Microbial β-Glucosidase: sources, production and applications

Cellulose is the most abundant biopolymer in biosphere and the major constituent of plant biomass. Cellulose polymer is made up of β-glucose units linked by β-glucosidic bonds. Cellulase is an enzymatic system that catalyzes the hydrolysis of cellulose polymer to glucose monomers. This enzymatic system consists of three individual enzymes namely endoglucanase, exoglucanase and β-glucosidase which act synergistically to degrade cellulose molecules into glucose. Cellulases are produced by bacteria, fungi, plants, and animals and used in many industrial applications such as textile industries, laundry and detergent industries, paper and pulp industry, animal feeds, and biofuels production. β-Glucosidase is a diverse group of enzymes with wide distribution in bacteria, fungi, plants and animals and has the potential to be utilized in various biotechnological processes such as biofuel production, isoflavone hydrolysis, flavor enhancement and alkyl/aryl β-D-glucoside and oligosaccharides synthesis. Thus, there is increased demand of β-glucosidase production from microbial sources under profitable industrial conditions. In this review, β-glucosidase classification, localization, and mechanism of action will be described. Subsequently, the various sources of β-glucosidase for industrial sector will be discussed. Moreover, Fermentation methods and various parameters affecting β-glucosidase production will be highlighted on the light of recent findings of different researchers. Finally, β-glucosidase applications in biofuel production, flavors enhancement, isoflavones hydrolysis, cassava detoxification and oligosaccharide synthesis will be described

Characterization of thermophilic β-Glucosidase of rhizospheric bacterial strain (LSKB15) isolated from Cholistan Desert, Pakistan

Fifty thermophilic bacterial strains isolated from rhizospheric soil of Cholistan desert, Pakistan, and designated as LSKB01-LSKB50 were screened for β-glucosidase gene (bgl) belonging to glycoside hydrolase family 1 (GH 1) using PCR technique. Subsequently, the same strains were screened for extracellular β-glucosidase production using esculin as substrate. All fifty strains were shown to be amplified for conserved region of bgl gene and to secrete extracellular β-glucosidase. One strain (LSKB15) secreted relative high amount of this enzyme as indicating by size of ferric-esculetin precipitate. This strain was further cultivated on cellulose containing media and β-glucosidase was purified by ammonium sulfate, dialysis and gel filtration chromatography. The purified enzyme showed an optimal temperature of 60°C and an optimal pH of 7. It also showed excellent temperature and pH stability retaining > 90% activity after incubation for 2 h at pH 5-8 and 40-60°C. Finally, the purified enzyme was run on Native-PAGE and subsequently incubated in phosphate buffer containing 5 mM of 4-methylumbelliferyl-β-D-glucoside (4-MUG) for 15 min at 50°C and visualized by UV light as white band. We concluded that thermophilic LSKB15 β- glucosidase may work with other cellulase to degrade available cellulose synthesized by plant and the properties exhibited by it such as high temperature and pH stability pointed out its potential industrial importance

Microbial β-Glucosidases: screening, characterization, cloning and applications

Cellulose is the most abundant biomaterial in the biosphere and the major component of plant biomass. Cellulase is an enzymatic system required for conversion of renewable cellulose biomass into free sugar for subsequent use in different applications. Cellulase system mainly consists of three individual enzymes namely: endoglucanase, exoglucanase and β-glucosidases. β-Glucosidases are ubiquitous enzymes found in all living organisms with great biological significance. β-Glucosidases have also tremendous biotechnological applications such as biofuel production, beverage industry, food industry, cassava detoxification and oligosaccharides synthesis. Microbial β-glucosidases are preferred for industrial uses because of robust activity and novel properties exhibited by them. This review aims at describing the various biochemical methods used for screening and evaluating β-glucosidases activity from microbial sources. Subsequently, it generally highlights techniques used for purification of β-glucosidases. It then elaborates various biochemical and molecular properties of this valuable enzyme such as pH and temperature optima, glucose tolerance, substrate specificity, molecular weight, and multiplicity. Furthermore, it describes molecular cloning and expression of bacterial, fungal and metagenomic β-glucosidases. Finally, it highlights the potential biotechnological applications of β-glucosidases

Synthesis of novel cyanoacetamides derivatives and their urease inhibition studies

The present study reports a convenient approach for the synthesis of cyanoacetamide based derivatives (7-27) via two-step process involving Knoevenagel reaction, followed by three component reaction to avail desired compounds. All the synthesized compounds were obtained in good to excellent yield and extensively characterized employing 1H NMR, 13C NMR, mass spectrometry and physical parameters. Further, these compounds were screened for urease inhibition. All of the synthesized compounds exhibited good to excellent urease activity notably compound 15 and 19 showed excellent urease inhibition activity with IC50 value ~17.34 μg/mL and 36.75 μg/mL in comparison to thiourea (used as standard) having IC50 value ~27.5 μg/mL

Isolation and Characteristics of Biotechnologically Important Antagonistic Thermophilic Bacteria from Rhizosphere of Haloxylon salicornicum

Rhizobacteria are an active part of microbial population in the rhizosphere of plants. In this study, twenty rhizobacteria were isolated from the rhizosphere of a perennial grass, Haloxylon salicornicum, found in Cholistan desert, an arid landmass near Bahawalpur Pakistan, in one set of experimental conditions. Colony characteristics, biochemical and molecular analyses of these isolates were performed. All isolates were bacilli, gram positive with off-white colonies and exhibited typical bacilli colony morphology. None of the isolates was gelatinase, urease, indole, H2S and catalase producer. Eleven isolates were amylase producers and 8 isolates were acid producers. All isolates fermented glucose, 3 fermented lactose and 19 fermented fructose. Molecular data revealed that out of twenty isolates, 14 isolates showed 91–99% identity with Brevibacillus borstelensis, 4 with Bacillus subtilis (97–98%) and 2 with Bacillus licheniformis (94–99%) through BLAST analysis. All identified bacterial isolates cladded with their respective groups in the phylogenetic tree. Many (11–15 out of 20) of the isolates were more effective in inhibiting growth of the tested bacterial strains as compared to the positive control (Ampicillin 50 μg/disc). We conclude that bacilli are the predominant form populating rhizosphere of this desert grass. Among the isolated bacteria Brevibacillus borstelensis, Bacillus subtilis and Bacillus licheniformis are the most predominant species

Design and synthesis of arylthiophene-2-Carbaldehydes via suzuki-miyaura reactions and their biological evaluation

A series of various novel 4-arylthiophene-2-carbaldehyde compounds were synthesized in moderate to excellent yields via Suzuki-Miyaura cross-coupling with different arylboronic pinacol esters/acids. The synthesized products were screened for their antibacterial, haemolytic, antiurease, and nitric oxide (NO) scavenging capabilities and interestingly, almost all products turned out to have good activities. 3-(5-Formyl-thiophene-3-yl)-5-(trifloromethyl)benzonitrile (2d) revealed excellent antibacterial activity, showing an IC50 value of 29.7 µg/mL against Pseudomonas aeruginosa, compared to the standard drug streptomycin with an IC50 value 35.2 µg/mL and was also found to be the best NO scavenger, with an IC50 value of 45.6 µg/mL. Moreover, 4-(3-chloro-4-fluoro-phenyl)thiophene-2-carbaldehyde (2i) exhibited a superior haemolytic action and an outstanding urease inhibition, showing an IC50 value of 27.1 µg/mL

Efficient synthesis of 2-amino-6-arylbenzothiazoles via Pd(0) Suzuki cross coupling reactions : potent urease enzyme inhibition and nitric oxide scavenging activities of the products

In general, benzothiazole derivatives have attracted great interest due to thier pharmaceutical and biological importance. New 2-amino-6-arylbenzothiazoles were synthesized in moderate to excellent yields via Suzuki cross coupling reactions using various aryl boronic acids and aryl boronic acid pinacol esters and the antiurease and nitric oxide (NO) scavenging activity of the products were also examined. The most active compound concerning urease enzyme inhibition was 6-phenylbenzo[d]thiazole-2-amine 3e, with an IC50 value of 26.35 µg/mL. Compound 3c, 6-(4-methoxyphenyl) benzo[d]thiazole-2-amine, exhibited the highest nitric oxide percentage scavenging at 100µg/mL

Distance and Engagement: Hegel’s Account of Critical Reflection

Hegel famously argues that Kant’s account of critical distance depends upon an impoverished conception of freedom. In its place, Hegel introduces a richer conception of freedom, according to which the self who is capable of self-determination is multifaceted: wanting and thinking, social and individual. This richer conception gives rise to an account of critical reflection that emphasizes engagement with our motives and practices rather than radical detachment from them. But what is most distinctive about Hegel’s account is the idea that when we reflect upon motives and practices, we draw upon shared self-understandings that are neither universal nor just particular to individuals. There is, Hegel argues, no presocial identity or self that can be detached from our socially constituted contexts of thought and value. This has important implications for how we conceive of critical reflection

A convenient method for the synthesis of (prop-2-ynyloxy)benzene derivatives via reaction with propargyl bromide, their optimization, scope and biological evaluation

A highly convenient method has been developed for the synthesis of (prop-2-ynyloxy) benzene and its derivatives. Differently substituted phenol and aniline derivatives were allowed to react with propargyl bromide in the presence of K2CO3 base and acetone as solvent. The compounds were synthesized in good yields (53–85%). Low cost, high yields and easy availability of compounds helped in the synthesis. Electron withdrawing groups favor the formation of stable phenoxide ion thus in turn favors the formation of product while electron donating groups do not favor the reaction. Phenol derivatives gave good yields as compared to that of aniline. As aprotic polar solvents favor SN2 type reactions so acetone provided best solvation for the reactions. K2CO3 was proved to be good for the synthesis. Antibacterial, Antiurease and NO scavenging activity of synthesized compounds were also examined. 4-bromo-2-chloro-1-(prop-2-ynyloxy)benze​ne2a was found most active compound against urease enzyme with a percentage inhibition of 82.00±0.09 at 100 µg/mL with IC50 value of 60.2. 2-bromo-4-methyl-1-(prop-2-ynyloxy)benze​ne2d was found potent antibacterial against Bacillus subtillus showing excellent inhibitory action with percentage inhibition of 55.67±0.26 at 100 µg/ml wih IC50 value of 79.9. Based on results, it can be concluded that some of the synthesized compounds may have potential antiurease and antibacterial effects against several harmful substances

Intronic Binding Sites for hnRNP A/B and hnRNP F/H Proteins Stimulate Pre-mRNA Splicing

hnRNP A/B proteins modulate the alternative splicing of several mammalian and viral pre-mRNAs, and are typically viewed as proteins that enforce the activity of splicing silencers. Here we show that intronic hnRNP A/B–binding sites (ABS) can stimulate the in vitro splicing of pre-mRNAs containing artificially enlarged introns. Stimulation of in vitro splicing could also be obtained by providing intronic ABS in trans through the use of antisense oligonucleotides containing a non-hybridizing ABS-carrying tail. ABS-tailed oligonucleotides also improved the in vivo inclusion of an alternative exon flanked by an enlarged intron. Notably, binding sites for hnRNP F/H proteins (FBS) replicate the activity of ABS by improving the splicing of an enlarged intron and by modulating 5′ splice-site selection. One hypothesis formulated to explain these effects is that bound hnRNP proteins self-interact to bring in closer proximity the external pair of splice sites. Consistent with this model, positioning FBS or ABS at both ends of an intron was required to stimulate splicing of some pre-mRNAs. In addition, a computational analysis of the configuration of putative FBS and ABS located at the ends of introns supports the view that these motifs have evolved to support cooperative interactions. Our results document a positive role for the hnRNP A/B and hnRNP F/H proteins in generic splicing, and suggest that these proteins may modulate the conformation of mammalian pre-mRNAs