Emerging contaminants of high concern and their enzyme-assisted biodegradation - A review.

Our current global environmental challenges include the reduction of harmful chemicals and their derivatives. Bioremediation has been a key strategy to control the massive presence of chemicals in the environment. Enzymes including the phenoloxidases, laccases and tyrosinases, are increasingly being investigated as “green products” in the removal of many chemical contaminants in waters and soils. Both phenoloxidases are widespread in nature and attractive biocatalysts due to their ability to use readily available molecular oxygen as sole cofactor for their catalytic elimination of a large number of chemicals. Taking advantage of their catalytic potentials, remarkable advances have been made in the engineering of laccases to produce suitable biocatalysts in environmental applications. Studies about novel strategies of laccase immobilization and insolubilization for the treatment of chemical contaminants were provided. Likewise, tyrosinases are gaining increasing interest in environmental applicatio...

Recent developments in the use of tyrosinase and laccase in environmental applications

The Actinomycetales order is one of great genetic and functional diversity, including diversity in the production of secondary metabolites which have uses in medical, environmental rehabilitation, and industrial applications. Secondary metabolites produced by actinomycete species are an abundant source of antibiotics, antitumor agents, anthelmintics, and antifungals. These actinomycete-derived medicines are in circulation as current treatments, but actinomycetes are also being explored as potential sources of new compounds to combat multidrug resistance in pathogenic bacteria. Actinomycetes as a potential to solve environmental concerns is another area of recent investigation, particularly their utility in the bioremediation of pesticides, toxic metals, radioactive wastes, and biofouling. Other applications include biofuels, detergents, and food preservatives/additives. Exploring other unique properties of actinomycetes will allow for a deeper understanding of this interesting taxonomic group. Combined with genetic engineering, microbial experimental evolution, and other enhancement techniques, it is reasonable to assume that the use of marine actinomycetes will continue to increase. Novel products will begin to be developed for diverse applied research purposes, including zymology and enology. This paper outlines the current knowledge of actinomycete usage in applied research, focusing on marine isolates and providing direction for future research.

Marine Actinomycetes, New Sources of Biotechnological Products

About 20,100 research publications dated 2000-2017 were recovered searching the PubMed and Web of Science databases for Streptomyces, which are the richest known source of bioactive molecules. However, these bacteria with versatile metabolism are powerful suppliers of biocatalytic tools (enzymes) for advanced biotechnological applications such as green chemical transformations and biopharmaceutical and biofuel production. The recent technological advances, especially in DNA sequencing coupled with computational tools for protein functional and structural prediction, and the improved access to microbial diversity enabled the easier access to enzymes and the ability to engineer them to suit a wider range of biotechnological processes. The major driver behind a dramatic increase in the utilization of biocatalysis is sustainable development and the shift toward bioeconomy that will, in accordance to the UN policy agenda "Bioeconomy to 2030," become a global effort in the near future. Streptomyces spp. already play a significant role among industrial microorganisms. The intention of this minireview is to highlight the presence of Streptomyces in the toolbox of biocatalysis and to give an overview of the most important advances in novel biocatalyst discovery and applications. Judging by the steady increase in a number of recent references (228 for the 2000-2017 period), it is clear that biocatalysts from Streptomyces spp. hold promises in terms of valuable properties and applicative industrial potential.

Streptomyces spp. in the biocatalysis toolbox.

Biocatalytic membranes for combating the challenges of membrane fouling and micropollutants in water purification: A review

The present study was focused on screening and characterization of tyrosinase enzyme produced by marine actinobacteria and its application in phenolic compounds removal from aqueous solution. A total of 20 strains were isolated from marine sediment sample and screened for tyrosinase production by using skimmed milk agar medium. Among 20 isolates, two isolates LK-4 and LK-20 showed zone of hydrolysis and these were taken for secondary screening by using tyrosine agar medium. Based on the result of secondary screening LK-4 was selected for further analysis, such as tyrosinase assay, protein content and specific activity of the enzyme. The tyrosinase enzyme was produced in a SS medium and was partially purified by ammonium sulfate precipitation, dialysis and SDS PAGE. The isolate (LK-4) was identified as Streptomyces espinosus using 16S rRNA gene sequencing and named as “Streptomyces espinosus strain LK4 (KF806735)”. The tyrosinase enzyme was immobilized in sodium alginate which was applied to remove phenolic compounds from water. The enzyme efficiently removed the phenolic compounds from aqueous solution within few hours which indicated that tyrosinase enzyme produced by Streptomyces espinosus strain LK-4 can be potently used for the removal of phenol and phenolic compounds from wastewater in industries.

Isolation and characterization of tyrosinase produced by marine actinobacteria and its application in the removal of phenol from aqueous environment

Cloud computing refers to a model for accessing computing resource like networks, servers, storage, applications, and services remotely. Cloud computing offers these resources as a service, namely infrastructure-as-a-service, platform-as-a-service, and software-as-a-service. To use these services, two roles involved: the cloud provider offers the service and the cloud customer consumes the service. These resources are efficiently shared and utilized by customers and it is called workload. The requirement of workload depends on customer demands that vary from higher to lower. Based on the customer demand, cloud provider makes the resource available efficiently. In the context of cloud, the workload is based on web-based service or jobs processed in batch mode. The arrival process of jobs in the cloud is not often deterministic. The irregular increase or decrease in workload has a vital impact on resource provision. Monitoring the resources helps in measuring the performance of the cloud so that the resource can be provisioned to customers efficiently.

Fault Tolerant Cloud Systems

In this paper we study the operation and working of a Dual Dynamic node hybrid flip-flop (DDFF-ELM) with an embedded logic module. It is one of the most efficient D-Flip-flops in terms of power and delay as compared to other dynamic flip flops. A double exponential current pulse is passed to the sensitive nodes of the circuit to model a radiation particle strike in the circuit. The faulty output is then corrected using a radiation hardening by design technique. All the circuits are implemented using Cadence 90 nm technology and a comparison is made between the power and delay of already implemented D- flip-flops.

A SEU Hardened Dual Dynamic Node Pulsed Hybrid Flip-Flop with an Embedded Logic Module

Due to the technology scaling the critical charge stored in active nodes is reducing very drastically, so even very small amount of radiation charge could able to disturb the values stored in the active node. In this paper, we have proposed soft-error tolerant flip flop design. The proposed flip-flop utilizes a cross-coupled inverter on the critical path in the master-stage and generates the required differential signals to facilitate the usage of the Quarto soft-error tolerant cell in the slave-stage. We have also designed the DICE cell and compared the area of both DICE (Dual Interlocked Storage Cell) and Quatro latch. The area required for the quarto latch is lesser than that of DICE cell. Total area decreased in the quarto latch is about 25% that of the DICE latch. The proposed design required only 18 transistors to build the DFF, which is very less as compared to the TSPC (True Single Phase Clocking) DFF and conventional DFF which require 25 and 44 transistors respectively. We have implemented a SEU (Single Event Upset) free 4 bit Johnson counter using the proposed DFF.

SEU hardened DFF and 4 bit johnson counter using quatro latch in 45 nm technology

CMOS based circuits are more susceptible to the radiation environment as the critical charge (Qcrit) decreases with technology scaling. A single ionizing radiation particle is more likely to upset the sensitive nodes of the circuit and causes Single Event Upset (SEU). Subsequently, hardening latches to transient faults at control inputs due to either single or multi-nodes is progressively important. This paper proposes a Fully Robust Triple Modular Redundancy (FRTMR) latch. In FRTMR latch, a novel majority voter circuit is proposed with a minimum number of sensitive nodes. It is highly immune to single and multi-node upsets. The proposed latch is implemented using CMOS 45 nm process and is simulated in cadence spectre environment. Results demonstrate that the proposed latch achieves 17.83 % low power and 13.88 % low area compared to existing Triple Modular Redundant (TMR) latch. The current induced due to transient fault occurrence at various sensitive nodes are exhibited with a double exponential current source for circuit simulation with a minimum threshold current value of 40 µA.

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S. Satheesh Kumar

Papers

Isolation and characterization of tyrosinase produced by marine actinobacteria and its application in the removal of phenol from aqueous environment

Fault Tolerant Cloud Systems

A SEU Hardened Dual Dynamic Node Pulsed Hybrid Flip-Flop with an Embedded Logic Module

SEU hardened DFF and 4 bit johnson counter using quatro latch in 45 nm technology

Low Power and High Reliable Triple Modular Redundancy Latch for Single and Multi-node Upset Mitigation