Extremophiles and their expanding biotechnological applications.

Microbial life is not restricted to any particular setting. Over the past several decades, it has been evident that microbial populations can exist in a wide range of environments, including those with extremes in temperature, pressure, salinity, and pH. Bacteria and Archaea are the two most reported types of microbes that can sustain in extreme environments, such as hot springs, ice caves, acid drainage, and salt marshes. Some can even grow in toxic waste, organic solvents, and heavy metals. These microbes are called extremophiles. There exist certain microorganisms that are found capable of thriving in two or more extreme physiological conditions simultaneously, and are regarded as polyextremophiles. Extremophiles possess several physiological and molecular adaptations including production of extremolytes, ice nucleating proteins, pigments, extremozymes and exopolysaccharides. These metabolites are used in many biotechnological industries for making biofuels, developing new medicines, food additives, cryoprotective agents etc. Further, the study of extremophiles holds great significance in astrobiology. The current review summarizes the diversity of microorganisms inhabiting challenging environments and the biotechnological and therapeutic applications of the active metabolites obtained as a response to stress conditions. Bioprospection of extremophiles provides a progressive direction with significant enhancement in economy. Moreover, the introduction to omics approach including whole genome sequencing, single cell genomics, proteomics, metagenomics etc., has made it possible to find many unique microbial communities that could be otherwise difficult to cultivate using traditional methods. These findings might be capable enough to state that discovery of extremophiles can bring evolution to biotechnology.

Deciphering the Antimicrobial Potential of Taxus wallichiana Zucc: Identification and Characterization Using Bioassay-Guided Fractionation.

Taxus wallichiana Zucc. is a high valued medicinal plant and has been mainly studied for its anti-cancer properties. However, research on its other important biological activities, such as its antimicrobial potential, still needs attention. The focus of the present study is to investigate the antimicrobial activity of secondary metabolites of T. wallichiana needles against 3 different groups of microorganisms, i. e., bacteria, actinobacteria, and fungi. Bioactive compounds from T. wallichiana needles were separated through column chromatography, and, TLC-bioautography. Mobile phases were optimized using Snyder's selectivity triangle. Antimicrobial spots were fractionated and compounds were identified by gas chromatography-mass spectroscopy (GC/MS) and liquid chromatography-mass spectrometry (LC/MS). Functional groups were characterized using Fourier transform infrared spectrometry (FTIR) and nuclear magnetic resonance (NMR) was used to identify the molecular structures. GC/MS and LC/MS data analysis confirm the presence of fatty acids (arachidic acid, behenic acid, palmitic acid, and stearic acid), vitamins (nicotinamide), and alkaloids (cinchonine, timolol), aminobenzamides (procainamide), carbocyclic sugar (myoinositol), and alkane hydrocarbon (hexadecane), having antimicrobial activity in the needles of T. wallichiana. To the best of our knowledge, this is the first report on the isolation and characterization of antimicrobial compounds from the needles of Taxus wallichiana (Himalayan yew). The data obtained from the present study will be supportive to the new drug discoveries in modern medicine with various combinations of medicinal plant's active constituents that can be used for curing many diseases.

Biodegradation of bisphenol A using psychrotolerant bacterial strain Pseudomonas palleroniana GBPI_508.

A psychrotolerant bacterial strain of Pseudomonas sp. (P. palleroniana GBPI_508), isolated from the Indian Himalayan region, is studied for analyzing its potential for degrading bisphenol A (BPA). Response surface methodology using Box-Behnken design was used to statistically optimize the environmental factors during BPA degradation and the maximum degradation (97%) was obtained at optimum conditions of mineral salt media pH 9, experimental temperature 25 °C, an inoculum volume of 10% (v/v), and agitation speed 130 rpm at the BPA concentration 270 mg L-1. The Monod model was used for understanding bacterial degradation kinetics, and 37.5 mg-1 half saturation coefficient (KS) and 0.989 regression coefficient (R2) were obtained. Besides, the utmost specific growth rate µmax was witnessed as 0.080 h-1 with the GBPI_508 during BPA degradation. Metabolic intermediates detected in this study by GC-MS were identified as valeric acid, propionic acid, diglycolic acid, and phenol. The psychrotolerant bacterial strain of Pseudomonas sp. (P. palleroniana GBPI_508), isolated from the Indian Himalayan region has shown good potential for remediation of BPA at variable conditions.

Bacterial diversity of geochemically distinct hot springs located in Maharashtra, India.

Bacterial diversity of four thermally different hot springs of Ratnagiri district, Maharashtra, India, was investigated using culture-dependent and culture-independent approaches. A total of 144 bacterial cultures were isolated and identified using MALDI-TOF MS (matrix-assisted laser desorption ionization-time of flight mass spectrometry) and 16S rRNA gene sequencing. Culture-independent analysis by Ion Torrent sequencing targeting the V3 region of the 16S rRNA gene revealed the predominance of Firmicutes across all the hot springs, followed by Chloroflexi, Bacteroidetes, Cyanobacteria, Proteobacteria, Armatimonadetes, Actinobacteria, Nitrospirae, Acidobacteria, and Deinococcus-Thermus, with subtle differences in their abundance. At the lower taxonomic rank of genus, we noted the prevalence of Acinetobacter followed by Clostridium, Planomicrobium, Bacillus, Streptomyces, and Leptolyngbya. Metagenomics imputation using in silico approach revealed divergence in the metabolic capabilities of bacterial communities along the thermal gradient of host springs, with site TS (63 °C) featuring the abundant functional gene families.

Comparative nutritional and antimicrobial analysis of Himalayan black and yellow soybean and their okara.

BACKGROUND: Soybean is believed to have good nutraceutical potential which is important for human health. Yellow soybean (YS) is generally used for the production of soymilk and other products, while black soybean (BS) is less explored. During the production of soymilk, residue, called okara is generated which is reported to have a good amount of nutrient content. Studies are generally performed with YS while BS is less explored. The present work is a comparison of the nutraceutical potential of BS and YS and their okara, mainly in terms of proximate, minerals, antinutrients, and isoflavone content and bioactivity of all types of samples in terms of antioxidant and antimicrobial activity. RESULTS: Compared to raw soybean, protein content decreased significantly in both types of okara. Phytochemicals like ascorbic acid, catechin, quercetin, and gallic acid were significantly (P < 0.05) high in BS residue in comparison to respective raw soybean. Among isoflavones, daidzin and genistin were found significantly varying among all the samples, and glycitin and glycitein were not present in YS. CONCLUSION: The nutraceutical potential and antimicrobial activity were comparative for both the raw beans and their okara, while the phytochemical contents and antioxidant activity were higher in the case of BS and its okara. © 2022 Society of Chemical Industry.

Plant Growth Promotion at Low Temperature by Phosphate-Solubilizing Pseudomonas Spp. Isolated from High-Altitude Himalayan Soil.

Scarcity of arable land, limited soil nutrient availability, and low-temperature conditions in the Himalayan regions need to be smartly managed using sustainable approaches for better crop yields. Microorganisms, able to efficiently solubilize phosphate at low temperatures, provide an opportunity to promote plant growth in an ecofriendly way. In this study, we have investigated the ability of psychrotolerant Pseudomonas spp., isolated from high altitudes of Indian Himalaya to solubilize P at low temperature. Quantitative estimation of phosphate solubilization and production of relevant enzymes at two different temperatures (15 and 25 °C) was performed for 4 out of 11 selected isolates, namely, GBPI_506 (Pseudomonas sp.), GBPI_508 (Pseudomonas palleroniana), GBPI_Hb61 (Pseudomonas proteolytica), and GBPI_CDB143 (Pseudomonas azotoformans). Among all, isolate GBPI_CDB143 showed highest efficiency to solubilize tri-calcium phosphate (110.50 ± 3.44 µg/mL) at 25 °C after 6 days while the culture supernatants of isolate GBPI_506 displayed the highest phytase activity (15.91 ± 0.35 U/mL) at 15 °C and alkaline phosphatase (3.09 ± 0.07 U/mL) at 25 °C in 6 and 9 days, respectively. Out of five different organic acids quantified, oxalic acid and malic acid were produced in maximum quantity by all four isolates. With the exception of GBPI_508, inoculation of bacteria promoted overall growth (rosette diameter, leaf area, and biomass) of Arabidopsis thaliana plants as compared to uninoculated control plants in growth chamber conditions. The plant growth promotion by each bacterial isolate was further validated by monitoring root colonization in the inoculated plants. These bacterial isolates with low-temperature phosphate solubilization potential along with phosphatases and phytase activity at low temperature could be harnessed for sustainable crop production in P-deficient agricultural soils under mountain ecosystems.

Microbial Degradation of Caffeine Using Himalayan Psychrotolerant Pseudomonas sp.GBPI_Hb5 (MCC 3295).

Caffeine, a xenobiotic compound, is continuously released into the environment. Fifteen psychrotolerant bacterial strains, isolated from the Indian Himalayan region, were screened for their caffeine degradation capacity. The medium for the growth of bacteria was optimized using Box-Behnken method. Among these bacteria, Pseudomonassp. (GBPI_Hb5), showing the best response, was further used for caffeine degradation in batch mode. The culture medium, having caffeine as a sole source of carbon, was used for analyzing the effect of pH, agitation speed, temperature, inoculum volume, and caffeine concentration on bacterial growth and its caffeine degradation potential. The bacterium GBPI_Hb5 showed approx. 93% caffeine degradation up to 96 h under controlled conditions. The compounds produced during the degradation of caffeine were also studied. The study is likely to have implications in the bioremediation of caffeine from polluted environments.

Bioprospecting cold-adapted plant growth promoting microorganisms from mountain environments.

Mountain soils are challenging environments for all kinds of living things, including plants and microorganisms. Many cold-adapted microorganisms colonizing these extreme soils play important roles as promoters of plant growth and development; for that reason, they are called collectively plant growth-promoting microorganisms (PGPM). Even though there is seldom doubt concerning the usefulness of PGPM to develop eco-friendly bioinoculants, including biofertilizers and biocontrollers, a series of aspects need to be addressed in order to make this technology field-applicable. Among these aspects, the ecological and rhizosphere competences of PGPM are of paramount importance, particularly when considering the development of bioinoculants, well suited for the intensification of mountainous agricultural production. Studies on native, cold-adapted PGPM conducted in the Indian Himalayan region (IHR) and the Tropical Andes (TA) lead nowadays the research in this field. Noticeably, some common themes are emerging. For instance, soils in these mountain environments are colonized by many cold-adapted PGPM able to mobilize soil nutrients and to inhibit growth of plant pathogens. Studies aimed at deeply characterizing the abilities of such PGPM is likely to substantially contribute towards a better crop productivity in mountainous environments. The present review focuses on the importance of this microbial resource to improve crop productivity in IHR and TA. We also present a number of successful examples, which emphasize the effectiveness of some bioinoculants-developed from naturally occurring PGPM-when applied in the field.

Wide pH range tolerance in extremophiles: towards understanding an important phenomenon for future biotechnology.

Microorganisms that inhabit the extreme pH environments are classified as acidophiles and alkaliphiles. A number of studies emerged from extreme high (hot springs, hydrothermal vents) as well as low temperature (arctic and antarctic regions, sea water, ice shelf, marine sediments, cold deserts, glaciers, temperate forests, and plantations) environments have highlighted the occurrence of microorganisms (thermophiles/psychrophiles) with the ability to tolerate wide pH range, from acidic to alkaline (1.5-14.0 in some cases), under laboratory conditions. However, the sampling source (soil/sediment) of these microorganisms showed the pH to be neutral or slightly acidic/alkaline. The aim of the present review is to discuss the phenomenon of wide pH range tolerance possessed by these microorganisms as a hidden character in perspective of their habitats, possible mechanisms, phylogeny, ecological and biotechnological relevance, and future perspectives. It is believed that the genome is a probable reservoir of the hidden variations. The extremophiles have the ability to adapt against the environmental change that is probably through the expression/regulation of the specific genes that were already present in the genome. The phenomenon is likely to have broad implications in biotechnology, including both environmental (such as bioremediation, biodegradation, and biocontrol), and industrial applications (as a source of novel extremozymes and many other useful bioactive compounds with wide pH range tolerance).

Trichoderma gamsii (NFCCI 2177): a newly isolated endophytic, psychrotolerant, plant growth promoting, and antagonistic fungal strain.

An endophytic fungus has been isolated from the lateral roots of lentil (Lens esculenta Moench), growing under mountain ecosystem of Indian Himalayan Region (IHR). While the fungus was observed as fast growing with white scanty mycelium turning to turmeric brown in 5 days of incubation at 25 °C, it also produced a unique odor. The fungus exhibited growth between 4 and 30 °C (optimum 25 °C) and tolerated pH between 2.0 and 13.5 (optimum 4-6). Based on phenotypic (colony morphology and microscopy) and genotypic (18S rRNA analysis) characters, the fungus was identified as Trichoderma gamsii (99% similarity). The fungus was evaluated for its plant growth promotion and biocontrol properties. The fungus was found to be positive for phosphate solubilization, chitinase activity, and production of ammonia and salicylic acid, while the results for production of IAA, HCN, and siderophores were negative. Out of the seven phytopathogenic fungi tested, it showed antagonism against six. Bioassays conducted under green house using four test crops (two cereals and two legumes) showed its potential in plant growth promotion. The fungus has potential to be developed as a bioformulation for application under mountain ecosystem.

Cold, pH and salt tolerant Penicillium spp. inhabit the high altitude soils in Himalaya, India.

Twenty five fungal cultures (Penicillium spp.), isolated from soil samples from the high altitudes in the Indian Himalayan region, have been characterized following polyphasic approach. Colony morphology performed on five different media gave varying results; potato dextrose agar being the best for the vegetative growth and sporulation as well. Microscopic observations revealed 18 isolates to be biverticillate and 7 monoverticillate. Based on the phenotypic characters (colony morphology and microscopy), all the isolates were designated to the genus Penicillium. Exposure to low temperature resulted in enhanced sporulation in 23 isolates, while it ceased in case of two. The fungal isolates produced watery exudates in varying amount that in many cases increased at low temperature. All the isolates could grow between 4 and 37 °C, (optimum 24 °C), hence considered psychrotolerant. While all the isolates could tolerate pH from 2 to 14 (optimum 5-9), 7 isolates tolerated pH 1.5 as well. While all the fungal isolates tolerated salt concentration above 10 %; 10 isolates showed tolerance above 20 %. Based on ITS region (ITS1-5.8S-ITS2) analysis the fungal isolates belonged to 25 different species of Penicillium (showing similarity between 95 and 100 %). Characters like tolerance for low temperature, wide range of pH, and high salt concentration, and enhancement in sporulation and production of secondary metabolites such as watery exudates at low temperature can be attributed to the ecological resilience possessed by these fungi for survival under low temperature environment of mountain ecosystem.

Endophytic fungi from Himalayan silver birch as potential source of plant growth enhancement and secondary metabolite production.

Mountain biodiversity is under unparalleled pressure due to climate change, necessitating in-depth research on high-altitude plant's microbial associations which are crucial for plant survival under stress conditions. Realizing that high-altitude tree line species of Himalaya are completely unexplored with respect to the microbial association, the present study aimed to elucidate plant growth promoting and secondary metabolite producing potential of culturable endophytic fungi of Himalayan silver birch (Betula utilis D. Don). ITS region sequencing revealed that the fungal isolates belong to Penicillium species, Pezicula radicicola, and Paraconiothyrium archidendri. These endophytes were psychrotolerant in nature with the potential to produce extracellular lytic activities. The endophytes showed plant growth promoting (PGP) traits like phosphorus solubilization and production of siderophore, indole acetic acid (IAA), and ACC deaminase. The fungal extracts also exhibited antagonistic potential against bacterial pathogens. Furthermore, the fungal extracts were found to be a potential source of bioactive compounds including the host-specific compound-betulin. Inoculation with fungal suspension improved seed germination and biomass of soybean and maize crops under net house conditions. In vitro PGP traits of the endophytes, supported by net house experiments, indicated that fungal association may support the growth and survival of the host in extreme cold conditions.

Plasmid-Mediated AmpC (pAmpC) Genotypes Among Uropathogenic Escherichia coli: A Hospital-Based Study From Western Uttar Pradesh.

Introduction Resistance due to AmpC and extended-spectrum beta (ß)-lactamases (ESBLs) in Escherichia coli is an emerging problem worldwide. AmpC enzymes are a subclass of ß-lactamases that have a capacity to hydrolyze and deactivate a large range of ß-lactam antibiotics, particularly cephalosporins, penicillins, and monobactams, although frequently being susceptible to carbapenems and fourth-generation cephalosporins. The prevalence of plasmid-mediated AmpC (pAmpC) genotypes in uropathogenic E. coli isolates were looked at a tertiary care teaching hospital of Western Uttar Pradesh. Materials and methods A total of 312 non-repeat clinical E. coli isolates among patients presented with urinary tract infections (UTIs) were investigated by standard microbiological methods. Isolates were screened for the presence of ampC using a cefoxitin (30 µg) disc and confirmed using an inhibitor-based assay. Using multiplex polymerase chain reaction (PCR), six AmpC genotypes, namely, CIT, DHA, EBC, ACC, FOX, and MOX, were genotypically identified. Results A total of 152 (48.72%) uropathogenic E. coli isolates tested positive on the cefoxitin screening. Out of which, AmpC production was confirmed in 118/152 (77.63%) using a phenotypic method. In particular, the pAmpC gene was found in 56/152 (36.84%) isolates. CIT was the most common gene detected in this geographical area (57.14 %). Multiple genes, i.e., CIT and FOX, were also detected in 14.29% of the isolates.  Conclusion Identifying AmpC producers is important in routine microbiology laboratory as they are a nosocomial threat requiring strict adherence to infection control protocols. A confirmatory phenotypic test followed by genotypic tests will help in the correct and accurate identification of this resistance.

Biosorption of Heavy Metal (Mn2+) by Thermophilic Bacterial Strains Isolated from Surya Kund Hot Spring, Yamunotri, Uttarakhand.

This investigation aimed to identify the bioremediation potential of Mn2+-resistant bacterial strains cultured from the Surya Kund hot spring, Yamunotri, Uttarakhand. In this study, eight heavy metal-resistant isolates belonging to two phyla, i.e., Firmicutes and Proteobacteria, were investigated for their Mn2+ biosorption potential. The metal tolerance potential of all the thermophilic bacterial strains was determined by MIC. Bioremediation assay of these metal-resistant strains was performed for Mn2+ through the live and dead biomass of the bacterial cell. The evaluation of the bioremediation rate of metal ions through bacteria was done by AAS. All the selected bacterial strains were evaluated with effective biosorption rates for Mn2+. Acinetobacter sp. LSN-10 (YII-1) has been showing the highest potential for the removal of Mn2+ in both live (41.202%) and dead biomass (64.721%) conditions. The bioremediation rate of dead biomass was observed quite higher in comparison to bioremediation through live bacterial cells in the maximum number of isolates. This study may provide a new eco-friendly and cost-effective approach to dealing with metal toxicity. However, further investigation is needed to identify the most effective applications and potential limitations of this method.

Cold adapted Pseudomonas: ecology to biotechnology.

The cold adapted microorganisms, psychrophiles/psychrotolerants, go through several modifications at cellular and biochemical levels to alleviate the influence of low temperature stress conditions. The low temperature environments depend on these cold adapted microorganisms for various ecological processes. The ability of the microorganisms to function in cold environments depends on the strategies directly associated with cell metabolism, physicochemical constrains, and stress factors. Pseudomonas is one among such group of microorganisms which is predominant in cold environments with a wide range of ecological and biotechnological applications. Bioformulations of Pseudomonas spp., possessing plant growth promotion and biocontrol abilities for application under low temperature environments, are well documented. Further, recent advances in high throughput sequencing provide essential information regarding the prevalence of Pseudomonas in rhizospheres and their role in plant health. Cold adapted species of Pseudomonas are also getting recognition for their potential in biodegradation and bioremediation of environmental contaminants. Production of enzymes and bioactive compounds (primarily as an adaptation mechanism) gives way to their applications in various industries. Exopolysaccharides and various biotechnologically important enzymes, produced by cold adapted species of Pseudomonas, are making their way in food, textiles, and pharmaceuticals. The present review, therefore, aims to summarize the functional versatility of Pseudomonas with particular reference to its peculiarities along with the ecological and biotechnological applications.

Polyamine metabolizing rhizobacteria Pseudomonas sp. GBPI_506 modulates hormone signaling to enhance lateral roots and nicotine biosynthesis in Nicotiana benthamiana.

Beneficial rhizobacteria in the soil are important drivers of plant health and growth. In this study, we provide the draft genome of a root colonizing and auxin-producing Pseudomonas sp. strain GBPI_506. The bacterium was investigated for its contribution in the growth of Nicotiana benthamiana (Nb) and biosynthesis of nicotine. The bacterium showed chemotaxis towards root exudates potentially mediated by putrescine, a polyamine compound, to colonize the roots of Nb. Application of the bacterium with the roots of Nb, increased plant biomass and total soluble sugars in the leaves, and promoted lateral root (LR) development as compared to the un-inoculated plants. Confocal analysis using transgenic (DR5:GFP) Arabidopsis showed increased auxin trafficking in the LR of inoculated plants. Upregulation of nicotine biosynthesis genes and genes involved in salicylic acid (SA) and jasmonic acid (JA) signaling in the roots of inoculated plants suggested increased nicotine biosynthesis as a result of bacterial application. An increased JA content in roots and nicotine accumulation in leaves provided evidence on JA-mediated upregulation of nicotine biosynthesis in the bacterized plants. The findings suggested that the bacterial root colonization triggered networking between auxin, SA, and JA to facilitate LR development leading to enhanced plant growth and nicotine biosynthesis in Nb.

A reduction in temperature induces bioactive red pigment production in a psychrotolerant Penicillium sp. GEU_37 isolated from Himalayan soil.

Filamentous fungi are being globally explored for the production of industrially important bioactive compounds including pigments. In the present study, a cold and pH tolerant fungus strain Penicillium sp (GEU_37), isolated from the soil of Indian Himalaya, is characterized for the production of natural pigments as influenced by varying temperature conditions. The fungal strain produces a higher sporulation, exudation, and red diffusible pigment in Potato Dextrose (PD) at 15 °C as compared to 25 °C. In PD broth, a yellow pigment was observed at 25 °C. While measuring the effect of temperature and pH on red pigment production by GEU_37, 15 °C and pH 5, respectively, were observed to be the optimum conditions. Similarly, the effect of exogenous carbon and nitrogen sources and mineral salts on pigment production by GEU_37 was assessed in PD broth. However, no significant enhancement in pigmentation was observed. Chloroform extracted pigment was separated using thin layer chromatography (TLC) and column chromatography. The two separated fractions i.e., fractions I and II with Rf values 0.82 and 0.73, exhibited maximum light absorption, λmax, at 360 nm and 510 nm, respectively. Characterization of pigments using GC-MS showed the presence of the compounds such as phenol, 2,4-bis (1,1-dimethylethyl) and eicosene from fraction I and derivatives of coumarine, friedooleanan, and stigmasterole in fraction II. However, LC-MS analysis detected the presence of derivatives of compound carotenoids from fraction II as well as derivative of chromenone and hydroxyquinoline as major compounds from both the fractions along with other numerous important bioactive compounds. The production of such bioactive pigments under low temperature conditions suggest their strategic role in ecological resilience by the fungal strain and may have biotechnological applications.

A global perspective on a new paradigm shift in bio-based meat alternatives for healthy diet.

A meat analogue is a casserole in which the primary ingredient is something other than meat. It goes by various other names, such as meat substitute, fake meat, alternative meat, and imitation meat. Consumers growing interest in improving their diets and the future of the planet have contributed to the move towards meat substitutes. This change is due to the growing popularity of low-fat and low-calorie diets, the rise of flexitarians, the spread of animal diseases, the loss of natural resources, and the need to cut down on carbon emissions, which lead to greenhouse effects. Plant-based meat, cultured meat, algal protein-based meat, and insect-based meat substitutes are available on the market with qualities like appearance and flavor similar to those of traditional meat. Novel ingredients like mycoprotein and soybean leg haemoglobin are mixed in with the more traditional soy proteins, cereals, green peas, etc. Plant-based meat is currently more popular in the West, but the growing interest in this product in Asian markets indicates the industry in this region will expand rapidly in the near future. Future growth in the food sector can be anticipated from technologies like lab-grown meat and its equivalents that do not require livestock breeding. Insect-based products also hold great potential as a new source of protein for human consumption. However, product safety and quality should be considered along with other factors such as marketability and affordability.

Genotypic characterization of group A rotavirus in children < 5 years of age at tertiary care hospital in North India.

PURPOSE: This study was undertaken to find out the positivity of rotavirus associated diarrhoea in children <5 years of age in Meerut district and to determine the genomic diversity of the circulating rotavirus strains in this geographical area. METHODS: A cross-sectional study was conducted in a tertiary care hospital for a period of one year. A total of 240 stool samples were collected from children suffering from acute diarrhoea and subjected for rotavirus antigen detection by enzyme immunoassay (EIA). The EIA-positive samples were further genotyped to determine the G and P types using semi nested multiplex reverse transcriptase-polymerase chain reaction (RT-PCR). Demographic and clinical parameters were recorded in a pre-designed proforma. RESULTS: The rotavirus antigen positivity rate was 14.58% in Meerut district. There was male predominance and highest positivity rate was seen in children 13-24 months of age, in winter months and majority of cases belonged to moderate degree of severity. A total of 64% children in the study area were vaccinated and positivity was low in the vaccine group. G9P[4] was the predominant genotype followed by G3P[8]. Uncommon strains G12P[6] and G12P[8] were also reported as circulating genotypes in this study. CONCLUSIONS: The positivity rate of rotavirus associated diarrhoea has reduced in Meerut district post vaccination. G9P[4] was the most common circulating RV genotype in Meerut. Our study highlights the importance of including the emerging rotavirus strains in future multivalent RV vaccines to make the vaccines regionally more specific.

Effectiveness of polyhexamethylene biguanide, chlorhexidine, and calcium hydroxide intracanal medicament against intraradicular mature polymicrobial biofilm: A microbiological study.

Aim: To compare the effectiveness of different intracanal medicaments against polymicrobial biofilm formed by Enterococcus faecalis, Staphylococcus aureus, and Candida albicans. Materials and Methods: Eighty mature human roots with intraradicular polymicrobial biofilm were randomly assigned into four groups (n = 20). Intracanal medicaments 0.2% polyhexamethylene biguanide (PHMB), 2% chlorhexidine (CHX), and calcium hydroxide (CH) were applied into the root canals. Collected dentine samples were tested at 7th, 15th, and 30th day for microbial growth, and the colony-forming units per ml (CFU/ml) were determined. Results: The CFU/ml data were analyzed using unpaired t-test and one-way ANOVA-F comparison test. All medicaments resulted in a significant reduction (P < 0.05) in microbial growth at all time intervals compared to the control group. CHX and PHMB showed a similar reduction in CFU/ml at 7th and 15th day but significantly more than CH at all time intervals. At 30th day, PHMB caused a significantly more reduction in CFU/ml than CHX. Conclusions: All the three tested intracanal medicaments such as CH, CHX, and PHMB Gel were effective in reducing the microbial count. CH has a limited antimicrobial effect against the polymicrobial biofilm found inside the root canal. 2% CHX gel has a time-dependent antimicrobial effect. PHMB has a superior antimicrobial effect in comparison with CHX and CH.