Biochemical characterization of thermostable cellulase enzyme from mesophilic strains of actinomycete

A few mesophilic strains of actinomycete were used for detection, extraction and characterization of cellulase enzymes. These strains responded to produce all the three components of cellulase complex (endoglucanase, exoglucanase and â-glucosidase) in balanced quantities. Cellulase activity was determined on solid medium supplemented with 1% carboxy methyl cellulose (CMC). Production of cellulase was detected by the formation of clear or transparent zone around colonies. The greater size of transparent zone has been found proportional to the higher capabilities of the strains for enzymes. The extraction of cellulase enzyme was done in liquid basal medium. The assay of cellulase was observed by measuring the release of reducing sugar (RS) by DNS method. All the three components of cellulase viz. endoglucanase, exoglucanase and â -glucosidase were assayed in terms of CMCase, FPase and cellobiase, respectively and expressed in International units (IU). These strains were further tested for their ability to produce cellulase complex enzyme by growing on a defined substrates as well as on delignified cellulosics. The optimization for â-glucosidase enzyme was carried out by studying the various parameters viz. effect of pH, incubation period and nitrogen sources.Key words: Cellulase, actinomycete, optimization, reducing sugar, carboxy methyl cellulose

Search for intermediate-mass black hole binaries in the third observing run of Advanced LIGO and Advanced Virgo

International audienceIntermediate-mass black holes (IMBHs) span the approximate mass range 100−105 M⊙, between black holes (BHs) that formed by stellar collapse and the supermassive BHs at the centers of galaxies. Mergers of IMBH binaries are the most energetic gravitational-wave sources accessible by the terrestrial detector network. Searches of the first two observing runs of Advanced LIGO and Advanced Virgo did not yield any significant IMBH binary signals. In the third observing run (O3), the increased network sensitivity enabled the detection of GW190521, a signal consistent with a binary merger of mass ∼150 M⊙ providing direct evidence of IMBH formation. Here, we report on a dedicated search of O3 data for further IMBH binary mergers, combining both modeled (matched filter) and model-independent search methods. We find some marginal candidates, but none are sufficiently significant to indicate detection of further IMBH mergers. We quantify the sensitivity of the individual search methods and of the combined search using a suite of IMBH binary signals obtained via numerical relativity, including the effects of spins misaligned with the binary orbital axis, and present the resulting upper limits on astrophysical merger rates. Our most stringent limit is for equal mass and aligned spin BH binary of total mass 200 M⊙ and effective aligned spin 0.8 at 0.056 Gpc−3 yr−1 (90% confidence), a factor of 3.5 more constraining than previous LIGO-Virgo limits. We also update the estimated rate of mergers similar to GW190521 to 0.08 Gpc−3 yr−1.Key words: gravitational waves / stars: black holes / black hole physicsCorresponding author: W. Del Pozzo, e-mail: [email protected]† Deceased, August 2020

Open data from the first and second observing runs of Advanced LIGO and Advanced Virgo

Advanced LIGO and Advanced Virgo are monitoring the sky and collecting gravitational-wave strain data with sufficient sensitivity to detect signals routinely. In this paper we describe the data recorded by these instruments during their first and second observing runs. The main data products are gravitational-wave strain time series sampled at 16384 Hz. The datasets that include this strain measurement can be freely accessed through the Gravitational Wave Open Science Center at http://gw-openscience.org, together with data-quality information essential for the analysis of LIGO and Virgo data, documentation, tutorials, and supporting software