KEYWORDS

perforation; stricture; tuberculosis.

Significance of adenosine deaminase in diagnosing tuberculous pleural effusion

Tuberculosis (TB) is a major public health problem in developing countries including Nepal. One of the common presentations of TB is pleural effusion. The diagnosis of tubercular pleural effusion can be difficult because of the low rate of detecting tubercule bacilli by direct stain and culture of pleural fluid for acid-fast bacilli (AFB). Pleural biopsy can be useful but is invasive and requires experts. In this context, pleural fluid Adenosine Deaminase (ADA) level has been proposed as easy, cheap and highly sensitive test for diagnosis of TB pleural effusion. The present study was undertaken to define the role ofpleural fluid ADA value in accurate diagnosis of TB pleural effusion. A Prospective analysis of 100 patients admitted in Nepal Medical College and teaching Hospital with pleural effusion was done. Pleural fluid ADA level was evaluated in all patients, and significance of pleural fluid ADA level in TB pleural effusion was studied. It was found that mean ADA level in pleural fluid was 105.8 +/- 67.23 U/L in cases of TB, as compared to 16.83 +/- 8.91 U/L in malignancy, 44.53 +/- 32.84 U/L in parapneumonic effusion and 15.94 +/- 4.88 U/L in patients with miscellaneous diagnosis. For a cut-off value of 42.19 U/L for diagnosis of TB pleural effusion, sensitivity was found to be 90.8% and specificity 82.8%. Almost all patients diagnosed to have TB pleural effusion responded completely to anti-tubercular treatment. So, we concluded that pleural fluid ADA analysis could be easy, cheap and highly sensitive and specific test for diagnosis of TB pleural effusion.

Prediction of individuals prone to suffer from early onset of hypertension

The present study was undertaken to predict the persons prone to suffer from early onset of hypertension. Healthy sedentary volunteers (age 18-25 years) having normal blood pressure were asked about their history of familial hypertension, smoking-habit, alcohol consumption, existing worries/anxieties; these being the predisposing factors of hypertension. The blood pressure of them was recorded (casual baseline blood pressure). Maximum voluntary contraction (MVC) was noted as maximum pressure (in Kg) sustained during 3 sec of handgrip using a handgrip dynamometer. Thereafter, the participant was asked to sustain isometric handgrip at one third of MVC for one minute with the same instrument (isometric handgrip-test). Then, blood pressure was measured and the subject was allowed to rest. Three minutes after the handgrip test, the blood pressure was noted again (recovery blood pressure). Handgrip-test produced a rise in systolic blood pressure in all male volunteers. Amongst them, with predisposing factors of hypertension, diastolic blood pressure remained significantly higher than casual baseline diastolic blood pressure even after 3 minutes of withdrawal of stressor. Whereas, in males with no predisposing factors of hypertension, the diastolic blood pressure approached almost the baseline casual blood pressure. In all female participants, no significant difference was noted between the casual baseline blood pressure and blood pressure after recovery. Results indicated that the young men who presented prolonged elevated diastolic blood pressure, in response to handgrip test would be at high risk of early onset of hypertension, as sympathetic over-activity prevails in them for longer time.

Internet addiction in a group of medical students: a cross sectional study

The use of Internet for education, recreation and communication is increasing day by day. Nevertheless, the possibility of exploitation and addiction leading to impairment in academic performance and emotional balance cannot be denied, especially among young population. The study was aimed to measure the degree of Internet addiction among a group of medical students. Internet addiction test questionnaire developed by Young was used to assess mild, moderate and severe addiction. Amongst the study population (n=130, age 19-23 years), 40% had mild addiction. Moderate and severe addiction was found in 41.53% and 3.07% of the participants respectively. The study revealed that 24% often and 19.2% always found themselves using Internet longer than they had planned or thought. Late night Internet surfing leading to sleep deprivation was found in 31.53% of the participants. Almost one fourth of them (25.38%) occasionally tried to cut down the time they spent on the Internet but failed and 31.53% sometimes experienced restlessness when deprived of Internet access. Results reflected that a significant number of participants suffered from mild to moderate addiction. The role of counseling and education should be emphasized for prevention of Internet addiction.

Association between maternal body mass index and the birth weight of neonates

Birth weight (BW) is an important determinant of infant's well being. Several factors such as mothers' genetic characteristics, socio-cultural, demographic, behavioral factors, prepregnancy body mass index (BMI), gestational weight gain (GWG) etc contribute to birth weight. This study assesses the anthropometric measurement of ethnic Nepalese women belonging to Sherpa/Tamang community and Brahmin/Chhetri community and the neonatal outcome in this population. A retrospective study was done in singleton pregnant women of Sherpa/Tamang and Brahmin/Chhetri community who delivered baby in Nepal Medical College and Teaching Hospital from April 2007 to March 2008 to examine the association between the maternal Body Mass Index (BMI) and the gestational weight gain among the two ethnic communities and the birth weight of newborns. Among 206 Sherpa women who met the eligibility criteria, the mean BMI of Sherpa/Tamang community was 23.53 +/- 2.28 which was statistically higher than the Brahmin/Chhetri community (21.6 +/- 2.32). Among Sherpa/Tamang community, the mean gestational weight gain was 12.8 +/- 3.4 kg and the mean birth weight was 3460 +/- 410 grams. Similarly among Brahmin/Chhetri community, mean gestation weight gain was 10.3 +/- 3.1 kg and the mean birth weight was 2960 +/- 340 gm. Maternal BMI, gestational weight gain and birth weight of the newborn was significantly higher in Sherpa/Tamang community and the Increasing BMI and the gestational weight gain was found to have strong association with the birth weight of the newborns among this ethnic community.

Color vison deficiency among medical students: an unnoticed problem

Color vision deficiency, most of the time remains an unnoticed problem; although it is not very rare. The faculty of appreciation of color is essential for our smooth daily activities. Unfortunately, even many doctors do not know the severity of their color vision deficiency and tend to assume it as slight, and a few, as in the general population, do not know about their disability. Some common difficulties reported by medical practitioners and medical students were in recognizing- widespread body color changes (pallor, cyanosis, jaundice, rashes, erythema of skin), colorful charts, slides, test-strips for blood and urine, body products: blood or bile in urine, faeces, sputum, vomit, microscopy, mouth and throat conditions, impressions presented in the Ishihara chart, titration end-points, tissue identification (surgery) etc. The present study was undertaken to evaluate the presence of congenital color vision deficiencies among the medical students. The study was carried out among the 1st and 2nd year medical students of Nepal Medical College and Teaching Hospital (n= 120) with the help of Ishihara chart, that was shown to all participants. They were asked to read the impressions in the color chart. The impression perceived by a person with normal color vision was different from the impression perceived by a person with color vision deficiency. It was noted that, among the study population (n=120) 5.83% of the volunteers were color weak. Amongst the color-deficient volunteers, 57.0% were protanopic while 43.0% were deuteranopic. Medical students must be made aware of their congenital color vision deficiency and its effects on their work. Screening will enable the student and later the doctor to become aware of limitations in their powers of observation and devise ways of overcoming them; the patient will be protected from harm and litigation may be avoided when doctors have adapted their practice to their deficiency. Medical students and physicians must be screened for color vision deficiency and advised about it so they can take special care in clinical practice.