Isolation and Characterization of Arsenic-Tolerable Bacteria from Groundwater and Their Implementation on Rice Seedling's Shoot and Root Enhancement.

Arsenic exerts detrimental impacts on primary metabolism in plants, leading to reduced crop yield. Some arsenic-resistant plant growth-promoting bacteria (PGPB) help plants by providing some plant hormones to sustain their growth and development under arsenic stress. Here, seven different species of Bacillus were isolated from arsenic-contaminated groundwater of West Bengal, India. Those species were capable of growing in the presence of > 3.12 g/L arsenate (AsV) and > 0.65 g/L arsenite (AsIII) salts and also resist different heavy metals like Cu2+, Fe2+, Co2+, Zn2+, Pb2+, etc. They were susceptible to multiple groups of antibiotics like beta-lactam, aminoglycosides, etc. All species were capable of detoxifying arsenite and influenced rice seedlings' growth in the presence of arsenic salts by their capabilities like nitrogen-fixing ability, phosphate solubilization, indole 3-acetic acid (IAA), gibberellic acid (GA), proline production, etc. Most species helped enhance root and shoot lengths under arsenic stress. These primary findings suggest that those Bacillus spp. could be used as potential bio-fertilizers in arsenic-contaminated agricultural fields.

Delving into the lifestyle of Sundarban Wetland resident, biofilm producing, halotolerant Salinicoccus roseus: a comparative genomics-based intervention.

BACKGROUND: Microbial community played an essential role in ecosystem processes, be it mangrove wetland or other intertidal ecologies. Several enzymatic activities like hydrolases are effective ecological indicators of soil microbial function. So far, little is known on halophilic bacterial contribution and function on a genomic viewpoint of Indian Sundarban Wetland. Considering the above mentioned issues, the aims of this study was to understand the life style, metabolic functionalities and genomic features of the isolated bacterium, Salinicoccus roseus strain RF1H. A comparative genome-based study of S. roseus has not been reported yet. Henceforth, we have considered the inclusion of the intra-species genome comparison of S. roseus to gain insight into the high degree of variation in the genome of strain RF1H among others. RESULTS: Salinicoccus roseus strain RF1H is a pink-red pigmented, Gram-positive and non-motile cocci. The bacterium exhibited high salt tolerance (up to 15% NaCl), antibiotic resistance, biofilm formation and secretion of extracellular hydrolytic enzymes. The circular genome was approximately 2.62978 Mb in size, encoding 574 predicted genes with GC content 49.5%. Presence of genomic elements (prophages, transposable elements, CRISPR-Cas system) represented bacterial virulence and multidrug-resistance. Furthermore, genes associated with salt tolerance, temperature adaptation and DNA repair system were distributed in 17 genomic islands. Genes related to hydrocarbon degradation manifested metabolic capability of the bacterium for potential biotechnological applications. A comparative pangenome analysis revealed two-component response regulator, modified C4-dicarboxylate transport system and osmotic stress regulated ATP-binding proteins. Presence of genes encoding arginine decarboxylase (ADC) enzyme being involved in biofilm formation was reported from the genome. In silico study revealed the protein is thermostable and made up with ~ 415 amino acids, and hydrophilic in nature. Three motifs appeared to be evolutionary conserved in all Salinicoccus sequences. CONCLUSION: The first report of whole genome analysis of Salinicoccus roseus strain RF1H provided information of metabolic functionalities, biofilm formation, resistance mechanism and adaptation strategies to thrive in climate-change induced vulnerable spot like Sundarban. Comparative genome analysis highlighted the unique genome content that contributed the strain's adaptability. The biomolecules produced during metabolism are important sources of compounds with potential beneficial applications in pharmaceuticals.

Copper removal capability and genomic insight into the lifestyle of copper mine inhabiting Micrococcus yunnanensis GKSM13.

Heavy metal pollution in mining areas is a serious environmental concern. The exploration of mine-inhabiting microbes, especially bacteria may use as an effective alternative for the remediation of mining hazards. A highly copper-tolerant strain GKSM13 was isolated from the soil of the Singhbhum copper mining area and characterized for significant copper (Cu) removal potential and tolerance to other heavy metals. The punctate, yellow-colored, coccoid strain GKSM13 was able to tolerate 500 mg L-1 Cu2+. Whole-genome sequencing identified strain GKSM13 as Micrococcus yunnanensis, which has a 2.44 Mb genome with 2176 protein-coding genes. The presence of putative Cu homeostasis genes and other heavy metal transporters/response regulators or transcription factors may responsible for multi-metal resistance. The maximum Cu2+ removal of 89.2% was achieved at a pH of 7.5, a temperature of 35.5 °C, and an initial Cu2+ ion concentration of 31.5 mg L-1. Alteration of the cell surface, deposition of Cu2+ in the bacterial cell, and the involvement of hydroxyl, carboxyl amide, and amine groups in Cu2+ removal were observed using microscopic and spectroscopic analysis. This study is the first to reveal a molecular-based approach for the multi-metal tolerance and copper homeostasis mechanism of M. yunnanensis GKSM13.

Bacterial Arsenic Metabolism and Its Role in Arsenic Bioremediation.

Arsenic contaminations, often adversely influencing the living organisms, including plants, animals, and the microbial communities, are of grave apprehension. Many physical, chemical, and biological techniques are now being explored to minimize the adverse affects of arsenic toxicity. Bioremediation of arsenic species using arsenic loving bacteria has drawn much attention. Arsenate and arsenite are mostly uptaken by bacteria through aquaglycoporins and phosphate transporters. After entering arsenic inside bacterial cell arsenic get metabolized (e.g., reduction, oxidation, methylation, etc.) into different forms. Arsenite is sequentially methylated into monomethyl arsenic acid (MMA) and dimethyl arsenic acid (DMA), followed by a transformation of less toxic, volatile trimethyl arsenic acid (TMA). Passive remediation techniques, including adsorption, biomineralization, bioaccumulation, bioleaching, and so on are exploited by bacteria. Rhizospheric bacterial association with some specific plants enhances phytoextraction process. Arsenic-resistant rhizospheric bacteria have immense role in enhancement of crop plant growth and development, but their applications are not well studied till date. Emerging techniques like phytosuction separation (PS-S) have a promising future, but still light to be focused on these techniques. Plant-associated bioremediation processes like phytoextraction and phytosuction separation (PS-S) techniques might be modified by treating with potent bacteria for furtherance.

Overview on the role of heavy metals tolerance on developing antibiotic resistance in both Gram-negative and Gram-positive bacteria.

Environmental health is a critical concern, continuously contaminated by physical and biological components (viz., anthropogenic activity), which adversely affect on biodiversity, ecosystems and human health. Nonetheless, environmental pollution has great impact on microbial communities, especially bacteria, which try to evolve in changing environment. For instance, during the course of adaptation, bacteria easily become resistance to antibiotics and heavy metals. Antibiotic resistance genes are now one of the most vital pollutants, provided as a source of frequent horizontal gene transfer. In this review, the environmental cause of multidrug resistance (MDR) that was supposed to be driven by either heavy metals or combination of environmental factors was essentially reviewed, especially focussed on the correlation between accumulation of heavy metals and development of MDR by bacteria. This kind of correlation was seemed to be non-significant, i.e. paradoxical. Gram-positive bacteria accumulating much of toxic heavy metal (i.e. highly stress tolerance) were unlikely to become MDR, whereas Gram-negative bacteria that often avoid accumulation of toxic heavy metal by efflux pump systems were come out to be more prone to MDR. So far, other than antibiotic contaminant, no such available data strongly support the direct influence of heavy metals in bacterial evolution of MDR; combinations of factors may drive the evolution of antibiotic resistance. Therefore, Gram-positive bacteria are most likely to be an efficient member in treatment of industrial waste water, especially in the removal of heavy metals, perhaps inducing the less chance of antibiotic resistance pollution in the environment.

Green polymeric nanomaterials for the photocatalytic degradation of dyes: a review.

Pure and drinkable water will be rarer and more expensive as the result of pollution induced by industrialisation, urbanisation and population growth. Among the numerous sources of water pollution, the textile industry has become a major issue because effluents containing dyes are often released in natural water bodies. For instance, about two years are needed to biodegrade dye-derived, carcinogenic aromatic amines, in sediments. Classical remediation methods based upon physicochemical reactions are costly and still generate sludges that contain amine residues. Nonetheless, recent research shows that nanomaterials containing biopolymers are promising to degrade organic pollutants by photocatalysis. Here, we review the synthesis and applications of biopolymeric nanomaterials for photocatalytic degradation of azo dyes. We focus on conducting biopolymers incorporating metal, metal oxide, metal/metal oxide and metal sulphide for improved biodegradation. Biopolymers can be obtained from microorganisms, plants and animals. Unlike fossil-fuel-derived polymers, biopolymers are carbon neutral and thus sustainable in the context of global warming. Biopolymers are often biodegradable and biocompatible.

Molecular and Genomic Characterization of PFAB2: A Non-virulent Bacillus anthracis Strain Isolated from an Indian Hot Spring.

BACKGROUND: Thermophilic bacilli in both aerobic or facultative anaerobic forms have been isolated for over a hundred years from different mesophilic or thermophilic environments as they are potential source of bioactive secondary metabolites. But the taxonomic resolution in the Bacillus genus at species or at strain level is very challenging for the insufficient divergence of the 16S rRNA genes. One such recurring problem is among Bacillus anthracis, B. cereus and B. thuringiensis. The disease-causing B. anthracis strains have their characteristic virulence factors coded in two well-known plasmids, namely pXO1 (toxin genes) and pXO2 (capsule genes). OBJECTIVE: The present study aimed at the molecular and genomic characterization of a recently reported thermophilic and environmental isolate of B. anthracis, strain PFAB2. METHODS: We performed comparative genomics between the PFAB2 genome and different strains of B. anthracis, along with closely related B. cereus strains. RESULTS: The pangenomic analysis suggests that the PFAB2 genome harbors no complete prophage genes. Cluster analysis of Bray-Kurtis similarity resemblance matrix revealed that gene content of PFAB2 is more closely related to other environmental strains of B. anthracis. The secretome analysis and the in vitro and in vivo pathogenesis experiments corroborate the avirulent phenotype of this strain. The most probable explanation for this phenotype is the apparent absence of plasmids harboring genes for capsule biosynthesis and toxins secretion in the draft genome. Additional features of PFAB2 are good spore-forming and germinating capabilities and rapid replication ability. CONCLUSION: The high replication rate in a wide range of temperatures and culture media, the non-pathogenicity, the good spore forming capability and its genomic similarity to the Ames strain together make PFAB2 an interesting model strain for the study of the pathogenic evolution of B. anthracis.

Molecular Mechanism of Antibiotic Resistance: The Untouched Area of Future Hope.

The treatment of bacterial infections is becoming increasingly ineffective due to rapid mutation which leads to antibiotic resistant and resistant bacteria become more prevalent. As a result the existing antibiotics are gradually obsolete and again new drugs are needed to be designed for the same threat. However, the prediction of evolutionary processes/antibiotic resistance is uncertain. Still, the understanding of mode of evolution of resistance in bacteria is a determining step in the preclinical development of new antibiotics, because drug developers assess the risk of resistance arising against a drug during preclinical development. Multidrug efflux pump systems play an important role for making multidrug resistance to a range of clinically important antibiotics in gram-negative bacteria like Pseudomonas aeruginosa, which lower the intracellular drug concentration by exporting incoming antibiotics across the membranes. We tried to show that the wild type susceptible bacteria P. aeruginosa modified its genetic makeup at mutational hotspots under stress. This strain may either become multidrug resistant or remain susceptible depending on position of amino acid changes in regulatory proteins of efflux pump. Multidrug resistant strain made significant changes at the amino acid positions, 103rd (G → A) and 126th (E → V) through the mutation on the nucleotide position of 308th (G → C); both 377th (A → T) and 378th (G → T), respectively in mexR, a repressor of mexAB-oprM efflux pump. This mutant protein showed low affinity with their operator. But the alteration at 103th position (G → A) in mexR may provide almost similar structural and functional stability as wild type. It was found that mutation was seemed to be well regulated within the limit and position specific under stress which might be back to its original form by supplying counter stress unless addition or deletion takes place.

Structural and Functional Properties of Exopolysaccharide Excreted by a Novel Bacillus anthracis (Strain PFAB2) of Hot Spring Origin.

Exopolysaccharide produced by a unique avirulent Bacillus anthracis strain PFAB2 of hot spring origin has been characterized and its functional properties are investigated which is a first report. Maximum yield of EPS is 7.66 g/l with 2% glucose and 1% peptone as optimum carbon and nitrogen source respectively. The EPS is found to be a homopolymer consisting of only glucose as principle monosaccharide component. Through 1H NMR study, different dextran-like proton peaks are observed. Molecular weight of the EPS resembles low molecular weight bacterial origin polysaccharides. Melting transition of the EPS has started after 276 °C which indicates good thermal stability. The EPS also shows potent antioxidant activity in terms of DPPH and ABTS mediated free radical scavenging property compared to standard ascorbic acid. Emulsifying property of the EPS is also observed and has shown good emulsification of vegetable oils. The polysaccharide forms a thermo resistant gel during the heating phase, with G' higher than G″ indicating excellent shear-thinning behaviour and viscoelastic nature of the EPS.

Structural and Functional Properties, Biosynthesis, and Patenting Trends of Bacterial Succinoglycan: A Review.

The exopolysaccharide succinoglycan is produced mainly by a large number of soil microbes of Agrobacterium, Rhizobium or Pseudomonas genera etc. Structural properties of succinoglycan are unique in terms of its thermal stability and superior viscosifying property. Unlike the other highly commercialized bacterial exopolysaccharides like dextran or xanthan, mass scale application of succinoglycan has not been that much broadly explored yet. Bacterial succinoglycan is found suitable as a viscosifying and emulsifying agent in food industry, in gravel packing or fluid-loss control agent etc. In this present review, the key aspects of succinoglycan study, in particular, developments in structural characterizations, exo/exs operon system involved in biosynthesis pathway, commercial applications in food and other industries and patenting trends have been discussed.

Stage-specific reprogramming of gene expression characterizes Lr48-mediated adult plant leaf rust resistance in wheat.

Wheat genotype CSP44 carrying a recessive gene Lr48 exhibits adult plant resistance (APR; incompatible reaction) but gives a compatible reaction (susceptibility) at the seedling stage against leaf rust. A comparative gene expression analysis involving cDNA-amplified fragment length polymorphism (cDNA-AFLP) and quantitative PCR (qPCR) was carried out for incompatible and compatible reactions in the genotype CSP44. cDNA-AFLP analysis was conducted using RNA samples that were isolated from flag leaves following inoculation with leaf rust race 77-5 (the most virulent race) and also after mock inoculation. As many as 298 of a total of 493 expressed transcript-derived fragments (TDFs) exhibited differential expression (262 upregulated and 36 downregulated). Of these 298 TDFs, 48 TDFs were eluted from gels, re-amplified, cloned, and sequenced. Forty two of these 48 TDFs had homology with known genes involved in the following biological processes: energy production, metabolism, transport, signaling, defense response, plant-pathogen interaction, transcriptional regulation, translation, and proteolysis. The functions of the remaining six TDFs could not be determined; apparently, these represented some novel genes. The qPCR analysis for 18 TDFs (with known and unknown functions, but showing major differences in expression) was conducted using RNA isolated from the seedlings as well as from the adult plants. The expression of at least 11 TDFs was induced and that of 4 other TDFs attenuated or remained near normal in adult plants following leaf rust inoculations. The remaining three TDFs had non-specific/developmental stage-specific expression. Functional annotation of TDFs that were upregulated suggest that the APR was supported by transient recruitment and reprogramming of processes like perception and recognition of pathogen effector by receptors, followed by CDPK and MAPK signaling, transport, metabolism, and energy release.

Characterization and functional analysis of eugenol O-methyltransferase gene reveal metabolite shifts, chemotype specific differential expression and developmental regulation in Ocimum tenuiflorum L.

Eugenol-O-methyltransferase (EOMT) catalyzes the conversion of eugenol to methyleugenol in one of the final steps of phenylpropanoid pathway. There are no comprehensive reports on comparative EOMT gene expression and developmental stage specific accumulation of phenylpropenes in Ocimum tenuiflorum. Seven chemotypes, rich in eugenol and methyleugenol, were selected by assessment of volatile metabolites through multivariate data analysis. Isoeugenol accumulated in higher levels during juvenile stage (36.86 ng g(-1)), but reduced sharply during preflowering (8.04 ng g(-1)), flowering (2.29 ng g(-1)) and postflowering stages (0.17 ng g(-1)), whereas methyleugenol content gradually increased from juvenile (12.25 ng g(-1)) up to preflowering (16.35 ng g(-1)) and then decreased at flowering (7.13 ng g(-1)) and post flowering (5.95 ng g(-1)) from fresh tissue. Extreme variations of free intracellular and alkali hydrolysable cell wall released phenylpropanoid compounds were observed at different developmental stages. Analyses of EOMT genomic and cDNA sequences revealed a 843 bp open reading frame and the presence of a 90 bp intron. The translated proteins had eight catalytic domains, the major two being dimerisation superfamily and methyltransferase_2 superfamily. A validated 3D structure of EOMT protein was also determined. The chemotype Ot7 had a reduced reading frame that lacked both dimerisation domains and one of the two protein-kinase-phosphorylation sites; this was also reflected in reduced accumulation of methyleugenol compared to other chemotypes. EOMT transcripts showed enhanced expression in juvenile stage that increased further during preflowering but decreased at flowering and further at postflowering. The expression patterns may possibly be compared and correlated to the amounts of eugenol/isoeugenol and methyleugenol in different developmental stages of all chemotypes.

In silico analysis of the structure and interaction of COP1 protein of Arabidopsis thaliana.

Previous studies have shown that COP1 (constitutive photomorphogenic 1) protein of Arabidopsis thaliana plays a crucial role in different aspects of photomorphogenesis. Interaction of COP1 with SPA1 (suppressor of phytochrome A) and other regulatory proteins actively affect light regulatory gene expression in diverse directions. Though several studies have explained the function of COP1 protein, method of its interaction with SPA1 and cryptochromes are still not explained in detail. In this study, in silico analysis was followed to predict the tertiary structure, active site residues, functionally important regions and regular expressions of COP1 protein. Its ease of its interaction with SPA1 and seven other regulatory proteins, namely bZIP transcription factor 56 (HY5), transcription factor HY5-like (HYH), serine/threonine-protein phosphatase 7 (AtPP7), protein long hypocotyl in FAR-RED 1 (HFR1), OBP3-responsive protein 1 (OBP3), transcription factor MYC2 (MYC2/ZBF1) and Z-box binding factor 2 protein (GBF1/ZBF2) was measured using protein-protein docking. Interaction with MYC2 was found to be stronger than with others with a global energy value of -22.46. It was also found that COP1 shared three regions of regular expression with SPA1, the last expression also being present in MYC2/ZBF1 and OBP3. Taken together, the insight into structural and functional properties of COP1 protein presented in this study would be helpful in determining the role of COP1 in unknown mechanisms of photomorphogenesis.

Screening of Prospective Antiallergic Compound as FcεRI Inhibitors and Its Antiallergic Efficacy Through Immunoinformatics Approaches.

The occurrence of allergy, a type I hypersensitivity reaction, is rising exponentially all over the world. Sometimes, allergy proves to be fatal for atopic patients, due to the occurrence of anaphylaxis. This study is aimed to find an anti-allergic agent that can inhibit the binding of IgE to Human High Affinity IgE Receptor (FCεRI), thereby preventing the degranulation of mast cells. A considerable number of potential anti-allergic compounds were assessed for their inhibitory strength through ADMET studies. AUTODOCK was used for estimating the binding energy between anti-allergic compounds and FCεRI, along with the interacting amino acids. The docked pose showing favorable binding energy was subjected to molecular dynamics simulation study. Marrubiin, a diterpenoid lactone from Lamiaceae, and epicatechin-3-gallate appears to be effective in blocking the Human High Affinity IgE Receptor (FCεRI). This in-silico study proposes the use of marrubiin and epicatechin-3-gallate, in the downregulation of allergic responses. Due to the better inhibition constant, future direction of this study is to analyze the safety and efficacy of marrubiin in anti-allergic activities through in-vivo clinical human trials.

Synthesis, kinetics, mechanisms, and bioactivity evaluations of a novel Zn(ii) complex.

Zn(ii)-based anticancer drugs can be suitable alternatives to conventional Pt(ii)-based drugs because of the unique chemical properties of Zn(ii) and low toxicity. In this study, a new hexadentate and heteroleptic Zn(ii) complex ([Zn(bpy)2(OAc)2], 1) was prepared with a conventional N,N-donor ligand (2,2'-bipyridine) and a leaving group (OAc) and characterized via ESI-MS, UV-Vis, and FT-IR spectroscopy. Kinetic and mechanistic investigations of 1 were performed using two biologically relevant ligands (dl-penicillamine and l-cysteine) to understand its selectivity and reactivity. Substitution reactions were determined to be two-step processes in the associative activation mode. Bioactivity studies of 1 revealed moderate to strong DNA-binding, cleaving ability, and antimicrobial properties.

Bacterial Polysaccharide-Stabilized Silver Nanoparticles Photocatalytically Decolorize Azo Dyes.

Bacterial polysaccharide is advantageous over plant, algal, and fungal polysaccharides in terms of stability, non-toxicity, and biodegradable nature. In addition, bacterial cell wall polysaccharide (CPs) is very little explored compared to exopolysaccharide. In this study, CPs have been isolated from thermotolerant Chryseobacterium geocarposphaerae DD3 (CPs3) from textile industry dye effluent. Structural characterization of the CPs was done by different techniques, viz., scanning electron microscopy-energy dispersive X-ray spectrometry (SEM-EDX), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) spectroscopy, and thermogravimetric analysis (TGA). CPs3 demonstrated compact non-porous amorphous surface composed of evenly distributed macromolecular lumps. TGA revealed a high thermostability (~ 350 °C) of the polysaccharide. FTIR and NMR confirm the polysaccharidic nature of the polymer, consisting of glucose units linked by both ß-(1 → 3) and ß-(1 → 4) glycosidic bonds. The functional properties of CPs3 were evaluated for industrial use as additive, especially antibacterial, emulsification, and flocculation capacities. A single-step green synthesis of silver nanoparticle (AgNP) was performed using CPs3. AgNP was characterized using ultraviolet-visible (UV-Vis) spectroscopy, transmission electron microscopy (TEM), AFM, and particle size analyses. The CPs3-stabilized AgNP exhibited potential photocatalytic activity against a broad range of azo dyes, congo red (88.33 ± 0.48%), methyl red (76.81 ± 1.03%), and malachite green (47.34 ± 0.90%) after only 3 h of reaction. According to our knowledge, this is the first report on CPs from C. geocarposphaerae. The results demonstrated multifunctionality of CPs3 in both prospective, CPs3 as additive in biotechnology industry as well as Cps3-stabilized AgNP for bioremediation of azo dye.

In silico comparative structural and functional analysis of arsenite methyltransferase from bacteria, fungi, fishes, birds, and mammals.

BACKGROUND: Arsenic, a ubiquitous toxic metalloid, is a threat to the survival of all living organisms. Bioaccumulation of arsenic interferes with the normal physiological pathway. To overcome arsenic toxicity, organisms have developed arsenite methyltransferase enzyme, which methylates inorganic arsenite to organic arsenic MMA (III) in the presence of S-adenosylmethionine (SAM). Bacteria-derived arsM might be horizontally transported to different domains of life as arsM or as3mt (animal ortholog). A systematic study on the functional diversity of arsenite methyltransferase from various sources will be used in arsenic bioremediation. RESULTS: Several arsenite methyltransferase protein sequences of bacteria, fungi, fishes, birds, and mammals were retrieved from the UniProt database. In silico physicochemical studies confirmed the acidic, hydrophilic, and thermostable nature of these enzymes. Interkingdom relationships were revealed by performing phylogenetic analysis. Homology modeling was performed by SWISS-MODEL, and that was validated through SAVES-v.6.0. QMEAN values ranged from - 0.93 to - 1.30, ERRAT score (83-96), PROCHECK (88-92%), and other parameters suggested models are statistically significant. MOTIF and PrankWeb discovered several functional motifs and active pockets within the proteins respectively. The STRING database showed protein-protein interaction networks. CONCLUSION: All of our in silico studies confirmed the fact that arsenite methyltransferase is a cytosolic stable enzyme with conserved sequences over a wide range of organisms. Thus, because of its stable and ubiquitous nature, arsenite methyltransferase could be employed in arsenic bioremediation.

Insight into the genome of an arsenic loving and plant growth-promoting strain of Micrococcus luteus isolated from arsenic contaminated groundwater.

Contamination of arsenic in drinking water and foods is a threat for human beings. To achieve the goal for the reduction of arsenic availability, besides conventional technologies, arsenic bioremediation by using some potent bacteria is one of the hot topics for researchers. In this context, bacterium, AKS4c was isolated from arsenic contaminated water of Purbasthali, West Bengal, India, and through draft genome sequence; it was identified as a strain of Micrococcus luteus that comprised of 2.4 Mb genome with 73.1% GC content and 2256 protein coding genes. As the accessory genome, about 22 genomic islands (GIs) associated with many metal-resistant genes were identified. This strain was capable to tolerate more than 46,800 mg/L arsenate and 390 mg/L arsenite salts as well as found to be tolerable to multi-metals such as Fe, Pb, Mo, Mn, and Zn up to a certain limit of concentrations. Strain AKS4c was able to oxidize arsenite to less toxic arsenate, and its arsenic adsorption property was qualitatively confirmed through X-ray fluorescence (XRF) and Fourier transform infrared spectroscopy (FTIR) analysis. Quantitative estimation of plant growth-promoting attributes like Indole acetic acid (IAA), Gibberellic acid (GA), and proline production and enhancement of rice seedling growth in laboratory condition leads to its future applicability in arsenic bioremediation as a plant growth-promoting rhizobacteria (PGPR).

Synthesis, Kinetics, Reaction Mechanism, and Bioactivity Assays of a Dimeric Palladium Complex.

A dimer of Pd(II), [(bpy)Pd(µ-OH)2Pd(bpy)]2+, (complex 1) (where bpy = 2,2'-bipyridyl) has been synthesized at physiological pH (7.4) and characterized by electronic spectroscopy, electrospray ionization mass spectrometry (ESI-MS) spectroscopy, and Fourier transform infrared (FT-IR) analysis. Reaction kinetics of 1 with glycine (L1H), l-glutamic acid (L2H), and l-arginine (L3H) were investigated in an aqueous medium at pH of 7.4 and constant ionic strength via a spectrophotometer as a function of temperature and different concentrations of substrate-complex and ligand. The interactions were supported by two discrete successive steps, i.e., ligand-dependent and ligand-independent steps. The equilibrium constant of complex formation (outer-sphere association) and the rate constant during complex-substrate-ligand interaction were calculated. The Eyring equation was applied to evaluate activation factors (ΔH‡ and ΔS‡), and associative mechanisms of all reactions were proposed. Thermodynamic parameters (ΔH° and ΔS°) were also estimated from the standard plot of ln KE against 103/T. Spectroscopic titration of 1 at pH 7.4 in Tris-HCl buffer with calf thymus DNA, electronic emission titration with ethidium bromide (EtBr), antimicrobial activities, and an agarose gel electrophoresis run of 1 on pBR322 plasmid DNA have shown strong evidence of anticancer activity. Moreover, it has nontoxic water molecules as leaving groups.

AFLP based assessment of genetic relationships among shiitake (Lentinula ssp.) mushrooms.

Despite the economical importance of shiitake (Lentinula ssp.) mushrooms, until the present date little information exists on cultivated and wild species in correlation with geographic origin applying molecular techniques. Use of a high resolution molecular tool like AFLP for assessing genetic similarity and geographical diversity would be an important step towards understanding of different Lentinula species. Thirteen wild and 17 cultivated accessions of 3 Lentinula species were analysed with 64 EcoRI-MseI primer combinations and finally 32 reproducible and polymorphic primer combinations were considered for the analysis. A total of 816 informative AFLP markers were generated and scored as binary data. These data were analysed using various method packages for cluster analysis, genetic diversity and genetic differentiation. Percentage polymorphism was high (62.99%) among the species studied. Different clustering analysis segregated the wild and the cultivated species into two major branches, with the wild samples being further grouped according to their geographic location. Overall polymorphisms among cultivated strains in the USA were higher than that of the cultivated strains in Japan (58.9%).