Bacteriophage immobilized graphene electrodes for impedimetric sensing of bacteria (Staphylococcus arlettae)

Bacteriophages are a class of viruses that specifically infect and replicate within a bacterium. They possess inherent affinity and specificity to the particular bacterial cells. This property of bacteriophages makes them an attractive biorecognition element in the field of biosensor development. In this work, we report the use of an immobilized bacteriophage for the development of a highly sensitive electrochemical sensor for Staphylococcus arlettae, bacteria from the pathogenic family of coagulase-negative staphylococci (CNS). The specific bacteriophages were covalently immobilized on the screen-printed graphene electrodes. Thus, the fabricated bacteriophage biosensor displayed quantitative response for the target bacteria (S. arlettae) for a broad detection range (2.0–2.0 × 10⁶ cfu). A fast response time (2 min), low limit of detection (2 cfu), specificity, and stability over a prolonged period (3 months) are some of the important highlights of the proposed sensor. The practical utility of the developed sensor has been demonstrated by the analysis of S. arlettae in spiked water and apple juice samples.     

Integrative insect taxonomy based on morphology,mitochondrial DNA,and hyperspectral reflectance profiling

Integrative taxonomy is considered a reliable taxonomic approach of closely related and cryptic species by integrating different sources of taxonomic data (genetic, ecological, and morphological characters). In order to infer the boundaries of seven species of the evacanthine leafhopper genus Bundera Distant, 1908 (Hemiptera: Cicadellidae), an integrated analysis based on morphology, mitochondrial DNA, and hyperspectral reflectance profiling (37 spectral bands from 411–870 nm) was conducted. Despite their morphological similarities, the genetic distances of the cytochrome c oxidase subunit I (COI) gene among the tested species are relatively large (5.8–17.3%). The species‐specific divergence of five morphologically similar species (Bundera pellucida and Bundera spp. 1–4) was revealed in mitochondrial DNA data and reflectance profiling. A key to identifying males is provided, and their morphological characters are described. Average reflectance profiles from the dorsal side of specimens were classified based on linear discriminant analysis. Cross‐validation of reflectance‐based classification revealed that the seven species could be distinguished with 91.3% classification accuracy. This study verified the feasibility of using hyperspectral imaging data in insect classification, and our work provides a good example of using integrative taxonomy in studies of closely related and cryptic species. © 2015 The Linnean Society of London     

Synthesis of pyrimidine-2,4,6-trione derivatives: Anti-oxidant,anti-cancer, α-glucosidase, β-glucuronidase inhibition and their molecular docking studies

This paper describes a facile protocol, efficient, and environmentally benign for the synthesis a series of barbiturate acid substituted at C5 position 3a–o. The desired compounds subjected in vitro for different set of bioassays including against anti-oxidant (DPPH and super oxide scavenger assays), anti-cancer, α-glucosidase and β-glucuronidase inhibitions. Compound 3m (IC₅₀ = 22.9 ± 0.5 μM) found to be potent α-glucosidase enzyme inhibitors and showed more activity than standard acarbose (IC₅₀ = 841 ± 1.73 μM). Compound 3f (IC₅₀ = 86.9 ± 4.33 μM) found to be moderate β-Glucuronidase enzyme inhibitors and showed activity comparatively less than the standard d-saccharic acid 1,4-lactone (IC₅₀ = 45.75 ± 2.16 μM). Furthermore, in sillico investigation was carried out to investigate bonding mode of barbiturate acid derivatives.     

Novel point mutations in the ERG11 gene in clinical isolates of azole resistant Candida species

The azoles are the class of medications most commonly used to fight infections caused by Candida sp. Typically, resistance can be attributed to mutations in ERG11 gene (CYP51) which encodes the cytochrome P450 14α-demethylase, the primary target for the activity of azoles. The objective of this study was to identify mutations in the coding region of theERG11 gene in clinical isolates of Candidaspecies known to be resistant to azoles. We identified three new synonymous mutations in the ERG11 gene in the isolates of Candida glabrata (C108G, C423T and A1581G) and two new nonsynonymous mutations in the isolates of Candida krusei - A497C (Y166S) and G1570A (G524R). The functional consequence of these nonsynonymous mutations was predicted using evolutionary conservation scores. The G524R mutation did not have effect on 14α-demethylase functionality, while the Y166S mutation was found to affect the enzyme. This observation suggests a possible link between the mutation and dose-dependent sensitivity to voriconazole in the clinical isolate of C. krusei. Although the presence of the Y166S in phenotype of reduced azole sensitivity observed in isolate C. kruseidemands investigation, it might contribute to the search of new therapeutic agents against resistant Candida isolates.     

Microbial Communities Associated with Zones of Elevated Magnetic Susceptibility in Hydrocarbon-Contaminated Sediments

Recent studies suggest that magnetic susceptibility (MS) measurements can play an important role in identifying zones where microbial-mediated iron mineral transformations are occurring. Here we investigated the microbial community variations within zones of elevated MS in a petroleum hydrocarbon-contaminated aquifer near Bemidji, Minnesota, USA. Our main objective was to 1) identify the key microbial populations that may play a role in hydrocarbon degradation, 2) analyze which microbial populations could be connected to the elevated MS and 3) explore the use of non-destructive geophysical techniques as a tool to guide microbial sampling. Clone libraries based on the 16S rRNA gene revealed the presence of iron-reducing β-Proteobacteria in the vadose zone, whereas the free petroleum phase on the water table was characterized by a methanogenic consortium, in which the syntrophic δ-proteobacterium Smithella and the hydrogenotrophic Methanoregula predominated. Nonmetric multidimensional scaling (NMDS) found a close relationship between elevated MS values and the methanogenic hydrocarbon-degrading consortium. Our results suggest that magnetic susceptibility measurements can guide microbiologists to zones of active microbial biodegradation in aged petroleum spills.     

Assessment of artificial substrates for evaluating groundwater microbial quality

Protection of groundwater resources requires the development of reliable ecological indicators. Microorganisms involved in ecological services or being associated with particular hosts or habitats could be used for this purpose. Nevertheless, their tracking remains limited because of sampling issues, and a lack of devices for their long term monitoring. In the present study, three artificial substrates (glass and clay beads, and gravel particles) were tested in terms of efficacy at favoring bacterial growth, and at capturing bacterial diversity of waters (i.e., groundwater, surface water and wastewater). Total proteins, total carbohydrates, dehydrogenase and hydrolytic activities were used to monitor biofilm development on these artificial substrates. Fingerprinting analyses based on rrs (16S rRNA) − rrl (23S rRNA) spacer analyses (ARISA) and next generation sequencing (NGS) of partial rrs DNA segments (V5-V6) were used to compare operating taxonomic units (OTUs), and infer bacterial genera trapped on these substrates. Glass beads were found less efficient than the other two artificial substrates at increasing protein contents and microbial activities (hydrolytic and dehydrogenase activities). ARISA showed a discrimination of bacterial communities developing on artificial substrates that was matching water types. An incubation period of 7 days allowed a reliable assessment of bacterial diversity. From this incubation period, around 75% of water genera with more than four V5-V6 rrs DNA sequences detected in a water type were recovered from biofilms growing on artificial substrates. Based on relative abundances of genera, clay beads and gravel particles were more efficient than glass beads to capture and obtain bacterial communities matching those of the initial waters. Between 45–67% of similarities were found for these artificial substrates while it was between 36 and 43% for glass beads. This study demonstrated clay beads and gravel particles as being efficient tools for capturing bacterial diversity and monitoring bacterial growth. Overall, clay beads appeared the best choice for field monitoring because of the ease of their size standardization in comparison with gravel particles.     

Synthesis and in vitro pharmacological evaluation of N-[(1-benzyl-1,2,3-triazol-4-yl)methyl]-carboxamides on d-secoestrone scaffolds

An efficient synthesis of several N-[(1-benzyl-1,2,3-triazol-4-yl)methyl]carboxamides in the 13β- and 13α-d-secoestrone series is reported. Novel triazoles were synthesized via the Cu(I)-catalyzed azide–alkyne cycloaddition of steroidal alkynyl carboxamides and p-substituted benzyl azides. Each of the products was evaluated in vitro by means of MTT assays for antiproliferative activity against a panel of human adherent cancer cell lines (HeLa, MCF-7, A431 and A2780). Some of them exhibited activities similar to those of the reference agent cisplatin. On change of the substitution pattern of the benzyl group of the azide, great differences in the cell growth-inhibitory properties were observed. The p-alkylbenzyl-substituted triazoles selectively exerted high cytostatic action against A2780 cells, with IC₅₀ values of 1?µM. We investigated the potential inhibitory action exerted on the human 17β-HSD1 activity of the new secosteroids. Three triazoles effectively suppressed the estrone to 17β-estradiol conversion with IC₅₀ values in low micromolar range.